Heck-Mizoroki reaction using palladium and nickel on yttria stabilized zirconia

Abstract

This work was composed of studies analysing the capacity of Pd-YSZ and Ni-YSZ as a heterogeneous catalyst for the Heck-Mizoroki reaction. Following an optimization, mechanistic studies were undertaken with Pd-YSZ. P-XRD measurements showed a decrease in the amount of metal present in the catalyst after a cycle of Heck reaction. Also, two triple phase test were done. Using a resin supported reactant, it was showed that palladium leaches into solution and reacts through a homogeneous cycle. Also, the contribution of true heterogeneous surface catalysis was examined by means of a thiol-based palladium scavenger that neutralised homogeneous catalysis. While it is impossible to completely dismiss true surface catalysis, the negative result showed that surface catalysis did not contribute significantly to the overall reactivity. Reactions showed reactivity up to 770'000 TON with mesoporous 5% Pd-YSZ calcinated to 600°C. Using the self-assembly and the co-precipitation method, Ni-YSZ catalysts of 1%, 5% and 10% were synthesized and calcinated to 400°C, 600°C and 950°C. Catalyst characterization through p-XRD, physisorption and chemisorption allowed knowledge of the crystallite size surface area and metallic surface area. A structure-reactivity relationship study showed a limited effect in the ability of high surface area and low particle sizes to accelerate catalysis.