载体对Pt-Sn催化乙酸加氢制乙醇性能的影响

Effects of Supporter on Pt-Sn Catalytic Performance in Selective Hydrogenation of Acetic Acid to Ethanol

以硝酸铂和草酸亚锡为金属前躯体,利用等体积共浸渍法制备了Pt含量为1.5%(wt)的Pt-Sn催化剂,考察了载体(Ca Si O3改性的Si O2,γ-Al2O3和Ti O2)对乙酸气相选择性催化加氢制备乙醇性能的影响。结果表明,Pt-Sn/Ca Si O3-SiO2、Pt-Sn/γ-Al2O3和Pt-Sn/TiO2催化剂上乙醇的选择性基本相同且高达86%左右,但前者的催化活性、乙酸的转化率和乙醇收率都要高于后两者。对于Pt-Sn/Ca Si O3-Si O2催化剂,在反应温度范围内,催化活性、乙酸转化率、乙醇选择性和收率随着反应温度的升高而增加,当反应温度超过300℃时,乙醇选择性基本保持不变。催化加氢生成乙醇的表观活化能相对较高,为47.6878 k J·mol-1。在2.2 MPa和325℃条件下,Pt-Sn/Ca SiO3-SiO2的催化活性、乙酸转化率、乙醇选择性和收率分别为0.35 mmol·s-1·g Pt-1、90.73%、86.96%和78.89%。

Pt-Sn catalysts with a Pt loading of 1.5 %（wt） were prepared by incipient-wetness co-impregnation method employing platinum nitrate and tin oxalate as precursor. Effects of supporter （CaSiO3 modified SIO2, γ-Al2O3 and TiO2） on the catalytic performance of selective hydrogenation of acetic acid to ethanol were investigated. Ethanol selectivity as high as 86% remains almost the same for Pt-Sv2CaSiO3-SiO2, Pt-Sn/γ-Al2O3 and Pt-Sn/TiO2 catalysts. Pt-Sn/CaSiO3-SiO2 catalyst shows the highest catalytic activity, acetic acid conversion and ethanol yield. For Pt-Sn/CaSiO3-SiO2 catalyst, the catalytic activity, acetic acid conversion, ethanol selectivity and yield increase with the increase of reaction temperature within the reaction temperature range. On the other hand, ethanol selectivity remains almost the same after 300℃. The apparent active energy of catalytic hydrogenation to ethanol is at a relative high level of 47.6878 kJ.moV1. For Pt-Sn/CaSiO3-SiO2 catalyst, at 2.2 MPa and 325℃, catalytic activity, acetic acid conversion, ethanol selectivity and yield ratio are 0.35 mmol.s-1.gPt-1, 90.73%, 86.96% and 78.89%, respectively.