【作者】 颜爱风；

【导师】 吴瑛； 吴廷华；

【作者基本信息】 浙江师范大学 ， 物理化学， 2011， 硕士

【摘要】 利用天然气资源直接或间接地生产乙烯可以有效的缓解因石油资源短缺而引发的矛盾。乙烷是天然气中的主要成分,以乙烷为原料生产乙烯对我国的石化工业具有重要的意义。工业上乙烷转化为乙烯主要是通过蒸汽裂解,该过程为一强吸热反应,耗能高,且受热力学平衡的限制。近年来,研究者开始致力于研究乙烷的催化氧化脱氢。但由于各种副反应的存在,且在热力学上这些副反应一般都要比乙烷氧化脱氢制乙烯反应更为有利。因此,如何在较低温度下获得较高乙烯收率具有重要的现实意义。纳米颗粒的氧化镍催化剂对乙烷氧化脱氢制乙烯(ODHE)反应具有较好的低温催化活性。本文首先用研磨法、直接沉淀法、尿素均匀沉淀法、溶胶凝胶法制备了纳米颗粒的NiO,并考察其乙烷氧化脱氢的催化性能,结果表明尿素均匀沉淀法制备的纳米氧化镍具有较好的催化活性,这可能与均匀沉淀法制备的催化剂颗粒较小,比表面积较大有关。在此基础上,我们用尿素沉淀法,通过简单的步骤合成了花状氧化镍,并考察了不同沉淀温度、不同沉淀时间对合成纳米片自组装的花状NiO的影响。由于其特殊的形貌具有堆积孔结构,具有较好的还原性能,因此与常规尺寸的NiO相比,花状的NiO具有较好的乙烷氧化脱氢催化活性。另外,由于介孔材料具有较大的比表面积、窄的孔径分布和大的孔道结构,本论文还采用了不同的制备方法合成了介孔NiO,发现在相同的反应条件下,软模板法制备的介孔NiO催化剂乙烯收率明显高于硬模板法制备的介孔NiO。因此通过软模板法选择不同表面活性剂合成了介孔NiO,并比较其乙烷氧化脱氢活性,结果表明,以十二烷基硫酸钠(SOD)为模板剂合成的介孔氧化镍具有较好的催化活性,在450℃时,可以获得25.6%的乙烯收率。在介孔氧化镍的研究基础上,添加不同的助剂,研究了双组分NiMO (M=Li、Mg、Al、Y、Zr)催化剂对乙烷氧化脱氢制乙烯活性的影响。结果表明,与单组分介孔NiO相比,除了NiLiO外,其他二组分催化剂的活性均有所提高,在450℃时,NiZrO催化剂可获得最高的乙烯收率34.6%。同时,采用XRD,氮气吸脱附,H2-TPR,及拉曼等方法对NiMO催化剂进行表征,结果表明,添加的助剂可以少量取代Ni离子进入晶格结构,从而使催化剂的还原性能和氧脱附性能有所改变,从而对其催化活性产生一定的影响。更多还原

【Abstract】 The effective use of natural gas resources can alleviate the shortage of oil resources. As the main component of natural gas, the conversion of ethane to ethylen is significant. Ethylene is currently produced mainly by the steam cracking of ethane. The steam cracking, however, is operated at a high temperature, consumes much energy. In recent years, the catalytic oxidative dehydrogenation of ethane(ODE) to ethylene has received much attention because it is an exothermic reaction that can be carried out at a low temperature with high conversion and selectivity. The disadvantage of this reaction is the existence of a variety of side-reaction. Therefore, it is import to get a low-temperature catalyst with high performance.Nanoscaled nickel oxide can greatly reduce the reaction temperature of oxidation dehydrogenation of ethane. In this thesis we firstly prepared nanoscaled NiO by grinding, direct precipitation, urea homogeneous precipitation method, sol-gel method and then investigated their catalytic performance on oxidative dehydrogenation of ethane to ethylene. The results indicated the NiO catalyst prepared with urea homogeneous precipitation method showed better catalytic performance. It may be related the small granule and large surface of the catalyst. On this basis we synthesized flower-like NiO via a simple route and investigated the effect of precipitating temperature and time on the self-assembled film of a flower-like NiO. Compared with the conventional bulk NiO, the flower-like NiO showed better catalytic performance for ODHE reaction. It’s attributed to its special morphology with accumulation of holes.Mesoporous materials have attracted a lot of attention because of their high surface area, narrow pore size distribution, and large pore volume. In this thesis, we also prepared mesoporous NiO with different method. The results indicated that under the same experimental conditions, the ethylene yield obtained on the mesoporous NiO catalyst synthesized with soft template was higher than the hard template. Therefore, different surfactant was used to prepared meso-NiO by soft template synthesis method and their catalytic activity was investigated. Thereinto the meso-NiO using SOD as surfactant showed better catalytic performance and the yield of ethylene can reach 25.6% under 450℃.On the basis of study of mesoporius nickel oxide, bi-component oxide NiMO (M=Li, Mg, Al, Y, Zr) catalyst was investigated on the the oxidative dehydrogenation of ethane to ethylene activity. Compared with meso-NiO, the performance of NiMO catalyst were improved catalytic activity beside NiLiO. At 450℃, the ethylene yield of 34.6% can be obtained on the NiZrO catalyst. The catalysts were characterized by XRD, nitrogen adsorption, H2-TPR, and Raman et al., and the results indicated that the M ion could substitute Ni in the lattice, and thus affect the reduction and disorption properties of the NiMO catalysts, thereby their catalytic performance on the oxidative dehydrogenation of ethane was promoted.更多还原