Zr(OH)4 was firstly applied to catalyze semi-hydrogenation of phenylacetylene. It can achieve a 95 % removal rate of 1 % mol of phenylacetylene in styrene, and the terminal hydroxyl group is confirmed as the active site.
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.