Influence of Pore Structure on the Performance of Pt/Ceramic Hydrophobic Catalyst

Pt/hydrophobic ceramic catalysts used for H₂-H₂O liquid phase catalytic exchange were prepared with five different carriers by the impregnation method. The influences of the pore structure of carriers on the performance of catalysts were studied, and the characteristics of catalysts were tested by XRD, SEM, H₂-TPR and CO adsorption. With the decrease of average pore size, the specific surface area of carriers increases and then the Pt particle dispersion enhances. The catalytic activity increases with the decrease of average pore size in the range of 30-70 nm, while the reactant gas will have more difficulty to spread into the inner tunnel of carrier with the average pore size under 20 nm, resulting in the decreased catalytic activity. Although the enhanced porosity of carrier can create higher specific surface area, it will weaken the strength of pore structure, which will be destroyed during the preparation process and have no benefit to obtain favorable catalytic activity. The catalyst prepared by the carrier with average pore size of 37.5 nm, specific surface area of 111.01 m²/g and the porosity of 68.76% can obtain the k_ya value of 6.45 s^-1 with 4.5 mL catalyst and 4.23 L/min gas velocity.