Zr(OH)-Catalyzed Semi-Hydrogenation of Phenylacetylene with Terminal Zr-O-H as Active Site: Inactive for Free Styrene.

In the field of industrial semi-hydrogenation of trace alkynes amidst alkene feedstocks, the pivotal challenge lies in circumventing the hydrogenation of alkenes. Herein, we present Zr(OH) as an innovative catalyst for the semi-hydrogenation of phenylacetylene, demonstrating remarkable selectivity towards styrene (>96 %), while exhibiting inactivity towards free styrene. Notably, Zr(OH) achieves a 95 % conversion of quasi-industry 1 mol % phenylacetylene within styrene, with a mere 0.44 % styrene loss. Experimental and theoretical results confirm both terminal Zr-O-H and bridge Zr-O-H can dissociate H, while the terminal Zr-O-H plays a crucial role on activating phenylacetylene through the sequential hydrogenation process of CHC≡CH→CHC=CH→CHCH=CH. The high rate of phenylacetylene removal is attributed to its strong adsorption capacity, while Zr(OH) has a significantly weaker adsorption capacity for styrene.