石墨烯负载Ru催化剂的制备及催化乳酸乙酯加氢反应研究

发布时间：2018-04-23 09:16

  本文选题：石墨烯 + 钌　； 参考：《成都理工大学》2016年硕士论文

【摘要】：1,2-丙二醇是一种非常重要的化工原料,同时也广泛应用于食品,医药,化妆品等其他卫生制品领域。以乳酸或乳酸酯为原料直接加氢制备1,2-丙二醇是一条可替代石油等不可再生资源的绿色环保工艺路线。由于羰基的惰性,乳酸及乳酸酯加氢反应一般都是在十分苛刻的条件下进行的。使乳酸或乳酸酯在较温和的条件下加氢生成1,2-丙二醇并提高1,2-丙二醇的选择性的关键在于开发一种高效的催化剂。负载型金属催化剂己被成功地用于许多反应体系中,都显示了良好的催化性能,这为温和条件下实现乳酸或乳酸酯加氢反应提供了可能。石墨烯是一种新型碳材料,具有超大比表面积,优异的机械强度以及良好的耐酸碱和耐高温的特性。与此同时,适当改变石墨烯的组成还可以有效调控其热稳定性及化学性质。钌基催化剂在羧酸及羧酸酯的催化加氢反应中显示了良好的催化活性。本文以两种不同的石墨烯基材料为载体,以金属Ru为活性组分,合成了两种不同的催化剂,并探讨了两种催化剂在乳酸乙酯催化加氢反应中的催化活性。(1)实验首先采用化学还原法(Hummers法)制备了还原氧化石墨烯(RGO),以此为载体,通过浸渍法负载贵金属Ru,制备了Ru/RGO催化剂。通过XRD、SEM、FTIR、XPS等测试方法对石墨烯载体和Ru/RGO催化剂的表征,证实制备的氧化石墨烯具有较高的氧化程度,片层结构良好;且催化剂中活性组分Ru以非晶态存在载体上。通过催化加氢条件的优化,当Ru/RGO催化剂负载量为5%,催化剂与底物配比为1:100,在氢气压力为5 MPa,反应温度为150℃,反应时间为12 h时,乳酸乙酯转化率和1,2-PDO的选择性达到最佳值,分别为:97.6%与98.8%。经过6次催化循环使用后,Ru/RGO催化剂仍然具有较高的催化活性,乳酸乙酯的转化率可达:95.2%,1,2-PDO的选择性为:71.9%。(2)以无金属酞菁为前驱体,采用高温裂解法首次制备了氮掺杂的石墨烯,通过UV、XRD、SEM、TEM和AFM等测试技术的表征,证实了高温固相裂解酞菁可以成功制备出氮掺杂石墨烯。(3)采用浸渍法合成了Ru/NG催化剂,并将其用于乳酸乙酯催化加氢反应。通过催化条件的优化,当Ru/NG催化剂负载量为5%,催化剂与底物配比为1:100,在氢气压力为5 MPa,反应温度为150℃,反应时间为12 h时,乳酸乙酯在该催化剂的作用下转化率可达:99.4%,1,2-PDO选择性可达到:98.3%。通过对催化剂的循环研究发现,经过6次催化循环使用后,Ru/NG催化剂仍然可以保持较高的催化活性,乳酸乙酯的转化率和1,2-PDO的选择性可以达到:97.7%和73.8%。比化学还原法(Hummers法)制备的石墨烯为载体的催化剂的催化性能有所提高,为1,2-PDO的制备提供了一种新的绿色环保工艺路线,同时NG有望成为一种性能稳定的新型催化剂载体。
[Abstract]:Propanediol is a very important chemical raw material, but also widely used in food, medicine, cosmetics and other sanitary products. The direct hydrogenation of lactic acid or lactate to propanediol is a green environmental protection process instead of petroleum and other non-renewable resources. Due to the inertia of carbonyl group, the hydrogenation of lactic acid and lactate is generally carried out under very harsh conditions. The key to hydrogenation of lactic acid or lactate to 1m2-propanediol under mild conditions and to improve the selectivity of lactic acid or lactate is to develop an efficient catalyst. Supported metal catalysts have been successfully used in many reaction systems and have shown good catalytic performance, which provides the possibility for the hydrogenation of lactic acid or lactate under mild conditions. Graphene is a new type of carbon material with high specific surface area, excellent mechanical strength, good acid and alkali resistance and high temperature resistance. At the same time, the thermal stability and chemical properties of graphene can be effectively controlled by changing the composition of graphene. Ruthenium-based catalysts showed good catalytic activity in the hydrogenation of carboxylic acids and carboxylic esters. In this paper, two kinds of catalysts were synthesized with two kinds of graphene based materials as support and metal Ru as active component. The catalytic activity of two catalysts in the hydrogenation of ethyl lactate was studied. Firstly, the reductive graphene oxide RGOA was prepared by chemical reduction method (Hummers method). The catalyst was prepared by impregnating the noble metal Ru. on the carrier. The graphene support and Ru/RGO catalyst were characterized by X-ray photoelectron spectroscopy (XPS). It was proved that the prepared graphene oxide had a high oxidation degree and a good lamellar structure, and the active component Ru in the catalyst existed on the support in amorphous state. Through the optimization of hydrogenation conditions, when the amount of Ru/RGO catalyst is 5, the ratio of catalyst to substrate is 1: 100, the hydrogen pressure is 5 MPa, the reaction temperature is 150 鈩，

本文编号：1791340