Innovative porous SiC-based materials: From nanoscopic understandings to tunable carriers serving catalytic needs

Abstract

Progress in developing a new class of catalyst carrier materials based on porous self-bonded silicon carbide (SiC) is reviewed. Since the demonstration of scalable economically viable β-SiC production process, innovative β-SiC-based materials with tunable physical and chemical properties were successfully synthesized. Silicon carbide has superior mechanical and thermal properties which, coupled to chemical inertness, avoids several of the problems inherent in the use of commercial oxide and carbon based supports and catalysts. High surface area SiC (35 m 2/g) can now be easily synthesized, with unmatched mechanical properties, tailored pore size distribution (meso- and macroporous network and total pore volume up to 1 cm 3/g) and at reasonable cost. It can be shaped directly into extrudates, (μ-) spheres, monoliths, open cell foams, 3D forms depending to the downstream applications. Furthermore, it can also be chemically modified for specific catalytic applications through the addition of promoters (oxides like Al 2O 3, TiO 2, ZrO 2, carbides and metals) rendering the fabrication simple and cost effective. In many respects, it combines the best properties of oxide and carbon based supports without suffering many of their disadvantages. New structured TiO 2/SiC composites have been prepared and are expected to be the next photocatalytic media. The ability of the SiC material to be used as catalyst support will be illustrated in the present work by two exothermic reactions, namely the selective oxidation of trace amount of H 2S and the Fischer–Tropsch synthesis. For this later, a direct comparison was also made with a traditional support, i.e. alumina.