Journal articles: 'Hydrocarbons Chemical reactions'

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Novikova, Anna A., and Mikhail E. Soloviev. "QUANTUM CHEMICAL STUDY OF OXIDATION REACTIONS IN UNSATURATED HYDROCARBONS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 7 (August 24, 2017): 14. http://dx.doi.org/10.6060/tcct.2017607.5516.

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In this article quantum-chemical calculations using DFT B3LYP/cc-pvdz method was used for the investigation of changes in thermodynamic functions of reactions of oxidation of unsaturated hydrocarbons such as heptane and heptadiene as low-molecular models of hydrocarbon residues of lipids. The effect of the position of the reaction center relative to the double bonds and conformations of double bonds on reactivity of the compounds in reactions of hydrogen abstraction by the hydroxyl radical, dioxygen accession and chain propagation were analyzed. By comparison of changes in thermodynamic functions of reactions it was shown that hydrocarbons with cis- conformations of double bonds are characterized with higher reactivity in reactions of hydrogen abstraction but peroxi-radicals of these conformers are more stable. The changes in thermodynamic functions of reaction of hydrogen abstraction for diene according to the calculation are smaller comparing with olefins. This is due to the difference in the stability of the radicals formed. The stability of hydrocarbon radicals of dienes in comparison with olefins is explained by their planar structure with electron density of unpaired electron delocalized between five carbon atoms. The emergence of such pentadienil-type radicals is the cause of a higher oxidation of dienes compared with olefins. The analysis of molecular structures of peroxi-radicals of dienes shows that after accepting dioxygen by hydrocarbon radical the isomerization takes place. According calculations it is preferable for the dioxygen molecule not to join with the central carbon atom from which the hydrogen atom has been abstracted but to attack the double bond joining with C2 carbon atom. During the isomerization the double bond moves to the center of the molecule forming thus the conjugated pair with the other double bond. Comparison of thermodynamic functions of reaction for cis- and trans- isomers shows that cis-trans isomerization is possible during the dioxygen accession to the hydrocarbon radical. These results are in good agreement with the experimental data published earlier.Forcitation:Novikova A.A., Soloviev M.E. Quantum chemical study of oxidation reactions in unsaturated hydrocarbons. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 14-20.

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Yue, Xiaoming, Yajun Wu, Shuangquan Zhang, Xiaoqin Yang, and Xianyong Wei. "Chemical Compositional Analysis of Catalytic Hydroconversion Products of Heishan Coal Liquefaction Residue." International Journal of Analytical Chemistry 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/4303596.

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Liquefaction residue of Heishan bituminous coal (HLR) was subject to two hydroconversion reactions under 5 MPa initial pressure of hydrogen at 300°C for 3 h, without catalyst and with acid supported catalyst (ASC), respectively. The reaction products were analyzed with gas chromatography/mass spectrometer (GC/MS). The results show that 222 organic compounds were detected totally in the products and they can be divided into alkanes, aromatic hydrocarbons (AHCs), phenols, ketones, ethers, and other species (OSs). The yield of hydroconversion over the ASC is much higher than that without catalyst. The most abundant products are aromatic hydrocarbons in the reaction products from both catalytic and noncatalytic reactions of HLR. The yield of aromatic hydrocarbons in the reaction product from hydroconversion with the ACS is considerably higher than that from hydroconversion without a catalyst.

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Kaiser, Ralf I., and Nadia Balucani. "Astrobiology – the final frontier in chemical reaction dynamics." International Journal of Astrobiology 1, no. 1 (January 2002): 15–23. http://dx.doi.org/10.1017/s1473550402001015.

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Crossed-beam experiments on the reactions of cyano CN(X2Σ+) and ethinyl C2H(X2Σ+) radicals with the unsaturated hydrocarbons acetylene, ethylene, methylacetylene allene and benzene have been carried out under single-collision conditions to investigate synthetic routes to form nitriles, polyynes and substituted allenes in hydrocarbon-rich atmospheres of planets and their moons. All reactions were found to proceed without an entrance barrier, to have exit barriers well below the energy of the reactant molecules and to be strongly exothermic. The predominant identification of the radical versus atomic hydrogen exchange channel makes these reactions compelling candidates for the formation of complex organic chemicals – precursors to biologically important amino acids – in Solar system environments and in the interstellar medium.

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Shin, Hyeon Ho, Yung Doug Suh, and Dong-Kwon Lim. "Recent Progress in Plasmonic Hybrid Photocatalysis for CO2 Photoreduction and C–C Coupling Reactions." Catalysts 11, no. 2 (January 22, 2021): 155. http://dx.doi.org/10.3390/catal11020155.

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Plasmonic hybrid nanostructures have been investigated as attractive heterogeneous photocatalysts that can utilize sunlight to produce valuable chemicals. In particular, the efficient photoconversion of CO2 into a stable hydrocarbon with sunlight can be a promising strategy to achieve a sustainable human life on Earth. The next step for hydrocarbons once obtained from CO2 is the carbon–carbon coupling reactions to produce a valuable chemical for energy storage or fine chemicals. For these purposes, plasmonic nanomaterials have been widely investigated as a visible-light-induced photocatalyst to achieve increased efficiency of photochemical reactions with sunlight. In this review, we discuss recent achievements involving plasmonic hybrid photocatalysts that have been investigated for CO and CO2 photoreductions to form multi-carbon products and for C–C coupling reactions, such as the Suzuki–Miyaura coupling reactions.

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KALDYGOZOV, Ye К., V. M. KAPUSTIN, G. M. IZTLEUOV, B. A. ABDIKERIMOV, and Ye S. TLEUBAEVA. "CATALYTIC REFORMING OF GASOLINE FRACTION OIL MIXTURES OF THE SOUTHERN REGION OF THE REPUBLIC OF KAZAKHSTAN." Neft i gaz 2, no. 116 (April 15, 2020): 100–108. http://dx.doi.org/10.37878/2708-0080/2020.006.

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This article discusses the results of a study of the process of catalytic reforming of straight-run gasoline obtained from a mixture of oil from a field located in the southern region of Kazakhstan. The individual and group hydrocarbon composition of the initial hydrotreated gasoline and reformate was studied in order to establish the degree of conversion of hydrocarbons at different stages of catalytic reforming. The qualitative characteristics of the catalysis of gasoline reforming obtained at different stages of the process allows us to establish the chemistry and reaction mechanism and the laws of the chemical degree of conversion of individual hydrocarbon groups during all stages of catalytic reforming. As a result of studying the process of catalytic reforming of straight-run gasoline fractions НЕФТЕХИМИЯ НЕФТЬ И ГАЗ 2020. 2 (116) 103 О 2 (85–180°С), a chemistry and a reaction mechanism are established that are based on the following reactions: dehydrocyclization of paraffin hydrocarbons, dehydrogenation and dehydroisomerization of naphthenic, isomerization of naphthenic and paraffin hydrocarbons. Comparison of the physicochemical properties and group hydrocarbon composition of the hydrogenate and reforming products shows that the amount of n-paraffin and naphthenic hydrocarbons after catalytic reforming is reduced by 3–4times than in the originalgasoline, and the concentration of aromatic hydrocarbons is significantly increased due to the cyclane dehydrogenation reaction and dehydrocyclization of normal paraffins. Set forth in article information on changing the group and individual hydrocarbon composition of gasoline in various stages of the catalytic reforming process, can serve as a basis for optimal control of technological process of catalytic reforming and is a priority in the production of highquality grades of motor fuel and petrochemical development in the processing of local oil and gas Republic of Kazakhstan.

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Frantsina, E. V., N. I. Krivtcova, and T. I. Babyi. "Thermodynamic Analysis of the Nitrogen-Containing Compounds Conversion in the Process of Diesel Fractions Hydrotreatment Based on Quantum Chemical Calculations." Oil and Gas Technologies 126, no. 1 (2020): 3–7. http://dx.doi.org/10.32935/1815-2600-2020-126-1-3-7.

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Based on quantum chemical calculations using the DFT density functional theory method (B3LYP theoretical approximation model, basis 3-21G), thermodynamic parameters of the nitrogen-containing compounds reactions in the diesel fractions hydrotreating process at a temperature of 400°C and a pressure of 2MPa were evaluated. The following groups of nitrogen-containing compounds: monoaromatic hydrocarbons position nitrogen atom in the ring, diaromatic hydrocarbons position nitrogen atom in the ring, monosubstituted diaromatic hydrocarbons with the position of the nitrogen atom in the ring, triaromatic hydrocarbons with the position of the nitrogen atom in the ring (acridine, carbazole), alkyl-substituted nitriles, aromatic nitriles, aromatic amines were identified. The probability of reactions was determined, a reaction scheme for the conversion of hydrocarbons was proposed, which can be used to develop a mathematical model of the diesel fractions hydrotreatment process taking into account the conversion of nitrogen-containing compounds.

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Li, Qian, B. S. Liu, P. J. Sarre, and A. S.-C. Cheung. "Laboratory astrochemistry: catalytic reactions of organic molecules over olivine-type silicates and SiC." Proceedings of the International Astronomical Union 13, S332 (March 2017): 320–25. http://dx.doi.org/10.1017/s1743921317006950.

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AbstractA series of catalytic reactions has been performed in our laboratory using olivine-type silicates (OTS) and SiC as catalysts for the conversion of carbon-containing molecules (such as acetylene, CO and methanol) to small organic molecules (C2H4, C3H3, CH3O) and also polycyclic aromatic hydrocarbons (PAHs). Experimentally, small-to-medium-sized gas-phase compounds such as PAHs, reaction intermediates and hydrocarbon compounds were detected in situ using the time-of-light mass-spectrometry technique. Solid deposition on the catalyst surface was examined by high-resolution transmission electron microscopy and thermo-gravimetric analysis techniques. Our laboratory results show that the conversion of acetylene to PAHs, the CO disproportionation reaction for producing CO2 and carbon deposition (graphitic and carbon nanostructures), and also the transformation of methanol to hydrocarbon compounds can easily be achieved with OTS as a catalyst. Furthermore, the conversion of acetylene to PAHs could also be achieved by SiC as the catalyst. It is proposed that these catalytic reactions mimic similar chemical processes in circumstellar envelopes (CSEs).

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Parikh, Harshal M., Harvey E. Jeffries, Ken G. Sexton, Deborah J. Luecken, Richard M. Kamens, and William Vizuete. "Evaluation of aromatic oxidation reactions in seven chemical mechanisms with an outdoor chamber." Environmental Chemistry 10, no. 3 (2013): 245. http://dx.doi.org/10.1071/en13039.

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Environmental context Regulatory air quality models used to develop strategies to reduce ozone and other pollutants must be able to accurately predict ozone produced from aromatic hydrocarbons. In urban areas, major sources of aromatic hydrocarbons are gasoline and diesel-powered vehicles. Our findings show that the representation of aromatic hydrocarbon chemistry in air quality models is an area of high uncertainty Abstract Simulations using seven chemical mechanisms are intercompared against O3, NOx and hydrocarbon data from photooxidation experiments conducted at the University of North Carolina outdoor smog chamber. The mechanisms include CB4–2002, CB05, CB05-TU, a CB05 variant with semi-explicit aromatic chemistry (CB05RMK), SAPRC07, CS07 and MCMv3.1. The experiments include aromatics, unsaturated dicarbonyls and volatile organic compound (VOC) mixtures representing a wide range of urban environments with relevant hydrocarbon species. In chamber simulations the sunlight is characterised using new solar radiation modelling software. A new heterogeneous chamber wall mechanism is also presented with revised chamber wall chemical processes. Simulations from all mechanisms, except MCMv3.1, show median peak O3 concentration relative errors of less than 25% for both aromatic and VOC mixture experiments. Although MCMv3.1 largely overpredicts peak O3 levels, it performs relatively better in predicting the peak NO2 concentration. For aromatic experiments, all mechanisms except CB4–2002, largely underpredict the NO–NO2 crossover time and over-predict both the absolute NO degradation slope and the slope of NO2 concentration rise. This suggests a major problem of a faster and earlier NO to NO2 oxidation rate across all the newer mechanisms. Results from individual aromatic and unsaturated dicarbonyl experiments illustrate the unique photooxidation chemistry and O3 production of several aromatic ring-opening products. The representation of these products as a single mechanism species in CB4–2002, CB05 and CB05-TU is not adequate to capture the O3 temporal profile. In summary, future updates to chemical mechanisms should focus on the chemistry of aromatic ring-opening products.

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Takahashi, Katsunobu, Ayako Ajima, Takayuki Yoshimoto, Masato Okada, Ayako Matsushima, Yutaka Tamaura, and Yuji Inada. "Chemical reactions by polyethylene glycol-modified enzymes in chlorinated hydrocarbons." Journal of Organic Chemistry 50, no. 18 (September 1985): 3414–15. http://dx.doi.org/10.1021/jo00218a036.

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Serovaiskii, Aleksandr, Elena Mukhina, Leonid Dubrovinsky, Aleksey Chernoutsan, Daniil Kudryavtsev, Catherine McCammon, Georgios Aprilis, et al. "Fate of Hydrocarbons in Iron-Bearing Mineral Environments during Subduction." Minerals 9, no. 11 (October 23, 2019): 651. http://dx.doi.org/10.3390/min9110651.

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Subducted sediments play a key role in the evolution of the continental crust and upper mantle. As part of the deep carbon cycle, hydrocarbons are accumulated in sediments of subduction zones and could eventually be transported with the slab below the crust, thus affecting processes in the deep Earth’s interior. However, the behavior of hydrocarbons during subduction is poorly understood. We experimentally investigated the chemical interaction of model hydrocarbon mixtures or natural oil with ferrous iron-bearing silicates and oxides (representing possible rock-forming materials) at pressure-temperature conditions of the Earth’s lower crust and upper mantle (up to 2000(±100) K and 10(±0.2) GPa), and characterized the run products using Raman and Mössbauer spectroscopies and X-ray diffraction. Our results demonstrate that complex hydrocarbons are stable on their own at thermobaric conditions corresponding to depths exceeding 50 km. We also found that chemical reactions between hydrocarbons and ferrous iron-bearing rocks during slab subduction lead to the formation of iron hydride and iron carbide. Iron hydride with relatively low melting temperature may form a liquid with negative buoyancy that could transport reduced iron and hydrogen to greater depths.

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Thangadurai, Tavayogeshwary, and Ching Thian Tye. "Performance of Activated Carbon Supported Cobalt Oxides and Iron Oxide Catalysts in Catalytic Cracking of Waste Cooking Oil." Periodica Polytechnica Chemical Engineering 65, no. 3 (May 13, 2021): 350–60. http://dx.doi.org/10.3311/ppch.16885.

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This work studied the catalyst activity of activated carbon (AC) supported Co, Fe and Co-Fe oxides in catalytic cracking of waste cooking oil. Reactions were carried out in a fixed bed reactor at 450 °C with WHSV 9 hr–1. Single metal Co/AC and Fe/AC catalysts with different metal loading (2.5–15 wt.%) and bimetal xCo-yFe/AC (x, y = 2.5 to 12.5 wt.%; x + y =15 wt.%) catalysts were investigated. Co/AC and Fe/AC catalysts both contributed to significant liquid yield with high selectivity towards C15 and C17 hydrocarbons. Fe/AC catalysts gave high C5 – C20 hydrocarbon yield whereas Co/AC attained more palmitic (C16) and oleic (C18) acid conversion. Synergistic effect in two metals Co-Fe/AC catalysts had further improved the liquid hydrocarbon yield (up to ~93 %) and fatty acid conversion (up to 94 %). The best catalyst, 10Co-5Fe/AC had been further tested under the effect of reaction temperature, feed flow rate (WHSV) and deactivation for its catalytic performance.

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Murga, M. S., M. S. Kirsanova, A. I. Vasyunin, and Ya N. Pavlyuchenkov. "Impact of PAH photodissociation on the formation of small hydrocarbons in the Orion Bar and the horsehead PDRs." Monthly Notices of the Royal Astronomical Society 497, no. 2 (July 11, 2020): 2327–39. http://dx.doi.org/10.1093/mnras/staa2026.

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ABSTRACT We study whether polycyclic aromatic hydrocarbons (PAHs) can be a weighty source of small hydrocarbons in photodissociation regions (PDRs). We modelled the evolution of 20 specific PAH molecules in terms of dehydrogenation and destruction of the carbon skeleton under the physical conditions of two well-studied PDRs, the Orion Bar, and the Horsehead nebula that represent prototypical examples of PDRs irradiated by ‘high’ and ‘low’ ultraviolet radiation field. PAHs are described as microcanonical systems. The acetylene molecule is considered as the main carbonaceous fragment of the PAH dissociation, as it follows from laboratory experiments and theory. We estimated the rates of acetylene production in gas phase chemical reactions and compared them with the rates of the acetylene production through the PAH dissociation. It is found that the latter rates can be higher than the former rates in the Orion Bar at AV < 1 and also at AV > 3.5. In the Horsehead nebula, the chemical reactions provide more acetylene than the PAH dissociation. The produced acetylene participate in the reactions of the formation of small hydrocarbons (C2H, C3H, C3H+, C3H2, C4H). Acetylene production via the PAH destruction may increase the abundances of small hydrocarbons produced in gas phase chemical reactions in the Orion Bar only at AV > 3.5. In the Horsehead nebula, the contribution of PAHs to the abundances of the small hydrocarbons is negligible. We conclude that the PAHs are not a major source of small hydrocarbons in both PDRs except some locations in the Orion Bar.

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Nicholas, Kenneth M., and Chandrasekhar Bandari. "Deoxygenative Transition-Metal-Promoted Reductive Coupling and Cross-Coupling of Alcohols and Epoxides." Synthesis 53, no. 02 (October 7, 2020): 267–78. http://dx.doi.org/10.1055/s-0040-1707269.

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AbstractThe prospective utilization of abundant, CO2-neutral, renewable feedstocks is driving the discovery and development of new reactions that refunctionalize oxygen-rich substrates such as alcohols and polyols through C–O bond activation. In this review, we highlight the development of transition-metal-promoted reactions of renewable alcohols and epoxides that result in carbon–carbon bond-formation. These include reductive self-coupling reactions and cross-coupling reactions of alcohols with alkenes and arene derivatives. Early approaches to reductive couplings employed stoichiometric amounts of low-valent transition-metal reagents to form the corresponding hydrocarbon dimers. More recently, the use of redox-active transition-metal catalysts together with a reductant has enhanced the practical applications and scope of the reductive coupling of alcohols. Inclusion of other reaction partners with alcohols such as unsaturated hydrocarbons and main-group organometallics has further expanded the diversity of carbon skeletons accessible and the potential for applications in chemical synthesis. Catalytic reductive coupling and cross-coupling reactions of epoxides are also highlighted. Mechanistic insights into the means of C–O activation and C–C bond formation, where available, are also highlighted.1 Introduction2 Stoichiometric Reductive Coupling of Alcohols3 Catalytic Reductive Coupling of Alcohols3.1 Heterogeneous Catalysis3.2 Homogeneous Catalysis4 Reductive Cross-Coupling of Alcohols4.1 Reductive Alkylation4.2 Reductive Addition to Olefins5 Epoxide Reductive Coupling Reactions6 Conclusions and Future Directions

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Karvatska, M., H. Lavrenyuk, V. P. Parhomenko, and B. Mykhalichko. "QUANTUM CHEMICAL SIMULATION OF THE INHIBITORY EFFECT OF AQUEOUS SOLUTIONS OF INORGANIC COPPER(II) SALTS ON THE COMBUSTION OF HYDROCARBONS." Bulletin of Lviv State University of Life Safety 23 (June 30, 2021): 33–38. http://dx.doi.org/10.32447/20784643.23.2021.05.

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Introduction. The search for chemicals that would have an effective fire extinguishing effect and the development of new fire extinguishers based on them is an extremely important problem of fire safety. It is known from the literature that new aqueous fire extinguishing agents (AFEAs) based on dissolved inorganic salts of transition metals, in particular, copper(II) chloride salts, have a rather efficient inhibitory effect on the hydrocarbon flame. However, the mechanism of inhibition of hydrocarbon combustion by this class of substances is not completely ascertained. However, it is reliable information about the processes that take place in the flame after the bringing in there of the aerosol of the mentioned AFEA will allow a systematic search for more optimal chemical composition of dissolved inorganic salts of d-metals. Purpose. The purpose of the work is to reveal the peculiarities of the interaction of concentrated aqueous solutions of copper(II) chloride salts with chemically active flame particles.Methods. Quantum chemical calculations of the chemical activity of radicals that appear in the flame and the physicochemical processes that occur in the flame after the bringing on there of AFEA aerosol.Results. The mechanism of a fire-extinguishing effect of aqueous solutions of inorganic copper(II) salts on a hydrocarbon flame is investigated by a calculation method. The sequence of stages of chemical processes that occur in the flame during the inhibiting combustion of hydrocarbons by AFEAs—concentrated solutions of CuCl2 and K2[CuCl4]—and the thermal effects of all reactions that accompany each of these stepwise transformations were ascertained. The stages of the interaction of gaseous Cu2Cl4 molecules with ×OH and ×H radicals in flame with the formation of first a radical-molecular complex and then a molecular complex are decisive in the process of inhibition and display the processes of interruption of chain reactions, i.e. deactivation of radicals in a flame.Conclusion. Thus, using the method of quantum chemical calculations the mechanism of inhibition of hydrocarbon combustion by copper(II) salts was offered. The mechanism of this process is considered to be associative, the decisive elementary act of which is carried out according to the scheme of addition of active radicals of a flame (×OH particles) to gaseous molecules Cu2Cl4 with the formation of radical-molecular complex [{Cu(×OH)Cl2}2] and with its subsequent deactivation by ×H particles.

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Lehmkuhl, H. "Specific reactions of organylmetal complexes with unsaturated hydrocarbons." Pure and Applied Chemistry 62, no. 4 (January 1, 1990): 731–40. http://dx.doi.org/10.1351/pac199062040731.

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Heimrich, M. J. "Diesel NOx Catalytic Converter Development: A Review." Journal of Engineering for Gas Turbines and Power 118, no. 3 (July 1, 1996): 668–72. http://dx.doi.org/10.1115/1.2816700.

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This paper summarizes the findings of several technical articles on diesel NOx catalytic converter technology. Simplified theoretical reactions for NOx removal are discussed. Currently, development of catalytic NOx control technology for diesel engines is focused on systems that incorporate fuel hydrocarbons as the chemical reducing agent. Copper-and zeolite-based catalysts have been the predominant systems studied to date, but now catalysts containing precious metals are being investigated. Observed NOx reduction efficiencies typically ranged from 10 to 30 percent on actual engine exhaust systems when exhaust hydrocarbon enrichment strategies were used. Effects of carbon monoxide, sulfur dioxide, and water on NOx reduction efficiencies are reviewed. Recommendations for future research include attempts to broaden the temperature range of efficient NOx reduction, improving hydrocarbon selectivity toward the NOx reduction reaction, and the development of a supplementary reductant delivery system suitable for transient diesel engine operation.

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Nakagawa, Tsuyoshi, Hiroshi Ozaki, Takashi Kamitanaka, Hidekazu Takagi, Tomoko Matsuda, Toshiyuki Kitamura, and Tadao Harada. "Reactions of supercritical alcohols with unsaturated hydrocarbons." Journal of Supercritical Fluids 27, no. 3 (December 2003): 255–61. http://dx.doi.org/10.1016/s0896-8446(02)00269-3.

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Jenkin, Michael E., Richard Valorso, Bernard Aumont, and Andrew R. Rickard. "Estimation of rate coefficients and branching ratios for reactions of organic peroxy radicals for use in automated mechanism construction." Atmospheric Chemistry and Physics 19, no. 11 (June 7, 2019): 7691–717. http://dx.doi.org/10.5194/acp-19-7691-2019.

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Abstract. Organic peroxy radicals (RO2), formed from the degradation of hydrocarbons and other volatile organic compounds (VOCs), play a key role in tropospheric oxidation mechanisms. Several competing reactions may be available for a given RO2 radical, the relative rates of which depend on both the structure of RO2 and the ambient conditions. Published kinetics and branching ratio data are reviewed for the bimolecular reactions of RO2 with NO, NO2, NO3, OH and HO2; and for their self-reactions and cross-reactions with other RO2 radicals. This information is used to define generic rate coefficients and structure–activity relationship (SAR) methods that can be applied to the bimolecular reactions of a series of important classes of hydrocarbon and oxygenated RO2 radicals. Information for selected unimolecular isomerization reactions (i.e. H-atom shift and ring-closure reactions) is also summarized and discussed. The methods presented here are intended to guide the representation of RO2 radical chemistry in the next generation of explicit detailed chemical mechanisms.

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McGlashan, N. R. "Chemical-looping combustion — a thermodynamic study." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 6 (June 1, 2008): 1005–19. http://dx.doi.org/10.1243/09544062jmes790.

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The poor performance of internal combustion (IC) engines can be attributed to the departure from equilibrium in the combustion process. This departure is expressed numerically, as the difference between the working fluid's temperature and an ideal ‘combustion temperature’, calculated using a simple expression. It is shown that for combustion of hydrocarbons to be performed reversibly in a single reaction, impractically high working fluid temperatures are required — typically at least 3500 K. Chemical-looping combustion (CLC) is an alternative to traditional, single-stage combustion that performs the oxidation of fuels using two reactions, in separate vessels: the oxidizer and reducer. An additional species circulates between the oxidizer and reducer carrying oxygen atoms. Careful selection of this oxygen carrier can reduce the equilibrium temperature of the two redox reactions to below current metallurgical limits. Consequently, using CLC it is theoretically possible to approach a reversible IC engine without resorting to impractical temperatures. CLC also lends itself to carbon capture, as at no point is N2 from the air allowed to mix with the CO2 produced in the reduction process and therefore a post-combustion scrubbing plant is not required. Two thermodynamic criteria for selecting the oxygen carrier are established: the equilibrium temperature of both redox reactions should lie below present metallurgical limits. Equally, both reactions must be sufficiently hot to ensure that their reaction velocity is high. The key parameter determining the two reaction temperatures is the change in standard state entropy for each reaction. An analysis is conducted for an irreversible CLC system using two Rankine cycles to produce shaft work, giving an overall efficiency of 86.5 per cent. The analysis allows for irreversibilites in turbine, boiler, and condensers, but assumes reactions take place at equilibrium. However, using Rankine cycles in a CLC system is considered impractical because of the need for high-temperature, indirect heat exchange. An alternative arrangement, avoiding indirect heat exchange, is discussed briefly.

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Pfaendtner, Jim, Xinrui Yu, and Linda J. Broadbelt. "Quantum Chemical Investigation of Low-Temperature Intramolecular Hydrogen Transfer Reactions of Hydrocarbons." Journal of Physical Chemistry A 110, no. 37 (September 2006): 10863–71. http://dx.doi.org/10.1021/jp061649e.

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Liu, Yingjie, Jihe Yang, Xingying Lan, and Jinsen Gao. "Numerical Simulation of Chemical Stripping Process in Resid Fluid Catalytic Cracking Stripper." International Journal of Chemical Reactor Engineering 12, no. 1 (January 1, 2014): 525–37. http://dx.doi.org/10.1515/ijcre-2014-0036.

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Abstract The chemical stripping process in a commercial scale V-baffled resid fluid catalytic cracking stripper was simulated using computational fluid dynamics method. At the outset, it was assumed that the stripping steam initially desorbs hydrocarbons from the catalysts, and the hydrocarbons are then cracked through thermal and catalytic cracking reactions before entering the disengager. The Eulerian–Eulerian two-fluid model coupled with a modified drag model was applied to simulate the gas–solid flow behavior. A desorption model and five-lump kinetic model for thermal and catalytic cracking were utilized to represent the desorption and cracking processes during stripping. The flow modeling results indicated that three different flow regions exist in the stripper: bubbling flow, intermediate flow and turbulent flow. Increasing gas velocity improves the flow conditions of the gas, but adversely affects the particle flow. The degree of mixing of the gas and solid increases along the flowing direction. The results of reaction modeling showed that about 80% of hydrocarbons desorbed from the catalysts. The amount of desorbed oil increases with bed height leading to an increase of heavy oil in the disengager which induces coking problem. By increasing the catalyst temperature, the partial pressure of heavy oil can be lowered down which helps to decrease the disengager coking.

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Parker, Dorian S. N., and Ralf I. Kaiser. "On the formation of nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) in circumstellar and interstellar environments." Chemical Society Reviews 46, no. 2 (2017): 452–63. http://dx.doi.org/10.1039/c6cs00714g.

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Al-Ahmed, Amir. "Metal Doped TiO₂ Photocatalysts for CO₂ Photoreduction." Materials Science Forum 757 (May 2013): 243–56. http://dx.doi.org/10.4028/www.scientific.net/msf.757.243.

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Greenhouse gases such as CO2, CH4 and CFCs are the primary causes of global warming. Worldwide, people are exploring techniques to reduce, capture, store CO2 gas and even convert this gas in to some useful chemicals. CO2 can be transformed into hydrocarbons in a photocatalytic reaction. The advantage of photo reduction of CO2 is to use inexhaustible solar energy. Knowledge of elementary steps in photocatalytic CO2 reduction under UV irradiation is required in order to improve the photo efficiency of the photocatalyst. A semiconductor photocatalyst mediating CO2 reduction and water oxidation needs to absorb light energy, generate electron hole pairs, spatially separate them, transfer them to redox active species across the interface and minimize electron hole recombination. This requires the semiconductor to have its conduction band electrons at higher energy compared to the CO2 reduction potential while the holes in the valence band need to be able to oxidize water to O2. A single semiconductor does not usually satisfy these requirements. Some recent developments in this field have been moves towards rational photocatalyst design, the use of highly active isolated Ti-species in mesoporous and microporous materials, metal-doping of TiO2, development of catalysts active at longer wavelengths than can be achieved with commercially available titania etc. The use of transition-metal loaded titanium dioxide (TiO2) has been extensively studied as a photocatalyst in photoreactions. Unlike traditional catalysts drive chemical reactions by thermal energy, semiconducting photocatalysts can induce chemical reactions by inexhaustible sunlight and convert CO2 in to the useful hydrocarbons. In this review article we will cover different aspects of metal doped nano structured TiO2 photocatalysts, used to convert/reduce CO2 in to useful hydrocarbons.

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Yavuz Corapcioglu, M., Kijune Sung, and Jeongkon Kim. "Parameter Determination of Sequential Reductive Dehalogenation Reactions of Chlorinated Hydrocarbons." Transport in Porous Media 55, no. 2 (May 2004): 169–82. http://dx.doi.org/10.1023/b:tipm.0000010677.47179.f1.

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Nayebzadeh, Maryam, and Morteza Vahedpour. "A Review on Reactions of Polycyclic Aromatic Hydrocarbons with the Most Abundant Atmospheric Chemical Fragments: Theoretical and Experimental Data." Progress in Reaction Kinetics and Mechanism 42, no. 3 (September 2017): 201–20. http://dx.doi.org/10.3184/146867817x14821527549293.

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Aerosols are ubiquitous in the atmosphere and have strong effects on climate and public health due to the importance of reactions of polycyclic aromatic hydrocarbon (PAH) compounds in air. Over the last decade, study of the reactions of PAHs and their derivatives in the atmosphere has become a key topic to find an effective way to decrease the impact of this spontaneous reaction and so reduce air pollution. This article aims to pool the majority of research on the reactions of PAHs with atmospheric agents such as oxygen, hydrogen and ozone and compare the theoretical and experimental results. In examining theoretical research, the number of aromatic rings is very important in calculating the rate constants and determining the main pathway of the reaction. So, while there are weak theoretical data, several papers issued in this field have concurred with key experimental results. For reactants with more than six aromatic rings, small basis sets have good conformity with experimental outcomes. Due to the abundance of OH in the atmosphere, much research has been done to find the best reaction pathway and calculate the associated rate constants experimentally and theoretically. In future, the opportunity exists for new researchers to detect the main intermediates, most important pathways, rate constants and the products of reactions with more than six aromatic rings and to detect PAHs in a dense atmosphere. Product identification will help to reduce air pollution.

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Jenkin, Michael E., Richard Valorso, Bernard Aumont, Andrew R. Rickard, and Timothy J. Wallington. "Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aromatic organic compounds for use in automated mechanism construction." Atmospheric Chemistry and Physics 18, no. 13 (July 4, 2018): 9329–49. http://dx.doi.org/10.5194/acp-18-9329-2018.

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Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for the reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving estimation of atmospheric lifetimes or oxidation rates for VOCs. A structure–activity relationship (SAR) method is presented for the reactions of OH with aromatic organic compounds, with the reactions of aliphatic organic compounds considered in the preceding companion paper. The SAR is optimized using a preferred set of data including reactions of OH with 67 monocyclic aromatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The SAR can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the reactions of the product radicals under tropospheric conditions are also summarized, specifically the rapid reaction sequences initiated by their reactions with O2.

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Wang, Zhandong, Denisia M. Popolan-Vaida, Bingjie Chen, Kai Moshammer, Samah Y. Mohamed, Heng Wang, Salim Sioud, et al. "Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds." Proceedings of the National Academy of Sciences 114, no. 50 (November 28, 2017): 13102–7. http://dx.doi.org/10.1073/pnas.1707564114.

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Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

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Kaiser, R. I., N. Balucani, O. Asvany, and Y. T. Lee. "Crossed Molecular Beam Experiments of Radical-Neutral Reactions Relevant to the Formation of Hydrogen Deficient Molecules in Extraterrestrial Environments." Symposium - International Astronomical Union 197 (2000): 251–64. http://dx.doi.org/10.1017/s0074180900164848.

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During the last 5 years, laboratory experiments relevant to the formation of carbon-bearing molecules in extraterrestrial environments have been performed employing the crossed molecular beam technique and a high intensity source of ground state atomic carbon, C(3Pj). These investigations unraveled for the first time detailed information on the chemical reaction dynamics, involved collision complexes and intermediates, and – most important – reaction products of neutral-neutral reactions. Here, we extend these studies even further, and report on very recent crossed beam experiments of cyano radical, CN(2Σ+), reactions with unsaturated hydrocarbons to form nitriles in extraterrestrial environments and Saturn's moon Titan. Further, preliminary results on reactions of small carbon clusters and with acetylene, ethylene, and methylacetylene to synthesize hydrogen-deficient carbon-bearing molecules are presented.

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Zhao, T. Q., Q. Li, B. S. Liu, R. K. E. Gover, P. J. Sarre, and A. S. C. Cheung. "Laboratory astrochemistry: catalytic conversion of acetylene to polycyclic aromatic hydrocarbons over SiC grains." Physical Chemistry Chemical Physics 18, no. 5 (2016): 3489–96. http://dx.doi.org/10.1039/c5cp06425b.

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Catalytic conversion reactions of acetylene on a solid SiC grain surface lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and are expected to mimic chemical processes in certain astrophysical environments.

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Olivo, Alberto, Danny Zanardo, Elena Ghedini, Federica Menegazzo, and Michela Signoretto. "Solar Fuels by Heterogeneous Photocatalysis: From Understanding Chemical Bases to Process Development." ChemEngineering 2, no. 3 (September 4, 2018): 42. http://dx.doi.org/10.3390/chemengineering2030042.

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The development of sustainable yet efficient technologies to store solar light into high energy molecules, such as hydrocarbons and hydrogen, is a pivotal challenge in 21st century society. In the field of photocatalysis, a wide variety of chemical routes can be pursued to obtain solar fuels but the two most promising are carbon dioxide photoreduction and photoreforming of biomass-derived substrates. Despite their great potentialities, these technologies still need to be improved to represent a reliable alternative to traditional fuels, in terms of both catalyst design and photoreactor engineering. This review highlights the chemical fundamentals of different photocatalytic reactions for solar fuels production and provides a mechanistic insight on proposed reaction pathways. Also, possible cutting-edge strategies to obtain solar fuels are reported, focusing on how the chemical bases of the investigated reaction affect experimental choices.

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31

Popov, Stasik, Brian Shao, Alex L. Bagdasarian, Tyler R. Benton, Luyi Zou, Zhongyue Yang, K. N. Houk, and Hosea M. Nelson. "Teaching an old carbocation new tricks: Intermolecular C–H insertion reactions of vinyl cations." Science 361, no. 6400 (July 26, 2018): 381–87. http://dx.doi.org/10.1126/science.aat5440.

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Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium–weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond–forming reactions, including carbon-hydrogen (C–H) insertion into unactivated sp3 C–H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C–H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.

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Jenkin, Michael E., Richard Valorso, Bernard Aumont, Andrew R. Rickard, and Timothy J. Wallington. "Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aliphatic organic compounds for use in automated mechanism construction." Atmospheric Chemistry and Physics 18, no. 13 (July 4, 2018): 9297–328. http://dx.doi.org/10.5194/acp-18-9297-2018.

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Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving the estimation of atmospheric lifetimes or oxidation rates for VOCs. Updated and extended structure–activity relationship (SAR) methods are presented for the reactions of OH with aliphatic organic compounds, with the reactions of aromatic organic compounds considered in a companion paper. The methods are optimized using a preferred set of data including reactions of OH with 489 aliphatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The information can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the subsequent reactions of the product radicals under tropospheric conditions are also summarized, specifically their reactions with O2 and competing processes.

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33

Kukueva, V. V. "Quantum-Chemical Research of Fluoro Containing Hydrocarbons, That Have Fire Extinguishing Effect." Фізика і хімія твердого тіла 16, no. 3 (September 15, 2015): 511–14. http://dx.doi.org/10.15330/pcss.16.3.511-514.

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Through quantum-chemical calculations, a study was conducted to find the probable products of the destruction of molecules of extinguishing agents. The formation of atomic fluorine and trifluoromethane radical has been shown to contribute to the retardation of elementary reactions in the flame. It has been shown that active inhibitory components are more easily dissociated from the silica surface than in the case of bulk molecules.

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34

Pauser, H., C. G. Schwärzler, J. Laimer, and H. Störi. "Reactions of hydrocarbons in a supersonic vacuum plasma jet." Plasma Chemistry and Plasma Processing 17, no. 2 (June 1997): 107–21. http://dx.doi.org/10.1007/bf02766810.

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35

Eakin, P. A., and A. P. Gize. "Reflected-light microscopy of uraniferous bitumens." Mineralogical Magazine 56, no. 382 (March 1992): 85–99. http://dx.doi.org/10.1180/minmag.1992.056.382.11.

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AbstractUraniferous bitumens from Great Britain, Scandinavia and South Africa have been studied by oilimmersion reflected-light microscopy and categorised into those formed either by replacement of preexisting uraninite and pitchblende or by complexation/reduction mechanisms in pre-existing hydrocarbons. The former are characterised by displaying normal replacive textures, and containing high concentrations of non-mineral-bound uranium, or later, occasionally exotic, uraniferous fracturefilling phases. Uraniferous bitumens formed during complexation/reduction reactions display monotonous mineralogies and ordered mineral-inclusion distributions.Radiolytic alteration of uraniferous bitumens induces both chemical and mechanical alteration. Early alteration is marked by the generation of mobile hydrocarbons during 'cracking reactions' with subsequent within-sample migration to form globular bitumens and dendritic interspersions of mineralrich and -poor uraniferous bitumen. Mobile hydrocarbons may act as lubricants during mechanical deformation. Advanced organic alteration is characterised by well-documented increased reflectance around uraniferous grains, and by fracturing of the bitumens.

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36

Barker, John R., and Isabelle Cherchneff. "Grains, or Molecules? Thermal, or non-Thermal?" Symposium - International Astronomical Union 135 (1989): 197–205. http://dx.doi.org/10.1017/s0074180900125239.

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The effects of size and energy on infrared fluorescence (IRF) and on chemical reaction rates are investigated, using polycyclic aromatic hydrocarbons (PAHs) as examples. The range of validity of the Thermal Approximation (TA) is examined. It is found that for properties that have a near-linear dependence on the internal energy, the TA provides an adequate description of the non-thermal, time-dependent processes associated with ultraviolet photon absorption. Since IRF at high energy is nearly linear, the TA is adequate for IRF at high excitation energies, but care must be taken, because the TA fails at low energies. The TA is never adequate for chemical reactions under these conditions.

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Endo, Yasuki, Hideto Kanamori, and Eizi Hirota. "Millimeter- and Submillimeter-wave Kinetic Spectroscopy of Reaction Intermediates." Laser Chemistry 7, no. 2-4 (January 1, 1987): 61–77. http://dx.doi.org/10.1155/lc.7.61.

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A spectroscopic method has been developed to study chemical reaction processes through in situ observation of the time profile of molecular absorptions in the millimeter- and submillimeter-wave regions. The method has been applied to oxidation reactions of unsaturated hydrocarbons initiated by mercury photosensitization. It has also been combined with the excimer laser photolysis to examine photodecomposition processes of SO2, CS2, and Cl2SO, where nascent distributions of photofragments such as SO and CS were measured. Advantages and disadvantages of the method have been discussed in some detail.

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38

Berdnikov, V. I., and Yu A. Gudim. "Chemical reactions at reduction of iron from oxides by natural gas." Izvestiya. Ferrous Metallurgy 63, no. 1 (March 30, 2020): 84–86. http://dx.doi.org/10.17073/0368-0797-2020-1-84-86.

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The main component of natural gas is methane CH4 , that is, a component consisting of two active reducing agents for iron – carbon and hydrogen. Previously, computer simulations have found that the reduction of iron from magnetite with carbon begins at 680 °C, and its reduction with hydrogen – at 350 °C. In this paper it is shown that the beginning of the reduction of iron with methane should be expected at a temperature of 530 °C. However, this temperature for natural gas, obtained from gas condensate fields and containing up to 10 % of heavy hydrocarbons and impurities, increases to 550 °C. When using natural gas together with oxygen in the ratio CH4 : O2 = 2:1, temperature of the beginning of reduction also increases to 620 °C. In addition, a calculation formula was proposed for Fe – O – C – H system, which allows predicting the formation of a “pure” phase of iron at 1500 °C based on the chemical composition of the reducing gas mixture.

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Uliasz-Misiak, Barbara, and Katarzyna Chruszcz-Lipska. "Hydrogeochemical Aspects Associated with the Mixing of Formation Waters Injected Into the Hydrocarbon Reservoir." Gospodarka Surowcami Mineralnymi 33, no. 2 (June 27, 2017): 69–80. http://dx.doi.org/10.1515/gospo-2017-0017.

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Abstract Formation waters extracted with crude oil and natural gas, due to their amount and chemical composition can be a problem for petroleum companies operating hydrocarbon deposits. On average, the world generates 2 to 3 times more water than oil. On average, the world generates 2 to 3 times more water than crude oil. T he amount of extracted water increases with the time of exploitation of the deposit, in the case of deposits at the final stage of depletion, the amount of extracted water is 5 to 8 times bigger than petroleum. Formation waters from hydrocarbons deposits are usually the highly mineralized brines. Large quantities of highly mineralized waters extracted with crude oil and gas are disposed of in various ways or neutralized. T he most common way of disposing of these waters is by injecting them into rock mass. As a result of injection of reservoir waters into hydrocarbon deposits, the waters interact with the storage formations. In these formations, there may be numerous reactions of mineral water with the rock environment. T he injection of reservoir waters will also cause mixing of waters that can disturb the state of thermodynamic equilibrium and will alter the chemistry of these waters. It was analyzed by the geochemical modeling of the interaction of the reservoir waters of Przemyśl natural gas field. Using the PHREEQC program, the chemical reactions related to the mixing of reservoir waters of different chemical types have been studied. It has been found that is possible to precipitation appropriated minerals as a result of mixing water with different chemical composition.

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Karaba, Adam, Petr Zamostny, Jaromir Lederer, and Zdenek Belohlav. "Generalized Model of Hydrocarbons Pyrolysis Using Automated Reactions Network Generation." Industrial & Engineering Chemistry Research 52, no. 44 (July 24, 2013): 15407–16. http://dx.doi.org/10.1021/ie4006657.

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Morandi, Bill. "Cluster Preface: Metathesis Reactions beyond Olefins." Synlett 30, no. 17 (October 2019): 1952–53. http://dx.doi.org/10.1055/s-0039-1690296.

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studied at the ETH Zurich from 2003–2012, earning a B.Sc. in biology, an M.Sc. in chemical biology and a Ph.D. in organic chemistry working with Prof. Erick M. Carreira. After a postdoc with Prof. Robert H. Grubbs at CalTech, he led an independent Max Planck Research Group from 2014–2018 at the Max-Planck-Institut für Kohlenforschung, Germany. Since July 2018, he is a tenured Associate Professor at the ETH Zurich where he holds a chair in synthetic organic chemistry. His independent research program targets the development of new concepts in catalysis, with a particular emphasis on employing inexpensive and sustainable catalysts to transform broadly available feedstocks, such as polyols and hydrocarbons, into valuable building blocks for applications in medicine and materials science.

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Hack, W., H. Kurzke, P. Rouveirolles, and H. Gg Wagner. "Hydrogen Abstraction Reactions by NH2(X̃2B1)-Radicals from Hydrocarbons in the Gas Phase." Berichte der Bunsengesellschaft für physikalische Chemie 90, no. 12 (December 1986): 1210–19. http://dx.doi.org/10.1002/bbpc.19860901218.

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Gaboury, Damien. "The Neglected Involvement of Organic Matter in Forming Large and Rich Hydrothermal Orogenic Gold Deposits." Geosciences 11, no. 8 (August 17, 2021): 344. http://dx.doi.org/10.3390/geosciences11080344.

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Orogenic gold deposits have provided most of gold to humanity. These deposits were formed by fluids carrying dissolved gold at temperatures of 200–500 °C and at crustal depths of 4–12 km. The model involves gold mobilization as HS− complexes in aqueous solution buffered by CO2, with gold precipitation following changes in pH, redox activity (fO2), or H2S activity. In this contribution, the involvement of carbonaceous organic matter is addressed by considering the formation of large and/or rich orogenic gold deposits in three stages: the source of gold, its solubilization, and its precipitation. First, gold accumulates in nodular pyrite within carbonaceous-rich sedimentary rocks formed by bacterial reduction of sulfates in seawater in black shales. Second, gold can be transported as hydrocarbon-metal complexes and colloidal gold nanoparticles for which the hydrocarbons can be generated from the thermal maturation of gold-bearing black shales or from abiotic origin. The capacity of hydrocarbons for solubilizing gold is greater than those of aqueous fluids. Third, gold can be precipitated efficiently with graphite derived from fluids containing hydrocarbons or by reducing organic-rich rocks. Black shales are thus a key component in the formation of large and rich orogenic gold deposits from the standpoints of source, transport, and precipitation. Unusual CO2-rich, H2O-poor fluids are documented for some of the largest and richest orogenic gold deposits, regardless of their age. These fluids are interpreted to result from chemical reactions involving hydrocarbon degradation, hence supporting the fundamental role of organic matter in forming exceptional orogenic gold deposits.

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Honorato de Oliveira, Brenda Fernanda, Luiz Ferreira de França, Nádia Cristina Fernandes Corrêa, Nielson Fernando da Paixão Ribeiro, and Mauricio Velasquez. "Renewable Diesel Production from Palm Fatty Acids Distillate (PFAD) via Deoxygenation Reactions." Catalysts 11, no. 9 (September 9, 2021): 1088. http://dx.doi.org/10.3390/catal11091088.

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The reactions to produce liquid biofuels from a palm fatty acid distillate (PFAD) under hydrogen absence were carried out using 10 wt% NiO/zeolite (Ni/Zeo), 10 wt% Co3O4/zeolite (Co/Zeo), and 10 wt% (NiO + Co3O4)/zeolite (NiCo/Zeo) as catalysts. The zeolite was synthesized by a thermal and chemical treatment from natural clay, obtaining a zeolite A and sodalite mixture. Catalytic activity was evaluated as a function of reaction temperature (250, 300, and 350 °C) during 0.5 h and using 5 wt% of catalyst. The reaction products were classified as organic liquid products (OLPs), gaseous products, and solid waste. The OLPs fractions were separated by fractional distillation, and the products were identified and quantified using gas chromatography coupled to a mass spectrometer detector (GC-MS). The results showed yields to OLPs above 50% for all catalysts and temperatures. However, the highest yield to OLPs of 67.9% was reached with a NiCoZeo catalyst at 300 °C. In this reaction, a higher yield to hydrocarbons was obtained (84.8%), indicating a cooperative effect between Ni and Co in the catalyst. Hydrocarbons such as heptadecane (C17H36), pentadecane (C15H26), and other alkanes-alkenes with lower carbon chains were the main products. Therefore, deoxygenation of PFAD using a low-cost Ni-Co catalyst was shown to be an economic and viable way to produce diesel-type biofuels.

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Chow, Toby Wai-Shan, Guo-Qiang Chen, Yungen Liu, Cong-Ying Zhou, and Chi-Ming Che. "Practical iron-catalyzed atom/group transfer and insertion reactions." Pure and Applied Chemistry 84, no. 8 (May 2, 2012): 1685–704. http://dx.doi.org/10.1351/pac-con-11-11-08.

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Iron-catalyzed reactions are receiving a surge of interest owing to the natural abundance and biocompatibility of Fe and the urge to develop practically useful sustainable catalysis for fine chemical industries. This article is a brief account of our studies on the C–O and C–N bond formation reactions catalyzed by Fe complexes supported by oligopyridine, macrocyclic tetraaza, and fluorinated porphyrin ligands. The working principle is the in situ generation of reactive Fe=O and Fe=NR intermediates supported by these oxidatively robust N-donor ligands for oxygen atom/nitrogen group transfer and insertion reactions. The catalytic reactions include C–H bond oxidation of saturated hydrocarbons (up to 87 % yield), epoxidation of alkenes (up to 96 % yield), cis-dihydroxylation of alkenes (up to 99 % yield), epoxidation–isomerization (E–I) reaction of aryl alkenes (up to 94 % yield), amination of C–H bonds (up to 95 % yield), aziridination of alkenes (up to 95 % yield), sulfimidation of sulfides (up to 96 % yield), and amide formation from aldehydes (up to 89 % yield). Many of these catalytic reactions feature high regio- and diastereoselectivity and/or high product yields and substrate conversions, and recyclability of the catalyst, demonstrating the applicability of Fe-catalyzed oxidative organic transformation reactions in practical organic synthesis.

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Manheim, Jeremy M., Jacob R. Milton, Y. Zhang, and Hilkka I. Kenttämaa. "Fragmentation of Saturated Hydrocarbons upon Atmospheric Pressure Chemical Ionization Is Caused by Proton-Transfer Reactions." Analytical Chemistry 92, no. 13 (May 26, 2020): 8883–92. http://dx.doi.org/10.1021/acs.analchem.0c00681.

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Cvetanović, R. J. "Evaluated Chemical Kinetic Data for the Reactions of Atomic Oxygen O(3P) with Unsaturated Hydrocarbons." Journal of Physical and Chemical Reference Data 16, no. 2 (April 1987): 261–326. http://dx.doi.org/10.1063/1.555783.

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Sun, Yong, Zhipeng Lin, Shao Hong Peng, Valérie Sage, and Zhi Sun. "A Critical Perspective on CO2 Conversions into Chemicals and Fuels." Journal of Nanoscience and Nanotechnology 19, no. 6 (June 1, 2019): 3097–109. http://dx.doi.org/10.1166/jnn.2019.16588.

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In this paper, we aim to focus on the utilization of carbon dioxide (CO2) as a feedstock for synthetic applications in chemical and fuel industries, through catalytic carboxylation and reduction reactions. Thermal catalytic conversion as well as non-thermal plasma assisted and photocatalytic conversion CO2 into fuels such as methane, methanol, and long-chain hydrocarbons using different catalyst especially nano catalyst are also thoroughly compared and reviewed in this paper. Among currently available technical routes, the thermal catalytic conversion of CO2 via the Fischer-Tropsch (FT) synthesis using nanoscale catalyst offers the most feasible, practical and mature alternative for industrial-scale applications on the short term basis, converting gigantic quantity of CO2 captured from power plants into hydrocarbons.

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H Musfer. "Biomass Gasification Process with Catalyst." International Journal for Modern Trends in Science and Technology 06, no. 09 (October 29, 2020): 38–53. http://dx.doi.org/10.46501/ijmtst060908.

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Gasification is a thermo-chemical process used to convert biomass fuelsinto a fuel gas. Biomass gasification is considered amongst the best methods to enhance biomass-based energy production’s efficiency as it allows common biomass utilization.It has become more important as a mean of converting low energy-density such as biomass feeds or into a transportable high value gas for heat and power generation, chemicals and fuels. Operating conditions are affecting the gasification reactions. the review identified that in high-temperature gasification, endothermic reactions the secondary cracking and reforming of heavy hydrocarbons are favored and hence enhances the whole process’s efficiency. Finally, catalysts are vital for the biomass gasification process, and it is important to select the appropriate ones taking into consideration possible setbacks discussed above and will be explored further in this study.

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Reizer, Edina, Imre Csizmadia, Árpád Palotás, Béla Viskolcz, and Béla Fiser. "Formation Mechanism of Benzo(a)pyrene: One of the Most Carcinogenic Polycyclic Aromatic Hydrocarbons (PAH)." Molecules 24, no. 6 (March 15, 2019): 1040. http://dx.doi.org/10.3390/molecules24061040.

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The formation of polycyclic aromatic hydrocarbons (PAHs) is a strong global concern due to their harmful effects. To help the reduction of their emissions, a crucial understanding of their formation and a deep exploration of their growth mechanism is required. In the present work, the formation of benzo(a)pyrene was investigated computationally employing chrysene and benz(a)anthracene as starting materials. It was assumed a type of methyl addition/cyclization (MAC) was the valid growth mechanism in this case. Consequently, the reactions implied addition reactions, ring closures, hydrogen abstractions and intramolecular hydrogen shifts. These steps of the mechanism were computed to explore benzo(a)pyene formation. The corresponding energies of the chemical species were determined via hybrid density funcional theory (DFT), B3LYP/6-31+G(d,p) and M06-2X/6-311++G(d,p). Results showed that the two reaction routes had very similar trends energetically, the difference between the energy levels of the corresponding molecules was just 6.13 kJ/mol on average. The most stable structure was obtained in the benzo(a)anthracene pathway.

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Journal articles on the topic 'Hydrocarbons Chemical reactions'

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