Catalytic performance of nanometer MCM-49 zeolite for alkylation reaction of benzene with 1-dodecene

Nanosize MCM-49 zeolite was synthesized under low alkalinity, and it was characterized by XRD, TEM, NH3-TPD, IR spectra of adsorbed pyridine and cumene cracking techniques. The shape of synthesized MCM-49 was of a sheet-like hexagonal structure with diameter of 300 similar to 500 nm and thickness of 20 similar to 25 nm. The TPD result showed that HMCM-49 contained both strong acid sites and weak acid sites, and IR spectra of adsorbed pyridine confirmed that the zeolite contained Lewis acid together with Bronsted acid. The total acid amount of nanosize and micrometer MCM-49 was 1.30 and 1.28 mmol/g, respectively. Nanometer MCM-49 showed high activity and selectivity for the alkylation reaction of benzene with I-dodecene in the temperature range of 30-160degreesC, the conversion of 1-dodecene was higher than 99.6%, the selectivity for linear alkylbenzene (LAB) was more than 97%, the selectivity for 2- and 3-LAB was over 67.5%. The catalytic activity of micrometer MCM-49 was lower than that of nanometer MCM-49 at low temperature. ZSM-5, M and MCM-41 zeolite exhibited poor activity and selectivity for the alkylation reaction, and Y zeolite displayed high activity but low selectivity for 2- and 3-LAB. The framework topology of MCM-49 was similar to the calcined MCM-22 and contained 12-ring channels on the external surface of the hexagonal plates, which played an important role in improving the activity and selectivity for the alkylation reaction.