Pt-Sn/H-β催化剂的制备及加氢性能研究

Preparation of Pt-Sn/H-βcatalyst and study on its hydrogenation performance

采用浸渍-原位还原法制备了一系列Pt基催化剂,研究了催化剂载体、活性中心、酸性中心等对催化剂活性的影响。通过XRD、FT-IR、H_(2)-TPR、NH_(3)-TPD、BET、XPS和TEM等手段对催化剂的结构和性质进行表征。结果表明,H-β分子筛具有较大的比表面积,可以较好地分散活性物种,Pt-Sn/H-β催化剂表面以弱L酸中心为主,Sn物种的加入使得Pt物种处于富电子状态。在肉桂醛选择性加氢反应中,肉桂醛的转化率达93.1%,肉桂醇的选择性达95.3%。更多较小尺寸的活性中心与L酸中心配合可以有效提高催化剂的活性及选择性。

A series of Pt-based catalysts are prepared through impregnation in-situ reduction method.The effects of the support,active center and acidic center on the activity of the catalysts are studied.The structure and properties of the catalysts are characterized by means of X-ray diffraction(XRD),infrared spectroscopy(FT-IR),hydrogen temperature programmed adsorption(H_(2)-TPR),NH_(3)temperature programmed desorption(NH_(3)-TPD),N2 physical adsorption,X-ray photoelectron spectroscopy(XPS)and transmission electron microscopy(TEM).It is shown that the H-βmolecular sieve has a larger specific surface area,which can disperse active species well.The prepared catalyst has more active sites and its surface is dominated by weak L-acid centers.The addition of Sn species makes Pt species show an electron-rich state.The larger specific surface and smaller active particle size are beneficial to the selective hydrogenation of cinnamaldehyde.As the catalyst is served in the selective hydrogenation of cinnamaldehyde,the conversion rate of cinnamaldehyde is 93.1%and the selectivity of cinnamyl alcohol is 95.3%.The activity and selectivity of catalyst can be improved effectively by the combination of active center and Lewis acid center.