苯甲醛对甲苯歧化与烷基转移催化剂的影响

Influence of Benzaldehyde on the Catalysis Performance forToluene Disproportionation and Transalkylation

甲苯歧化与烷基转移技术是重要的二甲苯生产技术,催化剂的稳定运行直接决定着装置产能和生产效率。考察了苯甲醛对甲苯歧化与烷基转移工业催化剂性能的影响,并初步探索了其活性影响机理以及催化剂性能恢复方法。研究发现:苯甲醛在催化剂酸中心上的吸附能力远大于甲苯,降低了催化剂烷基转移活性;苯甲醛还能影响催化剂金属活性中心,导致加氢脱烷基活性显著降低;但同时苯甲醛也能抑制苯环加氢副反应,提高苯产品纯度。歧化催化剂上苯甲醛的吸附为可逆行为,可以通过提高反应温度或者高温脱附处理的方式,降低苯甲醛与活性中心的相互作用,逐渐恢复催化剂的活性。

Toluene disproportionation and alkyltransfer technology is an important xylene production technology.The stable operation of catalyst directly determines the unit capacity and production efficiency.The effects of benzaldehyde on toluene disproportionation and alkylation catalyst is studied,and the activity influencing mechanism and recovery method of catalyst performance are preliminarily explored.It is found that benzaldehyde,as a new poison,has much greater adsorption capacity on the acid center than toluene,which reduces the alkyltransfer activity of the catalyst.At the same time,benzaldehyde can also affect the metal active center of the catalyst and significantly reduce the hydrodealkylation activity,but it can also inhibit the side reaction of benzene ring hydrogenation and improve the purity of benzene products.The adsorption of benzaldehyde on disproportionation catalyst is reversible.By increasing the reaction temperature or high-temperature desorption treatment,the interaction between benzaldehyde and active center can be effectively reduced,and the activity of catalyst can be gradually restored.