Academic literature on the topic 'Glucose. Biomass gasification'

Hydrogen production by biomass gasification in supercritical water has special different distinct characteristics and advantage, this technology has become one of the international research focuses in the field of hydrogen energy. This paper gives a detail introduction of the process, characteristics and route of hydrogen production by biomass gasification in supercritical water, the biomass include glucose, cellulose methanol, and other waste effluents, the catalyst innovations and reactor development have also demonstrated, the prospects of are also presented in this paper.

The glucose as a test sample of biomass is gasified in supercritical water with different heating methods driven by renewable solar energy. The performance comparisons of hydrogen production of glucose gasification are investigated. The relations between temperature raising speed of reactant fluid, variation of volume fraction, combustion enthalpy, and chemical exergy of H2of the product gases with reactant solution concentration are presented, respectively. The results show that the energy quality of product gases with preheating process is higher than that with no preheating unit for hydrogen production. Hydrogen production quantity and gasification rate of glucose decrease obviously with the increase of concentration of material in no preheating system.

On the basis of ASPEN PLUS-based Gibbs free energy minimization, a biomass gasification model was modified by the restricted equilibrium of the RGIBBS reactor and developed and used to simulate glucose. It is showed that the simulation result and experiment result fit well. In the process of pomace gasification in supercritical water, a sensitivity analysis with temperature and pressure is performed and the research of the gas heating value has been done. From the analysis result, without using catalyst, the temperature has influenced on the gas product most and the pressure has little effect on gas product.

Based on the integration of different systems and the comprehensive step utilization of energy, the system of hydrogen production by biomass gasification in supercritical water using concentrated solar energy has been coupled by using the combination of solar and biomass as an energy source. As a model compound of biomass, glucose was gasified in supercritical water at 25MPa and 873K, whether there is pre-heater water in the hydrogen production system was compared by the way of thermodynamic analysis. The results show that energy and exergy efficiency is high in the hydrogen production system with pre-heat water.

A high-pressure absorption method can realize separation of H2 from CO2 since they have different solubility in high-pressure water. The gas-liquid equilibrium model of hydrogen production from glucose gasification in supercritical water based on the modified SAFT model and SAFT equation of state was developed to predict the effect of absorber’s pressure on the molar fraction of product gases in gas phase, absorption rate in liquid phase and gas yield. It was found that molar fraction of H2, CH4 and CO increased with the increasing pressure, while molar fraction of CO2 decreased. It indicates that higher pressure facilitate purity of H2. But H2 yield reduces from 0.00736mol to 0.00332mol while pressure increases from 0 MPa to 20MPa. It demonstrates that higher pressure can reduce gas yield. As a result, the purity and gas yield of H2 should be considered simultaneously for selecting proper pressure. Additionally, it is difficult to separate H2 from CH4 and CO using the high-pressure absorption method. This work is very useful for process design, development and optimization of biomass gasification in supercritical water.

Des nouveaux procédés éco-efficients basés sur une meilleure utilisation des ressources renouvelables sont nécessaires pour assurer la continuité du développement énergétique. La thèse étudie le procédé de gazéification en eau supercritique (T>374°C et P>22,1 MPa) de la biomasse très humide pour l’obtention de l’hydrogène, molécule ayant un potentiel énergétique très intéressant à valoriser avec un impact environnemental très favorable. L’étude porte sur l’application du procédé à la biomasse modèle (solutions de glucose, glycérol et leur mélange) ainsi qu’au bioglycérol, résidu de la fabrication du biodiesel. Les propriétés du solvant et les mécanismes prépondérants développés par l’eau en phase souset supercritique peuvent être contrôlés par les paramètres opératoires imposés au processus : température, pression, concentration en molécules organiques et catalyseur alcalin, temps de réaction... Les études paramétriques des systèmes réactionnels ont été menées dans des réacteurs batch à deux échelles différentes, les phases résultantes étant caractérisées par des protocoles analytiques élaborés et validés dans le cadre de l’étude. Le suivi du milieu réactionnel en batch lors de son déplacement vers l’état supercritique a mis en évidence une conversion avancée des molécules organiques et une identification de certains intermédiaires générés. Parmi les paramètres étudiés, la température et le temps de réaction influent le plus le rendement à l’obtention d’hydrogène en présence de catalyseur (K2CO3) dans les réacteurs batch, rendements de 1,5 et 2 mol d’H2 respectivement par mol de glycérol et de glucose introduites. Les gaz obtenus contiennent des proportions variables d’hydrocarbures légers et du CO2. Environ 75% du carbone est converti en phase gaz et liquide (sous forme de carbone organique et inorganique), le restant étant déposé sous forme solide ou huileuse. L’analyse du solide généré (plus de 90% de C) laisse apparaître différentes phases, y compris la formation de nanoparticules sphériques. Enfin, la gazéification en réacteur continu du glycérol préchauffé a montré de meilleurs rendements en hydrogène que le procédé batch, pendant que celle du bioglycérol demande une évolution du procédé à cause de la précipitation en phase supercritique des sels contenus dans le réactant. En conclusion, la gazéification en eau supercritique de la biomasse peut être considérée comme une alternative intéressante à d’autres procédés physico-chimiques de production de l’hydrogène. L’amélioration du procédé sera possible par son intensification menée en parallèle avec l’utilisation de matériaux plus performants et le contrôle de la salinité de la phase réactante
Supercritical water (T > 374 ° C and P > 22.1 MPa) gasification of wet biomass for hydrogen production is investigated. This process converts a renewable resource into a gas, which is mainly composed of hydrogen and hydrocarbons with interesting energy potential, and which can be separated at high pressure. In addition, the greenhouse gas effect of the process is zero or negative. Model biomasses (glucose, glycerol and their mixture) and bio-glycerol, residue from bio-diesel production, have been gasified by different processes: two-scale batch reactors (5 mL and 500 mL) and a continuous gasification system. Supercritical water acts as a reactive solvent, its properties can be adjusted by the choice of the experimental (P, T) couple. The operating parameters, e.g. temperature, pressure, concentration of biomass and alkaline catalysts, reaction time… allow favoring certain reaction mechanisms. In order to characterize the processes, specific analytical protocols have been developed and validated. The intermediates, formed during the heating time in the batch reactors, have been identified. Among the investigated operating parameters, temperature and reaction time have the greatest influence on the hydrogen production in batch reactors. In the presence of catalyst (K2CO3), H2 yields of 1.5 mol/mol glucose and 2 mol/mol glycerol have been respectively observed. The obtained gas contains different proportions of light hydrocarbons and CO2. About 75% of the carbon is converted into gas and liquid (in form of organic and inorganic carbon). The conversion leads also to a solid or oily residue. In the generated solid phase (composed over 90% of C), spherical nanoparticles are observed via electronic microscopy. The hydrogen production from glycerol is improved in the continuous process compared to batch reactors, however, bio-glycerol supercritical water gasification requests process improvement due to the precipitation of the salt contained in the reactant. In conclusion, supercritical water gasification of biomass can be considered as an promising alternative process for hydrogen production. The process should be improved by more performing equipments and by the control of the salinity content of the crude biomass

Hydrothermal gasification is a promising technology for the treatment of wet organic biomass, and as such, has been subject to significant research effort. It is well known that two groups of catalysts exhibit high activity for hydrothermal gasification—broadly classified as platinum group metals and alkali salts. In the present work, this effect is further investigated through a study of the synergistic effects of sodium carbonate and Pt/Al2O3 on gas yield from cellulose at 315°C. Results indicate that dilute alkali appears far more efficient in promoting gasification reactions in the presence of Pt/Al2O3. Potential mechanisms and a comparison with the alkaline degradation pathways of glucose are discussed.