ADSORPTIVE REMOVAL OF CATALYST POISONS FROM COAL-GAS FOR METHANOL SYNTHESIS

As an integral part of the liquid-phase methanol (LPMEOH) process development program, the present study evaluated adsorptive schemes to remove traces of catalyst poisons such as iron carbonyl, carbonyl sulfide, and hydrogen sulfide from coal gas on a pilot scale. Tests were conducted with coal gas from the Cool Water gasification plant at Daggett, California. Iron carbonyl, carbonyl sulfide, and hydrogen sulfide were effectively removed from the coal gas. The adsorption capacities of Linde H-Y zeolite and Calgon BPL carbon for Fe(CO)5 compared well with previous bench-scale results at similar CO2 partial pressure. Adsorption of COS by Calgon FCA carbon appeared to be chemical and nonregenerable by thermal treatment in nitrogen. A Cu/Zn catalyst removed H2S very effectively. With the adsorption system on-line, a methanol catalyst showed stable activity during 120 h of operation, demonstrating the feasibility of adsorptive removal of trace catalyst poisons from the synthesis gas. Mass transfer coefficients were estimated for Fe(CO)5 and COS removal which can be directly used for design and scale up.