Novel Sorbents for Removal of Mercury, Arsenic, Sulfur and Halides from Coal-Derived Synthesis Gas

Although the Fischer-Tropsch (FT) process for the production of liquid fuels from coal, natural gas, and biomass is run on a commercial scale in both South Africa and Malaysia, several challenges remain, in particular, the need to supply a clean, essentially-contaminant-free synthesis gas feed stream. This project will develop a low-cost, high-capacity sorbent that can remove trace contaminants ¿ including sulfur, halides, arsenic, and mercury ¿ from coal-derived synthesis gas. The sorbent will reduce the concentration of all these contaminants to ppbv levels, providing optimum protection for the FT synthesis catalysts used to convert coal derived synthesis gas into liquid fuels. Unlike the commercially available trace metal adsorbents or sulfur polishing sorbents, the proposed sorbent will operate at the exit temperature of the warm gas clean-up step (500oF). Phase I developed a highly active sorbent that can reduce the concentration of sulfur, halides, nitrogen compounds and trace metals (such as arsenic and mercury) to ultra low levels. In a preliminary cost analysis, the economic viability of the process was demonstrated. Phase II will continue to improve the performance of the sorbent, and its production will be scaled-up using commercial manufacturing techniques. The concept will be demonstrated at a larger scale using actual coal-derived synthesis gas, and a detailed system analysis and engineering assessment will be conducted. Commercial Applications and other Benefits as described by the awardee: A viable alternative to crude oil is needed to moderate the effect of oil price hikes and provide an interim bridge until some other fuel source can commercially supplant petroleum-based fuels. Coal is the most promising resource with over 250 billion tons of known domestic reserves. FT synthesis is the most economically viable method of converting coal into transportation fuels. The proposed gas clean-up technology should become an enabling technology for coal-to-­liquids production.