Catalyst In Biomass Gasification Research Articles

Red mud enhanced biomass gasification to produce syngas: Mechanism, simulation and economic evaluation

Red mud (RM) has the potential to balance catalytic activity and recycling stability. To achieve the efficient utilization of RM, this study systematically explores the RM potential as the catalyst in biomass gasification through three aspects: catalytic experiment, simulation of biomass gasification coupled with solid oxide electrolysis cells for methanol and economic analysis. The catalytic experimental results indicate that RM has a positive effect on the biomass gasification, with a gas yield of 615.9 ml/gbiomass, representing an increment of 40.9 %. Fe2O3 and Al2O3 are the main catalytic components in RM. The simulation results on biomass gasification coupled with SOEC for methanol show that RM has increased the methanol yield to 381.83 kg/tonBiomass, with an increase of 23.9 %. The economic analysis indicates that the RM can reduce the methanol production cost, demonstrating a promising application prospect. This paper providing strong support for RM high-value synergistic utilization.

Biomass to hydrogen-rich syngas via tar removal from steam gasification with La1-XCeXFeO3/dolomite as a catalyst

Biomass gasification produces hydrogen, which is a clean and promising technology. One of the most important aspects of the biomass gasification process is choosing the right catalyst. In this study, 10% La1-XCeXFeO3/Dolomite (X = 0,0.2,0.4,0.6,0.8) synthesized using the sol-gel method was used as a catalyst in biomass gasification for the production of hydrogen-rich syngas. Gasification tests were carried out in a fixed bed reactor. The effects of an elemental substitution in LaFeO3, temperature on the product were examined. Ce-substitution boosted the activity of LaFeO3/DOL according to the data. Among the prepared catalysts, La0.8Ce0.2FeO3/DOL performed the best, yielding a greater H2 production and tar with a higher naphthalene concentration. As the temperature rises, so does the H2 yield, at 850 °C, the highest H2 yield is 0.69Nm3/Kg. Furthermore, the aromatization of phenols in tar is more likely to occur at high temperatures.

An overview on catalysts for biomass gasification

Biomass gasification may be a viable alternative to burning fossil fuels directly. Biomass, a CO-neutral renewable fuel source, may help meet demand for heat, power, and 2 synthesis gas. Nevertheless, inefficiencies in the technique make biomass gasification commercially unviable at the moment. Because the resulting gas contains condensable organic molecules including methane, it is inappropriate for some uses. The economic feasibility of biomass gasification will be improved if condensable organic molecules and methane can be removed using a low-cost method. This article includes a comprehensive overview of the three major categories of catalysts that have been tested for the removal of these hydrocarbons. Dolomite, alkali metals, as well as nickel are the three types of catalysts.

Hydrogen production enhancement using hot gas cleaning system combined with prepared Ni-based catalyst in biomass gasification

This paper investigates the hot gas temperature effect on enhancing hydrogen generation and minimizing tar yield using zeolite and prepared Ni-based catalysts in rice straw gasification. Results obtained from this work have shown that increasing hot gas temperature and applying catalysts can enhance energy yield efficiency. When zeolite catalyst and hot gas temperature were adjusted from 250 °C to 400 °C, H2 and CO increased slightly from 7.31% to 14.57%–8.03% and 17.34%, respectively. The tar removal efficiency varies in the 70%–90% range. When the zeolite was replaced with prepared Ni-based catalysts and hot gas cleaning (HGC) operated at 250 °C, H2 contents were significantly increased from 6.63% to 12.24% resulting in decreasing the hydrocarbon (tar), and methane content. This implied that NiO could promote the water-gas shift reaction and CH4 reforming reaction. Under other conditions in which the hot gas temperature was 400 °C, deactivated effects on prepared Ni-based catalyst were observed for inhibiting syngas and tar reduction in the HGC system. The prepared Ni-based catalyst worked at 250 °C demonstrate higher stability, catalyst activity, and less coke decomposition in dry reforming. In summary, the optimum catalytic performance in syngas production and tar elimination was achieved when the catalytic temperature was 250 °C in the presence of prepared Ni-based catalysts, producing 5.92 MJ/kg of lower heating value (LHV) and 73.9% tar removal efficiency.

Characterization of Coal Bottom Ash &its Potential to be used as Catalyst in Biomass Gasification

Abstract A potential renewable and sustainable green energy source is biomass gasification. The role of catalyst is significant in biomass gasification technology to overcome associated problems like tar reduction and to make it economically viable. Several catalysts like dolomite, alkaline metal, nickel, etc. have been incorporated which plays an essential role in higher product yield and tar reduction but holds problems like inactivity, regeneration, and cost. In this study, physio-chemical properties of coal bottom ash have been studied for its application as a catalyst in biomass steam gasification. The characterization of coal bottom ash comprises of surface morphology analysis, existing elements, pore size, and volume, as well as surface area and bulk density, were reported. The results showed that elements like Si, Fe, Al, Ca and Mg were present in coal bottom ash which have been previously used as a catalyst in biomass gasification. The pore diameter of coal bottom ash is 4 nm, the specific pore volume is 0.01474 cm3/g, specific surface area of 17.64 m2/g which lies it in mesoporous classification. Also, it is observed that CaO mineral exists in coal bottom ash support in reducing the CO2 gas while improving syngas yield. The presence of SiO2 shows that it can use as bed material while Fe2O3 improves the tar reduction in the product gas whereas CaO assists to capture CO2 in the process whereas, alumina resist sintering of metal catalyst. Coal bottom ash is economically viable due to abundance and low cost. Based on its composition (presence of Ca, Mg and other alkali metal) as analyzed .it can be used as an alkaline metal catalyst.

Pyrolysis behavior of biomass with different Ca-based additives

CaO is an important catalyst in biomass gasification and pyrolysis. However, CaO can stem from many precursors. And, the effect between different precursors has still not been studied. Calcined natural limestone, natural dolomite, calcium oxide, calcium carbonate, calcium acetate, and calcium propionate were used to investigate their pyrolysis reactivity of biomass (peanut shells and pine sawdust) at high temperature (>800 °C). Experiments were conducted using a thermogravimetric apparatus and a fixed-bed pyrolysis system. Pine sawdust displayed higher pyrolysis reactivity than peanut shells. During pyrolysis, Ca-based additives fixed carbon dioxide mainly in the temperature range of 300–700 °C. By addition of Ca-based additives, the concentrations of hydrogen and carbon monoxide were increased and the concentrations of methane and carbon dioxide (over 18 vol%) were decreased. De-carbonation started around 700 °C. The emission of CO2 by de-carbonation promoted the reduction of char by the Boudouard reaction and methane by the dry reforming reaction. The total pyrolysis conversion decreased as PI-Dol > PI-CaA > PI-Lime > PI-Ca > PI-CaP > PI Raw > PI-CaC. The excellent pyrolysis reactivity of biomass in the presence of calcined calcium acetate can be ascribed to its preeminent physical structure. Addition of Ca-based additives increased the activation energy of the main devolatilization region. The activation energy of biomass with calcined natural dolomite, about 110 kJ mol−1, was much lower than that of other Ca-based additives studied at high temperatures. Pyrolysis of the pure biomass sample can be simply hypothesized as a first order reaction, but it varied significantly with the addition of additives.

Olivine as tar removal catalyst in biomass gasification: Catalyst dynamics under model conditions

Olivine ((Mg,Fe)2SiO4) has been extensively explored as an active bed material for catalytic cracking of tars during gasification of biomass in dual fluidized bed reactors. It is known that both the elemental composition, addition of Fe and high temperature calcinations influence the catalytic properties of this mineral. However, it is not clear how olivine responds to the fairly hostile environments present during gasification or what chemical state Fe takes during operation. We have investigated the stability of Austrian olivine under model conditions, resembling those in a gasifier. Powder samples were heated to 750°C in a quartz-tube flow-reactor and sequentially exposed to oxidizing (O2, H2O, CO2) or reducing gases (CO, H2) or mixtures thereof, for various durations of time. Significant changes in phase composition of the material, depending on the gas composition and the duration of the treatments, were found using X-ray photo-electron spectroscopy (XPS), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and scanning electron microscopy (SEM). A large fraction of the Fe in the investigated material is present as free Fe-phases, which are sensitive to changes in the gas environment. After exposure to oxidizing gases, the free Fe phases are: Fe2O3 and Fe3O4 or MgFe2O4. Upon exposure to reducing gases, the iron oxides are converted into Fe0 and Fe3C and formation of graphitic carbon is observed. In addition, the elemental composition of the surface changes dramatically depending on the gas composition. After exposure to oxidizing environments, the amount of Fe at the surface is twice as high as after reduction. Both the change in chemical state of the Fe-phases, the amount of surface Fe and the build-up of surface carbon are fast processes under the applied conditions and significant changes are observed on the time scale of one minute. These observations have important implications for olivine as a tar cracking catalyst, especially when used in dual fluidized bed gasifiers. The fast reduction of the iron oxides upon switching from oxidizing to reducing conditions shows that olivine transports oxygen from the combustor into the gasifier. Furthermore, the catalytic properties of Fe depend strongly on its chemical state. Therefore, the catalytic function of olivine depends strongly on the gas environment and on the catalysts residence time in the gasifier. Finally, both the decreasing amount of surface-Fe and the carbon deposition observed after exposing olivine to reducing conditions can result in significant catalyst deactivation.

Development of a nano-Ni-La-Fe/Al2O3 catalyst to be used for syn-gas production and tar removal after biomass gasification

The objective of this study was to develop a supported tri-metallic catalyst (nano-Ni-La-Fe/γ-Al2O3) for tar removal in biomass steam gasification, to significantly enhance the quality of the produced gas. For this purpose, the supported tri-metallic catalysts were prepared by a deposition-precipitation (DP) method. Different analytical approaches were used to characterize the synthesized catalysts. The results showed that the prepared tri-metallic catalysts had an egg-shell structure with a specific surface area of 214.7 m2/g. The activity of the catalysts for gas production and tar removal in the process of biomass gasification was also investigated using a bench-scale combined fixed bed reactor. The experiments indicated that the tar yield after adding catalyst was reduced significantly and the efficiency of tar removal reached 99% for the biomass steam gasification at 800oC, while the gas yield after adding catalysts increased markedly and less coke was found over the catalyst. Meanwhile, the compositions of gas products before and after adding catalyst in the process also changed significantly; in particular, the content of hydrogen in catalytic steam gasification was improved by over 10 vol%. Therefore, using the prepared tri-metallic catalyst in biomass gasification can significantly improve the quality of the produced gas and efficiently eliminate the tar generation, preventing coke deposition on the catalyst surfaces, thus demonstrating a long lifetime of the catalyst.

Robust glass‐ceramics catalysts for biomass gasification

AbstractGlass‐ceramics offer high melting points (1200–1500°C), excellent attrition‐resistance, and very low coefficients of thermal expansion. We have found that these materials can be employed to create active supported catalysts, bulk catalysts, or a combination of the two. Supported catalysts are created by the process of thermal impregnation in which thermal energy is employed to graft oxides of catalytically active metals directly into the surfaces of glass‐ceramic and mineral‐based supports. Bulk catalysts are prepared by heat‐treating specially formulated Li and Mg‐aluminosilicate glasses containing up to 40 wt % NiO to create a fine‐grained (0.5–5 μm) multiphase, crystalline ceramic. When any of these materials are reduced with hydrogen, exposed surfaces reveal a metallic state. Laboratory testing with simulated syngas mixtures containing surrogate tars (naphthalene and toluene) shows that these new materials can exhibit strong catalytic activity for tar and methane decomposition as well as methanation at lower temperatures. This work is supported by US‐DOE Cooperative Agreement DE‐FG36‐04GO14314 and GTI internal research funding. © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Oxidation Reduction Behavior of Iron‐Bearing Olivines (FexMg1‐x)2SiO4 Used as Catalysts for Biomass Gasification.

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Syngas production by biomass gasification using Rh/CeO 2/SiO 2 catalysts and fluidized bed reactor

We have been developed novel catalysts for gasification of biomass with much higher energy efficiency than conventional methods (non-catalyst, dolomite, commercial steam reforming Ni catalyst). From the result of the gasification of cellulose over novel Rh/CeO 2/SiO 2 catalysts, it is found that the gasification process consists of the reforming of tar and the combustion of solid carbon. We also tested novel Rh/CeO 2/SiO 2 in the gasification with air, pyrogasification, and steam reforming of cedar wood. As a result, Rh/CeO 2/SiO 2 gave higher yield of syngas than the conventional steam reforming Ni catalyst. Furthermore, we compared the performance between single and dual bed reactors. Single bed reactor was effective in the gasification of cedar, however, it was not suitable for the gasification of rice straw since a rapid deactivation was observed. Gasification of rice straw, jute stick, baggase using the fluidized dual-bed reactor and Rh/CeO 2/SiO 2 was also investigated. Especially, the catalyst stability in the gasification of rice straw clearly was enhanced by using the fluidized dual bed reactor.

Novel Catalysts for Gasification of Biomass with High Conversion Efficiency

We have developed catalysts for the gasification of biomass with much higher energy efficiency than the conventional methods (noncatalyst, dolomite, and commercial steam reforming Ni catalyst). In our investigation, the Rh/CeO2 gave high yields of syngas for cellulose gasification using a fluidized-bed reactor with batch feeding of cellulose. However, the catalyst was deactivated because of sintering of CeO2 during the reaction. To prevent the CeO2 sintering, we have further improved the catalyst and found that Rh/CeO2/SiO2 was quite stable for the gasification of cellulose. It was demonstrated that Rh/CeO2/SiO2 gave almost complete gasification of real biomass (wood powder) at 873 K. These results indicate that the combination of this kind of catalyst and fluidized-bed reactor can realize the energy-efficient biomass gasification.

97/01029 Calcined dolomite, magnesite, and calcite for cleaning hot gas from a fluidized bed biomass gasifier with steam: life and usefulness

We have been developed novel catalysts for gasification of biomass with much higher energy efficiency than conventional methods (non-catalyst, dolomite, commercial steam reforming Ni catalyst). From the result of the gasification of cellulose over novel Rh/CeO2/SiO2 catalysts, it is found that the gasification process consists of the reforming of tar and the combustion of solid carbon. We also tested novel Rh/CeO2/SiO2 in the gasification with air, pyrogasification, and steam reforming of cedar wood. As a result, Rh/CeO2/SiO2 gave higher yield of syngas than the conventional steam reforming Ni catalyst. Furthermore, we compared the performance between single and dual bed reactors. Single bed reactor was effective in the gasification of cedar, however, it was not suitable for the gasification of rice straw since a rapid deactivation was observed. Gasification of rice straw, jute stick, baggase using the fluidized dual-bed reactor and Rh/CeO2/SiO2 was also investigated. Especially, the catalyst stability in the gasification of rice straw clearly was enhanced by using the fluidized dual bed reactor.