Influence of Pd precursors on the catalytic performance of Pd-H4SiW12O40/SiO2 in the direct oxidation of ethene to acetic acid
文献类型：会议论文
| 作者 | Xu SL(徐庶亮) ; Chu WL(楚文玲) ; Wang LX(王丽霞) ; Yang WS(杨维慎) |
| 出版日期 | 2008-07-09 |
| 会议名称 | a pre-conference of the 14th international congress on catalysis |
| 会议日期 | 2008-7-9 |
| 会议地点 | 中国 |
| 页码 | 258/1 |
| 通讯作者 | weishen yang |
| 中文摘要 | acetic acid, one of the world’s most important chemical products, is currently manufactured via methanol carbonylation. considering the environmentally benign and lower expenditure in investment, in 1997, showa denko succeeded in developing a process employing direct oxidation of ethene to acetic acid over pd-h4siw12o40/sio2 catalyst system. as known from the literatures that the palladium is necessary to obtain higher catalytic activity for this process. but, there are few reports about the effect of palladium precursors on direct oxidation ethene to acetic acid on pd-h4siw12o40/sio2 catalyst. for this reason, a series of catalysts pd-h4siw12o40/sio2 with different palladium precursors (e.g. pdcl2, (nh4)2pdcl4, pd(nh3)2cl2, pd(no3)2 and pd(c2h3o2)2) were prepared by a wetness impregnation method and investigated by various of characterization techniques. it is well-known that the acidic properties of the catalyst have a strong influence on its catalytic performance. our findings indicated that the difference of palladium precursors could lead to the obvious changes for the density of lewis (l) and brønsted (b) acid sites. according to the ir of pyridine adsorption, it can be found that the existence of palladium resulted in the decrease of the brønsted acid sites, but the ratio of l/b acid sites decreased as following: pdcl2>(nh4)2pdcl4> pd(no3)2>pd(c2h3o2)2>pd(nh3)2cl2, which is in good agreement with the results of catalytic activity, namely, the more the l/b ratio is, the higher the catalytic activity is. so it can be proposed that l/b acid sites responsible for the high catalytic activity of pd-h4siw12o40/sio2. furthermore, the results from h2-pulse chemical adsorption revealed that the dispersion of palladium is strongly dependent on the palladium precursor. for pdcl2 and (nh4)2pdcl4 precursors, in which pd existed as pdcl4 2-polyanion, higher dispersions of palladium were obtained due to the strong metal-support resulted from the anion-exchange reaction between pdcl4 2- and oh- group. as a result, the agglomeration of palladium on the surface was inhibited and led to a highly dispersed state of palladium. but for other palladium precursors, pd existed as pd2+ or pd(nh3)2 2+, the situation is contrary, in which considerably low dispersion of palladium was observed. from above, it can be concluded that the palladium precursors have significant influence on the acidic properties and palladium dispersion of the pd-h4siw12o40/sio2 catalysts and further on the catalytic performance. and the pd-h4siw12o40/sio2 prepared from pdcl2 or (nh4)2pdcl4 precursor exhibited the most excellent catalytic activity, for which the maximum yield of acetic acid (~120g/h•l-cat) was achieved, which is comparable with the results in the literatures. |
| 会议主办者 | 大连化学物理研究所 |
| 学科主题 | 物理化学 |
| 语种 | 中文 |
| 源URL | [http://159.226.238.44/handle/321008/112992]  |
| 专题 | 大连化学物理研究所_中国科学院大连化学物理研究所 |
| 推荐引用方式 GB/T 7714 | Xu SL,Chu WL,Wang LX,et al. Influence of Pd precursors on the catalytic performance of Pd-H4SiW12O40/SiO2 in the direct oxidation of ethene to acetic acid[C]. 见:a pre-conference of the 14th international congress on catalysis. 中国. 2008-7-9. |
入库方式： OAI收割
来源：大连化学物理研究所
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