Supported Metal Oxide Catalyst For Oxidative Coupling Reaction Of Toluene And Methane Cross

The catalysts used for oxidative coupling of methane, MgO, Al₂O₃,CaO,TiO₂, for example, were employed for oxidative cross coupling of methane withtoluene, the comparative performance were observed in this paper, Li+/MgO wereused as a typical catalyst to analysis the effect of Li⁺ content, reaction temperature,composition of feed gases, and gas-state oxygen on oxidative cross coupling ofmethane with toluene. The results dicated that the active sites of this reaction onLi+MgO catalyst were Li-O-, similar to that of oxidative coupling of methane onthe catalyst , on Li+/MgO with low Li loading, the selectivity and yield of C8 werelow. LI+O- site and suitable L acid points were the sites of adsorption of reactant.The activity of MgO,AI2O3, CaO,hO2 with higher Li loading were comparedwith one another. On pure MgO and A1203 catalyst, no performance and productionof C8 were detected. While on pure CaO and Ti02 catalysts, C8 were produced butthe selectivity of C8 were very low, when promoted by alkali metal (Lix Na)compounds, the selectivity of C8 increased drastically on all the doped catalysts.On the catalysts with same Li loading the activity increased according to the order asfollows: CaO>Ti02>MgO>AI2O3. In the view of crystallic structure, the radius ofMg ion is more near to Li ion, fascilating Li incorporation into Mg-O crystallattice. While from the consideration of value ballance, Mg ion of +2 value match Liion better than Al ion of +3 value. JR spectra showed that some strong L acid stiesformed on the surface of calcined A12O3 during the preparation of catalyst. Theadsorption of toluene molecular on the sites was strong and the desorption of toluenewas very difficult reasoning for the toluene molecular contained a methyl group at a-position on an electronwithdrawing function group. So as the consequence of this,the formation of reactive intermediate was hindered and finally the formation of theexpected product (C8) was affected. The difference in performance between MgOand CaO were related to their base strength. Ti02, as a transition metal oxide, Itscatalic activity characterized by transferring active oxygen species to reactant for itsd-electron. The best temperature for this reaction is 75000, at this temperature, flowratio V(CH4)V(O,)V(C7H8)=7.21.61 (N2 as diluent) the bestperformance of all the examined catalysts appeared on 1 O%LV/CaO, the selectivityof C8 was 39.7%, yield was 23.l%。...