Characterization and catalytic properties of hydrothermally dealuminated MCM-22

Abstract MCM-22 has been synthesized and dealuminated by hydrothermal treatments. The resulting solids were characterized by different techniques in order to know how the acid properties of the dealuminated solids were modified. It appears that the number of acid sites was decreased by hydrothermal treatments but the acid strength was not modified. Nondealuminated and dealuminated solids were used in the n -octane hydroconversion. Results suggested that for both types of solids the hydroisomerization is mainly occurring in the 10-membered ring (MR) channels whereas the hydrocracking is mainly coming from acid sites located in 12-membered ring channels. According to the observed distribution of monobranched isomers, MCM-22 shows some “shape-selective” character typical of the pentasil family, whereas, according to the absolute yield of isopentane in the hydrocracked products at low hydrocracking conversions, “MCM-22 behaves more like a 12 MR zeolite” (6). Similar conclusions were proposed in (7).