Catalyst Of Toluene Alkylation With Methanol To Para-Xylene

As oil resources dying up, para-Xylene(p-X) obtained from oil is severely constrained; meanwhile, product of methanol(M) is excessive with the development of domestic coal chemical industry in recent years, which lead to a highly concerned about process of toluene alkylation methanol to synthesis p-X. However, the deactivation of catalyst has been a difficult problem under the condition of high p-X selectivity in Xylene, which is also the core problem to be solved for industrialization of this process.In this paper, the performance of different zeolites, such as SAPO-11, ZSM-22, MCM-22, ZSM-35and ZSM-5, was investigated, finding that ZSM-5zeolites is suitable catalyst ontology for this process; the effect of grain size and silica to alumina ratio (SiO2/Al2O3) on the performance of ZSM-5zeolites was studied, identifying that ZSM-5zeolites with big grain size, high silica to alumina ratio (SiO2/Al2O3^) had better performance in this process.Then, The performance of ZSM-5zeolites modified with metallic and non-metallic compounds was studied on this process, finding that para-selectivity of modified ZSM-5zeolites was greatly improved. The regeneration performance of ZSM-5zeolites modified with SiO2and La2O3was studied, fingding that activity of the regenerated catalysts decreased significantly; On the basic of characterization data and references, we speculate that catalyst deactivation can be described as the framework dealumination of zeolites. For this reason, a targeted third modifier P2O5was introduced, selectivity and activity of ZSM-5zeolites modified with SiO2,La2O3and P2O5was greatly improved; Under the optimal reaction conditions, reaction for more than100h, toluene conversion (CT%) was24.3%. selectivity of p-X in xylene (Sp-x%) was93.9%; meanwhile, the regeneration performance of ZSM-5zeolites modified with P2O5, La2O3and SiO2had greatly improved; On the basic of characterization data and references, we speculate that P2O5could inhibit the loss of framework aluminum; all else being equal, life of catalyst was up to more than433h with increase of mole ratio of toluene/methanol, CT%was more than24.3%, Sp-x%was more than93.9%.Hydrogen as the carrier gas, stability of ZSM-5zeolites modified with SiO2, La2O3P2O5and precious metal U had greatly improved, reaction for more than1100h, CT%was19.3%～22.3%, Sp-x%was90.7%～93.3%; On the basic of characterization data and references, we speculate that precious metal U inhibited the generation of coke on the catalyst.Lastly, Hierarchical ZSM-5zeolites had better mass transfer performance and greater carbon capacity, whose stability had improved greatly compared with ordinary ZSM-5zeolites under high space velocity reaction conditions.