A structured catalyst with high dispersity of Au species based on hollow SiC foam with porous walls for acetylene hydrochlorination

Abstract

It is essential to improve the catalytic stability of Au-based catalysts for acetylene hydrochlorination. In this study, a novel hollow SiC foam with porous walls (HSF_p) is proposed to modify the Au catalyst distribution on the foam-based structured catalyst. The scanning electron microscopy and 3D X-ray tomography results showed that the hollow structure and the porous ceramic wall of HSF_p were successfully obtained. An Au/AC/HSF structured catalyst was prepared by the slurry-coating and impregnation method. Then the effects of the wall pore structure of HSF_p on the distribution of Au species and the stability of the catalyst were studied by comparison with a hollow SiC foam with compact walls (HSF_c). The HSF_p with 3D interconnected hollow channel structure was demonstrated to have a promotion effect on the reaction stability due to its ability to refine the catalyst particles during the impregnation and drying processes. The result indicates that the time on stream of acetylene conversion above 90% over the Au/AC/HSF_p structured catalyst reaches about 380 h at an acetylene gaseous hourly space velocity of 130 h⁻¹, which is much longer than that of the Au/AC/HSF_c. In addition, a bidirectional diffusion effect that can enhance the catalyst distribution by the porous wall of HSF was proposed in this paper. This may have positive significance in the field of preparation of structured catalysts.