偏三甲苯甲醇烷基化制备均四甲苯的工艺研究

研究了偏三甲苯与甲醇在HZSM-5催化剂上烷基化制均四甲苯的反应工艺。采用管式等温反应器考察了温度、压力、空速和原料配比等对反应的影响以及催化剂寿命和再生催化剂的性能,采用热天平研究了催化剂积碳情况。获得了适宜的反应条件:压力0.80 MPa,温度350℃,n(甲醇):n(偏三甲苯)=1.5～2.0,偏三甲苯空速0.8～0.9 h~(-1)。结果表明,积碳是催化剂活性衰减的主要原因,再生催化剂能够达到新鲜催化剂性能,工业生产宜采用反应-消碳工艺。

SYNTHESIS OF 1,2,4,5-TETRAMETHYLBENZENE BY ALKYLATION OF 1,2,4-TRIMETHYLBENZENE WITH METHANOL

Synthesis of 1,2,4,5-tetramethylbenzene by alkylation of 1,2,4-trimethylbenzene with methanol over HZSM-5 catalyst was studied.First,the effect of reaction temperature,pressure, WHSV of 1,2,4-trimethylbenzene and molar ratio of methanol to 1,2,4-trimethylbenzene on the catalytic performance was investigated.Then,the stability test of the fresh catalyst,the regeneration of the deactivated catalyst and the stability test of the regenerated catalyst were carried out.The behavior of carbon deposition on HZSM-5 catalyst was investigated by means of thermogravimetric analysis. The suitable reaction conditions were obtained as follows:reaction temperature of 350℃,pressure of 0.8 MPa,WHSV of 0.8-0.9 h~(-1) and the molar ratio of 1.5-2.0.The characterization results indicated that the carbon deposition on the catalyst is the main reason of the deactivation,and the catalytic performance of the regenerated catalyst can reach the level of the fresh catalyst.It is suggested that the reacting-decarbonizing process should be adopted in the industrial production.