Palladium catalysts on porous cobalt-carbon composite materials derived from PVC for n-pentanal hydrogenation

Abstract

A porous carbon material (PCM) and series of porous cobalt-carbon composite materials (PCoCCMs) with different metal content have been synthesized by dehydrochlorination of polyvinyl chloride and mixtures of Co(NO₃)₂ with polyvinyl chloride, respectively, followed by carbonization and activation in CO₂ flow at temperatures of 673 and 1173 K. These materials were used to obtain supported palladium catalysts. The effect of cobalt content on catalytic performance in the reaction of liquid-phase hydrogenation of n-pentanal was analyzed. It was found that all Pd/PCoCCMs samples with cobalt content of 18.5–64.2 wt%, with a minimum micropore number of 52–66% and that of surface acidic groups of 0.05–0.15 mmol g⁻¹ are more active than the Pd/PCM sample with a maximum micropore number of 88% and that of surface acidic groups of 0.30 mmol g⁻¹. The highest n-pentanal conversion of 96 wt% and 70 wt% selectivity to 1−pentanol was obtained for a catalyst with cobalt content of 25.3 wt% at reaction time of 6 h, temperature of 353 K, and hydrogen pressure of 1.0 MPa. A multi-cycle experimental study of the catalyst showed its reduced activity and increased selectivity to the products of acetalization, self-condensation and etherification. In general, the results obtained open up prospects for creating catalysts based on the available synthetic organic raw material.