Simultaneous removal of H{sub 2}S and NH{sub 3} in coal gasification process. Quarterly progress report, October 1--December 31, 1994

The objective of this study is to develop advanced high-temperature coal gas desulfurization mixed-metal oxide sorbents with stable ammonia decomposition materials at 550--800 C. The specific objectives of the project are to: (1) develop combined sorbent-catalyst materials which shall be capable of removing hydrogen sulfide to less than 20 ppmv and ammonia by at least 90%; (2) carry out comparative fixed-bed studies of absorption and regeneration with various formulations of sorbent-catalyst systems and select the most promising sorbent-catalyst type; and (3) conduct long-term (at least 30 cycles) durability and chemical reactivity in the fixed-bed with the superior sorbent-catalyst. Characterization of HART-36, HART-37 and HART-38 samples was performed using BET and X-ray diffraction analyses. The BET surface area was increased from 17.4 to 26.7 m{sup 2}/g with an increase in nickel content. The fresh sorbent-catalysts predominantly contains Zn{sub 2}Ti{sub 3}O{sub 8} with a very little amount of rutile type TiO{sub 2}. Zinc oxide-based sorbent-catalysts containing 5% nickel showed moderate catalytic activity for NH{sub 3} decomposition. In order to further improve the catalytic activity for ammonia decomposition, zinc oxide based sorbent-catalysts containing 5 wt% nickel with various amounts of cobalt (2.5--10 wt%) were prepared