CAJ | 학술논문

制备了100%SAPO-34,30%SAPO-34和介孔-SAPO-34三种不同类型的SAPO-34分子筛催化剂,并采用氮吸附、扫描电镜、X射线衍射和红外光谱等方法对催化剂进行了表征.三种催化剂的微孔结构、比表面积和总酸最近似,但具有不同的催化剂组成和次级结构.以1-己烯裂解为模型反应考察了三种催化剂的催化活性.对于30%SAPO-34催化剂,由于添加了粘结剂.其外表面酸性和扩散性能下降,导致催化活性降低:100%SAPO-34催化剂则具有较好的催化性能:介孔 SAPO-34催化剂次级结构的存在使其失活较慢,从而提高了原料的转化率.详细讨论了1-己烯催化裂解制丙烯的活性和选择性曲线,以进一步说明催化剂组成和结构的影响.
제비료100%SAPO-34,30%SAPO-34화개공-SAPO-34삼충불동류형적SAPO-34분자사최화제,병채용담흡부、소묘전경、X사선연사화홍외광보등방법대최화제진행료표정.삼충최화제적미공결구、비표면적화총산최근사,단구유불동적최화제조성화차급결구.이1-기희렬해위모형반응고찰료삼충최화제적최화활성.대우30%SAPO-34최화제,유우첨가료점결제.기외표면산성화확산성능하강,도치최화활성강저:100%SAPO-34최화제칙구유교호적최화성능:개공 SAPO-34최화제차급결구적존재사기실활교만,종이제고료원료적전화솔.상세토론료1-기희최화렬해제병희적활성화선택성곡선,이진일보설명최화제조성화결구적영향.
Three SAPO-34 catalysts, 100% SAPO-34, 30% SAPO-34, and meso-SAPO-34, with different bulk topologies were prepared. The catalysts were characterized by N_2 adsorption, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy techniques. The pore size, total acidity, and internal cage structure of the catalysts were almost identical, but they had different bulk appearances. The role of the bulk topology/structure of the catalysts was studied using 1-hexene cracking. On 30% SAPO-34, the surface acidity and diffusion rate decreased due to blocking by binder, which adversely affected catalytic activity. 100% SAPO-34 gave better cracking ability and higher propylene selectivity because of suitable acid sites and effective shape selectivity, respectively. In order to study the effect of diffusion, meso-SAPO-34 was used. The different bulk structure gave different feed conversion and selectivity profiles. A superior control of the stereochemistry was observed in the cracking by the meso-SAPO-34 and 100% SAPO-34 catalysts, in which enhanced diffusion mass transport played an appreciable role. Most of the propylene was produced by the direct cracking pathway by the β-scission carbenium ion mechanism. Hydrogen transfer reactions became significant at higher conversions. Decreasing the residence time to a certain extend is an appropriate way to obtain high propylene yield and selectivity. Activity and selectivity patterns for 1-hexene cracking to propylene were compared to justify superior SAPO-34 topology for 1-hexene cracking to propylene.