Hengqiang Zhang

Low-temperature activation of methane over rare earth metals promoted Zn/HZSM-5 zeolite catalysts in the presence of ethylene

Abstract At low temperature of 723 K, methane can be easily activated in the presence of ethylene in the feed, and converted to higher hydrocarbons (C 2 -C 4 ) and aromatics (C 6 -C 10 ), through its reaction over rare metals modified Zn/HZSM-5 zeolite catalysts without undesirable carbon oxides formation. Methane can get 37.3% conversion over the above catalysts under low temperature, and the catalysts show a longer lifetime than usual metal supported HZSM-5 zeolite catalysts without adding any rare earth metals. The effects of methane activation over various rare earth metal promoted Zn/HZSM-5 catalysts on the products and influences of several reaction conditions such as temperature, catalyst lifetime and molar ratio of CH 4 /C 2 H 4 have been discussed.

A three-dimensional supramolecular vanadium hydroxylamide complex: poly[di-μ2-aqua-bis(hydroxylamido)-μ3-malonato-oxidosodiumvanadium(V)]

The crystal structure of the title compound, [NaV(C3H2O4)(NH2O)2O(H2O)2], is built up of NaO6 and VO5N2 polyhedra connected through malonate bridges. The NaO6 octahedra are linked by edge sharing in the equatorial plane to form one-dimensional infinite chains. These chains are linked together by the malonate bridges to form two-dimensional layers. The distorted VO5N2 pentagonal bipyramid is grafted on to the layer by a malonate carboxylate O atom. Adjacent layers are connected through O-H...O and N-H...O hydrogen bonds to build up a three-dimensional supramolecular structure.

Synthesis and Crystal Structure of the Novel Three-dimensional Vanadium Coordination Compound Potassium Oxo-bis(hydroxylamido)malonatovanadate(V)

In the crystal structure of the title complex, K2[(VO)2(NH2O)4(C3H2O4)2] ・ 3H2O, the V(V) centre is bound to a chelating malonate ligand, two bidentate hydroxylamido ligands and one oxo ligand, defining a pentagonal bipyramidal coordination (VO5N2). The potassium cations are found to adopt two types of coordination geometry with the malonate ligand, the bidentate hydroxylamido ligand and water molecules: the first one is hepta-coordinate in an irregular K(1)O7 polyhedron, and the second one is octa-coordinate in an irregular K(2)O8 polyhedron. The K(1)O7/K(2)O8 and VO5N2 polyhedra are closely linked by sharing faces to form K-V dinuclear units KVO9N2 and KVO10N2, respectively. The two close-packed units, KVO9N2 and KVO10N2, are connected by sharing edges to generate a tetrameric unit K2V2O17N4. Each of these units is joined to four neighbouring units by sharing corners, providing further propagation into a two-dimensional layer. Adjacent layers are connected via the carboxylic oxygen atoms of the malonate units to give a three-dimensional framework in the crystals. Graphical Abstract Synthesis and Crystal Structure of the Novel Three-dimensional Vanadium Coordination Compound Potassium Oxo-bis(hydroxylamido)malonatovanadate(V)