磷改性HZSM-5分子筛对甲醇制汽油催化反应性能的影响

Effect of phosphorus modified HZSM-5 zeolite on catalytic performance for methanol to gasoline

采用水热晶化法合成出HZSM-5分子筛催化剂A,对其进行磷改性制备出催化剂B,利用X射线荧光法、X射线衍射法、氮气吸附法等测试方法考察了磷改性对催化剂物化性质的影响,并采用微型固定床反应器对比研究了2种催化剂的甲醇制汽油反应性能。结果表明:催化剂A和催化剂B均具有较好的孔结构,前者的酸性分布主要以弱酸和强酸中心为主,后者在450℃以上主要以弱酸为主;在甲醇制汽油催化反应中,与催化剂A相比,催化剂B有利于低碳烯烃的产生,甲醇转化率较高,汽油收率至少提高8个百分点,使用寿命延长,稳定性和活性提高,且催化剂B的异构化能力提高,液相产物中异构烷烃质量分数增加5.24个百分点,芳烃质量分数降低4.84个百分点。

The HZSM-5 zeolite catalyst A was synthesized by the hydrothermal crystallization,and the catalyst B was prepared by the catalyst A modified by phosphorus. The effects of phosphorus modification on the physicochemical properties of catalysts were investigated by X-ray fluorescence(XRF), X-ray diffraction(XRD) and nitrogen adsorption, and the two catalytic performances of methanol to gasoline were compared and investigated in a micro fixed-bed reactor. The results showed that both catalyst A and B had better pore structure. The acidity distribution of the former was mainly weak acid and strong acid center, while that of the latter above 450 ℃ was mainly weak acid. In the catalytic reaction of methanol to gasoline, compared with the catalyst A, the catalyst B was advantageous to the production of low-carbon olefins, with higher methanol conversion rate, improved gasoline yield(at least 8 percentage points), longer service life, higher stability and activity;the catalyst B had higher isomerization ability, the mass fraction of isoparaffins in liquid products increased by 5.24 percentage points and that of aromatics decreased by 4.84 percentage points.