Co-M-Al复合金属氧化物薄膜制备及其选择性氧化性能

发布时间：2018-02-03 03:32

  本文关键词： 层状双金属氢氧化物 复合金属氧化物 薄膜 结构化催化剂 催化氧化　出处：《北京化工大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,新型薄膜催化剂的设计合成已成为催化研究领域的热点之一。催化氧化反应是一类重要的化学反应,其中烃类的氧化和醇类的氧化现代催化工业生产中占据十分重要的地位,代表反应有苯甲醇的氧化和乙苯的氧化。苯甲醇和乙苯都是重要的化工原料,而且其氧化产物苯甲醛和苯乙酮具有广泛的应用价值。本文采用氨原位合成法在阳极氧化铝基片上制备了Co-M-Al三元层状双金属氢氧化物(LDH)薄膜,再经高温焙烧合成了相应的复合金属氧化物薄膜。以苯甲醇和乙苯的氧化为探针反应,考察了三元LDH薄膜及其复合金属氧化物薄膜的选择性氧化性能,并探讨了薄膜的组成及表面结构与催化性能之间的关系。主要研究内容如下：(一)在阳极氧化铝基片上,以氨水-硝酸铵为沉淀剂,原位合成了CoNiAl三元层状双金属氢氧化物(LDH)薄膜；经500℃高温焙烧后得到CoNiAl-MMO薄膜。对所得薄膜催化剂进行了结构、组成及表面形貌表征,结果表明CoNiAl-MMO薄膜是由多种尖晶石固体溶液组成(C0304,CoAl2O4, NiAl2O4和NiCo2O4),其表面化学组成均匀,呈均匀的多孔网状表面结构。将CoNiAl-LDH(MMO)薄膜应用于苯甲醇的催化氧化反应,结果表明与三元粉体催化剂和二元薄膜催化剂相比,CoNiAl-MMO薄膜催化剂表现出显著提高的催化活性,室温反应条件下,转化率可达29.3%,是CoNiAl-MMO粉体催化剂的2.44倍,CoAl-MMO二元薄膜催化剂的1.66倍。此外,CoNiAl-LDH薄膜催化剂的转化率可达14.6%,是CoNiAl-LDH粉体的3.11倍,基于独特CoNiAl-MMO表面组成和结构,其显著提高的催化活性与活性物种钴和镍之间的强相互作用和多孔的表面结构密切相关。(二)采用原位生长技术和高温焙烧技术相结合法制备了三元钴锰复合金属氧化物薄膜。采用XRD、SEM和TPR等表征手段对薄膜的组成和结构进行了分析,以乙苯氧化反应为探针反应,研究了不同配比氧化物薄膜材料的催化性能以及催化条件对乙苯催化氧化反应的影响。结果发现:[Mn2+]/[Co2++Mn2+]为0.50时复合金属氧化物薄膜催化剂显示出最高的的催化乙苯氧化活性,这主要是归因于其高的比表面、高分散可接近的活性物种及其相互相协同。
[Abstract]:In recent years, the design and synthesis of novel thin-film catalysts have become one of the hot spots in the field of catalytic research. Catalytic oxidation is an important chemical reaction. The oxidation of hydrocarbons and alcohols occupies a very important position in the modern catalytic industrial production, representing the oxidation of benzyl alcohol and ethylbenzene. Benzyl alcohol and ethylbenzene are important chemical raw materials. The oxidation products of benzaldehyde and acetophenone have wide application value. In this paper, Co-M-Al ternary layered bimetallic hydroxide (Co-M-Al) was prepared on anodic alumina substrate by in situ synthesis of ammonia. Film. Then the corresponding composite metal oxide films were synthesized by calcination at high temperature. The selective oxidation properties of ternary LDH films and their composite metal oxide films were investigated using the oxidation of benzyl alcohol and ethylbenzene as probes. The relationship between the composition, surface structure and catalytic performance of the film was discussed. The main contents are as follows: (1) on anodic aluminum oxide substrate, ammonia and ammonium nitrate are used as precipitators. CoNiAl ternary layered bimetallic hydroxide (CoNiAl) thin films were synthesized in situ. CoNiAl-MMO films were prepared by calcination at 500 鈩，

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