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%。
Membrane separation and foam separation are widely used separation techniques.To make use of their advantages,membrane separation and foam separation were integrated to dispose waste water with low concentration of linear alkylbenzene sulfonate(LAS).A method of forcing bubbles through a single hollow fiber ultrafiltration tube was put forward to study the separation efficiency of the integrated process.The effects of pressure,gas-liquid ratio and LAS concentration on the separation efficiency were investigated.Under the conditions of pressure 0.03—0.1 MPa,gas-liquid ratio 0—0.9,and LAS concentration 0—70 mg·L-1,the membrane permeate flux was raised from 26.5 to 38.6 L·m-2·h-1,increased by 48.6%,and the retention rate was raised from 37.0% to 64.9%,increased by 75.5%.The results show that the integrated process can reduce the concentration polarization and membrane fouling.Moreover,this method reduces the back-mixing of foam separation and increases the concentration of bulk liquid phase for foam separation.Therefore,the integrated separation promotes mass transfer and improves separation efficiency.
