| 查看: 405 | 回复: 1 | ||
1135725495兑换贵宾
|
[求助]
英文翻译
|
| The amount of 10 wt%-WO3 was supported on alumina, titania or silica by impregnation with aqueous solution of ammonium paratungstate and subsequent calcination at 500℃ for 10 h. Tungstate-related chemical and physical changes in the calcination products were resolved by ex-situ infrared (IR) spec-troscopy. Nature of exposed surface acid sites were probed by in-situ IR spectroscopy of adsorbed pyridine (Py) molecules at room temperature (RT). The relative strength of the acid sites thus probed was gauged by combining results of temperature-programmed desorption (TPD) measurements of the RT-adsorbed Py with those communicated by in-situ IR spectra of residual Py on the surface after a brief thermoevacuation at high temperatures (100–300℃). Reactivity of the surface acid sites was tested toward 2-propanal catalytic decomposition, and observed by in-situ IR gas phase spectra. Results obtained were correlated with predominant structures assumed by the supported tungstate species. Accordingly, polymerization of the supported tungstate into 2-/3-dimensional structures, was found to be relatively most advanced on favorable locations of titania surfaces as compared to the case on alumina or silica surfaces. Consequently, the Lewis acidity was strengthened, and strong Bronsted acidity was evolved, leading to a 2-propanol dehydration catalyst (tungstate/titania) of optimal activity and selectivity. Strong tungstate/support interfacial interactions were found to hamper the formation of the strongly acidic and catalytically active polymeric structures of the supported tungstate (i.e., the case on alumina or silica). |
回复此楼» 猜你喜欢
291求调剂
已经有25人回复
-
一志愿北京科技大学085601材料工程英一数二初试总分335求调剂
已经有6人回复
-
一志愿北京科技，085601总分305求调剂
已经有10人回复
-
化学工程专硕324分，一志愿中国矿业大学求调剂
已经有6人回复
-
279求调剂
已经有3人回复
-
26年申博
已经有4人回复
-
材料工程322分
已经有5人回复
-
318求调剂，计算材料方向
已经有7人回复
-
292分，材料与化工，申请调剂
已经有20人回复
-
085600 295分求调剂
已经有18人回复
2楼2014-10-10 08:14:02
