多相贵金属催化剂对芳香化合物催化加氢研究进展

综述了近年来多相贵金属催化剂对芳香化合物加氢的研究；揭示了负载型铂、钯、钌、铑以及二元金属催化剂各自在加氢反应中的特点，以及载体、助催化剂对其活性和选择性的重要作用；同时介绍了TCSM和Raney型贵金属催化剂的概况。     

含氟芳香族硝基化合物加氢用钯催化剂的研究

介绍了以浸渍法制备Pd-Fe/SiO2催化剂,研究其载体、金属组分、还原剂、焙烧温度和时间等因素对催化剂催化性能的影响.确定了最优工艺条件:w(Pd)=5%,w(Fe)=0.2%,硼氢化钾作还原剂,焙烧温度500℃,焙烧时间4h.重复使用试验、优化验证试验、与其它催化剂如Raney Ni、Pt/C和Pd/C等对比试验结果表明,Pd-Fe/SiO2催化剂用于含氟芳香族硝基化合物的常压催化加氢反应,收率大于97.5%,纯度达到98.0%以上,选择性好,催化剂可重复使用10次.     

高效芳香硝基化合物选择性加氢催化剂的研究

以廉价的工业二氧化硅为原材料,以葡萄糖为碳源,尿素为氮源,制备了氮掺杂碳包覆二氧化硅载体(SiO_2-CN),通过浸渍法制备了负载型Pt/SiO_2-CN催化剂。通过X-射线衍射、N2吸脱附实验、透射电子显微镜等表征方法对所制备的催化剂进行表征。结果表明,Pt/SiO~2-CN催化剂有大的比表面积(193 m~2/g),催化剂上Pt纳米颗粒分散度高,其颗粒大小约为1. 4 nm。Pt/SiO_2-CN可将多种不同芳香硝基化合物还原为相应的芳香胺,目标产物选择性 99%。催化剂在循环使用7次后仍保持良好的催化性能。     

氯代芳香硝基化合物催化加氢研究

对氯代硝基苯的加氢工艺进行了研究。综述了温度、压力、溶剂等七个因素对加氢的影响。     

Ni-B/SiO2非晶态催化剂对卤代芳香硝基化合物的催化加氢性能

对Ni-B／SiO2非晶态催化剂在卤代芳香硝基化合物加氢制卤芳胺反应中的催化活性和选择性进行了研究。研究表明,该催化剂不仅具有很高的催化活性,且反应中卤芳胺脱卤率低,反应选择性高,寿命长,优于Raney Ni催化剂。晶化导致催化剂失活。载体能提高催化剂的分散度,使催化剂的活性比表面积增大。将催化剂保存在乙醇溶液中可保持其活性不变。通过催化剂的表征结果,讨论了Ni-B／SiO2非晶态催化剂及Raney Ni催化剂的催化活性与其机构的关系。     

Pd亚纳米簇@SiO2催化芳香硝基化合物加氢制芳胺

以新配制的硝酸钯溶液为原料，在十六烷基三甲基溴化铵/正丁醇/环己烷形成的反相微乳液体系中采用一锅法制备Pd亚纳米簇@SiO2核壳材料，得到质量分数达4%（以SiO2的质量计）、平均粒径为0.7 nm的Pd亚纳米簇。采用TEM、XRD、XPS、N2吸附-脱附对材料的物化性质进行了表征，探讨了其对芳香硝基化合物加氢制芳胺反应的催化性能。结果表明，在温和的反应条件下（50 ℃、1.0 MPa H2），催化剂Pd亚纳米簇@SiO2上硝基苯加氢反应4 h，苯胺的收率高达99.5%。在该催化剂上，其他多种芳硝基化合物加氢反应同样获得了较高的芳胺收率（98.5%~100%）。催化剂Pd亚纳米簇@SiO2循环4次后，活性无明显下降。     

负载型双金属催化剂对邻硝基苯胺液相催化加氢的研究

研究了活性碳负载的Ｐｄ、Ｐｄ－Ｆｅ、Ｐｄ－Ｓｎ、Ｐｄ－Ｎｉ、Ｐｄ－Ｃｕ、Ｐｄ－Ｐｂ催化剂对邻硝基苯胺催化加氢。活性大小依次为：Ｐｄ－Ｓｎ／Ｃ〉Ｐｄ－Ｆｅ／Ｃ〉Ｐｄ－Ｎｉ／Ｃ〉Ｐｄ／Ｃ〉Ｐｄ－Ｃｕ／Ｃ￣Ｐｄ－Ｐｂ／Ｃ，先浸Ｐｄ后浸Ｆｅ与Ｐｄ、Ｆｅ共浸制备的Ｐｄ－Ｆｅ／Ｃ具有相同催化活性，ＸＰＳ研究表明两种金属间存在的较强的相互作用。考察了温度对反应的影响及无溶剂反应时压力的影响。     

负载型双金属催化剂对邻硝基苯胺液相催化加氢的研究

研究了活性炭负载的Ｐｄ、Ｐｄ─Ｆｅ、Ｐｄ—Ｓｎ、Ｐｄ—Ｎｉ、Ｐｄ—ＣＵ、Ｐｄ—Ｐｂ催化剂对邻硝基苯胺催化加氢。活性大小依次为：Ｐｄ—Ｓｎ／Ｃ＞Ｐｄ—Ｆｅ／Ｃ＞Ｐｄ—Ｎｉ／Ｃ＞Ｐｄ／Ｃ＞Ｐｄ—Ｃｕ／Ｃ～Ｐｄ─Ｐｂ／Ｃ，先浸Ｐｄ后浸Ｆｅ与Ｐｄ、Ｆｅ共浸制备的Ｐｄ─Ｆｅ／Ｃ具有相同催化活性，ＸＰＳ研究表明两种金属间存在较强的相互作用。考察了温度对反应的影响及无溶剂反应时压力的影响。     

负载型金属催化剂催化4-硝基苯酚加氢研究进展

4-硝基苯酚是一种典型的有机污染物,采用催化加氢的方式将其转化为具有工业价值的4-氨基苯酚,保护环境的同时还可以创造一定的经济价值,具有重要的科学意义.本文简要介绍了近期国内外研究成果,从负载型催化剂的活性组分、载体类型、两个方面归纳总结了负载型催化剂催化4-硝基苯酚加氢反应的研究进展,并对未来的研究趋势进行了展望.     

负载型纳米贵金属催化剂的催化氢化反应研究

研究了负载型的高分散纳米贵金属催化剂和含钌的双金属催化剂对2-吡啶甲酸甲酯加氢反应的催化活性.结果表明,单金属催化剂Ru(5 %)/C对吡啶及其衍生物具有较好的催化活性.用XRD、HRTEM和XPS对还原后的Ru/C催化剂表征,表明钌处于高分散零价态,其平均粒径小于5 nm.在50 ℃、5.0 MPa的条件下,催化2-吡啶甲酸甲酯,其加氢转化率达100 %,TOF达到了10.     

负载型Ru催化剂的制备及加氢性能

通过Ru固载同水滑石修饰的Al2O3（HTc-Al2O3）合成的同步化，制得Ru-HTc-Al2O3，对其进行XRD、ICP-AES、SEM、HRTEM、BET、NH3-TPD和XPS表征，并将其用于对苯二甲酸二甲酯催化加氢制取1,4-环己烷二甲酸二甲酯。以溶液浸渍法制得Ru/HTc-Al2O3和Ru/Al2O3对照。结果表明：相较于Ru/Al2O3和Ru/HTc-Al2O3，Ru-HTc-Al2O3具有更大的比表面积（105.4 m2/g）；其大粒径Ru粒子的形成和Ru的损失受到明显抑制、Ru粒子尺寸分布集聚区间向小尺寸方向偏移，并可提供更多的表面酸性位，尤其是中性强度的酸性位。通过考察催化剂质量与原料DMT初始摩尔量的比例（CRR）、压力和温度的影响以及循环使用反应性能，发现催化反应活性顺序为：Ru-HTc-Al2O3 > Ru/HTc-Al2O3 > Ru/Al2O3；在CRR为100 g/mol，反应温度为180 ℃，反应压力为8 MPa时，Ru-HTc-Al2O3的催化性能达到最佳：DMT转化率为98.2%，DMCD选择性为96.9%。     

Selective Hydrogenation of Cinnamaldehyde to Hydrocinnamaldehyde over SiO2 Supported Nickel Phosphide Catalysts

The heterogeneous mercury reaction mechanism, reactions among elemental mercury (Hg⁰) and simulated flue gas across laboratory-scale selective catalytic reduction (SCR) reactor system was studied. The surface of SCR catalysts used in this study was analyzed to verify the proposed reaction pathways using transmission electron microscopy with energy dispersive X-ray analyses (TEM-EDX) and X-ray photoelectron spectroscopy (XPS). The Langmuir–Hinshelwood mechanism was proven to be most suitable explaining first-layer reaction of Hg⁰ and HCl on the SCR catalyst. Once the first layer is formed, successive layers of oxidized mercury (HgCl₂) are formed, making a multi-layer structure.     

Pd/C催化剂上烯酮的选择性加氢反应

采用釜式反应器,在无溶剂条件下考察了金属Pd的负载量、催化剂粒度、载体预处理方式和反应温度等因素对Pd/C催化剂6,10,14-三甲基-13-烯-2-十五烷酮(FA-4H)选择性加氢性能的影响规律。实验结果表明:随着Pd负载量的增加,Pd/C催化剂FA-4H加氢的活性逐渐增加;当Pd负载量在0.5%~3.0%(wt),FA-4H完全转化时目标产物六氢法呢基丙酮(PA)的选择性为99.3%~99.5%。较小的催化剂粒度对应较短的催化剂孔道,有利于减少产物PA在催化剂孔道内停留的时间,从而在一定程度上防止了C=O双键的过度加氢。此外,活性炭载体的硝酸或氨水预处理、较低的反应温度等也有利于减少Pd/C催化剂上FA-4H完全转化时加氢副产物6,10,14-三甲基-13-烯-2-十五烷醇(FA-alcohol)和6,10,14-三甲基-2-十五烷醇(PA-alcohol)的生成量,从而使目标产物PA的选择性接近100%。     

TiO2负载Pd-Fe催化3-氯-4-氟硝基苯常压加氢反应动力学

以TiO2负载的Pd-Fe为催化剂,考察了反应温度和催化剂用量对3-氯-4-氟硝基苯常压加氢反应的影响,拟合实验数据并建立了动力学方程,然后对动力学方程进行了统计学检验.结果表明,在3-氯-4-氟硝基苯0.1 mol,乙醇80 mL,催化剂0.26 g,氢气分压0.1 MPa的条件下,加氢反应对3-氯-4-氟硝基苯表现为一级,加氢反应的活化能为19 959.4 J/mol,指前因子为56.79.所获得的动力学方程能较好地描述3-氯-4-氟硝基苯的常压加氧反应.     

Selective Hydrogenation of 5‐Ethoxymethylfurfural over Alumina‐Supported Heterogeneous Catalysts

We report here the synthesis and testing of a set of 48 alumina‐supported catalysts for hydrogenation of 5‐ethoxymethylfurfural. This catalytic reaction is very important in the context of converting biomass to biofuels. The catalysts are composed of one main metal (gold, copper, iridium, nickel, palladium, platinum, rhodium, ruthenium) and one promoter metal (bismuth, chromium, iron, sodium, tin, tungsten). Using a 16‐parallel trickle‐flow reactor, we tested all 48 catalyst combinations under a variety of conditions. The results show that both substrate conversion and product selectivity are sensitive towards temperature changes and solvent effects. The best results of >99% yield to the desired product, 5‐ethoxymethylfurfuryl alcohol, are obtained using an iridium/chromium (Ir/Cr) catalyst. The mechanistic implications of different possible reaction pathways in this complex hydrogenation system are discussed.     

Carbon Monoxide Hydrogenation over Zirconia Supported Ni and Co-Ni Bimetallic Catalysts

Zirconia supported nickel and cobalt-nickel bimetallic catalysts were prepared and characterized for various physico-chemical properties. The hydrogenation of carbon monoxide was studied over these catalysts in the pressure range of 101.3–1654kPa, temperature range of 513–533K, weight hourly space velocity range of 8–14h^–1 and H2/CO mole ratio of 2. Catalysts containing both Co and Ni were found to give higher C₅₊ hydrocarbons selectivity compared to that containing only Ni. A maximum C₅₊ hydrocarbons selectivity of 55wt% was obtained at 655kPa pressure, 523K and 9.6h^–1 of WHSV with catalyst containing 4.03wt% Co and 2.64wt% Ni. The C₂ and C₃ olefin contents of the products decreased with increase in pressure. Improved deactivation behavior of the catalysts was observed when operated at high pressure.     

Selective Protection of Carbonyl Compounds over Nano-sized Nickel Catalysts

Abstract An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Graphical Abstract Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,^a Santosh Kumar,^a Amit Saxena,^a Arnab De,^b Subho Mozumdar^a* ^aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; ^b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield.      

Selective Hydrogenation of Cinnamaldehyde on Pt and Pt-Fe Catalysts Supported on Zeolite P

Abstract  

Pt– and Pt–Fe based catalysts on zeolite P (ZP) support have been prepared and widely characterized by surface area and porosity, XRD, SEM, TEM, TPR, in order to investigate their morphological and microstructural properties. The catalysts have been tested in the selective liquid-phase hydrogenation of cinnamaldehyde. Kinetic tests have shown the beneficial effect of Fe promoter on the catalysts behaviour towards the selective formation of cinnamyl alcohol (85% selectivity to 90% conversion). The ZP supported catalysts have been compared with a catalyst supported on P-zeolitized Fe containing pumice (Z-PM), confirming the role of Fe Lewis acid site in promoting the reactivity of zeolite P-based materials.