(346d) High Pressure Flow Reactor Test and in -Situ Ftir Characterization of Ammonia Absorption/desorption Performance Over Zeolites

A large number of components in coal form corrosive and toxic compounds in coal gasification process. Ammonia is one of the impurities formed during IGCC process and it has to be removed before the coal syngas could be utilized for many applications, such as SOFC. U.S. DOE/NETL is developing sorbents for ammonia removal. Zeolites have been selected as one of the candidates and studied using high pressure flow reactor. The results of multi-cycle adsorption/desorption tests over various zeolites (13X. 5A, 3A, 4A and HZSM5) indicate that zeolite samples possess high absorption capacity and stability after several regeneration for ammonia removal. The removal capacity was greatly enhanced at the lower absorption temperature, higher regeneration temperature and higher reaction pressure. Preliminary results indicate that water adding slightly affect the adsorption performance. High pressure In-situ FTIR spectroscopy reveals that there are three ammonia adsorption sites over zeolites: physisorbed ammonia, ammonia on Bronsted acidic sites and Lewis acidic sites, which contribute to absorbent performance. Differential scanning calorimetry will be conducted to clarify the adsorption/desorption site and reaction mechanism