ISOPROPYLATION OF POLYNUCLEAR AROMATIC-HYDROCARBONS ON AL-CONTAINING M41S MESOPOROUS CATALYSTS

MCM-48 with Al incorporated into the walls constructing its mesopores (Al-MCM-48) was synthesized by a hydrothermal method. Al-MCM-48 posses ses almost the same surface area, thermal stability and pore size as M CM-48, and has an acidity equivalent to Al-MCM-41. However, in the iso propylation of naphthalene, Al-MCM-48 exhibits a higher activity than Al-MCM-41. This is attributed to its larger pore size and three-dimens ional pore system, which is more advantageous for molecular diffusion than the relatively narrow and one-dimensional pore system of Al-MCM-4 1. Compared with the yields of 2,6-diisopropylnaphthalene on large-por e zeolites, those on Al-M41S (Al-MCM-41 and Al-MCM-48) are not high be cause of their fewer acid sites. Al-MCM-48 also shows a higher activit y than Al-MCM-41 in the isopropylation of pyrene, and the activities o n the mesoporous M41S materials were much higher than that on zeolite Y. Isopropylation of pyrene occurs inside the mesopores of M41S, while pyrene derivatives cannot be produced inside the micropores of zeolit e Y. However, coke formation and adsorption of the reactant and/or pro duct proceeded in the mesoporous channels and caused catalyst deactiva tion. The product distributions, especially the ratio of 2-isopropylpy rene/1-isopropylpyrene in pyrene isopropylation, indicate that shape s electivity occurs inside the regular mesopores of M41S.