Alkylation of isobutane with n-butene over solid catalysts.

摘要

Alkylation of isobutane with butene is an important industrial process for producing high-octane gasoline. Current industrial alkylations use either H{dollar}sb2{dollar}SO{dollar}sb4{dollar} or HF as a catalyst. Compared to the liquid catalyst, the use of a solid acid catalyst tremendously reduces or eliminates the potential hazard of large acid spills.; In this study, a HY zeolite, sulfate-promoted titania, mixed oxide of TiO{dollar}sb2{dollar}/ZrO{dollar}sb2,{dollar} TiO{dollar}sb2{dollar}/Al{dollar}sb2{dollar}O{dollar}sb3,{dollar} and ZrO{dollar}sb2{dollar} were synthesized. Two different sulfate-promoted zirconias, (MSG-ZrO{dollar}sb2{dollar}-S and PPT-ZrO{dollar}sb2{dollar}-S) were synthesized by the modified sol gel method and the precipitation method. The alkylation results indicated MSG-ZrO{dollar}sb2{dollar}-S had a significant larger butene conversion, C{dollar}sb8{dollar} yield, and C{dollar}sb8{dollar}/C{dollar}sb9{dollar}+ ratio than PPT-ZrO{dollar}sb2{dollar}-S. MSG-ZrO{dollar}sb2{dollar}-S also had a larger C{dollar}sb8{dollar}/C{dollar}sb9{dollar}+ ratio than HY. MSG-TiO{dollar}sb2{dollar}-S and its related binary oxide were not active. MSG-ZrO{dollar}sb2{dollar}-S had more acid sites over the entire acidity range than PPT-ZrO{dollar}sb2{dollar}-S. Compared to HY, MSG-ZrO{dollar}sb2{dollar}-S has a fewer number of weak and medium acid sites, as well as a greater number of strong acid sites. MSG-TiO{dollar}sb2{dollar}-S had the smallest amount of acid sites indicated by the ammonia TPD analysis.; The reaction temperature significantly affected alkylation activity of HY. Butene conversion, C{dollar}sb5{dollar}+ yield, and n-butane production were dramatically increased with the increase of temperature with the decrease of C{dollar}sb8{dollar}/C{dollar}sb9{dollar}+.; Isobutane to butene ratio had no significant effect on alkylation. A larger isobutane to butene ratio, however, was more favorable for the production of C{dollar}sb8{dollar} than the production of light ends.; All active catalysts used in this study showed rapid deactivation. The cause of deactivation is believed to be the deposit of polymer on the active sites.; The experimental data obtained from HY-catalyzed alkylation were well fitted by the simulated results based on a simplified kinetic model. All 16 parameters used in the kinetic model were evaluated through the parameter estimation.