New Insights into the Deactivation and Stabilization Causes of Plugged AlSBA‐15 in Liquid‐phase Friedel‐Crafts Organic Reactions

Abstract

AbstractDeactivation is the major challenge of heteroatom‐substituted mesoporous silica materials for large scale applications. Here we report the impact of plugging of mesochannels of AlSBA‐15 on activity and stability of liquid‐phase acylation of anisole with (extremely) low catalyst loadings of 0.15–0.6 wt.% and 0.6–3 wt.% in batch and in repeated batch reactions, respectively. The analysis of property‐catalytic performances showed that deactivation of the plugged AlSBA‐15 was partially from a physical cause by deposition of a uniform nanometer layer of coke on the surface blocking the active sites which could be restored by calcination and partially from an irreversible chemical cause by Al leaching. The catalytic performance of plugged AlSBA‐15 was compared with that of open AlSBA‐[15]. The plugged AlSBA‐15 showed lower but more sustained activity than that by open AlSBA‐15 coming from less and different type of coke deposition. These properties of plugged AlSBA‐15 resulted in two times higher productivity (44.3 vs 23.3 mg‐product/mg‐catalyst) than that by open AlSBA‐[15] . The plugging of mesochannels thus reduced the amount of coke deposition and stabilized the catalyst; however, it exerted no effect on Al leaching. In conclusion, understanding the role of plugging of mesochannels in stabilization and Al leaching and coke deposition in deactivation are useful to design and synthesize efficient solid acid catalysts for liquid‐phase organic reactions.