糖类对SAPO-34分子筛的结构以及MTO性能的影响

以廉价的木糖、蔗糖、淀粉和葡甘聚糖为硬模板剂成功合成出含多级孔道的SAPO-34分子筛，采用XRD、BET、SEM、TEM、ICP和NH₃-TPD等手段对催化剂进行了表征，并在固定床上，研究了糖类硬模板剂对SAPO-34分子筛的结构以及MTO性能的影响。结果表明，糖类硬模板剂能够提升SAPO-34分子筛的比表面积、微孔和介孔体积。与常规SAPO-34分子筛相比，多级孔道SAPO-34分子筛的双烯选择性和寿命均高。介孔体积最大、酸量最少、酸性最弱的SAPO-34-z分子筛的寿命最长（130 min），高出常规SAPO-34分子筛（100 min）30%，分子筛寿命从长到短顺序为SAPO-34-z > SAPO-34-h > SAPO-34-d > SAPO-34-m > SAPO-34 > SAPO-34-p。含多级孔道的SAPO-34分子筛的双烯选择性均高于常规SAPO-34分子筛。

Effects of sugars on the structure of SAPO-34 and its MTO performance

Hierarchical SAPO-34 zeolites were successfully synthesized using cheap xylose, sucrose, starch and glucomannan as hard template and characterized by means of XRD, BET, SEM, TEM, ICP and NH₃-TPD. The effects of sugar hard template on the structure and MTO properties of as-prepared SAPO-34 zeolites were studied on a fixed bed. The results showed that introduction of carbohydrate hard template could increase the specific surface area, microporous and mesoporous volume of SAPO-34 zeolites. The olefin selectivity and lifetime of SAPO-34 were both higher than those of ordinary SAPO-34. The SAPO-34-z with the largest mesoporous volume, the least acidity amounts and the weakest acidity showed the longest lifetime (130 min), which was 30% longer than that of ordinary SAPO-34 (100 min). The lifetime of zeolites decreased in the order of SAPO-34-z > SAPO-34-h > SAPO-34-d > SAPO-34-m > SAPO-34 > SAPO-34-p. The olefin selectivity of hierarchical SAPO-34 zeolites is higher than that of conventional SAPO-34 zeolites.