ZSM-5分子筛的磷改性及其碳四烯烃催化裂解性能

ZSM-5分子筛的磷改性及其碳四烯烃催化裂解性能
薛扬，袁桂梅*，陈胜利，李淑娟，袁锐
（中国石油大学（北京）重质油国家重点实验室，北京 102249） 为了提高丙烯和乙烯产率，增强催化剂的稳定性，采用等体积浸渍法对硅铝物质的量比为38的ZSM-5分子筛进行磷改性，对制备的催化剂进行SEM、XRD、N2吸附-脱附和NH3-TPD表征，考察不同磷含量ZSM-5分子筛对C4烯烃催化裂解反应性能的影响。表征结果表明，随着磷含量的升高，磷改性后的ZSM-5分子筛晶体结构变化不大，比表面积和孔容逐渐减小，结晶度降低，酸强度减弱，酸量减小。性能评价结果表明，随着磷含量的升高，丁烯转化率逐渐下降，丙烯和乙烯选择性、收率先升后降，磷质量分数为2%时，ZSM-5分子筛催化性能较好，相对结晶度为84.66%，平均孔径2.334 nm,孔容0.154 cm3·g-1，微孔孔容0.082 8 cm3·g-1，比表面积264.1 m2·g-1，总酸量0.559 mmol-NH3·g-1，丙烯选择性约40%，乙烯和丙烯总收率约57%。

Phosphorus modified ZSM-5 molecular sieves and their catalytic performance for the cracking of butylenes

In order to improve the yield of propene and ethene,and enhance the stability of ZSM-5 molecular sieve,the phosphorus modified ZSM-5 molecular sieves with ratio of silica to alumina of 38 were prepared by incipient impregnation method.The phosphorus modified ZSM-5 molecular sieves were characterized by SEM,XRD,N2 adsorption-desorption and NH3-TPD,and their catalytic performance for the cracking of butylenes was investigated.The characterization results showed that although the crystallinity decreased during the phosphorus modification,phosphorus modified ZSM-5 molecular sieves retained their crystal structure.With the increase of phosphorus contents,the specific surface area,pore volume and acid amount decreased and acid strength were weakened.The results of performance evaluation indicated that with the increase of phosphorus contents in phosphorus modified ZSM-5 molecular sieves,butylene conversion gradually declined,while the selectivity to and the yield of propene and ethene first increased,and then decreased.When phosphorus mass fractioh was 2%,ZSM-5 molecular sieves exhibited better catalytic activity with the selectivity to propene and the total yield of ethene and propene of about 40% and 57%,respectively,and its relative crystalinity was 84.66%,average pore size was 2.334 nm,porous volume 0.154 cm3 · g-1,micro porous volume 0.082 8 cm3 · g-1,specific surface area 264.1 m2 · g-1,total acid amount 0.559 mmol-NH3 · g-1.