Comparative catalytic studies on alkylaromatics transformations over [Al]MCM-22 and boron-substituted [Al, B]MCM-22

The catalytic performance of [Al]MCM-22 and boron-containing [Al, B]MCM-22 was compared in the conversion of four alkyl aromatic hydrocarbons in view of the impact of their cage/channel pore structure. The contribution of the pore geometry to the observed molecular-sieve effects is discussed on the basis of the XRD, thermal analysis (TGA) of template and coke removal, N2 adsorption, 11B-MAS NMR and the catalytic test reactions. It was found that the reaction products distribution is thermodynamically or selectively controlled, depending on the type of the pores to which the different feed molecules and reaction intermediates have an access, and on the presence or absence of boron in the framework. The geometric constraints caused by the introduction of framework boron and the framework Al- and B-atoms positioning regulate the product selectivity in these transformations.