分子筛结构及磷改性对催化苯与乙醇烷基化反应性能的影响

EFFECT OF MOLECULAR SIEVE STRUCTURE AND PHOSPHORUS MODIFICATION ON THE CATALYTIC PERFORMANCE OF CATALYST DURING ALKYLATION OF BENZENE WITH ETHANOL

采用 BET,NH_3～TPD,Py-IR 方法对 Mor,Beta,SAPO-11,HZSM-5四种分子筛原粉进行表征,在连续流动固定床反应装置上对这四种分子筛进行苯与乙醇烷基化反应活性评价,并比较了四种分子筛在相同反应时间下的积炭量。结果表明,Mor 和 Beta 分子筛失活快,SAPO-11分子筛反应活性低,而 HZSM-5分子筛具有较高的反应活性和较长的寿命,是比较合适的催化剂;相同反应时间下四种分子筛的积炭量由高到低的顺序为:Mor>Beta>SAPO-11>HZSM-5。针对HZSM-5分子筛乙苯选择性低的问题,考察了不同含量磷改性 HZSM-5分子筛的催化性能。结果表明,质量分数为3%磷改性 HZSM-5分子筛的效果最佳,苯的转化率变化不大,乙苯选择性比未改性的分子筛提高了约20%。

Alkylation of benzene with ethanol were investigated using a continuous fixed-bed reaction device over catalysts having various structure molecular sieves, such as Mor zeolite, Beta zeolite, SAPO-11 and HZSM 5 zeolite. The molecular sieve were characterized by BET, NH3-TPD and Py-IR. The test results showed that Mor zeolite and Beta zeolite deactivated quickly, the alkylation activity of SAPO-11 was low since its acid strength was weak,among them HZSM-5 exhibited appropriate reaction activity and service life. It was found that under the same reaction time,the contents of coke deposited on these four molecular sieve were in the order from high to low of Mor〉Beta〉SAPO-11〉 HZSM-5. Phosphorus modification was used to improve the ethylbenzene selectivity of HZSM-5 molecular sieve, and the results showed that the ethylbenzene selectivity of molecular sieve was increased by modification. A molecular sieve containing 3% phosphorus possessed the optimum acid amount and acid strength,a 20% increase of ethylbenzene selectivity was obtained and its benzene conversion was still good as compared with molecular sieve prior to phosphorus modification.