高岭土负载金属氧化物催化剂的制备表征及丙烷氧化脱氢催化性能的研究

发布时间：2018-05-07 09:50

  本文选题：高岭土 + 丙烷　； 参考：《内蒙古师范大学》2017年硕士论文

【摘要】：随着科技的快速发展,天然粘土资源的研发和利用成为国内外科研应用领域的前沿课题。其应用研究水平成为影响一个国家科技水平发展的重要方面。高岭土是一种重要的非金属矿产,它的主要成分为高岭石族矿物,由Si-O四面体和Al-O八面体构成层状结构,是质地纯净的细粒粘土,具有良好的可塑性、吸附性、易分散性、高白度和优良的电绝缘性,目前被广泛应用于化工、环保、农业、建筑等领域。内蒙古自治区高岭土资源丰富,价廉易得,将高岭土改性可以得到具有一定孔结构和高比表面积的材料,用于新型多相催化领域,是很好的催化剂及催化剂载体,对高岭土资源的综合利用具有重要意义。丙烯是石油化工基础原料之一。随着聚丙烯腈、丙烯醛及丙烯酸等丙烯下游产品需求量的快速增加,全球丙烯需求量也快速增长。传统丙烯制备方法难以满足需求。丙烷氧化脱氢制丙烯具有巨大的经济应用前景,已经成为催化领域研究的热点。但在有氧条件下,丙烯易深度氧化,丙烯选择性不理想。因此,制备稳定且具有低温高丙烯选择性的催化剂是其研究关键。本研究采用介孔改性-浸渍法和共沉淀-焙烧法,制备高岭土负载金属氧化物催化剂,并进行XRD,N_2吸附脱附,H_2-TPR,NH_3-TPD,XPS和电导性能等表征,优化其丙烷氧化脱氢制丙烯催化性能,探究其催化性能的影响因素。1.将200目高岭土用硫酸回流酸化,再加P123改性,550℃焙烧,制备孔道较均一的介孔改性高岭土,比表面积389.4 m~2/g。2.采用浸渍法制备了V_2O_5/改性高岭土系列催化剂。研究表明,该系列催化剂表面存在弱酸性位;改性高岭土为p型半导体,负载V_2O_5催化剂为n型半导体;负载5%V_2O_5催化剂表面V5+较多;随晶格氧含量增加,丙烯选择性提高,600℃催化性能最佳:丙烷转化率28.11%,丙烯选择性62.38%。3.采用浸渍法制备NiO/改性高岭土催化剂。研究表明,随镍负载量增加,催化剂电导类型保持p型半导体。NiO负载7.5%的催化剂低温丙烷氧化脱氢制丙烯性能最好:450℃丙烷转化率18.20%、丙烯选择性49.80%。4.通过共沉淀-焙烧法制备了Ni-Al-O/高岭土和Ni-Cr-O/高岭土复合氧化物系列催化剂。10%Ni-Al-O/高岭土复合氧化物催化剂在反应温度为525℃时丙烷转化率19.88%,丙烯选择性47.71%。10%Ni-Cr-O/高岭土复合氧化物催化剂,在450℃时丙烷转化率22.98%,丙烯选择性44.50%。
[Abstract]:With the rapid development of science and technology, the research and utilization of natural clay resources has become a frontier subject in the field of scientific research and application at home and abroad. Its applied research level has become an important aspect that affects the development of a country's science and technology level. Kaolin is an important nonmetallic mineral, its main composition is kaolinite group mineral, which is composed of Si-O tetrahedron and Al-O octahedron. It is a pure fine clay with good plasticity, adsorption and dispersibility. High whiteness and excellent electrical insulation are widely used in chemical industry, environmental protection, agriculture, construction and other fields. Kaolin in Inner Mongolia Autonomous region is rich in resources and cheap and easy to obtain. By modifying kaolin, materials with certain pore structure and high specific surface area can be obtained, which can be used in the field of new heterogeneous catalysis, and it is a good catalyst and catalyst carrier. It is of great significance for comprehensive utilization of kaolin resources. Propylene is one of the basic raw materials in petrochemical industry. With the rapid increase of demand for downstream products such as polyacrylonitrile, acrolein and acrylic acid, the global demand for propylene is also increasing rapidly. The traditional propene preparation method is difficult to meet the demand. Oxidative dehydrogenation of propane to propylene has a great economic application prospect and has become a hot spot in the field of catalysis. However, under aerobic conditions, propylene is easy to be oxidized in depth, and the selectivity of propylene is not ideal. Therefore, the preparation of stable catalyst with low temperature and high propylene selectivity is the key to its research. In this study, kaolin supported metal oxide catalysts were prepared by mesoporous modification-impregnation method and coprecipitation-roasting method, and their catalytic properties were optimized by means of XRD- N2 adsorptive desorption, H2-TPRN NH3-TPD-XPS, conductivity, etc, to optimize their catalytic properties for oxidative dehydrogenation of propane to propylene. Explore the influence factors of its catalytic performance. 1. The mesoporous kaolin with homogeneous pore channels was prepared by refluxing and acidizing with sulfuric acid and calcination at 550 鈩，

本文编号：1856448