Abstract: This paper reviews the technical feasibility and economics of biomass integrated gasification–Fischer Tropsch (BIG-FT) processes in general, identifies most promising system configurations and identifies key R&D issues essential for the commercialisation of BIG-FT technology. The FT synthesis produces hydrocarbons of different length from a gas mixture of H2 and CO. The large hydrocarbons can be hydrocracked to form mainly diesel of excellent quality. The fraction of short hydrocarbons is used in a combined cycle with the remainder of the syngas. Overall LHV energy efficiencies, 1 calculated with the flowsheet modelling tool Aspenplus, are 33–40% for atmospheric gasification systems and 42–50% for pressurised gasification systems. Investment costs of such systems ( 367 MW th ) are MUS$ 280–450, 2 depending on the system configuration. In the short term, production costs of FT-liquids will be about US$ 16/GJ. In the longer term, with large-scale production, higher CO conversion and higher C5+ selectivity in the FT process, production costs of FT-liquids could drop to US$ 9/GJ. These perspectives for this route and use of biomass-derived FT-fuels in the transport sector are promising. Research and development should be aimed at the development of large-scale (pressurised) biomass gasification-based systems and special attention must be given to the gas cleaning section.

Abstract: The Fischer–Tropsch (FT) synthesis is used to produce chemicals, gasoline and diesel fuel. The FT products are predominantly linear, hence the quality of the diesel fuel is very high, having cetane numbers of up to 75. Since purified synthesis gas is used in the FT process all the products are S- and N-free. In this review the production of syngas and the various options used in the FT process (reactors and catalyst types, and high and low temperature operation) are discussed. The best FT option for producing high quality diesel is using cobalt-based catalyst in slurry phase reactor, gearing the process for high wax production and then selectively hydrocracking the wax to diesel fuel. The overall diesel pool has a high cetane number, the aromatic S and N contents are zero and the exhaust emissions are significantly lower than for standard diesel fuels. © 2001 Society of Chemical Industry

Abstract: The effect of Ni content on the Ni/Ce-ZrO2 catalyst has been investigated in the methane conversion reactions to syngas, such as oxy-reforming, steam reforming and oxy-steam reforming. Among the catalysts examined, Ni/Ce-ZrO2 catalyst with 15% Ni loading exhibits not only the highest catalytic activity and selectivity but also remarkable stability. The TPR results reveal that strong interaction between support and metal exists and that some part of NiO incorporates into the surface of the Ce-ZrO2 support. Combined with H2 chemisorption results, one may deduce that Ni surface area and the chemical environment of nickel, as well as the properties of the Ce-ZrO2 support, play very important roles in the catalytic activity and stability of Ni/Ce-ZrO2 catalysts. It seems that two kinds of active sites, i.e. one for methane and the other for steam or oxygen, are well-balanced on 15% Ni/Ce-ZrO2 catalyst.

Abstract: The excellent catalytic performance and high stability of MgO–NiO solid solution catalysts in CH4 conversion to syngas generated the recent outburst of interest for the binary MgO-based solid solutions. This review will focus on the relationship between the catalytic performance of the binary MgO-based solid solution and its properties in the CO2 reforming, the partial oxidation and the steam reforming of methane. First, the development of methane conversion to syngas will be summarized. Second, the role of the basicity and of the solid solution in the design of a catalyst that can inhibit carbon deposition and active metal sintering will be examined. Third, the main results regarding the catalytic performance of the MgO-based solid solutions will be presented. Fourth, detailed information regarding the effects of the NiO/MgO composition, surface area, pore distribution, crystal lattice parameter, precursors, and preparation condition on its catalytic behavior will be provided.

Abstract: A coal syngas or other syngas fired power plant is provided with no atmospheric emissions. Coal or other starter fuel is gasified within a gasifier which also receives oxygen and steam therein. The oxygen is provided from an air separator. Syngas produced within the gasifier is combusted within a gas generator along with oxygen from the air separator. Water is also introduced into the gas generator to control the temperature of combustion of the syngas with the oxygen. Products of combustion including steam and carbon dioxide are produced within the gas generator. The combustion products are expanded through a turbine for power output and then separated, such as within a condenser. Water discharged from the condenser is at least partially recirculated back to the gasifier and the gas generator. Carbon dioxide from the separator is compressed for capture without release into the atmosphere.

Abstract: A rigorous kinetic model was derived for the formation on a nickel catalyst of filamentous carbon by the Boudouard reaction and for the gasification of filamentous carbon by carbon dioxide, by hydrogen, and by steam. The experimental study was performed in an electrobalance unit. Carbon formation and gasification experiments were performed at temperatures ranging from 773 to 848 K. The partial pressures of the various components were chosen in the ranges encountered in industrial steam reformers. The influence of the carbon formation reaction on the subsequent gasification process was also investigated. The mode of experimentation ensured that the rates of growth or gasification of the carbon filaments were always based on the same number of carbon filaments. The same reaction mechanism was derived from the study both of methane cracking and the Boudouard reaction and of the reverse reactions, gasification by hydrogen and carbon dioxide. Using the results of the parameter estimation, energy diagrams were ...

Abstract: Methane reforming by carbon dioxide was investigated over 5 wt.% Ni/CaO-Al2O3 catalyst. X-ray diffraction (XRD) and temperature-programmed reduction (TPR) techniques were applied to characterise the catalyst. The catalyst exhibited high activity and very good stability at stoichiometric methane and carbon dioxide feed. The addition of steam in the reacting mixture was tested and proved beneficial for the conversion of methane and the drastic decrease in carbon deposition. The kinetic behaviour of the catalyst was investigated as a function of temperature and methane and carbon dioxide partial pressures. The apparent activation energies of the two reactants CH4 and CO2 were estimated 25.5 ± 2.0 and 23.6 ± 1.8 kcal/mol, respectively and that of CO was 24.6 ± 1.2 kcal/mol while hydrogen activation energy was estimated at 35.2 ± 3.2 kcal/mol. Partial pressure dependencies of the reaction rates were obtained at 630 ◦ C. The increase of H2 partial pressure resulted in an acceleration of the CO formation, while an increase in CO partial pressure demonstrated the inhibiting role in H 2 formation and the conversion of the reactants. © 2002 Elsevier Science B.V. All rights reserved.

Abstract: A steam biomass gasification process has been demonstrated in Gussing, AT. The combined heat and power (CHP) plant has a fuel capacity of 8 MW and an electrical output of about 2 MWel with an electrical efficiency of about 25 %. Wood chips with a water content of 20 - 30 % are used as fuel. The plant consists of a dual fluidized bed steam gasifier, a two stage gas cleaning system , a gas engine with an electricity generator, and a heat utilization system. The start up of the plant was in January 2002 and until September 2002 2500 hours of operation with the gasifier and the gas cleaning system and 750 hours of operation with the gas engine could be reached. The overall performance of the CHP plant is very good, however, some minor problems had to be solved. The most important parts operate quite well only the cooler of the producer gas had to be improved. In Austria and also in other European countries there are currently good conditions for an economical operation of an CHP-plant based on biomass due to high prices for green electricity. Nevertheless, further efforts have to be done to reduce the investment as well as the operating costs. The producer gas has a high amount of H2 and CO and is therefore also well suited for the production of synthesis gas.

Abstract: The impact of the Group I alkali metals upon the activity of iron catalysts has been obtained at medium pressure synthesis conditions and at the same conversion levels. The relative impact of the alkali metal depends upon the conversion level with potassium being the promoter that impacts the highest activity at all conversion levels. At low conversions, Li is nearly as effective as potassium in improving the catalytic activity but is the poorest promoter at high conversion levels. In fact, three alkalis (Li, Cs and Rb) should be viewed as inhibitors since they decrease the catalytic activity for CO conversion below that of the unpromoted iron catalyst. The differences in the impact of the various Group I alkali metals at lower (≲40%) conversions are slight but become much greater at higher CO conversion levels. The major differences of the alkali metals at higher conversion levels is due to the impact of the promoter upon the water–gas-shift (WGS) reaction. At higher conversion levels, with a synthesis gas or “syngas” of H2/CO=0.7, the WGS reaction becomes rate controlling because hydrogen production becomes the rate limiting factor in the Fischer–Tropsch synthesis (FTS). The basicity of the promoter appears to be the determining factor for the rate of catalyst deactivation and on the secondary hydrogenation of ethene.

Abstract: The present invention relates to a process and apparatus for processing agricultural waste to make alcohol and/or biodiesel. The agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon monoxide and hydrogen. The syngas is converted to an alcohol which may be stored, sold, used, or fed directly to a reactor for production of biodiesel. The solids effluent from the anaerobic digester can be further utilized as slow release, organic certified fertilizer. Additionally, the wastewater from the process is acceptable for immediate reuse in agricultural operations.

Abstract: The structure, reduction/carburization, and catalytic performance of K- and Cu-promoted Fe2O3 during initial contact with synthesis gas were examined by combining kinetic analysis of the initial stages of Fischer−Tropsch synthesis (FTS) with X-ray absorption spectroscopy. Oxygen removal initially occurs without FTS reactions as Fe2O3 is reduced to inactive oxygen-deficient Fe2O3 species. Hydrocarbon synthesis reactions become detectable only as Fe3O4 forms and rapidly converts to FeCx. FTS reactions require only the incipient conversion of the surface layers to a dynamic and active surface phase, which consists of FeCx with steady-state surface coverages of vacancies, formed via oxygen and carbon removal during the formation of monomers, CO2, and H2O. Such surfaces tend to respond to changes in the contacting gas phase within turnover times by changing the relative surface concentration of carbon, oxygen, CO, and hydrogen. The catalytic behavior of these dynamic surfaces is largely independent of the carb...

Abstract: CO2 reaction and formation pathways during Fischer–Tropsch synthesis (FTS) on a co-precipitated Fe–Zn catalyst promoted with Cu and K were studied using a kinetic analysis of reversible reactions and with the addition of 13C-labeled and unlabeled CO2 to synthesis gas. Primary pathways for the removal of adsorbed oxygen formed in CO dissociation steps include reactions with adsorbed hydrogen to form H2O and with adsorbed CO to form CO2. The H2O selectivity for these pathways is much higher than that predicted from WGS reaction equilibrium; therefore readsorption of H2O followed by its subsequent reaction with CO-derived intermediates leads to the net formation of CO2 with increasing reactor residence time. The forward rate of CO2 formation increases with increasing residence time as H2O concentration increases, but the net CO2 formation rate decreases because of the gradual approach to WGS reaction equilibrium. CO2 addition to synthesis gas does not influence CO2 forward rates, but increases the rate of their reverse steps in the manner predicted by kinetic analyses of reversible reactions using non-equilibrium thermodynamic treatments. Thus the addition of CO2 could lead to the minimization of CO2 formation during FTS and to the preferential removal of oxygen as H2O. This, in turn, leads to lower average H2/CO ratios throughout the catalyst bed and to higher olefin content and C5+ selectivity among reaction products. The addition of 13CO2 to H2/12CO reactants did not lead to significant isotopic enrichment in hydrocarbon products, indicating that CO2 is much less reactive than CO in chain initiation and growth. We find no evidence of competitive reactions of CO2 to form hydrocarbons during reactions of H2/CO/CO2 mixtures, except via gas phase and adsorbed CO intermediates, which become kinetically indistinguishable from CO2 as the chemical interconversion of CO and CO2 becomes rapid at WGS reaction equilibrium.

Abstract: Partial oxidation of methane to synthesis gas over 0.5 wt.% Pt/Al_2O_3 and 0.5 wt.% Pt/CeO_2 catalysts was studied in a packed-bed reactor and supplementary runs of methane reforming with carbon dioxide were carried out. Fresh and used catalysts were characterized by nitrogen adsorption (BET method) for total surface area, and by H_2 and CO chemisorption or by the rate of propene hydrogenation for metal surface area. At temperatures up to 650°C, the Pt/CeO_2 catalyst gave considerably higher methane conversion and higher selectivity to CO and H_2 but above 700°C, the activities and selectivities of both catalysts were comparable. The Pt/CeO_2 catalyst maintained high selectivity to CO and H_2 when the CH_4:O_2 feed ratio varied from 1.7 to 2.3 while the Pt/Al_2O_3 catalyst had lower activity and selectivity under methane-rich conditions. The Pt/CeO_2 catalyst was also more active for methane reforming by carbon dioxide.

Abstract: The gasification of biomass is a thermal treatment, which results in a high production of gaseous products and small quantities of char and ash. Steam reforming of hydrocarbons, partial oxidation of heavy oil residues, selected steam reforming of aromatic compounds, and gasification of coals and solid wastes to yield a mixture of H 2 and CO (syngas), followed by water-gas shift conversion to produce H 2 and CO 2 , are well-established processes. The steam capability can be significantly improved by permitting the classical Ni-alumina or Ni-silica/alumina formulations with Ca and/or K. Three types of catalysts were tested: alumina, aluminosilicate material, and nickel-supported catalyst.

Abstract: The main objective of this project is the development of an economically viable thermocatalytic process for production of hydrogen and carbon from natural gas or other hydrocarbon fuels with minimal environmental impact. The three major technical goals are: (i) to accomplish efficient production of hydrogen and carbon via sustainable catalytic decomposition of methane or other hydrocarbons using inexpensive, durable catalysts, (ii) to obviate the concurrent production of CO/CO2 byproducts and drastically reduce (preferably, eliminate) CO2 emissions from the process, and (iii) to produce valuable carbon products in order to reduce the cost of hydrogen production The approach is based on thermocatalytic decomposition of hydrocarbons over carbon-based catalysts in an air/water-free environment. The important feature of the process is that the reaction is catalyzed by carbon particulates produced in the process, so no external catalyst is required (except for the start-up operation). This results in the following advantages: (1) no CO/CO2 byproducts are generated during hydrocarbon decomposition stage, (2) no expensive catalysts are used in the process, (3) no catalyst regeneration is required (in contrast to metal catalyst-based processes), (4) several valuable forms of carbon can be produced in the process depending on the process conditions (e.g., turbostratic carbon, pyrolytic graphite, spherical carbon particles, carbon filaments etc.), (5) CO2 emissions could be drastically reduced (compared to conventional processes). The following is a brief description of major findings:

Abstract: A method and a plant for simultaneous production of a gas for injection into an oil field and production of methanol, dimethyl ether and/or other oxygenated hydrocarbons or production of higher hydrocarbons from natural gas is disclosed. An air separation unit (ATR) for production of pure nitrogen for injection and pure oxygen for production of synthesis gas ('syngas') by authermal reformation of a natural gas is an essential part of the method and plant.

Abstract: The effect of water on the catalytic properties of a ruthenium promoted Co/TiO2 catalyst (10 wt.%) during Fischer–Tropsch synthesis (FTS) was investigated in a continuously stirred tank reactor (CSTR) by adding water into the feed gas at varying space velocity. At higher synthesis gas (syngas) space velocities (SV=8 or 4 NL g cat.−1 h−1), the addition of water did not have significant effect on the CO conversion. At lower space velocity (SV=2 NL g cat.−1 h−1), the addition of water decreased the CO conversion; however, the decrease was reversible with the catalyst quickly recovering the activity that it exhibited prior to water addition. At high CO conversion (space velocity of SV=1 NL g cat.−1 h−1), the addition of water resulted in permanent catalyst deactivation.

Abstract: The direct conversion of methane and carbon dioxide to produce C4 hydrocarbons (C4H8, n-C4H10, i-C4H10) and synthesis gas (H2 + CO) was investigated over quartz fleece, zeolite NaA, zeolite NaY, and zeolite HY catalysts promoted by dielectric-barrier discharges (DBDs) at relatively low temperatures and ambient pressure. Both pore size and electrostatic properties of zeolites influence the reaction under plasma conditions. Zeolite HY is the most promising catalyst in producing synthesis gas (H2 + CO) and C4 hydrocarbons (C4H8, n-C4H10, i-C4H10) with high selectivity at low temperatures and ambient pressure. The important variables affecting the activity and selectivity of a zeolite HY catalyst in a DBD reactor such as temporal stability, discharge power, mixing ratios of methane to carbon dioxide, space velocity, operating pressure, and wall temperature were studied. The conversion of methane was 55.1% and that of carbon dioxide 26.7%, and the selectivity to CO was 21.7% and that to C4 hydrocarbons reached...

Abstract: An active and relatively stable Ni-Ce-ZrO2 catalyst has been designed and prepared conveniently by a novel one-step co-precipitation/digestion method. This catalyst exhibited higher stability compared with a catalyst having the same composition but prepared using the conventional impregnation method. It was found that 15% Ni (w/w) co-precipitated with Ce-ZrO2 making the cubic phase of Ce0.8Zr0.2O2 gave synthesis gas with CH4 conversion more than 97% at 800 °C and that the activity was maintained for 100 h during the reaction. The higher activity, conversion and stability of these catalysts are mainly related to the nano-crystalline nature of cubic Ce1-xZrxO2 producing strong interaction with finely dispersed nano-sized NiOx crystallites.

Abstract: The effect of the addition of small amounts of boron, ruthenium and rhenium on the Fischer–Tropsch (F–T) catalyst activity and selectivity of a 10 wt.% Co/TiO2 catalyst has been investigated in a continuously stirred tank reactor (CSTR). A wide range of synthesis gas conversions has been obtained by varying space velocities over the catalysts. The addition of a small amount of boron (0.05 wt.%) onto Co/TiO2 does not change the activity of the catalyst at lower space times and slightly increases synthesis gas conversion at higher space times. The product selectivity is not significantly influenced by boron addition for all space velocities investigated. Ruthenium addition (0.20 wt.%) onto Co/TiO 2 and CoB/TiO2 catalysts improves the catalyst activity and selectivity. At a space time of 0.5 h-g cat./NL, synthesis gas conversion increases from 50–54 to 68–71% range and methane selectivity decreases from 9.5 to 5.5% (molar carbon basis) for the promoted catalyst. Among the five promoted and non-promoted catalysts, the rhenium promoted Co/TiO 2 catalyst (0.34 wt.% Re) exhibited the highest synthesis gas conversion, and at a space time of 0.5 h-g cat./NL, synthesis gas conversion was 73.4%. In comparison with the results obtained in a fixed bed reactor, the catalysts displayed a higher F–T catalytic activity in the CSTR. © 2002 Elsevier Science B.V. All rights reserved.

Abstract: The temperature profile of the fixed catalyst bed in methane reforming with CO 2 and O 2 was investigated over Pt/Al 2 O 3 and Ni/Al 2 O 3 . The activities on Pt/Al 2 O 3 and Ni/Al 2 O 3 were in the same level in methane reforming with CO 2 . On the other hand, the activity of methane combustion over the catalysts was significantly different (Pt/Al 2 O 3 ⪢Ni/Al 2 O 3 ). In methane reforming with CO 2 and O 2 , methane conversion over Pt/Al 2 O 3 was considerably higher than over Ni/Al 2 O 3 . From the profiles of bed temperature measurements under various reaction conditions, one sees that the distance between combustion and reforming zones becomes very short. This is related to the high reducibility of Pt metal itself, and Pt maintains metallic state in the combustion zone and under the presence of oxygen. In this case, the combustion heat can be supplied to the reforming reaction very effectively. The result can be connected to the synthesis gas production with high energy efficiency.

Abstract: This paper discusses novel schemes of combined cycle, where natural gas is chemically treated to remove carbon, rather than being directly used as fuel. Carbon conversion to CO 2 is achieved before gas turbine combustion. Therefore CO 2 can be removed from fuel (rather than from exhausts, thus utilizing less demanding equipment) and made available for long-term storage, to avoid dispersion toward the atmosphere and the consequent contribution to the greenhouse effect. The strategy here proposed to achieve this goal is natural gas partial oxidation. The second part of the paper will address steam/methane reforming. Partial oxidation is an exothermic oxygen-poor combustion devoted to CO and H 2 production. The reaction products are introduced in a multiple stage shift reactor converting CO to CO 2 . Carbon dioxide is removed by means of physical or chemical absorption processes and made available for storage, after compression and liquefaction. The resulting fuel mainly consists of hydrogen and nitrogen, thus gas turbine exhausts are virtually devoid of CO 2 . The paper discusses the selection of some important parameters necessary to obtain a sufficient level of conversion in the various reactors (temperature and pressure levels, methane-to-air or methane-to-steam ratios) and their impact on the plant integration and on the thermodynamic efficiency. Overall performance (efficiency, power output, and carbon removal rate) is predicted by means of a computational tool developed by the authors. The results show that a net efficiency of 48.5 percent, with a 90 percent CO 2 removal, can be obtained by combined cycles based on large heavy duty machines of the present technological status, either by using chemical or physical absorption.

Abstract: A method of producing syn gas from biomass or other carbonaceous material utilizes a controlled devolatilization reaction in which the temperature of the feed material is maintained at less than 450°F until most available oxygen is consumed. This minimizes pyrolysis of the feed material. The method and apparatus utilizes the formed synthesis gas to provide the energy for the necessary gasification. This provides for a high purity syn as and avoids production of slag.