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DOE Project OfficerReporting Period OBJECTIVESThe objective of this study is to develop advanced high-temperature coal gas desulhrization mixed-metal oxide sorbents with stable ammonia decomposition materials at 550-800" C ( 1022-1472" F). The specific objectives of the project are to:(i) Develop a combined sorbent-catalyst materials shall be capable of removing hydrogen sulfide to less than 20 ppmv and ammonia by at least 90 percent.(ii) Carry out comparative fixed-bed studies of absorption and regeneration with various formulations of sorbent-catalyst systems and select most promising sorbent-catalyst type.(iii) Conduct long-term (at least 30 cycles) durability and chemical reactivity in the fixed-bed with the superior sorbent-catalyst. BACKGROUND INFORMATION

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The objective of this study is to develop advanced high-temperature coal gas desulhrization mixed-metal oxide sorbents with stable ammonia decomposition materials at 550-800" C (1022-1472" ' F). The specific objectives of the project are to: (i) Develop a conibined sorbent-catalyst materials sliall be capable of removing hydrogen sulfide to less than 20 ppniv and ammonia by at least 90 percent. (ii) Carry out coinparative fixed-bed studies of absorption and regeneration with various formulations of sorbent-catalyst systems and select most promising sofbent-catalyst type. (iii) Conduct long-term (at least 30 cycles) clurability and chemical reactivity in the fixed-bed with the superior sorbent-catalyst. BACKGROUND INFORMATION Nitrogen (NJ occurs in coal in the form of tightly bound organic ring compounds, typically at levels of 1 to 2 wt% on a dry-ash-free basis. Diiring, coal gasification, this fuel

Advanced integrated gasification combined cycle (IGCC) power plants nearing completion, such as Sierra-Pacific, employ a circulating fluidized-bed (transport) reactor hot-gas desulfurization (HGD) process that uses 70-180 µm average particle size (aps) zinc-based mixed-metal oxide sorbent for removing H 2 S from coal gas down to less than 20 ppmv. The sorbent undergoes cycles of absorption (sulfidation) and air regeneration. The key barrier issues associated with a fluidized-bed HGD process are chemical degradation, physical attrition, high regeneration light-off (initiation) temperature, and high cost of the sorbent. Another inherent complication in all air-regeneration-based HGD processes is the disposal of the problematic dilute SO 2 containing regeneration tail-gas. Direct Sulfur Recovery Process (DSRP), a leading first generation technology , efficiently reduces this SO 2 to desirable elemental sulfur, but requires the use of 1-3 % of the coal gas, thus resulting in an energy penalty to the plant. Advanced second-generation processes are under development that can reduce this energy penalty by modifying the sorbent so that it could be directly regenerated to elemental sulfur. The objective of this research is to support the near and long term DOE efforts to commercialize the IGCC-HGD process technology. Specifically we aim to develop: 5 (i) optimized low-cost sorbent materials with 70-80 µm average aps meeting all Sierra specs. (ii) attrition resistant sorbents with 170 µm aps that allow greater flexibility in the choice of the type of fluidized-bed reactor eg they allow increased throughput in a bubbling-bed reactor.and (iii)modified fluidizable sorbent materials that can be regenerated to produce elemental sulfur directly with minimal or no use of coal gas. Forty Five sorbents were synthesized in this work. Details of the preparation technique and the formulations are proprietary, pending a patent application, thus no details regarding the technique are divulged in this report. Sulfidations were conducted with a simulated gas containing (vol %): H 2 =10%, CO=15%, CO 2 =5%, H 2 S=0.4-1%, H 2 O=15% and bal N 2 in the temperature range of 343-538 o C. The gas hourly space velocity for the test was about 2500 h-1 both in sulfidation and in regeneration. Regeneration between cycles were conducted at temperatures in the range of 500-700 o C with pure air. To prevent sulfation, catalyst additives were investigated that promote regeneration at lower temperatures. Characterization were performed for fresh, sulfided and regenerated sorbents. Based on fixed-bed microreactor screening of numerous sorbents, an attrition-resistant fludizable sorbent designated FHR-32 was selected for high temperature, high pressure testing. A 50 cycle test was conducted using the microreactor system. The sorbent demonstrated high reactivity over the 50 cycle test and its attrition resistance was comparable to equilibrium fluidized cracking catalyst (FCC). No sulfate formation was observed during neat air regeneration. These promising t...