Pore Size of Mesoporous Molecular Sieve Catalysts and Their Deactivation by Coke Formation

在高温下烃类反应期间通过焦炭形成而使固体酸催化剂失活可取决于催化剂的孔径。由于焦炭堵塞孔隙是导致失活的主要原因。本研究通过混合两种不同烷基链长的模板剂，实现了对MCM-41孔径的精细控制，制备了具有规则孔结构和不同孔径的铝硅酸盐介孔分子筛Al-MCM-41，并研究了催化剂的失活速率与孔径的关系。而Al-MCM-41材料作为固体酸催化剂的失活与孔径大小无关。这是因为活性污泥的失活不是由孔塞引起的，而是由表面污染引起的。由此可见，MCM-41的失活不同于沸石。

Deactivation of solid-acid catalysts by coke formation during reactions of hydrocarbons at high temperatures may depend on the pore size of the catalysts. Because the main reason for deactivation is pore-plugging with coke formed. In this study I expected to prepare aluminosilicate mesoporous molecular sieves, Al-MCM-41, with regular pore arrangement and with various pore sizes, and to clarify the relationship between the deactivation rate and pore size of the catalyst.The fine control of the pore size of MCM-41 has been achieved by mixing two templates with different alkyl chain length. However the deactivation of Al-MCM-41 materials as solid acid catalysts was independent of the pore size. Because the deactivation took place caused not by pore-plugging but by surface-fouling. Thus it is apparent that the deactivation of MCM-41 is different from that of zeolites.