一步法合成Pt@ZIF-8及其在1,4-丁炔二醇选择加氢中的应用（英文）

发布时间：2018-01-11 06:20

本文关键词：一步法合成Pt@ZIF-8及其在1,4-丁炔二醇选择加氢中的应用（英文）　出处：《催化学报》2016年09期 　论文类型：期刊论文

【摘要】：1,4-丁炔二醇(BYD)部分加氢生成1,4-丁烯二醇(BED),BED进一步加氢生成1,4-丁二醇(BDO).此外,BYD,BED和BDO还会发生脱水反应生成单醇类产物.工业上BYD加氢反应主要用于生产BDO.由于传统的单金属加氢催化剂很难控制反应的加氢程度,因此一般通过提高反应温度和压力使BYD尽量转化为完全加氢产物BDO,以减少部分加氢产物BED对最终产品收率的影响.部分加氢产物BED在精细化工领域也具有重要的应用,所以选择合适的催化剂和反应条件来提高部分加氢产物BED的选择性具有重要的理论意义和潜在应用价值.文献中常采用Zn、微生物等活性抑制剂来降低贵金属催化剂的加氢活性.这些方法往往比较复杂,所使用的添加剂不仅存在毒性和污染产物,还会增加成本.这些方法得到的催化材料虽然可以提高烯醇的选择性,但是仍需要严格控制反应条件才能得到较高收率的部分加氢产物.本文基于MOFs材料独特的结构和性质,探索了MOFs负载型贵金属催化剂在选择加氢反应中的催化性能.首先制备了一种羧酸根保护的Pt纳米溶胶,并以水为溶剂,增加2-甲基咪唑的加入量,实现了室温下ZIF-8晶体的快速生成.在室温合成ZIF-8的过程中加入羧酸根保护的Pt纳米溶胶,通过羧酸根与ZIF-8之间存在的化学吸附力,实现ZIF-8对Pt纳米粒子的包覆.羧酸根不仅可以稳定溶液中的纳米粒子,同时还起着"桥梁"的作用.羧酸根中的C=O基团与ZIF-8中的Zn原子或有机骨架之间弱的配位作用,增加了纳米粒子和ZIF-8之间的亲和力,实现了金属纳米粒子被ZIF-8包围.Pt纳米粒子的引入对ZIF-8的形成也没有影响,得到的Pt@ZIF-8材料拥有良好的晶体结构和高的比表面积.采用XRD、N2吸附和TEM等表征揭示了Pt@ZIF-8的结构特点,并研究了其在水相1,4-丁炔二醇加氢反应中的催化性能.结果显示,该材料不仅具有很高的活性,还具有突出的部分加氢选择性.在5次循环反应中,BYD转化率没有明显变化,说明催化剂在反应过程中活性没有降低.在多次反应之后,反应产物的分布也没有发生明显变化,1,4-丁烯二醇选择性在5次反应中都保持在94%以上.结构表征结果则显示,在4次循环使用之后,催化剂的结构已经遭到破坏;5次循环使用之后,催化剂的XRD谱图中ZIF-8的特征衍射峰完全消失.其余谱峰为Zn O特征衍射峰,说明由于反应温度较高,催化剂在多次反应之后其载体ZIF-8发生了分解.循环寿命实验说明,ZIF-8中Zn离子和含氮有机骨架的抑制作用是导致1,4-丁烯二醇高选择性的重要原因.ZIF-8的分解虽然会使孔道塌陷,但是结构中的Zn和含氮的有机骨架组成依然存在,仍然可以达到抑制烯醇进一步加氢的效果,并且Pt纳米溶胶主要存在于外表面,所以催化剂的活性和选择性没有发生明显变化.
[Abstract]:1,4- butynediol (BYD) partially hydrogenated to 1,4- butylene glycol (BED), BED further hydrogenation of 1,4- butanediol (BDO). In addition, BYD, BED and BDO will generate the dehydration of alcohol products. Single industry BYD hydrogenation is mainly used for the production of BDO. due to hydrogenation degree of traditional single gold a hydrogenation catalyst is difficult to control the reaction, so by increasing the reaction temperature and pressure to make BYD into full hydrogenation products of BDO, in order to reduce the influence of partial hydrogenation of BED product to the final product yield. Partial hydrogenation products of BED in fine chemical industry also has important applications, so the choice of catalyst and reaction the appropriate condition has important theoretical significance and potential application value of selective partial hydrogenation products of BED to improve Zn. Often used in the literature, the hydrogenation activity of microbial inhibitors to reduce the activity of noble metal catalysts. These methods to Compared to the complex additives used not only the toxicity and pollution products, will increase the cost. Although the catalytic material obtained by these methods can improve the selectivity of alcohol, but still need to strictly control the reaction conditions to get partial hydrogenation products in high yield. This paper is based on the structure and properties of MOFs materials are unique, to explore the MOFs supported noble metal catalysts and catalytic performance in hydrogenation reactions in the first choice. Pt nano sol a carboxylate protection by taking water as solvent, increasing the amount of 2- methyl imidazole, realize the rapid generation of ZIF-8 crystal at room temperature. Pt nano sol adding carboxylate protection in process synthesis at room temperature in ZIF-8, by chemical adsorption force between the carboxyl group and ZIF-8, ZIF-8 of Pt nanoparticles coated with carboxylate. Nanoparticles in solution can not only stable, at the same time Play the role of bridge between C=O and ZIF-8 groups. The carboxylate Zn atoms in the organic framework or weak coordination effect, increase the affinity between nanoparticles and ZIF-8, the metal nanoparticles were introduced surrounded by ZIF-8.Pt nanoparticles on the formation of ZIF-8 did not affect the Pt@ZIF-8 material has good crystal structure and high specific surface area. By XRD, N2 adsorption and TEM characterization revealed the structural characteristics of Pt@ZIF-8, and the study of their catalytic properties in aqueous 1,4- butynediol hydrogenation reaction. The results showed that the material not only has high activity, but also has some prominent selective hydrogenation in 5 cycles of reaction, the conversion rate of BYD did not change significantly, indicating that the catalyst during the reaction activity does not decrease. In many reactions, the distribution of reaction products did not change significantly, 1,4- butylene glycol In the 5 reaction selectivity is maintained at more than 94%. The characterization results showed that after 4 cycles, the structure of the catalysts has been destroyed; after 5 cycles, the characteristic diffraction peaks in the XRD spectra of the catalysts of ZIF-8 disappeared. The other peak is Zn O characteristic diffraction peaks, indicating that due to high reaction temperature, catalyst in the reaction times after the carrier ZIF-8 decomposes. The cycle life test, the inhibition effect of Zn ion and nitrogen containing organic framework in ZIF-8 is to make the pore collapse although an important reason for.ZIF-8 decomposition 1,4- butylene glycol selectivity, but the structure of the Zn and nitrogen-containing organic framework which still exists, still can inhibit the further hydrogenation of enol effect, and mainly on the outer surface of Pt nano sol, so the activity and selectivity of the catalyst did not change significantly.

【作者单位】：大连理工大学化工学院先进材料和催化工程实验室;爱荷华州立大学生物质可再生能源实验室;
【基金】：supported by the National Natural Science Foundation of China(21573031 and 21428301) the Fundamental Research Funds for the Central Universities(DUT15ZD106 and DUT15RC(4)09)~~
【分类号】：O643.36
【正文快照】： 1.Introduction The selective hydrogenation of carbon-carbon triple bonds to double bonds is an important process in the fine chemicals industry,and is relevant to commodities and other specialty chemicals production[1,2].The partial hydrogenation of1,4-

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