n-Hexane Conversion Catalyzed by Sulfated Zirconia and by Iron- and Manganese-Promoted Sulfated Zirconia: Catalytic Activities and Reaction Network

The conversion of n-hexane catalyzed by unpromoted sulfated zirconia and Fe- and Mn-promoted sulfated zirconia was investigated with a flow reactor at atmospheric pressure, temperatures of 0-25°C, and an n-hexane partial pressure of 0.001 atm. The n-hexane conversion initially increased as a function of time on stream, followed by a rapid decline. The major primary reaction was isomerization, giving monobranched isomers (predominantly 2-methylpentane). The secondary isomerization reactions gave dibranched products (predominantly 2,3-dimethylbutane). Disproportionation reactions were apparently secondary, giving isobutane, isopentane, heptanes, and octanes from the isomerization products. Small amounts of cracking products (methane, ethane, and propane) were also observed at the shortest times on stream, before the catalyst deactivated significantly. On the basis of the different induction times observed for the various reaction products, it is inferred that the disproportionation is bimolecular and the isomerization (predominantly) monomolecular.