SnO2-Pt/γ-Al2O3催化葡萄糖制备乳酸甲酯的研究

Preparation of Methyl Lactate from Glucose Using SnO2-Pt/γ-Al2O3 Catalyst

以γ-Al2O3为载体,采用浸渍法制备了SnO2-Pt/γ-Al2O3催化剂,探讨工艺参数(反应温度、反应时间、催化剂用量)对葡萄糖催化转化制备乳酸甲酯的影响,并对催化剂的重复使用性能以及放大实验进行探索。同时采用扫描电子显微镜(SEM)、X光射线电子能谱(XPS)、X射线衍射(XRD)、氮气吸附-脱附、NH3程序升温脱附(NH3-TPD)等对SnO2-Pt/γ-Al2O3催化剂进行了表征。结果表明:金属Pt和SnO2均匀地分散到γ-Al2O3载体上,催化剂体系同时具有B酸和L酸的分布,比表面积为117.08m^2/g,孔容为0.23cm^3/g,平均孔径为6.54nm,催化活性明显。当葡萄糖为1g、催化剂用量(以葡萄糖质量计)为10%、葡萄糖与甲醇料液比为1∶10(g∶mL)、反应温度220℃、反应10h的条件下,SnO2-Pt/γ-Al2O3表现出较高催化活性,葡萄糖转化率为92.63%,乳酸甲酯选择性高达20.08%,且催化剂表现出良好的重复使用性能和放大稳定性,重复使用3次时,葡萄糖转化率仍达88.43%,乳酸甲酯选择性达19.27%;物料投加量放大10倍时,葡萄糖转化率仍达86.27%,乳酸甲酯选择性达18.71%。

SnO2-Pt/γ-Al2O3 catalysts were prepared by impregnation method usingγ-Al2O3 as supporter.The effects of reaction parameters,including reaction temperature,reaction time and amount of catalyst,on the catalytic conversion of glucose to methyl lactate(MLA)were investigated.The reusability of the catalysts and the scale-up experiments were also explored.SnO2-Pt/γ-Al2O3 catalysts were characterized by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),nitrogen adsorption-desorption,temperature programmed desorption(NH 3-TPD).The results showed that the metal Pt and SnO2 were uniformly dispersed on theγ-Al2O3 supporter.The catalyst system had the distribution of B and L acid sites at the same time.The surface area was 117.08 m^2/g,the pore volume was 0.23 cm^3/g,and the average pore diameter was 6.54 nm.SnO2-Pt/γ-Al2O3 exhibited high catalytic activity with the conversion of 92.63%for glucose and the selectivity of 20.08%for glucose 1 g,methyl lactate when the catalyst dosage 10%,the ratio of glucose to methanol 1∶10(g∶mL),the reaction temperature 220℃and the reaction time 10 h.The catalyst exhibited good reusability and amplification stability.The conversion of glucose and selectivity of methyl lactate were 88.43%and 19.27%after reusing for three times,86.27%and 18.71%respectively when the dosage of materials increased 10 times.