Journal articles: 'Temperature-programmed reduction (TPR)'

1

Rynkowski, J. M. "Temperature-programmed reduction (TPR) of Co−Ni/Al2O3 catalysts." Reaction Kinetics and Catalysis Letters 30, no. 1 (March 1986): 33–39. http://dx.doi.org/10.1007/bf02068143.

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Pirola, Carlo, Federico Galli, and Gregory S. Patience. "Experimental methods in chemical engineering: Temperature programmed reduction-TPR." Canadian Journal of Chemical Engineering 96, no. 11 (October 8, 2018): 2317–20. http://dx.doi.org/10.1002/cjce.23317.

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Ebitani, Kohki, and Hideshi Hattori. "Combined Temperature-Programmed Reduction (TPR)- Temperature-Programmed Desorption (TPD) Study of Supported Platinum Catalysts." Bulletin of the Chemical Society of Japan 64, no. 8 (August 1991): 2422–27. http://dx.doi.org/10.1246/bcsj.64.2422.

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Yan, Aiyu, Bin Liu, Baofeng Tu, Yonglai Dong, Mojie Cheng, Shuqin Song, and Panagiotis Tsiakaras. "A Temperature-Programmed-Reduction Study on La1−xSrxCrO3 and Surface-Ruthenium-Modified La1−xSrxCrO3." Journal of Fuel Cell Science and Technology 4, no. 1 (June 13, 2006): 79–83. http://dx.doi.org/10.1115/1.2393308.

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A series of La1−xSrxCrO3(0⩽x⩽0.3) composite oxides were prepared by a modified citric method. These perovskite oxides were further modified with Ru through impregnation. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature-programmed-reduction (TPR) techniques were adopted to investigate the properties of both the as-prepared perovskite oxides and the surface-Ru-modified La1−xSrxCrO3 samples. XPS results indicated the existence of Cr6+ ions in the fresh samples and transformed to Cr3+ after reduction. The hydrogen consumed by these perovskite oxides during TPR increased with the Sr doping, which was more than twice of the theoretical value according to Kröger-Vink notation. The reduction temperature of Cr ions of Ru∕La1−xSrxCrO3 significantly decreased with an increase of the Ru loading. A small reduction peak at ∼540°C, which was not shifted by increasing Ru loadings, was observed and could be ascribed to the reduction of trace chromate phases. On all TPR profiles of the three doped perovskites with unity of the A-site and B-site ratio, the reduction of Ru species could not be observed at low Ru loadings (0.05% and 0.1%). A reduction peak from RuO2 particles appeared at temperatures prior to the perovskite reduction on the TPR plots of modified La0.9Sr0.1CrO3 and La0.8Sr0.2CrO3 with high Ru loading (0.5% and 1%, respectively), but it did not occur with the Ru modified La0.7Sr0.3CrO3 in the investigated Ru loading range. The TPR results of the Ru modified La0.8Sr0.2Cr0.95O3 depicted that some Ru ions might be stabilized due to the incorporation into the oxide.

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Portnyagin, Arseniy, Alexey Golikov, Evgenii K. Papynov, and Valentin Avramenko. "Rate Constant Approximation with Cubic Splines for Kinetic Analysis of Temperature-Programmed Reduction Data." Key Engineering Materials 806 (June 2019): 87–92. http://dx.doi.org/10.4028/www.scientific.net/kem.806.87.

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Temperature-programmed reduction (TPR) is a widely used method for characterization of oxide-based catalysts, sorbents, and functional materials, but its results lack quantitative assessment. Here, we present a novel approach to kinetic analysis of the TPR that can be applied to a large variety of systems involving multiple limiting stages. Implementation of cubic splines to approximate rate constant vs. conversion dependencies obtained from several TPR curves recorded at different heating rates yields in a set of kinetic parameters (activation energy and preexponential factors) for all reduction stages. Relationship between preexponential factor of the first reduction stage and the specific surface area of the sample has been shown. Reduction of hematite has been studied to prove the performance of the developed kinetic analysis technique.

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Dancheva, Snejana, Liuba Ilieva, Nikolay Kotsev, and Atanas Andreev. "TPSR, TPR, and TPO Studies of Pd-V2O5/Al2O3 Catalysts in Complete Catalytic Oxidation of Benzene." Collection of Czechoslovak Chemical Communications 59, no. 9 (1994): 1922–30. http://dx.doi.org/10.1135/cccc19941922.

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Alumina-supported palladium vanadium-pentoxide catalysts were studied by means of temperature-programmed surface reaction, temperature-programmed reduction, temperature-programmed oxidation, and by ESR spectroscopy in the complete oxidation of benzene. The surface reaction measurements indicated that 0.5% Pd - 30% V2O5 / Al2O3 produced most oxidation products, compared to 0.5% Pd / Al2O3 or 30% V2O5 / Al2O3 samples. A drastic fall of peak maxima in temperature-programmed oxidation and reduction spectra indicates the decisive role of palladium in the mixed metal metal oxide system in facilitating the vanadium redox transitions. During initial period of catalysts operation, there proceeds formation of vanadium oxide phases which contain clustered V4+ ions in a matrix of vanadium pentoxide. These ions are responsible for the high activity of the palladium vanadium pentoxide catalyst.

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Heidebrecht, Peter, Vladimir Galvita, and Kai Sundmacher. "An alternative method for parameter identification from temperature programmed reduction (TPR) data." Chemical Engineering Science 63, no. 19 (October 2008): 4776–88. http://dx.doi.org/10.1016/j.ces.2007.10.012.

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Latif, Mohd Nor, Alinda Samsuri, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Reduction of Molybdenum Trioxide by Using Hydrogen." Materials Science Forum 888 (March 2017): 404–8. http://dx.doi.org/10.4028/www.scientific.net/msf.888.404.

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Metallic molybdenum was synthesized through reduction of molybdenum trioxide (MoO3) by using hydrogen as a reducing agent. The reduction behavior of MoO3 were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The XRD results indicate that the reduction of MoO3 proceed in two steps reduction (MoO3 → MoO2 → Mo) with formation of intermediate phases of Mo4O11 during first step of reduction. However, the TPR results showed only one broad peak that correspond to all reduction step that was merge into one peak. It seem that, increasing the temperature cause the rapid reduction that correlated with thermodynamic consideration data that show the formation of metallic molybdenum is become feasible by increasing the temperature.

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9

Jung, D. H., N. Umirov, T. Kim, Z. Bakenov, J. S. Kim, and S. S. Kim. "Thermal and Structural Stabilities of LixCoO2 cathode for Li Secondary Battery Studied by a Temperature Programmed Reduction." Eurasian Chemico-Technological Journal, no. 1 (February 20, 2019): 3. http://dx.doi.org/10.18321/ectj780.

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Temperature programmed reduction (TPR) method was introduced to analyze the structural change and thermal stability of LixCoO2 (LCO) cathode material. The reduction peaks of delithiated LCO clearly represented the different phases of LCO. The reduction peak at a temperature below 250 °C can be attributed to the transformation of CoO2–like to Co3O4–like phase which is similar reduction patterns of CoO2 phase resulting from delithiation of LCO structure. The 2nd reduction peak at 300~375 °C corresponds to the reduction of Co3O4–like phase to CoO–like phase. TPR results indicate the thermal instability of delithiated LCO driven by CoO2–like phase on the surface of the delithiated LCO. In the TPR kinetics, the activation energies (Ea) obtained for as-synthesized LCO were 105.6 and 82.7 kJ mol-1 for Tm_H1 and Tm_H2, respectively, whereas Ea for the delithiated LCO were 93.2, 124.1 and 216.3 kJ mol-1 for Tm_L1, Tm_L2 and Tm_L3, respectively. As a result, the TPR method enables to identify the structural changes and thermal stability of each phase and effectively characterize the distinctive thermal behavior between as-synthesized and delithiated LCO.

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Ma, Lingjuan, Dawei Han, Hongbin Ma, Longgang Liu, and Huichao Guo. "Characterization of Highly Dispersed Rod- and Particle-Shaped CuFe19Ox Catalysts and Their Shape Effects on WGS." Catalysts 8, no. 12 (December 7, 2018): 635. http://dx.doi.org/10.3390/catal8120635.

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Highly dispersed CuFe19Ox catalysts with different shapes were prepared and further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), and in-situ XRD. XRD and TEM results showed that the synthesized CuFe19Ox nanoparticles consisted of CuO and Fe2O3, while CuFe19Ox nanorods consisted of CuFe2O4 and Fe2O3. The reduction properties of CuFe19Ox samples were finely studied by H2-TPR, and the phase composition was identified by in-situ XPS, HR-TEM, and surface TPR (s-TPR). In-situ X-ray photoelectroscopy (XPS) indicated that the metallic Cu and Fe3O4 were the main species after reduction. Moreover, s-TPR studies showed that the reduction performance of copper was significantly affected by the shapes of the Fe3O4 supports. Low-temperature water gas shift (LT-WGS) was chosen to characterize the Cu species on the surface. It was found that reduced CuFe19Ox nanorods had no activity. On the contrary, reduced CuFe19Ox particles showed higher initial WGS activity, where the active Cu0 should originate from the reduction of Cu2O at lower temperatures, as confirmed by the s-TPR profiles.

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Lee, So Yeon, Yong Kul Lee, S. Ted Oyama, Seok Hee Lee, and Hee Chul Woo. "Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique." Solid State Phenomena 124-126 (June 2007): 1765–68. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1765.

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Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590 oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The process of solid transformation and properties of materials prepared from ammonium hydrogen phosphate (AMP)-impregnated samples were compared with those of phosphide made from phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2 was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous reagent

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12

Perego, C. "Temperature Programmed Reduction (TPR) Characterization of NiO/YSZ For Solid Oxide Fuel Cell." ECS Proceedings Volumes 1993-4, no. 1 (January 1993): 454–63. http://dx.doi.org/10.1149/199304.0454pv.

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13

Nagashima, Makoto, Daisuke Hirabayashi, and Kenzi Suzuki. "Oxygen Radicals Occlusion/Release Behavior of Nanoporous Aluminosilicate, Ca₁₂Al_14-XSi_XO_33+0.5X (0≦X≦4)." Advances in Science and Technology 45 (October 2006): 2105–9. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2105.

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Oxygen radicals occlusion / release behavior of nanoporous aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4), synthesized under different condition was examined by the temperature programmed reduction (TPR) in an atmosphere of hydrogen in the temperature range of 200-1000°C and temperature programmed oxidation (TPO) measurement at 800°C. From the TPR results of Ca12Al14O33 (X=0) and Ca12Al10Si4O35 (X=4), it was found that there were three oxygen release peaks, denoted as α, β and γ, on each sample and the peaks appeared in the temperature range 300-420°C, 420-600°C, and 600-750°C, respectively. The oxygen contents of α and γ of samples were almost the same. However, the oxygen content of β in the sample with x = 4 was much larger, almost double, compared to that in x = 0. From the TPR, TPO results and catalytic performance, it was concluded that the oxygen content of β peak strongly influenced the catalytic activity of the nanoporous aluminosilicate in the propylene combustion.

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14

Liu, Liping, Xiaodong Wu, Yue Ma, Jinyi Wang, Rui Ran, Zhichun Si, and Duan Weng. "Tungsten Oxide Modified V2O5-Sb2O3/TiO2 Monolithic Catalyst: NH3-SCR Activity and Sulfur Resistance." Processes 10, no. 7 (July 8, 2022): 1333. http://dx.doi.org/10.3390/pr10071333.

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In this study, a V2O5-Sb2O3/TiO2 monolithic catalyst was modified by introducing WO3. The WO3-modified catalyst exhibited enhanced catalytic activity in the measuring temperature range of 175–320 °C. The changes in dispersion of vanadia species were investigated by ultraviolet-visible (UV-Vis) spectroscopy and H2 temperature-programmed reduction (H2-TPR). A durability test was conducted in a wet SO2-containing atmosphere at 220 °C for 25 h. The sulfate deposition was estimated by temperature-programmed decomposition (TPDC) of sulfates, thermo-gravimetric (TG) analysis, and temperature-programmed desorption (TPD) of NH3. Isothermal SO2 oxidation and temperature-programmed surface reaction (TPSR) of NH4HSO4 with NO were performed. Based on these characterizations, effects of WO3 modification on the sulfate tolerance of the catalyst were explored.

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15

Matsumoto, Hiroshige, and Shuji Tanabe. "Formation of Reactive Clusters in Pd-Y Zeolite by Reduction-Reoxidation Treatment." Collection of Czechoslovak Chemical Communications 57, no. 4 (1992): 817–25. http://dx.doi.org/10.1135/cccc19920817.

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Preparation of a finely dispersed Pd-Y zeolite has been investigated by temperature-programmed reduction (TPR) and extended X-ray absorption fine structure (EXAFS) techniques. Upon the treatment by a sequence of calcination, reduction, and reoxidation, the original Pd(NH3)42+ ions in the zeolite transformed to reactive species, which were reduced with hydrogen at room temperature and characterized as small PdO clusters of about 25 Pd atoms.

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16

Salleh, Fairous, Tengku Shafazila Tengku Saharuddin, Alinda Samsuri, Rizafizah Othaman, Mohammad Wahab Mohammad Hisham, and Mohd Ambar Yarmo. "Influence of Cerium Additive on the Reduction Behaviour of Tungsten Oxide under Carbon Monoxide Atmosphere." Materials Science Forum 888 (March 2017): 389–93. http://dx.doi.org/10.4028/www.scientific.net/msf.888.389.

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The reduction of pure WO3 and Ce/WO3 has been studied by using temperature programmed reduction (TPR), X-ray diffraction (XRD), and FESEM analysis. The reduction behavior were examined by non-isothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR results shows that reduction peak of Ce/WO3 were shifts to lower temperature as compared with to the pure WO3. In addition, TPR results indicate that addition with ceria give better reducibility compared to pure WO3. Based on the characterization of the reduction products after hold 45 min using XRD, pure WO3 were completely converted to WO2 and W metal phases. While, after addition of Ce to the WO3, the reduction was enhanced to W phases and some suboxide W5O14 and W3O5 with no WO2 phase remained and carbide observed. This is associated to the formation of alloy complex Ce2WO6 which gave remarkable effect to the reduction.

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17

Yafarova, Liliya V., Grigory V. Mamontov, Irina V. Chislova, Oleg I. Silyukov, and Irina A. Zvereva. "The Effect of Transition Metal Substitution in the Perovskite-Type Oxides on the Physicochemical Properties and the Catalytic Performance in Diesel Soot Oxidation." Catalysts 11, no. 10 (October 19, 2021): 1256. http://dx.doi.org/10.3390/catal11101256.

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The paper is focused on the Fe for Co substitution effect on the redox and catalytic properties in the perovskite structure of GdFeO3. The solid oxides with the composition GdFe1−xCoxO3 (x = 0; 0.2; 0.5; 0.8; 1) were obtained by the sol-gel method and characterized by various methods: X-ray diffraction (XRD), temperature-programmed reduction (H2-TPR), N2 sorption, temperature-programmed desorption of oxygen (TPD-O2), simultaneous thermal analysis (STA), and X-ray photoelectron spectroscopy (XPS). The H2-TPR results showed that an increase in the cobalt content in the GdFe1−xCoxO3 (x = 0; 0.2; 0.5; 0.8; 1) leads to a decrease in the reduction temperature. Using the TPD-O2 and STA methods, the lattice oxygen mobility is increasing in the course of the substitution of Fe for Co. Thus, the Fe substitution in the perovskite leads to an improvement in the oxygen reaction ability. Experiments on the soot oxidation reveal that catalytic oxidation ability increases in the series: GdFe0.5Co0.5O3 ˂ GdFe0.2Co0.8O3 ˂ GdCoO3, which is in good correlation with the increasing oxygen mobility according to H2-TPR, TPD-O2, and STA results. The soot oxidation over GdFeO3 and GdFe0.8Co0.2O3 is not in this range due to the impurities of iron oxides and higher specific surface area.

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Achary, S. N., S. Varma, and A. K. Tyagi. "On reduction behavior of Al2(WO4)3: A combined powder XRD and temperature programmed reduction (TPR) studies." Journal of Physics and Chemistry of Solids 66, no. 7 (July 2005): 1200–1205. http://dx.doi.org/10.1016/j.jpcs.2005.03.003.

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19

Lu, Long, Xueman Wang, Chunhua Hu, Ying Liu, Xiongbo Chen, Ping Fang, Dingsheng Chen, and Chaoping Cen. "Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO." Catalysts 10, no. 2 (February 7, 2020): 202. http://dx.doi.org/10.3390/catal10020202.

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Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

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20

Cheng, Feng, and Xiuwei Li. "Temperature-Programmed Reduction of NiO/Al2O3 by Biochar In Situ Generated from Citric Acid." Processes 10, no. 8 (August 5, 2022): 1542. http://dx.doi.org/10.3390/pr10081542.

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The reduction of metal oxides by biochar is an important reaction for many biomass utilization technologies. This work investigated the temperature–programmed reduction (TPR) of NiO/Al2O3 by in situ generated biochar from citric acid pyrolysis. Firstly, NiO/Al2O3 was loaded with citric acid by impregnation and then heated from ambient temperature to 900 °C in a N2 flow. The process was on–line analyzed by the TGA–FTIR technique. Secondly, a series of intermediates was obtained and characterized by XRD, CHNO elemental analysis, and temperature programmed oxidation (TPO). Lastly, a control experiment of unsupported NiO was conducted to show the influence of Al2O3 support on the NiO reduction. Results showed that the whole heating process could be resolved into two parts that is citric acid pyrolysis and NiO reduction at a heating rate of 5 °C/min. The NiO reduction occurred above 400 °C with the biochar from citric acid pyrolysis as reductant. In the temperature–programmed reduction process, the Al2O3–supported NiO exhibited three reduction phases in contrast with only one reduction phase for the unsupported NiO. A hypothesis was proposed to explain this. The presence of Al2O3 support may result in different deposition sites of biochar (on NiO or on Al2O3), and consequently different reduction mechanisms.

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Zabihi, Vahid, Mohammad Hasan Eikani, Mehdi Ardjmand, Seyed Mahdi Latifi, and Alireza Salehirad. "Selective catalytic reduction of NO by Co-Mn based nanocatalysts." International Journal of Chemical Reactor Engineering 19, no. 5 (April 22, 2021): 533–40. http://dx.doi.org/10.1515/ijcre-2020-0240.

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Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

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Zhang, Yanbing, Zhe Xu, Xie Wang, Xiulian Lu, and Yuying Zheng. "Fabrication of Mn-FeOx/CNTs Catalysts for Low-Temperature NO Reduction with NH3." Nano 10, no. 04 (June 2015): 1550050. http://dx.doi.org/10.1142/s1793292015500502.

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Mn - FeO x/carbon nanotubes (CNTs) catalysts were firstly prepared via simple incipient wetness method and used for low-temperature selective catalytic reduction (SCR) of NO with NH 3. The structure and surface properties of the catalysts were characterized by N 2 sorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen ( H 2-TPR). It was found that Mn - FeO x/CNTs catalyst exhibited excellent low-temperature SCR activity and SO 2 resistance. XRD patterns revealed that metal oxides catalysts were possessed of amorphous structure. FESEM and TEM images showed that metal oxides catalysts were successfully supported on CNTs. The XPS results indicated that the obtained catalyst presented high Mn 4+/ Mn 3+ and OS/(OS + OL) ratios. The H 2-TPR profiles showed that Mn - FeO x/CNTs catalyst possessed better low-temperature reducibility. Besides, the obtained catalyst exhibited better SO 2 resistance.

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Dzakaria, Norliza, Maratun Najiha Abu Tahari, Salma Samidin, Tengku Shafazila Tengku Saharuddin, Fairous Salleh, Azizul Hakim Lahuri, and Mohd Ambar Yarmo. "Effect of Cobalt on Nickel Oxide Toward Reduction Behaviour in Hydrogen and Carbon Monoxide Atmosphere." Materials Science Forum 1010 (September 2020): 373–78. http://dx.doi.org/10.4028/www.scientific.net/msf.1010.373.

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The reduction behaviour of cobalt doped with nickel oxide and undoped nickel oxide (NiO) by hydrogen (H2) in nitrogen (20%, v/v) and carbon monoxide (CO) in nitrogen (40%, v/v) atmospheres have been investigated by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Co doped and undoped nickel oxide in both reductants proceed in one step reduction (NiO → Ni) without intermediate. TPR results also suggested that by adding Co metal into NiO, the reduction to metallic Ni by both reductant gaseous give different intensity of the peak. The reduction process of Co and undoped NiO become faster when H2 was used as a reductant. Furthermore, in H2 atmosphere, Co-NiO give complete reduction to metallic Ni at 700 °C. Meanwhile, XRD analysis indicated that NiO without Co composed better crystallite phases of NiO with higher intensity.

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Li, Xue, Rui Sheng Hu, Jia Nan Hu, and Ya Qin Bai. "Comparison Study on Support Effect of Co-Series Compound Oxide Catalysts Supported Rare Earth." Advanced Materials Research 356-360 (October 2011): 439–44. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.439.

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The catalysts were prepared by the impregnation method and characterized thought X-ray powder diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), measurement of surface area, differial thermal and thermogravimetric analysis. Rare-earth compound oxides La0.8Sr0.2CoO3act as active component; Alumina act as carriers. The effects were investigated on loading amounts of active components, calcinations temperature and the addition components on the catalytic oxidation of xylene.

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Salleh, Fairous, Alinda Samsuri, Tengku Shafazila Tengku Saharuddin, Rizafizah Othaman, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Temperature-Programmed and X-Ray Diffractometry Studies of WO₃ Reduction by Carbon Monoxide." Advanced Materials Research 1087 (February 2015): 73–76. http://dx.doi.org/10.4028/www.scientific.net/amr.1087.73.

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Tungsten (VI) oxide (WO3) reduction by carbon monoxide were examined using temperature-programmed reduction (TPR) and X-ray powder diffractometry (XRD) studies. Results show that WO3 start to reduce at 20% (CO in N2) at temperature 900 °C and the intermediate phases WO2.9 and WO2.83 were observed. The WO3 was reduced and transformed the completely to the WO2.72. As comparison, reduction by using 10% (H2 in N2), WO3 was reduced completely toWO2. The WO3 is a stable oxide because the reduction agent used to promote the reduction was not sufficient enough to reduce to zero metal tungsten.

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26

Pai, M. R., A. M. Banerjee, S. R. Bharadwaj, and S. K. Kulshreshtha. "Synthesis, characterization, thermal stability and redox behavior of In3+2Ti4+1–xTm3+xO5–δ, (Tm = Fe3+ and Cr3+, 0.0 ≤ x ≤ 0.2) mixed-oxide catalysts." Journal of Materials Research 22, no. 7 (July 2007): 1787–96. http://dx.doi.org/10.1557/jmr.2007.0240.

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Mixed metal oxide catalysts with nominal compositions of In2Ti1–xFexO5–δ, In2Ti1–xCrxO5–δ, where 0.0 ≤ x ≤ 0.2, have been synthesized by the ceramic route and characterized using the powder x-ray diffraction technique. The In2Ti1–xFexO5–δ samples were single-phase compositions, isomorphic with In2TiO5 phase. The particle size of the In2Ti1–xFexO5–δ samples was lower compared to the parent In2TiO5 oxide. Thermal stability (by thermogravimetry-differential thermal analysis) in varying atmospheres, and temperature-programmed reduction (TPR)/temperature-programmed oxidation cycles have been recorded to investigate their redox behavior as a function of the value of x in this study. The amount of H2 consumed under TPR curves was correlated with the nonstoichiometry generated in the In2Ti1–xFexO5–δ samples. Fe substitution induced ease in the reducibility (i.e., maximum temperature) of the substituted oxides compared to that in In2TiO5. X-ray photoelectron spectroscopy has been used to confirm the oxidation states of indium and other metal ions in fresh and reduced samples.

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27

Logan, A. D., and M. Shelef. "Oxygen availability in mixed cerium/praseodymium oxides and the effect of noble metals." Journal of Materials Research 9, no. 2 (February 1994): 468–75. http://dx.doi.org/10.1557/jmr.1994.0468.

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Oxyreduction studies of mixed Ce/Pr oxides have been carried out. Temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) were used to study the uptake and release of the oxygen. Large amounts of oxygen, exceeding those in ceria, are accessible in the mixed metal oxides at moderate temperatures. The addition of small amounts of noble metals to the mixed oxides shifts the accessibility of the “stored” oxygen to still lower temperatures with the effect of Pd being more pronounced than that of Pt. In a sample containing 45 mol % ceria and 55 mol % praseodymia, a small addition of Pd (0.24 mol %) was found to lower the reduction temperature by more than 100 °C. The addition of Pt had a lesser effect. Similarly, in pure praseodymia (Pr6O11) Pd influences the reduction much more strongly than Pt. In the mixed samples, whether doped with a noble metal or not, the whole oxyreduction effect can be accounted for by the change in oxidation state of the praseodymium ions solely. This notwithstanding, the reduction of the mixed oxides, without noble metals or doped by Pt, is more facile than that of praseodymia. Only the incorporation of Pd makes the reduction of praseodymia proceed at a temperature below that registered for a mixed ceriapraseodymia sample.

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Afzal, M., F. Mahmood, and S. Karim. "A study of metals supported on active carbon with a temperature programmed reduction (TPR) technique." Journal of Thermal Analysis 41, no. 5 (May 1994): 1119–28. http://dx.doi.org/10.1007/bf02547201.

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Tengku Saharuddin, Tengku Shafazila, Alinda Samsuri, Fairous Salleh, Rizafizah Othaman, Mohammad Kassim, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "The Reduction Behaviour of Cerium Doped Iron Oxide in Hydrogen and Carbon Monoxide Atmosphere." Materials Science Forum 840 (January 2016): 381–85. http://dx.doi.org/10.4028/www.scientific.net/msf.840.381.

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The reduction behaviour of 3% cerium doped (Ce-Fe2O3) and undoped iron oxide (Fe2O3) by hydrogen in nitrogen (10%,v/v) and carbon monoxide in nitrogen (10%,v/v) atmospheres have been investigate by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Ce doped and undoped iron oxide in both reductants proceed in three steps reduction (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO were the intermediate. TPR results also suggested that by adding Ce metal into iron oxide the reduction to metallic Fe by using both reductant gaseous give better reducibility compare to the undoped Fe2O3. The reduction process of Ce and undoped Fe2O3 become faster when CO was used as a reductant instead of H2. Furthermore, in CO atmosphere, Ce-Fe2O3 give complete reduction to metallic iron at 700 0C which about 200 0C temperature lower than other samples. Meanwhile, XRD analysis indicated that Ce doped iron oxide composed better crystallite phases of Fe2O3 with higher intensity and a small amount of FeCe2O4.

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Liu, Ye, Chonglin Song, Gang Lv, Chenyang Fan, and Xiaodong Li. "Promotional Effect of Cerium and/or Zirconium Doping on Cu/ZSM-5 Catalysts for Selective Catalytic Reduction of NO by NH3." Catalysts 8, no. 8 (July 28, 2018): 306. http://dx.doi.org/10.3390/catal8080306.

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The cerium and/or zirconium-doped Cu/ZSM-5 catalysts (CuCexZr1−xOy/ZSM-5) were prepared by ion exchange and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by hydrogen (H2-TPR). Activities of the catalysts obtained on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia were measured using temperature programmed reactions. Among all the catalysts tested, the CuCe0.75Zr0.25Oy/ZSM-5 catalyst presented the highest catalytic activity for the removal of NO, corresponding to the broadest active window of 175–468 °C. The cerium and zirconium addition enhanced the activity of catalysts, and the cerium-rich catalysts exhibited more excellent SCR activities as compared to the zirconium-rich catalysts. XRD and TEM results indicated that zirconium additions improved the copper dispersion and prevented copper crystallization. According to XPS and H2-TPR analysis, copper species were enriched on the ZSM-5 grain surfaces, and part of the copper ions were incorporated into the zirconium and/or cerium lattice. The strong interaction between copper species and cerium/zirconium improved the redox abilities of catalysts. Furthermore, the introduction of zirconium abates N2O formation in the tested temperature range.

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Batubara, Shahad, Mogbel Alrushaid, Muhammad Amtiaz Nadeem, and Hicham Idriss. "Study of the Kinetics of Reduction of IrO2 on TiO2 (Anatase) by Temperature-Programmed Reduction." Inorganics 11, no. 2 (January 31, 2023): 66. http://dx.doi.org/10.3390/inorganics11020066.

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The interaction between IrO2 and TiO2 (anatase) in non-isothermal reduction conditions has been studied by the temperature programmed reduction technique. IrO2 clusters are of sizes between 0.5 and 0.9 nm as determined from High Resolution Transmission Electron Microscopy (HRTEM). Largely, two main regions for reduction were found and modeled at ca. 100 and 230 °C. The first region is attributed to the partial reduction of IrO2 clusters, while the second one is due to reduction of the formed crystalline (rutile IrO2), during TPR, to Ir metal. Two methods for calculating kinetic parameters were tested. First, by applying different ramping rates on a 3.5 wt.% IrO2/TiO2 using Kissinger’s method. The apparent activation energy values for the first and second reduction regions were found to be ca. 35 and 100 kJ/mol, respectively. The second method was based on fitting different kinetic models for the experimental results in order to extract qualitative information on the nature of interaction during the reduction process. It was found that the first reduction is largely due to the amount of IrO2 (reactant concentration) while the second one involved phase boundary effect as well as nucleation.

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Bulánek, Roman, and Pavel Čičmanec. "Kinetics of Reduction of Cu Ions in MFI Zeolite Investigated by H2-TPR Method." Collection of Czechoslovak Chemical Communications 73, no. 8-9 (2008): 1132–48. http://dx.doi.org/10.1135/cccc20081132.

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The temperature programmed reduction with hydrogen (H2-TPR) profiles of the Cu-MFI zeolite matrix were measured. The effect of the Cu ions loading and the heating rate on the H2-TPR profiles was investigated. The obtained TPR profiles were evaluated by different methods in order to obtain kinetic parameters and the reduction process mechanism. It was observed that the results given by convenient methods based on the simple power-law kinetics cannot be used for evaluation of at least the reduction of monovalent copper. Based on the reaction rate dependence on the degree of conversion, an autocatalytic reaction mechanism model was suggested for monovalent copper reduction. The autocatalytic effect was ascribed to nanoclusters of metallic copper, which is formed during the reduction. The parameters of this model were obtained by fitting the reaction rate equation to experimental data. The simulated TPR profiles well describe the position and relative height of peaks in experimental TPR profiles. Using our approach to evaluation of kinetic parameters we found the activation energies for reduction of Cu2+, direct reduction of Cu+ and autocatalytic reduction of Cu+ equal to 91, 67 and 38 kJ mol-1, respectively. All the mentioned processes are controlled by the kinetics of order ca. 1.5.

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Tengku, Shafazila, Alinda Samsuri, Fairous Salleh, Rizafizah Othaman, Mohammad bin Kassim, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Temperature Programmed Reduction and X-Ray Diffraction Studies of Fe₂O₃ Reduction by Different Concentration of Carbon Monoxide." Advanced Materials Research 1087 (February 2015): 55–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1087.55.

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Reduction of Fe2O3 by carbon monoxide (CO) have been studied by temperature programmed reduction (TPR) and X-ray diffraction spectroscopy (XRD). The influences of carbon monoxide concentration on the reducibility of iron oxides have been investigated. This study deals with the comparison in the reduction of Fe2O3 between 5% to 20% of CO concentration in the temperature range of 40–900 °C. The result shows that reducing behaviour of Fe2O3 is strongly dependent on the concentration of CO. It is suggested by using 20% of CO complete reduction takes place at lower temperature due to absence of intermediate FeO giving only two-steps reduction (Fe2O3 → Fe3O4 → metallic Fe). Moreover, excess of CO results the formation of iron carbide phase.

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Centeno, M. A., J. J. Benítez, P. Malet, I. Carrizosa, and J. A. Odriozola. "In Situ Temperature-Programmed Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TPDRIFTS) of V2O5/TiO2 Catalysts." Applied Spectroscopy 51, no. 3 (March 1997): 416–22. http://dx.doi.org/10.1366/0003702971940305.

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Temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy (TPDRIFTS) is proposed to follow in situ temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) experiments of catalytic systems, as a method for observing relationships between the surface structure and the reducibility of the catalyst under the actual reaction conditions. TPDRIFTS studies of desorption and reduction of a conventional V2O5/TiO2 catalyst have been carried out, showing the presence in both processes of four stages. Both desorption and reduction experiments result in similar DRIFTS spectra for temperatures below 400 °C, accounting for two processes: (1) water desorption and (2) condensation of highly dispersed vanadium species in between V2O5 islands on the anatase surface. V2O5 reduction by H2 takes place between 400 and 680 °C, being characterized by elimination of the first-overtone bands of V= O groups. DRIFTS is shown to be a very powerful tool to characterize both hydrogen-consuming and nonconsuming processes such as O= migration above 725 °C (stage IV). Relationships between the area of V = O overtones bands obtained by TPDRIFTS and the oxidation state of vanadium are proposed as a method to estimate this parameter under actual reaction conditions.

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Virgilio, Emanuel Martín, Cristina Liliana Padró, and Maria Eugenia Sad. "BUTENEDIOLS PRODUCTION FROM ERYTHRITOL ON Rh PROMOTED CATALYST." Latin American Applied Research - An international journal 50, no. 2 (March 29, 2020): 89–94. http://dx.doi.org/10.52292/j.laar.2020.353.

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The C-O hydrogenolysis of Erythritol to Butanodiols was studied in aqueous solution at 473 K and 25 bar of H2 using Rh/ReOx/TiO2 and the monometallic Rh/TiO2 and ReOx/TiO2 catalysts. The solids were characterized by temperature programmed reduction (TPR), TEM and XPS. TPR and XPS showed that ReOx species are close to Rh particles leading to reduction at lower temperature than Re on monometallic catalyst. However, some segregated Rhenium species were suspected by TPR profile for the bimetallic catalyst and detected by TEM. Re/TiO2 exhibited low activity forming only products from dehydration and epimerization. Although Rh/TiO2 showed high activity (total conversion at 14 h), was more selective to C-C cleavage leading to lower carbon products. Rh/ReOx/TiO2, showed instead, a good activity and selectivity towards C-O hydrogenolysis route yielding 37.5% of Butanodiols. Activation energy and reaction orders on ERY (0.58) and H2 (0.53) were estimated from experiences made at different reaction conditions

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36

Samsuri, Alinda, Fairous Salleh, Tengku Shafazila Tengku Saharuddin, Rizafizah Othaman, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Effect of Noble Metal Silver on the Reduction Behaviour of Molybdenum Oxide Using Carbon Monoxide." Materials Science Forum 888 (March 2017): 377–81. http://dx.doi.org/10.4028/www.scientific.net/msf.888.377.

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The reduction behavior of silver doped molybdenum trioxide (Ag/MoO3) and undoped MoO3 by using carbon monoxide, CO were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction (XRD). In the carbon monoxide atmosphere, the XRD results indicated that the reduction of Ag/MoO3 and undoped MoO3 to MoO2 phase proceed in two steps (MoO3 → Mo4O11 → MoO2) with Mo4O11 present as an intermediate state. A complete reduction to metallic molybdenum for both samples cannot occurred since in an excess CO atmosphere, MoO2 is promoted to form carbides rather than reduce to metallic molybdenum. Nevertheless, addition of silver to modified MoO3 shows the better reducibility compared to MoO3 alone by lower the reducing temperature of MoO3. TPR results show that the reduction peak of Ag/MoO3 is slightly shifts to lower temperature as compared with the undoped MoO3. The interaction between silver and molybdenum ions leads to this slightly decrease of the reduction temperature of silver doped MoO3. It can be seen that doping with silver has a remarkable influence in the reduction process of the MoO3 catalyst.

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Salleh, Fairous, Tengku Shafazila Tengku Saharuddin, Alinda Samsuri, Rizafizah Othaman, Mohamed Wahab Mohamed Hisham, and Mohd Ambar Yarmo. "Reduction Behaviour of WO₃ to W under Carbon Monoxide Atmosphere." Materials Science Forum 840 (January 2016): 305–8. http://dx.doi.org/10.4028/www.scientific.net/msf.840.305.

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The reduction behaviour of tungsten oxide has been studied by using temperature programmed reduction (TPR) and X-ray diffraction (XRD). The reduction behavior were examine by nonisothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min time under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR signal clearly shows one peak attributed to formation of suboxide W18O49 (more) and WO2 (less) observed at 80 min. The reduction product was investigated by varying the holding reaction time. Based on the characterization of the reduction products by using XRD, it was found that, nonisothermal reduction of WO3 at temperature 900 oC partially converted to some W18O49 and WO2 phases. However, after increased the reaction holding time for 45 min, WO3 phases disappeared and converted to WO2 and W metal phases. It is obviously shows that by hold the reduction time could improve the reducibility of the sample oxide. Furthermore, it is suggested that reduction by using CO as reducing agent follows the consecutives steps WO3 → WO2.92 → W18O49 → WO2 → W.

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Samojeden, Bogdan, Marta Kamienowska, Armando Izquierdo Colorado, Maria Elena Galvez, Ilona Kolebuk, Monika Motak, and Patrick Da Costa. "Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures." Catalysts 9, no. 12 (December 14, 2019): 1066. http://dx.doi.org/10.3390/catal9121066.

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Cenospheres from coal fly ashes were used as support in the preparation of Ni–Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 °C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 °C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

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Ali, Sardar, Noor Asmawati Mohd Zabidi, and Duvvuri Subbarao. "Synthesis and Characterization of γ-Alumina-Supported Cobalt and Iron Nanocatalysts." Advanced Materials Research 545 (July 2012): 129–36. http://dx.doi.org/10.4028/www.scientific.net/amr.545.129.

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The present work deals with the synthesis of cobalt monometallic and bimetallic Co/Fe nanocatalysts supported on alumina. The nanocatalysts were prepared by a wet impregnation method. The samples were characterized in terms of reducibility, dispersion, metal particle size, textural characteristics and crystallinity. These characteristics were revealed using hydrogen temperature-programmed reduction (TPR), CO-chemisorption, transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption analysis. H2-TPR analysis of Co/Al2O3indicated three temperature regions at 507◦C (low temperature), 650◦C (medium temperature) and 731◦C (high temperature) while characteristic peaks of Fe/ Al2O3appeared at 454◦C, 635◦C and 716◦C, respectively. Bimetallic nanocatalysts exhibited different physicochemical properties than those of the monometallic nanocatalysts. The incorporation of iron into cobalt nanocatalysts up to 50% of the total metal loaded enhanced the reducibility, increased the CO and H2chemisorbed and degree of reduction (DRT) while surface area decreased, further increase in the iron content resulted in a decrease in the crystallinity, increase in the average metal particle size and shift in the reduction towards higher temperatures.

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Zhang, Haojian. "Au Nanoparticles Supported on Mn- or/and La-Doped CeO2 Nanorods for One-Step Oxidative Esterification of Methacrolein and Methanol to Methyl Methacrylate." Catalysts 13, no. 4 (April 18, 2023): 767. http://dx.doi.org/10.3390/catal13040767.

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Mn- or/and La-doped CeO2 nanorods supporting Au catalysts were prepared using the hydrothermal method and deposition precipitation (DP) method and applied to the direct oxidative esterification of methacrolein (MAL) and methanol into methyl methacrylate (MMA). Various characterization techniques such as N2-physical adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (TPR) and CO2 temperature programmed desorption (TPD) were utilized to analyze the structural properties, reducibility and basicity of Au catalysts. The catalyst with Mn doping only showed the best performance, and particularly the highest conversion, while the catalyst with Mn and La doping showed the highest selectivity.

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Yang, Wen, Yanyan Feng, and Wei Chu. "Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2Methanation." International Journal of Chemical Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/2041821.

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The catalysts Ni/Al2O3and CaO modified Ni/Al2O3were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2adsorption/desorption, temperature-programmed reduction of H2(H2-TPR), X-ray diffraction (XRD), and temperature-programmed desorption of CO2and H2(CO2-TPD and H2-TPD) techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2and H2adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3showed high CO2conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4was very close to 1. The high CO2conversion over Ni/CaO-Al2O3was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3surface.

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Maina, Silvia Carolina Palmira, Irene María Julieta Vilella, Adriana Daniela Ballarini, and Sergio Rubén de Miguel. "Performance of Modified Alumina-Supported Ruthenium Catalysts in the Reforming of Methane with CO2." Catalysts 13, no. 2 (February 3, 2023): 338. http://dx.doi.org/10.3390/catal13020338.

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Ruthenium (1 wt%) catalysts supported on alumina doped with alkaline (Na and K) and alkaline earth metals (Ba, Ca, and Mg) of different concentrations (1, 5, and 10 wt%) were tested in the dry reforming of methane. All catalysts were prepared by the successive impregnation method. Supports were characterized by X-ray diffraction, BET surface area, temperature-programmed desorption of CO2, and 2-propanol dehydration. Additionally, catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Stability tests to study coke deposition were performed using long-time dry reforming reactions. All the catalysts showed good catalytic activity, and activity falls were never detected. Ru metallic phase seemed to be resistant to coke formation even though its particles are sintered during a long-term reaction.

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Gorimbo, Joshua, Ralph Muvhiiwa, Ephraim Llane, and Diane Hildebrandt. "Cobalt Catalyst Reduction Thermodynamics in Fischer Tropsch: An Attainable Region Approach." Reactions 1, no. 2 (November 17, 2020): 115–29. http://dx.doi.org/10.3390/reactions1020010.

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A fundamental understanding of the precise reduction reaction pathway of cobalt-based catalysts is a crucial piece of knowledge in terms of the Fischer–Tropsch Synthesis (FTS) reaction. The use of hydrogen (H2) as the reduction agent results in a two-stage reduction of cobalt tetraoxide (Co3O4) to cobalt oxide (CoO) and then to metallic Co. The objective of the present work is to apply the Thermodynamic Attainable Region (TAR) to cobalt catalyst reduction using H2 so as to gain better insight regarding the thermodynamics of reduction reaction. TAR space diagrams suggest that complete Co3O4 reduction is feasible through two reaction pathways. Thus, the observed AR results suggest that the temperature programmed reduction’s (TPR) first reaction peak may be attributed to direct reduction of Co3O4 → Co and/or reduction to an intermediate compound Co3O4 → CoO. The second peak is a result of the reduction of either of the cobalt oxides to Co (Co3O4 → Co or CoO → Co).

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Udomsap, Parncheewa, and Somsak Supasitmongkol. "Effect of Gallium Loading on Reducibility and Dispersion of Copper-Based Catalyst." Key Engineering Materials 659 (August 2015): 211–15. http://dx.doi.org/10.4028/www.scientific.net/kem.659.211.

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The effect of gallium-promoted copper-based catalysts has been investigated in connection with the characteristic of the active copper phase. CuO-ZnO-Ga2O3catalysts with different gallium loadings were prepared using oxalate co-precipitation method. The effects of gallium loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). The dispersion and metal area of copper were also determined by dissociative nitrous (N2O) adsorption technique conducted on a metal dispersion analyzer (BELCAT). The TPR profiles showed that the presence of two different reduction regions in the CuO-ZnO catalysts can be attributed to the reduction of highly dispersed copper oxide species (reduced at 246 °C) and bulk-like CuO (reduced at above 390 °C). By contrast, the only low-temperature reduction peak was presented in the TPR profiles after the Ga2O3loading was higher than 4 wt%. With the same molar ratio (Cu/Zn = 2:1), the reducibility of CuO-ZnO-Ga2O3was found to be more facile than CuO-ZnO due to the lower copper oxide crystallite sizes of gallium-promoted catalysts. Higher Ga2O3loadings resulted in an increase in both copper dispersion and metal surface area of all the catalysts studied in good agreement with the reduction behaviors in the TPR profiles, although all the gallium-promoted catalysts were slightly different for the reducibility.

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Tang, Chih Wei, Jiunn Jer Hwang, Shie Hsiung Lin, and Chin Chun Chung. "Study of Preparation, Characterization and Temperature-Programmed Reduction of NiO-ZnO Binary Materials." Advanced Materials Research 664 (February 2013): 515–20. http://dx.doi.org/10.4028/www.scientific.net/amr.664.515.

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The NiO-ZnO binary materials had been prepared by co-precipitation method. The weight percent of nickel of NiO-ZnO materials were 5, 10 and 20; they were pretreated under air at temperature of 300, 500 and 700°C, respectively. The characterization of NiO-ZnO materials were the thermal gravity analysis(TGA), X-ray diffraction(XRD), N2 adsorption-desorption at 77K, scaning electron microscope(SEM) and temperature-programmed reduction(TPR). The results revealed that surface areas of NiO-ZnO materials order from large to small were 20NiZn(OH)x(66 m2·g-1) > 10NiZn(OH)x(34 m2·g-1) > 5NiZn(OH)x(9 m2·g-1) after being calcined at the temperature of 500°C. Further, NiO-ZnO materials had two main reductive peaks at 390-415°C and 560-657°C, respectively. In all NiO-ZnO materials, 20NiZn(OH)x-C500 material had the highest surface area and the best interaction between NiO and ZnO.

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Wang, Li, Junbo Wang, Heping Cheng, Xiangxiang Zhou, and Zhen Ma. "Ce1−xFexVO4 with Improved Activity for Catalytic Reduction of NO with NH3." Catalysts 12, no. 5 (May 17, 2022): 549. http://dx.doi.org/10.3390/catal12050549.

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A series of Ce1−xFexVO4 (x = 0, 0.25, 0.50, 0.75, 1) catalysts prepared by modified hydrothermal synthesis were used for selective catalytic reduction (SCR) of NOx with NH3. Among them, Ce0.5Fe0.5VO4 showed the highest catalytic activity. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction using H2 (H2-TPR), and temperature-programmed desorption of NH3 (NH3-TPD). The results indicated the formation of Ce-Fe-V-O solid solutions. The average oxidation states (AOS) of Ce, Fe, V, and O atoms changed obviously with the incorporation of Fe3+ into CeVO4, and the acidity of Ce0.5Fe0.5VO4 differs from that of CeVO4 and FeVO4. The presence of more acid sites and a sharp increase in active oxygen species in Ce0.5Fe0.5VO4 effectively improved the selective catalytic reduction (SCR) activity.

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Teodorescu, M., A. C. Banciu, I. Sitaru, and E. Segal. "Investigation concerning bimetallic catalysts using nonisothermal (temperature programmed reduction (TPR) and temperature programmed desorption (TPD)) and isothermal methods. Part 2. Nickel—chromium prereduced catalysts." Thermochimica Acta 240 (July 1994): 199–205. http://dx.doi.org/10.1016/0040-6031(94)87041-1.

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Li, Junhui, Norman Wilken, Krishna Kamasamudram, Neal W. Currier, Louise Olsson, and Aleksey Yezerets. "Characterization of Active Species in Cu-Beta Zeolite by Temperature-Programmed Reduction Mass Spectrometry (TPR-MS)." Topics in Catalysis 56, no. 1-8 (April 3, 2013): 201–4. http://dx.doi.org/10.1007/s11244-013-9952-1.

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49

Maes, I. I. "The study of coal-derived pyrite using atmospheric pressure temperature programmed reduction (AP-TPR) and TGA." Fuel and Energy Abstracts 37, no. 3 (May 1996): 171. http://dx.doi.org/10.1016/0140-6701(96)88345-7.

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Gervasini, Antonella, and Simona Bennici. "Dispersion and surface states of copper catalysts by temperature-programmed-reduction of oxidized surfaces (s-TPR)." Applied Catalysis A: General 281, no. 1-2 (March 2005): 199–205. http://dx.doi.org/10.1016/j.apcata.2004.11.030.

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Journal articles on the topic 'Temperature-programmed reduction (TPR)'

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