Effect of Hydrophobic Modification on the Catalytic Performance of PdCl 2 /Cu-HMS with Different Silylation Temperatures
- PDF / 421,757 Bytes
- 5 Pages / 595.276 x 790.866 pts Page_size
- 27 Downloads / 174 Views
Effect of Hydrophobic Modification on the Catalytic Performance of PdCl2/Cu-HMS with Different Silylation Temperatures Pingbo Zhang • Yan Zhou • Mingming Fan • Pingping Jiang • Xianglan Huang • Jiang Lou
Received: 22 July 2013 / Accepted: 8 September 2013 / Published online: 12 October 2013 Ó Springer Science+Business Media New York 2013
Abstract A new class of organic–inorganic hybrid materials were prepared by combining Cu-HMS with a silylation agent, trimethylchlorosilane (TMCS) via a simple silylation process at different silylation temperatures. They were characterized by a series of techniques including FT-IR, powder XRD, Nitrogen adsorption–desorption, TG analysis and water adsorption capacity test. It was demonstrated that silylation of PdCl2/Cu-HMS catalysts with TMCS enhanced their hydrophobicity, improved their activity and stability and importantly kept the excellent selectivity to diethyl carbonate (DEC) by oxidative carbonylation of ethanol in the gas-phase reaction. Moreover, the silylated samples obtained at 60 °C showed a better conversion of EtOH of 6.1 % and STY of DEC of 140.8 mg g-1 h-1. Keywords Organic–inorganic hybrid materials Trimethylchlorosilane (TMCS) Hydrophobicity Silylation temperature Diethyl carbonate (DEC)
1 Introduction Diethyl carbonate (DEC) is recognized as an environmentally benign chemical because of its negligible ecotoxicity and low bioaccumulation and persistence. Because of its high oxygen content (40.6 wt%), DEC has been proposed as a replacement
P. Zhang Y. Zhou M. Fan (&) P. Jiang X. Huang J. Lou The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, People’s Republic of China e-mail: [email protected]
123
for tert-butyl ether (MTBE) as an attractive oxygen-containing fuel additive, and the gasoline/water distribution coefficients for DEC are more favorable than for dimethyl carbonate and ethanol [1, 2]. In addition, as a chemical intermediate, DEC is also drawing attention as a safe solvent and an additive in lithium cell electrolyte [3, 4]. Currently, oxidative carbonylation of ethanol in the gas-phase has been deemed as one of the most promising routes for DEC synthesis based on the ‘‘green chemistry’’ principles [5]. Various catalysts have been investigated for oxidative carbonylation which were prepared by impregnating the active carbon [2, 6, 7], oxides [8, 9] or other zeolites in methanol solution of CuCl2 [5, 10–13]. In the previous research [14, 15], PdCl2/Cu-HMS has been demonstrated an excellent selectivity to DEC by oxidative carbonylation of ethanol in the gas-phase reaction. Moreover, it was also found that H2O in the feed decreased the conversion of methanol and the selectivity of carbon monoxide to dimethyl carbonate [16, 17]. So removal of water from the catalyst surface would reduce the hydrolysis of DEC and, therefore, would benefit activity and stability of the reaction. Catalytic activities can be improved by taking different
Data Loading...
