High resistance to carbon deposition of silica-coated Ni catalysts in propane stream reforming

The catalytic performance of Ni metal catalysts uniformly covered with layers of silica for propane steam reforming was compared with the performances of Ni metal catalysts supported on substrates of magnesia (MgO), alumina (Al2O3) and silica (SiO2). The silica-coated Ni catalysts showed high activity for propane steam reforming at 873 K. This catalytic activity is higher than the activity of effective light alkane steam reforming Ni/Al2O3 and Ni/MgO catalysts and we found that the catalytic activity of the silica-supported Ni metal was poor. The coverage of Ni metal particles with silica thus improves their catalytic activity for this reaction. Carbon deposition on silica-coated Ni catalysts during the steam reforming of propane at 873 K was lower than that on Ni/MgO and Ni/Al2O3. Ni K-edge XANES and EXAFS spectra of silica-coated Ni catalyst showed a strong interaction between Ni metal and silica. This interaction prevents the sintering of Ni metal particles during the propane steam reforming, which results in the reduction of carbon deposition on silica-coated Ni catalysts. These properties of silica-coated Ni catalysts result in high catalytic activity and improved catalyst stability. (C) 2008 Elsevier B.V. All rights reserved.