Durable Zinc Oxide-Based Regenerable Sorbents for Desulfurization of Syngas in a Fixed-Bed Reactor

A fixed-bed regenerable desulfurization sorbent, identified as RVS-land developed by researchers at the U.S. Department of Energy's National Energy Technology Laboratory, was awarded the R&D 100 award in 2000 and is currently offered as a commercial product by Sued-Chemie Inc. An extensive testing program for this sorbent was undertaken which included tests at a wide range of temperatures, pressures and gas compositions both simulated and generated in an actual gasifier for sulfidation and regeneration. This testing has demonstrated that during these desulfurization tests, the RVS-1 sorbent maintained an effluent H2S concentration of <5 ppmv at temperatures from 260 to 600 C (500-1100 F) and pressures of 203-2026 kPa(2 to 20 atm) with a feed containing 1.2 vol% H{sub 2}S. The types of syngas tested ranged from an oxygen-blown Texaco gasifier to biomass-generated syngas. The RVS-1 sorbent has high crush strength and attrition resistance, which, unlike past sorbent formulations, does not decrease with extended testing at actual at operating conditions. The sulfur capacity of the sorbent is roughly 17 to 20 wt.% and also remains constant during extended testing (>25 cycles). In addition to H{sub 2}S, the RVS-1 sorbent has also demonstrated the ability to remove dimethyl sulfide and carbonyl sulfide from syngas. During regeneration, the RVS-1 sorbent has been regenerated with dilute oxygen streams (1 to 7 vol% O{sub 2}) at temperatures as low as 370 C (700 F) and pressures of 304-709 kPa(3 to 7 atm). Although regeneration can be initiated at 370 C (700 F), regeneration temperatures in excess of 538 C (1000 F) were found to be optimal. The presence of steam, carbon dioxide or sulfur dioxide (up to 6 vol%) did not have any visible effect on regeneration or sorbent performance during either sulfidation or regeneration. A number of commercial tests involving RVS-1 have been either conducted or are planned in the near future. The RVS-1 sorbent has been tested by Epyx, Aspen Systems and McDermott Technology (MTI), Inc for desulfurization of syngas produced by reforming of hydrocarbon liquid feedstocks for fuel cell applications. The RVS-1 sorbent was selected by MTI over other candidate sorbents for demonstration testing in their 500-kW ship service fuel cell program. It was also possible to obtain sulfur levels in the ppbv range with the modified RVS-1 sorbent

Low Temperature Sorbents for Removal of Sulfur Compounds from Fluid Feed Streams

A sorbent material is provided comprising a material reactive with sulfur, a binder unreactive with sulfur and an inert material, wherein the sorbent absorbs the sulfur at temperatures between 30 and 200 C. Sulfur absorption capacity as high as 22 weight percent has been observed with these materials

Catalysts for Conversion of Methane to Higher Hydrocarbons

Catalysts for converting methane to higher hydrocarbons such as ethane and ethylene in the presence of oxygen at temperatures in the range of about 700 to 900{degrees}C are described. These catalysts comprise calcium oxide or gadolinium oxide respectively promoted with about 0.025--0.4 mole and about 0.1--0.7 mole sodium pyrophosphate. A preferred reaction temperature in a range of about 800 to 850{degrees}C with a preferred oxygen-to-methane ratio of about 2:1 provides an essentially constant C{sub 2} hydrocarbon yield in the range of about 12 to 19 percent over a period of time greater than about 20 hours