Zr(OH)4-Catalyzed Semi-Hydrogenation of Phenylacetylene with Terminal Zr-O-H as Active Site: Inactive for Free Styrene.

ABSTRACT

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)4 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)4 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 H2, while the terminal Zr-O-H plays a crucial role on activating phenylacetylene through the sequential hydrogenation process of C6H5C≡CH→C6H5C=CH2→C6H5CH=CH2. The high rate of phenylacetylene removal is attributed to its strong adsorption capacity, while Zr(OH)4 has a significantly weaker adsorption capacity for styrene.