Catalysts of Ordered Mesoporous Alumina with a Large Pore Size for Low-Temperature Hydrolysis of Carbonyl Sulfide

Abstract

Carbonyl sulfide (COS) generated from various chemical and metallurgical industry sectors has been receiving considerable attention due to its environmental impact and threat to production chains. The catalytic hydrolysis of COS has been considered an economic way for converting the unremovable COS into H₂S that subsequently can be easily removed through the mature wet or dry desulfurization process. Searching for an effective catalyst with stable activity is always crucial for COS hydrolysis. In this study, alkali-free ordered mesoporous Al₂O₃ with a larger pore size, incorporated with Ni, Cu, or Fe as an additive, and synthesized via a one-pot approach has been investigated for the catalytic hydrolysis of COS at low temperatures. It has been demonstrated that alumina with ordered mesoporous structures exhibits significant catalytic activity over COS hydrolysis whose activity improved further when incorporated with transition metals. More importantly, the enlargement of mesopore size for all the catalysts is critical for maintaining their catalytic performance. By optimizing the pore size and the type of additive, a highly active and stable catalyst of Ni-containing mesoporous Al₂O₃ with a large pore size has been established, which exhibits a long-term COS conversion above 95% and strong sulfur resistance. With the help of various characterization techniques, the details of the hydrolysis reaction, as well as the sulfur poisoning mechanism, have been revealed. It is envisaged that the synthesized catalyst of alkali-free ordered mesoporous Al₂O₃ holds great application potential for the catalytic hydrolysis of COS in practical industrial applications.