Methane steam reforming for synthetic diesel fuel production from steam-hydrogasifier product gases

Abstract

Steam-methane reforming (SMR) reaction was studied using a tubular reactor packed with NiO/γ-Al 2 O 3 catalyst to obtain synthesis gases with H 2 /CO ratios optimal for the production of synthetic diesel fuel from steamhydrogasification of carbonaceous materials. Pure CH 4 and CH 4 -CO 2 mixtures were used as reactants in the presence of steam. SMR runs were conducted at various operation parameters. Increasing temperature from 873 to 1,023 K decreased H 2 /CO ratio from 20 to 12. H 2 /CO ratio decreased from 16 to 12 with pressure decreasing from 12.8 to 1.7 bars. H 2 /CO ratio also decreased from about 11 to 7 with steam/CH 4 ratio of feed decreasing from 5 to 2, the lowest limit to avoid severe coking. With pure CH 4 as the feed, H 2 /CO ratio of synthesis gas could not be lowered to the optimal range of 4-5 by adjusting the operation parameters; however, the limitation in optimizing the H 2 /CO ratio for synthetic diesel fuel production could be removed by introducing CO 2 to CH 4 feed to make CH 4 -CO 2 mixtures. This effect can be primarily attributed to the contributions by CO 2 reforming of CH 4 as well as reverse water-gas shift reaction, which led to lower H 2 /CO ratio for the synthesis gas. A simulation technique, ASPEN Plus, was applied to verify the consistency between experimental data and simulation results. The model satisfactorily simulated changes of H 2 /CO ratio versus the operation parameters as well as the effect of CO 2 addition to CH 4 feed.