Advanced Syngas Upgrading Process for Conversion of Low-Rank Coals to Liquid Fuels

Abstract

Syngas cleanup is a major challenge in any coal or biomass gasification application. A modified syngas cleanup process is under development to improve syngas from low rank coals for CTL (coal to liquids) applications. Novel steam reforming catalysts were developed to convert tars and light hydrocarbons and decompose ammonia in the presence of syngas contaminants such as H 2 S (< 500 ppm). Process goals are to improve syngas yield and H 2 :CO ratio while reducing water gas shift and downstream gas cleanup requirements. Laboratory reforming experiments were focused on developing information to support a techno-economic analysis using TRIG (transport reactor integrated gasifiers) or LURGI gasifiers. A CTL with carbon capture model was developed to compare the economics of the new process including the catalytic steam reforming to DOE (Department of Energy) baseline CTL. Reforming catalysts were developed that had high methane, tar, and ammonia conversion in presence of 90 ppm H 2 S. Higher concentrations of H 2 S affected conversion of methane but catalyst performance was fairly stable for the duration of testing. Results of modeling indicated that economics of the new process were nearly identical to the baseline CTL case, but greenhouse gas emissions for a given production of fuels were approximately 50% lower.