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

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 m2/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 cm3/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 Al2O3, TiO2, ZrO2, 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 TiO2/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 H2S and the Fischer–Tropsch synthesis. For this later, a direct comparison was also made with a traditional support, i.e. alumina.

New porous self-bonded beta silicon carbide (SiC) materials have been prepared using metallic silicon powder and carbon black. Pore size distribution has been tailored by varying the raw materials and by adding pore formers. The surface chemistry can be tuned by adding promoters in the process.Figure optionsDownload high-quality image (88 K)Download as PowerPoint slideResearch highlights▶ Synthesis of highly porous shaped self bonded beta SiC and use as catalyst support. ▶ Tailored pore size distribution and specific surface area. ▶ High activity in selective H2S oxidation. ▶ High selectivity toward Fischer–Tropsch synthesis. ▶ ZrO2, TiO2 promoting.