Entity

Time filter

Source Type


Li Z.,Beijing University of Chemical Technology | Li Z.,Key Laboratory of Fine Petrochemical Engineering of Jiangsu Province | Xiang X.,Beijing University of Chemical Technology | Tian Z.,Beijing University of Chemical Technology
Advanced Materials Research | Year: 2012

The synthesis of α-nickel hydroxide has been achieved via a facile liquid-phase precipitation approach, using the mixed solvents of ethylene glycol and water as reaction medium at low temperature. The XRD characterization indicates that pure phase α-Ni(OH)2 can be obtained under variable temperature and pH value. The products present a flower-like micro-/nano-structure assembled with curved nanosheets. The nanosheets have the width of 100∼500 nm and the thickness of 20∼70 nm. The cavities are formed in the structure due to the interconnection of curved nanosheets. The solvents play a key role in the formation of Ni(OH)2 with different forms. Pure phase α-Ni(OH)2 can only be synthesized in the mixed solvents of ethylene glycol and water. Cyclic voltammetry was applied to test the electrochemical activity of the as-synthesized α-Ni(OH) 2. The findings suggest that the α-Ni(OH)2 with a micro-/nano-structure exhibits excellent electrochemical activity, which may be considered as a promising candidate of electrode material. © (2012) Trans Tech Publications, Switzerland. Source


Li Z.,Beijing University of Chemical Technology | Li Z.,Key Laboratory of Fine Petrochemical Engineering of Jiangsu Province | Xiang X.,Beijing University of Chemical Technology | Bai L.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Applied Clay Science | Year: 2012

NiAl-layered double hydroxide/carbon (LDH/C) nanocomposites were prepared by a hydrothermal process simultaneously involving the crystallization of LDH and carbonization of glucose. The nanocomposites calcined in air lead to porous NiAl-mixed-metal oxides with tunable surface areas. The porosity of resultants is ascribed to the templating effect, resulting from the depletion of carbonaceous products with the elevating temperature under air atmosphere. The specific surface areas of products are sensitive to carbonaceous product content in the composite precursor, Ni/Al ratio and as well the calcination temperature. The specific surface area reaches a maximum under medium carbon content in the precursor and decreases with the increasing calcination temperature. On a basis of the nature of metal oxides and their high surface areas, the mixed-metal oxides are utilized for catalytic thermal decomposition of ammonium perchlorate (AP) and exhibit excellent catalytic activity. The peak temperature of AP decomposition was greatly decreased compared to that of pure AP. And the temperature is strongly dependent on the surface areas of mixed oxides. Furthermore, the decomposition activation energy of AP with the mixed oxide additives was calculated to be 74.6 and 80.4kJmol -1 by two methods of kinetics, respectively, both of which are smaller than that of pure AP. © 2012 Elsevier B.V. Source


Tian Z.,Beijing University of Chemical Technology | Tian Z.,Key Laboratory of Fine Petrochemical Engineering of Jiangsu Province | Xiang X.,Beijing University of Chemical Technology | Xie L.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2013

The gold nanocrystals supported over CeO2-containing mixed-metal oxides were synthesized by a reduction-deposition approach followed by calcination. The zerovalent Au0 was obtained from the reduction of Au3+ ion by the hydrolysis of sucrose in an aqueous solution. The thermal post-treatment led to supported gold catalysts, in which Au nanoparticles with adjustable sizes were anchored onto the mixed oxides. The incorporation of cerium (Ce) into the support remarkably enhanced the selectivity toward C=C bond (hydrocinnamaldehyde, HCAL, ca. 83%) in cinnamaldehyde hydrogenation than the catalyst with no cerium (ca. 42%) under a high conversion (above 91%). The enhancement of selectivity to HCAL could be attributed to the decreasing sizes of Au and/or CeO2, the morphology effect of Au, and the interaction of Au and CeO2 components in the support, revealed by XRD, HRTEM, and XPS. The increasing Ce3+ amount in the catalysts leads to more oxygen vacancies. The surface electron density of Au diminishes due to the presence of oxygen vacancies. The morphological and electronic aspects of Au particles result in favorable adsorption of C=C bond versus C=O bond. A control experiment showed that the Au/CeO2 catalyst has a relatively low activity and selectivity under the identical reaction conditions. This finding indicated that a better dispersion and decreased size of CeO2 in the mixed oxides could be the key factors to enhancing the selectivity of supported Au catalysts. © 2012 American Chemical Society. Source


Xiang X.,Beijing University of Chemical Technology | He W.,Beijing University of Chemical Technology | He W.,Key Laboratory of Fine Petrochemical Engineering of Jiangsu Province | Xie L.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Catalysis Science and Technology | Year: 2013

Hydrotalcite-supported platinum nanocrystals (Pt NCs) were synthesized by a facile solution chemistry method, and then applied as an efficient catalyst for the selective hydrogenation of cinnamaldehyde (CMA) in neat water. The reduction of metal precursor ions was achieved in an aqueous solution at a low temperature (323 K), simultaneously accompanied by the crystallization of the hydrotalcite support. The size of the Pt NCs can be delicately tuned by the relative ratio of surfactant to metal precursor ions, and characterized by HRTEM and CO-adsorption infrared spectroscopy. The Pt particle sizes are closely associated with the hydrogenation selectivity toward cinnamyl alcohol (CMO), with a higher selectivity up to 85% over the larger-sized Pt in an aqueous medium. The effects of alkali (NaOH) on the catalytic performance were explored. The findings indicated that the addition of alkali enhances the selectivity toward CMO (to 90%). The catalysts showed high stability with a marginal decrease in activity and selectivity after repeated use. The hydrogenation products could be easily separated from the solvent by simple extraction, which is a greener and more convenient process than those using organic solvents. © 2013 The Royal Society of Chemistry. Source

Discover hidden collaborations