Development and reactivity of novel heterogeneous catalysts for hydrocarbon conversions

Preparation of the novel solid acid catalyst AlCl{dollar}sb2{dollar}(SG){dollar}sb{lcub}rm n{rcub}{dollar} has been accomplished in a sealed tube vapor deposition process using an extended time period comparable to that for a previously reported CCl{dollar}sb4{dollar} synthesis. Reactivity studies and spectroscopic investigations indicate a similar structure for surface acid sites in the catalysts prepared via the two different methods. It has also been determined that excessively dry silica is deficient in surface silanol (Si-OH) moieties such that effective reaction of Al{dollar}sb2{dollar}Cl{dollar}sb6{dollar} is not achieved. Exposure to humid air is sufficient to hydrate the silica to a level where the active catalyst can be prepared.; The activity of AlCl{dollar}sb2{dollar}(SG){dollar}sb{lcub}rm n{rcub}{dollar} in a number of acid-catalyzed reactions has been studied. In the alkylation of benzene and toluene, the catalyst was found to be active in batch reactions but gives poor selectivity at elevated temperature in a flow reactor. The isomerization of butane and hexane have been examined with especially successful results obtained for the butane reactant. Cracking of hydrocarbon polymers as a possible recycling procedure is promising with AlCl{dollar}sb2{dollar}(SG){dollar}sb{lcub}rm n{rcub}{dollar}. At 100{dollar}spcirc{dollar}C in a batch reactor the activity of the catalyst for cracking polymers is comparable to that observed with n-hexadecane.; Catalysts comprised of metal oxides dispersed on porous carbons are very effective in the oxidative decomposition of halogenated hydrocarbons at 250{dollar}spcirc{dollar}C in air. Methylene chloride, 1,2-dichloroethane, 1,2,4-trichlorobenzene, tetrachloroethylene, tetrachloroethane and carbon tetrachloride are decomposed to CO{dollar}sb2{dollar}, CO and HCl over the carbon catalysts with high selectivity to HCl for the chlorinated products. Trends in reactivity with support variation indicate that a determining factor in the activity of the catalysts appears to be the micropore volume of the carbon support. The presence of water in the reaction mixture has no effect on the activity of the carbon catalysts. Reactions comparing CH{dollar}sb2{dollar}Cl{dollar}sb2{dollar} with CD{dollar}sb2{dollar}Cl{dollar}sb2{dollar} indicate a rate dependence on cleavage of a carbon-hydrogen bond. Kinetic studies in the methylene chloride experiment show a first order dependence on CH{dollar}sb2{dollar}Cl{dollar}sb2{dollar} concentration and an activation energy of 11.0 kcal/mol.