Transformation of C6 hydrocarbons over sulfated zirconia catalysts

The conversion of the C6 saturated hydrocarbons hexane, methylcyclopentane and cyclohexane was studied in a flow microreactor in the temperature range 120-240 degrees C. Sulfated zirconia with different sulfate contents were used as catalysts. Catalysts were characterized before and after reactant exposure using Raman spectroscopy and XPS. The obtained results confirm data on the reaction mechanism already reported in the literature. The first step is the hydrogen abstraction which could occur to a more or less advanced extent as a function of the sulfate density species. This process is the main cause of the catalyst reactivity but also of the catalyst deactivation. More advanced dehydrogenated species lead to polymerized species which remain strongly chemisorbed on the catalyst surface. XPS data also indicated that during these redox processes a part of the sulfur remained on the catalysts surface. Higher sulfate densities lead to the cyclization of hexane. (C) 1999 Elsevier Science B.V. All rights reserved.