镍基纳米催化剂调控下苯甲酸和肉桂酸加氢反应的研究

发布时间：2018-06-01 16:49

本文选题：镍基纳米催化剂 + 单宁酸　；参考：《河北大学》2017年硕士论文

【摘要】：在催化反应研究中,不饱和化合物的催化加氢反应一直是国内外研究的热点。目前,以Pd、Pt、Ru、Rh等为代表的贵金属催化剂在催化加氢反应中表现出高的活性和稳定性,部分已经应用于实际生产中。但贵金属催化剂昂贵的价格在一定程度上限制了它的应用。因此,进行价格低廉且具有高活性和稳定性的非贵金属催化剂的设计和制备是非常有必要的。基于此,本文使用价格相对较低的镍为催化剂的活性组分,设计并制备了一系列高活性的镍基纳米催化剂,并应用于苯甲酸和肉桂酸的加氢反应中。首先,采用化学还原法制备了单宁酸改性的非晶态镍硼催化剂NiB-TA,并以苯甲酸加氢制备环己甲酸为模型反应对多不饱和化合物中的芳环加氢进行了研究。该催化剂在苯甲酸加氢反应中具有很好的活性,苯甲酸的转化率为98.8%,环己甲酸的选择性为94.1%。通过表征发现,相比于传统方法制备的镍硼非晶态合金催化剂,单宁酸的添加可以有效地提高活性组分的分散性,使催化剂具有更多的活性中心,从而使NiB-TA催化剂的活性显著提高。然后,为了提高镍基纳米催化剂的稳定性,本文还通过对载体的筛选和制备方法的优化制备了一系列负载型镍基纳米催化剂。结果表明以介孔二氧化硅为载体,通过蒸氨法制备的负载型镍基纳米催化剂Ni/mSiO2-AE在催化苯甲酸加氢反应中使用4次时,催化剂的活性和选择性都没有明显下降,具有较好的稳定性,并通过XRD、TEM、H_2-TPR等表征阐述了该催化剂活性和稳定性高的原因。最后,我们又以肉桂酸选择性加氢制备氢化肉桂酸为模型反应对多不饱和化合物中的碳碳双键加氢进行了研究。考虑到催化剂的活性、稳定性和分离回收效率等问题,设计制备了一种磁性核壳镍基纳米催化剂Fe_3O_4@LDH@NiB。在肉桂酸的加氢反应中,肉桂酸的转化率和对氢化肉桂酸的选择性均接近100%,同时,利用催化剂的磁性可实现催化剂与反应物的高效分离,在循环使用11次后,该催化剂的性能没有明显下降,显示出了良好的稳定性。
[Abstract]:The catalytic hydrogenation of unsaturated compounds has been a hot spot in the research of catalytic reaction. At present, the noble metal catalysts, such as PD, PtN, Ruzon Rh and so on, have shown high activity and stability in catalytic hydrogenation, and some of them have been used in practical production. But the expensive price of noble metal catalyst limits its application to some extent. Therefore, it is necessary to design and prepare non-precious metal catalysts with low cost, high activity and stability. Based on this, a series of nickel based nanocrystalline catalysts with high activity were designed and prepared using relatively low price nickel as the active component of the catalyst, and applied to the hydrogenation of benzoic acid and cinnamic acid. Firstly, niB-TAB catalyst modified by tannic acid was prepared by chemical reduction method. The hydrogenation of aromatic rings in polyunsaturated compounds was studied using benzoic acid hydrogenation to cyclohexanoic acid as a model reaction. The catalyst has good activity in the hydrogenation of benzoic acid. The conversion of benzoic acid is 98.8 and the selectivity of cyclohexanoic acid is 94.1. Compared with the Ni-B amorphous alloy catalyst prepared by traditional method, the addition of tannic acid can effectively improve the dispersity of the active component and make the catalyst have more active centers. Thus, the activity of NiB-TA catalyst was improved significantly. Then, in order to improve the stability of Nickel-based nanocatalysts, a series of supported Nickel-based nanocatalysts were prepared by the selection of support and the optimization of preparation methods. The results showed that the catalytic activity and selectivity of the supported nickel based nanometer catalyst Ni/mSiO2-AE, which was prepared with mesoporous silica as the carrier, did not decrease obviously when it was used for 4 times in the hydrogenation of benzoic acid. The reason for the high activity and stability of the catalyst was explained by means of XRDX TEMX H _ 2O _ 2-TPR and so on. Finally, the hydrogenation of carbon and carbon double bonds in polyunsaturated compounds by selective hydrogenation of cinnamic acid to hydrogenated cinnamic acid was studied. Considering the activity, stability and recovery efficiency of the catalyst, a magnetic core-shell nickel nanocatalyst Fe3O _ 4S _ 4 / LDHH@ NiB was designed and prepared. In the hydrogenation of cinnamic acid, the conversion of cinnamic acid and the selectivity to hydrogenated cinnamic acid are close to 100. At the same time, the high efficiency separation of catalyst and reactant can be realized by using the magnetic properties of catalyst. The performance of the catalyst did not decrease obviously and showed good stability.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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