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To fulfill the requirement for synthetic fuel (synfuel) production in theFischer-Tropsch process, in which syngas fed to the process has a H2/CO mole ratio approaching 2, gasification of lignite coal is needed. In this research, char particles were prepared by pyrolysis of lignite coal at controlled heating rates to obtain the highest possible surface area for gasification. In the gasification process, char with a surface area of 172.5 m 2 /g was used, along with the catalyst K2CO3 in a fixed bed reactor. In this research, there were variations in the steam/char mass ratio Results of this research showed that the highest H2/CO mole ratio of 2.07 corresponding to the mole ratio of gas yield/carbon of 1.13 was achieved at the gasification temperature of 675 o C using the catalyst K2CO3; the steam/char mass ratio was 2.0. However, at the same gasification conditions-but without a catalyst-the H2/CO mole ratio and corresponding mole ratio of gas yield/carbon were 3.02 and 0.42, respectively. A finding of this research was that the addition of the catalyst K2CO3 to gasification of lignite char adversely reduced the mole ratio of H2/CO compared to gasification without catalysis. It is suspected that the high composition of mineral ash in coal ash reacted with the K2CO3 catalyst, thus causing the Boudouard reaction to compete considerably with the water-gas reaction. The increases in gasification temperature and the steam/carbon ratio lowered the mole ratio of H2/CO in syngas.

This study investigated lump kinetic analysis of Fischer-Tropsch synthesis over Cobalt and CobaltRhenium Alumina supported catalyst (Co/γ-Al2O3 and Co-Re/γ-Al2O3) at 20 bars and 483 K using feed gas with molar H2/CO ratios of 1.0 to 2.1. Syngas with H2/CO molar ratio of 1.0 represents syngas characteristic derived from biomass, while the 2.1 molar ratio syngas derived from coal. Rhenium was used as the promoter for the cobalt catalyst. Isothermal Langmuir adsorption mechanism was used to build kinetic model. Existing kinetic model of Fischer-Tropsch synthesis over cobalt alumina supported catalysts only valid for operating pressure less than 10 bar. CO insertion mechanism with hydrogenation step of catalyst-adsorbed CO by catalyst-adsorbed H component as the rate-limiting step is valid for operating condition in this research. Higher H2/CO ratio makes faster hydrogenation step and lessproduct dominated in the associative CO adsorption step and dissociative H2 adsorption equilibrium step. Kinetic constant for hydrogenation step increases 73-421% in syngas with 2.1 H2/CO molar ratio compared to condition with 1.0 H2/CO molar ratio. Faster hydrogenation step (with higher kinetic constant) results in higher reactant conversion. Equilibrium constant for associative CO adsorption and dissociative H2 adsorption step decreases 53-94% and 13-82%, respectively, in syngas with higher H2/CO molar ratio. Less product dominated reactant adsorption step (lower equilibrium constant for CO and H2 adsorption step) gives higher CH4 product selectivity, which occurred on 2.1 molar ratio of syngas. Rhenium (Re) metal on cobalt catalyst with composition 0.05%Re-12%Co/γ-Al2O3 only gives effect as structural promoter, which only increases reactant conversion with the same product selectivity.

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