An unusual hierarchical ZSM-5 microsphere with good catalytic performance in methane dehydroaromatization

In this paper, a novel hierarchical ZSM-5 microsphere (simplified as ZSM-5-MS hereafter) of about 3 jam, which is assembled by many French fries-like crystals (in shape of French fries) of about 100 nm in width, was synthesized by using SBA-15 as the silica source. ZSM-5-MS exhibited a unique geometrical shape which was entirely distinct from the conventional MFI shape. The N-2 adsorption isotherm suggested that the ZSM-5-MS had a uniform mesopores of 15 nm with a tail up to 45 nm. The ZSM-5-MS was modified to form a Mo/HZSM-5-MS catalyst which exhibited good catalytic performance in methane dehydroaromatization (MDA) due to the presence of both micropores and mesopores. A time trial study was carried out by SEM, XRD and TEM analysis for the insight into the growth of the obtained ZSM-5-MS. A growth model via self-assembly combined with crystallization process was proposed based on the time trial observations. The demonstrated route may be extended to synthesize other types of zeolites with unusual structure and properties. (C) 2008 Elsevier Inc. All rights reserved.