Study of ammonia removal in coal gasification processes: Final report

The objective of this program was to investigate the removal of fuel-bound nitrogen that appears as ammonia and hydrogen cyanide in coal gas in the temperature range 540/degree/ to 870/degree/C and the pressure range 1 to 20 atm. Following a comprehensive literature search, catalytic decomposition was selected as the most promising concept. Ten catalysts were tested at two temperatures in three different simulated coal gas streams containing ammonia and hydrogen sulfide impurities. A proprietary nickel catalyst (HTSR-1) exhibited high activity at 800/degree/C and excellent physical stability. An Ir-promoted nickel catalyst (G-65/star/) had significant activity for removing ammonia in the temperature range 550/degree/ to 600/degree/C but physically deteriorated at higher temperature. Other tested catalysts were inferior in performance to these two catalysts. Parametric studies were conducted with HTSR-1 and G-65/star/ catalysts to determine the rate of ammonia removal as a function of temperature, pressure, space velocity, and concentrations of ammonia, hydrogen, and steam. The influence of several other impurities commonly present in the hot gas was studied also. 27 refs., 24 figs., 14 tabs.