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负载Pt催化剂上氯代硝基苯、肉桂醛选择性加氢性能的研究

Selective Hydrogenation of Chloronitrobenzene or Cinnamaldehyde over Supported Platinum Catalysts

【作者】 韩晓祥

【导师】 郑小明; 周仁贤;

【作者基本信息】 浙江大学 , 有机化学, 2004, 博士

【摘要】 氯代苯胺是一类重要的有机中间体,它们广泛用于合成染料、农药、医药、颜料等精细化工产品。肉桂醛是α,β-不饱和醛分子中的一种,肉桂醛分子中C=C键及C=O键加氢生成半加氢产物加氢肉桂醛和肉桂醇更是医药、香料等的重要原料及中间体。因此,对氯代硝基苯和α,β-不饱和醛的选择性加氢研究具有重要的理论意义和工业应用前景。催化加氢法技术以其环境友好,产品质量稳定,工艺先进而受到人们重视。均相催化加氢虽然具有较高的活性和选择性,但是产物与催化剂难以分离。采用多相催化加氢时,催化剂很容易与最终产物分离,同时催化剂得以有效地恢复,从而减少了催化剂的流失和环境污染。 氯代硝基苯中N=O极性键的加氢较C-CI键的氢解容易进行,肉桂醛中C=O极性键较C=C键的加氢难。通过调节吸附氢的数目、活性使催化剂表面有更多与N=O、C=C及C=O等不饱和键加氢相适应的活性中心,从而选择性地催化加氢氯代硝基苯及肉桂醛。基于对氯代硝基苯和肉桂醛选择性加氢规律的认识,我们选择PVP、ZrO2、TiO2为载体设计一系列催化剂,其在催化加氢氯代硝基苯的反应中,不仅取得了文献报导高的氯代苯胺选择性,同时也提高了氯代硝基苯的加氢反应活性。在肉桂醛的选择性加氢反应中同样获得了较好的加氢活性和选择性。得到的主要结果如下: 第一章综述了卤代硝基苯和α,β-不饱和醛选择性加氢研究进展,并阐述了各种方法的优缺点。 第二章研究了不同水溶性高分子载体负载Pt催化剂上催化加氢氯代硝基苯(CNB),同时研究了稀土元素的添加及其它影响因素对PVP负载Pt催化剂催化加氢性能的影响。常压、303K反应条件下,不同水溶性高分子载体负载铂催化剂上催化加氢CNB时具有较好催化活性和氯代苯胺(CAN)选择性。加氢反应的活性顺序为:PVP-Pt*,PVP-Pt>EC-Pt>PEG-Pt,而选择性变化不大。适量的无机和有机碱的存在有助于提高PVP负载Pt催化剂催化加氢CNB反应的活性和产物CAN的选择性。稀土元素(Sm3+,pr3+,Ce3+,Nd3+和La3+)的添加对PVP负载Pt催化剂催化加氢CNB催化反应活性均有不同程度的抑制作用,但生成CAN的选择性

【Abstract】 Haloamine is important intermediates for synthesis of organic fine chemicals, such as dyes, drugs, herbicides and pesticides. Cinnamaldehyde (CMA), a member of α,β-unsaturated aldehydes, and its semi- hydrogenated products such as cinnamyl alcohol(CMO) and hydrocinnamaldehyde (HCMA) are important fine chemicals and intermediates especially in perfume industry and medicine manufacture. Study on the selective hydrogenation of α,β-unsaturated aldehydes is of great importance in potential industrial applications and theoretical aspects. The selective hydrogenation has been attention for its lower impact on the environment. Homogeneous hydrogenation shows higher activity and selectivity, however, it is difficult to separate catalyst from product. From the point of view of green chemistry, the development of industrial processes for direct production of organic intermediates using heterogeneous catalysts is an industrially meaningful target, since the catalysts could be easily removed from the reaction mixtures and wastes could be largely diminished.Hydrogenation of N=O group is easier than hydrogenolysis of the C-Cl bond on the hydrogenation of chloronitrobenzene (CNB). It is easier for the hydrogenation of C=C group than hydrogenation of C=O group on the hydrogenation of CMA. More activated adsorptive hydrogen and more active sites for the hydrogenation of unsaturated bond on catalyst’s surface improve catalytic activity and selectivity on the hydrogenation of CNB and CMA. Based on the rule of selective hydrogenation of CNB and CMA, we design a series of catalysts supported by ZrO2 or TiO2. They show better hydrogenation properties on the selective hydrogenation of CNB and CMA. The results we obtained are as follows:In chapter 1, we review the results on the selective hydrogenation of CNB and CMA.In chapter 2, hydrogenation properties of CNB have been studied over different support materials of Pt catalyst (such as polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and ethyl cellulose (EC)) in ethanol at 303K and atmosphere pressure.

  • 【网络出版投稿人】 浙江大学
  • 【网络出版年期】2006年 12期
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