A single-crystalline mesoporous ZSM-5 (SCMZ) with sheet-like pores, a uniform thickness of ~2 nm and a wide range of lengths (5-50 nm) along the a-and c-axes was synthesised using an amphiphilic template with three diquaternary ammoniumterminated alkyl chain branches that were bound to a benzene ring in the 1,3,5-positions. The triply branched diquaternary ammonium head groups of template broke the extending of lamellar assembly along the a-and c-axes, which led to the formation of SCMZ with three-dimensional (3D) mesopores having abundant crystal faces along the a-, b-and c-axes. By increasing the length of the hydrophobic chain, we obtained the mesoporous ZSM-5 with intercrossed nanosheets (MZIN) with only a-c planes, whose mesopores were maintained after calcination because of the structural connectivity around the crossed joints. The SCMZ exhibited significantly higher catalytic efficiencies and unique selectivity compared with the conventional MFI and MZIN.

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The direct synthesis of a millimeter-sized coreÀshell-like catalyst that can be used in the hydrogenation of carbon dioxide to dimethyl ether was achieved by in situ hydrothermal synthesis. The capsule catalyst exhibited a special coreÀshell-like structure of a coprecipitated CuO/ZnO/Al 2 O 3 core enwrapped by one layer of metal-doped amorphous silicaÀalumina (ASA) membrane and was characterized by XRD, SEM, and thermal analysis. The effects of metal oxide cores and membranes prepared with different precipitants, structure-directing templates, and hydrothermal synthesis conditions, as well as temperatures and pressures, on the catalytic activity of the capsule catalyst for the hydrogenation of CO 2 to dimethyl ether were investigated. Under reaction conditions of a pressure of 3.0 MPa, a space velocity (SV) of 1800 mL 3 g cat À1 3 h À1 , a CO 2 /H 2 volume ratio of 1:3, and a temperature of 266 °C, the capsule catalysts with cores coprecipitated by urea using n-butylamine as the templating agent to enwrap the amorphous silicaÀalumina membranes had excellent catalytic properties for dimethyl ether synthesis, and the conversion of CO 2 reached 47.1%, with a dimethyl ether yield and selectivity of 19.9% and 42.4%, respectively.

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