Catalytic conversion of CH3Br to aromatics over PbO-modified HZSM-5

The catalytic conversion of CH3Br to aromatics was investigated over PbO-modified HZSM-5. The effects of PbO loading, SiO2/Al2O3 molar ratio of HZSM-5. and calcination conditions of catalyst on catalytic performance were studied. It was found that the most suitable PbO loading and SiO2/Al2O3 ratio are 5 wt% and 70, respectively. The 5 wt% PbO/HZSM-5 calcined at 450 degrees C for 8 h performs the best. Also, PbO is superior to the other metal oxides selected to modify HZSM-5, and HZSM-5 is better than SiO2, Al2O3 or ZrO2 as support. The characterization results indicate that (i) the PbO species is highly dispersed on the HZSM-5 support, (ii) the role of PbO is to promote hydrocarbon aromatization, and (iii) the acid sites of HZSM-5 are indispensable for CH3Br conversion into aromatics, We found that the deactivation of catalyst is due to pore blocking by carbonaceous deposits. The overall results demonstrate that the method is efficient for the conversion of CH4 to aromatics. (C) 2009 Published by Elsevier B.V.