More than just a reactant: H2O promotes carbonyl sulfide hydrolysis activity over Ni-MgAl-LDO by inhibiting H2S poisoning

Abstract

Sulfur poisoning was a bottleneck in the development of Carbonyl sulfide (COS) catalytic hydrolysis technology. Herein, the sulfur poisoning process over Ni-doped MgAl layered double oxide (Ni-MgAl-LDO) catalysts during COS hydrolysis was simulated by H2S processing and the effect of H2O on sulfur poisoning were investigated. H2S would be deposited on the weak and medium basic sites of Ni-MgAl-LDO, which lead to the catalyst poisoning and deactivation. The presence of excess water would inhibit COS hydrolysis performance over conventional catalysts, but interestingly, the poisoning effect of H2S on the Ni-MgAl-LDO catalyst was greatly suppressed with the introduction of H2O. H2O molecules were adsorbed and activated on the Ni-MgAl-LDO catalyst surface, which could inhibit the deactivation by promoting desorption of H2S. Therefore, H2O, not only as a reactant, but also as a protector, took part in the COS hydrolysis over the Ni-MgAl-LDO catalyst.