基于镍铝水滑石的高分散纳米催化剂的制备及其性能研究

发布时间：2018-05-31 00:39

  本文选题：水滑石 + 纳米钌催化剂　； 参考：《北京化工大学》2017年硕士论文

【摘要】：镍基催化剂在反应过程中存在结构坍塌,活性组分失活的现象,以氧化铝为铝源,原位生长水滑石材料,在其表面负载钌纳米颗粒,实现钌纳米颗粒的高分散,用于生物质平台分子5-羟甲基糠醛选择性加氢性能研究。此外,制备三元镍铜铝水滑石,通过焙烧和还原获得高分散的镍铜双金属催化剂用于生物质衍生物乙酰丙酸乙酯氢转移加氢性能研究。水滑石(LDHs)是一种二维层状材料,因具有组成元素和比例可调变、制备方法丰富、催化活性优异的特性而得到科研工作者们的广泛关注。目前,在催化、光电、环境污染、阻燃、生物传感、医药等方面吸引了科研人员的深入研究。本文利用原位生长法制备了镍铝水滑石(NiAl-LDHs),利用水滑石载体的丰富孔道,通过硼氢化钠还原法高分散负载钌纳米颗粒,将制备的催化剂用于5-羟甲基糠醛选择性加氢性能研究。此外,合成三元镍铜铝水滑石(NiCuAl-LDHs),焙烧还原制备镍铜双金属催化剂,结构仍能保持,将催化剂用于乙酰丙酸乙酯氢转移加氢性能研究,进一步分析了催化剂的结构与活性之间的关系。(一)利用原位生长法制备的NiAl-LDHs材料表面含有大量羟基,通过硼氢化钠一步还原法将钌纳米颗粒负载在NiAl-LDHs表面。经过XRD、SEM、HRTEM、BET、XPS等表征手段,证明钌纳米颗粒在载体表面均匀分散,并且与载体之间的相互作用十分强烈。另外,NiAl-LDHs丰富的孔道结构和较高的比表面积,有利于实现贵金属钌的高分散。特别的是,制备的Ru/NiAl催化剂能够在以氢气为氢源的条件下高效催化5-羟甲基糠醛生成2,5-二甲基呋喃,催化剂在重复利用五次后,催化活性没有发生显著降低。(二)利用原位生长法制备三元镍铜铝水滑石(NiCuAl-LDHs)前体,经过焙烧、还原合成高分散的镍铜双金属催化剂。通过XRD、STEM、BET、TPD、FT-IR、XPS等表征手段,分析了催化剂结构与活性之间的关系。研究结果显示催化剂中高分散的镍铜双金属纳米颗粒和催化剂表面酸碱性位的协同作用,使得镍铜双金属催化剂可以在常压氮气、异丙醇作氢源的条件下(220℃ atm N2)高效催化乙酰丙酸乙酯氢转移加氢生成γ-戊内酯。并且,催化剂在重复利用五次后,催化活性没有发生显著降低。
[Abstract]:During the reaction, the structure of nickel based catalyst collapsed and the active component was deactivated. The hydrotalcite material was grown in situ with aluminum oxide as the source. The high dispersion of ruthenium nanoparticles was realized by loading ruthenium nanoparticles on the surface of the catalyst. It was used to study the selective hydrogenation of 5-hydroxymethyl furfural. In addition, ternary nickel-copper-aluminum hydrotalcite was prepared, and highly dispersed Ni-Cu bimetallic catalysts were prepared by roasting and reduction for hydrogen transfer hydrogenation of ethyl levulinate, a biomass derivative. Hydrotalcite (LDHs) is a kind of two-dimensional layered material, which is widely concerned by researchers because of its variable composition and proportion, rich preparation methods and excellent catalytic activity. At present, catalysis, photoelectricity, environmental pollution, flame retardancy, biosensor, medicine and so on have attracted more and more researchers. In this paper, Ni-Al hydrotalcite NiAl-LDHsN was prepared by in-situ growth method. The selective hydrogenation of 5-hydroxymethylfurfural was studied by using the rich pore channels of hydrotalcite carrier and highly dispersed supported ruthenium nanoparticles by sodium borohydride reduction method. In addition, the structure of Ni-Cu bimetallic catalyst prepared by the synthesis of nickel-copper-aluminum hydrotalcite, NiCuAl-LDHsN, was prepared by roasting reduction. The catalyst was used to study the hydrogen transfer hydrogenation of ethyl levulinate. The relationship between the structure and activity of the catalyst was further analyzed. (1) the surface of NiAl-LDHs prepared by in-situ growth method contains a large number of hydroxyl groups. Ruthenium nanoparticles are loaded on the surface of NiAl-LDHs by one step reduction of sodium borohydride. The results showed that ruthenium nanoparticles dispersed uniformly on the surface of the support and the interaction with the support was very strong. In addition, the rich pore structure and high specific surface area of NiAl-LDHs are conducive to the realization of high dispersion of precious metal ruthenium. In particular, the prepared Ru/NiAl catalyst can efficiently catalyze the formation of 5 hydroxymethyl furfural into 2'5 '-dimethylfuran under the condition of hydrogen as the hydrogen source, and the catalytic activity of the catalyst does not decrease significantly after being reused for five times. (2) the precursor of nickel-copper-aluminum hydrotalcite NiCuAl-LDHswas prepared by in-situ growth method and calcined to form highly dispersed Ni-Cu bimetallic catalyst. The relationship between the structure and activity of the catalyst was analyzed by means of XPS and other characterization methods. The results show that the highly dispersed Ni-Cu bimetallic nanoparticles and the acid-base sites on the surface of the catalyst make the Ni-Cu bimetallic catalyst can be used in nitrogen at atmospheric pressure. The hydrogen transfer hydrogenation of ethyl levulinate to 纬 -pentanolactone was efficiently catalyzed by isopropanol at 220 鈩，

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