甘油催化氧化制备二羟基丙酮的研究

阐述了采用不同方法合成了一系列的贵金属Pt单金属及多金属催化剂,研究了它们对甘油选择性催化氧化反应的催化性质。当反应温度为55℃,反应时间为8 h时,催化剂9%Pt-5%Bi/C双金属催化剂可以有效地将甘油选择性催化氧化成二羟基丙酮。     

甘油催化氧化制备二羟基丙酮的研究

阐述了采用不同方法合成了一系列的贵金属Pt单金属及多金属催化剂,研究了它们对甘油选择性催化氧化反应的催化性质。当反应温度为55℃,反应时间为8 h时,催化剂9%Pt-5%Bi/C双金属催化剂可以有效地将甘油选择性催化氧化成二羟基丙酮。     

金属催化剂选择性催化氧化甘油及其衍生物的研究

阐述了甘油氧化的路径,利用Pd、Pt和Au等金属催化剂,选择性催化氧化甘油及其衍生物制备甘油酸、1,3-二羟基丙酮、羟基丙酮酸、丙醇二酸和丙酮二酸等一系列重要化学品的研究,此方法选择性高,反应温和,对环境友好,前景广阔。     

炭载Pt基催化剂上甘油氧化反应路径的探究

结合透射电镜(TEM)和X射线光电子能谱(XPS)等表征技术,比较研究了碳纳米管(CNTs)负载的单金属Pt和双金属Pt-Sb催化剂的结构及其非碱性条件下催化甘油氧化反应的性能与路径。结果表明:Sb的引入对催化剂的粒径以及Pt电子性质的影响较小,但Sb可能选择性沉积在Pt原子表面形成空间位阻,控制甘油的转化向有利于其仲羟基氧化的方向进行,从而改变了反应的选择性和路径。Pt/CNTs催化剂主要选择性氧化甘油的伯羟基生成甘油醛(GLyD)和甘油酸(GLYA),GLYA再进一步氧化生成羟基丙酮酸(HPYA)和亚酒石酸(TA);Pt-Sb/CNTs催化剂则优先氧化甘油的仲羟基生成二羟基丙酮(DHA),DHA进一步氧化生成HPYA;两种反应路径下生成的HPYA和TA最终都会氧化断键生成乙醇酸(GLYCA)等产物。     

甘油选择性氧化的催化体系研究进展

甘油是生物柴油生产过程中的副产物,甘油选择性氧化制备高值含氧衍生物开辟了从生物质到有机酸的生产路径,有效缓解了甘油大量过剩的困境并创造了潜在利用价值。论述了甘油高值转化为甘油酸和二羟基丙酮的催化体系研究进展,重点研究了Au基、Pd基、Pt基贵金属催化剂的催化性能,旨在提高甘油酸和二羟基丙酮的选择性,并介绍了催化剂的反应机理、催化剂失活的可能性以及相应的改进措施。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

多相催化剂用于高级烯烃分子氧选择性氧化的研究进展

针对以高级烯烃作为底物进行的分子氧氧化反应,所用多相催化剂按其结构和组成不同,可分为金属-有机配体复合催化剂、金属氧化物催化剂、无机分子筛催化剂、多氧金属盐类催化剂和负载型催化剂等。综述了各类催化剂用于高级烯烃分子氧选择性氧化的研究进展,并比较了各自的优缺点,指出负载型催化剂在一定程度上克服了其他几类催化剂存在的催化氧化选择性差、重复利用率低、稳定性差等缺点,有望在无溶剂的条件下获得较佳的转化率及选择性,是未来高级烯烃绿色氧化催化剂的重要研究方向。     

1,2-丙二醇空气选择氧化合成α-羟基丙酮和丙酮醛

采用电解银催化剂,选择催化氧化1,2-丙二醇联产α-羟基丙酮和丙酮醛。研究了反应条件对产物组成的影响。实验结果表明,以电解银催化氧化1,2-丙二醇可以同时得到α-羟基丙酮和丙酮醛,当温度为360℃,氧醇比为0.25,液时空速为8.73h-1时,单程转化率36%,它们的选择性之和接近100%。氧醇比是选择性氧化合成α-羟基丙酮和丙酮醛的关键因素。     

生物质甘油催化转化为羟基丙酮

探索了生物质甘油在铜铬催化剂作用下催化转化为羟基丙酮的反应条件,采用乙醇为溶剂,考察了甘油浓度、催化剂用量和反应温度等因素的影响。较优反应条件:反应温度240℃,采用连续滴样的进样方式,甘油浓度80%,未还原的铜铬催化剂[n(Cu)∶n(Cr)=1]用量为原料质量的2.5%,甘油转化率和羟基丙酮选择性分别达到95.4%和89.9%。     

Zn(Al)O复合氧化物负载Au催化剂催化氧化甘油制备1,3-二羟基丙酮

以尿素为沉淀剂,采用均匀沉积沉淀法制备了Zn(Al)O复合氧化物负载Au催化剂,并用于无碱条件下催化氧化甘油制备1,3-二羟基丙酮（DHA）反应,值得注意的是随着载体中Zn/Al摩尔比的不同,负载Au催化剂的催化活性和产物DHA的选择性呈现明显差距。结合X射线衍射（XRD）、X射线光电子能谱（XPS）、透射电镜（TEM）、CO吸附傅里叶变换红外光谱（CO吸附FTIR）等表征手段,发现载体Zn(Al)O复合氧化物中Zn/Al摩尔比会影响表面氧物种的含量并进一步会影响催化剂的催化活性和选择性。当Zn/Al摩尔比为7∶1、反应温度为80℃、氧气压力为10bar、反应2h时获得最佳的甘油转化率（58.5%）和DHA的选择性（95.3%）。同时,还考察了反应温度、反应时间、反应压力及载体的焙烧温度对催化性能的影响,并发现反应条件对催化剂的催化活性和选择性均有不同程度的影响。此外,以Au/Zn(Al)O-7∶1催化剂为基准考察了催化剂的稳定性,并通过表征手段分析了催化剂失活的主要原因。     

改性镧系钙钛矿催化剂强化挥发性有机物催化氧化的研究进展

钙钛矿因其结构稳定并具有优异的物化性质,近年来在催化剂方面的应用受到了广泛关注。本文综述了采用不同方法对镧系钙钛矿进行改性来增强催化剂的活性、抗毒性、稳定性和选择性的研究进展;分析了镧系钙钛矿的结构、表面参数、活性氧和低温还原性对于挥发性有机物转化效率的影响,重点阐述了通过优选钙钛矿的制备方法、制备负载型钙钛矿和掺杂型钙钛矿等改性方法来提高镧系钙钛矿催化剂的性能,由此展望了未来改性镧系钙钛矿催化剂的研究方向：采用非金属元素掺杂或多种强化方法结合制备高效催化剂、利用催化燃烧协同光催化氧化转化挥发性有机物、进一步通过实验和仿真模拟制备理想钙钛矿催化剂催化氧化多种挥发性有机物混合物以满足工业化需求。     

负载型纳米金催化剂在乙炔选择性加氢反应中的研究进展

介绍了乙炔选择性加氢制乙烯催化剂的研究和开发进展。针对负载型纳米金催化剂的发展趋势及其对乙炔加氢反应产物中乙烯的独特选择性,重点对比单金属纳米金催化剂及合金型催化剂的催化性能差异,发现合金型纳米金催化剂具有较高的乙炔转化率和稳定性。影响催化性能的主要因素有纳米粒子的大小及活性组分之间的相互协同作用。分析积炭的形成以及导致催化剂失活的原理。展望低温条件下具有高转化率与高稳定性的合金型纳米金催化剂的应用前景。     

Use of renewables for the production of chemicals: Glycerol oxidation over carbon supported gold catalysts

As a renewable feedstock and due to its high functionality glycerol is an attractive reactant for the production of a large number of valuable compounds. We report on an environmentally friendly alternative to produce chemicals from the glycerol oxidation, which are currently produced either by stoichiometric oxidation processes or by enzymatic routes. We investigate the heterogeneously catalyzed liquid-phase oxidation of glycerol with carbon supported gold catalysts. The prepared nanosized gold catalysts are highly active, so that the reaction could be performed under atmospheric pressure. The influence of the preparation method of the catalysts has been investigated. Moreover, the support effect on the catalytic process has been studied and discussed in terms of pore structure of the investigated carbon materials. The promotor effect of platinum on Au/C catalysts was examined and it could be shown that the presence of Pt increases not only the catalyst activity but also the selectivity. By promoting the gold catalysts with platinum the selectivity to dihydroxyacetone could be increased from 26% (Au/C) to 36% (Au–Pt/C).     

Silica-Supported Gold Catalyst Modified by Doping with Titania for Cyclohexane Oxidation

Amorphous silica was modified by doping with titania through a surface sol–gel process and applied as the support for depositing gold. These doped silica-supported gold catalysts were tested in the selective cyclohexane oxidation to cyclohexanone and cyclohexanol using oxygen. Under the oxidation conditions of 150 °C, 1.5 MPa and 3 h, a selectivity of 91.7% for cyclohexanone and cyclohexanol could be reached over the gold catalyst, affording a cyclohexane conversion of 8.4% and a turnover frequency up to 40,133 per hour. Moreover, the catalytic activity and selectivity could be well retained in 4 recycling oxidation reactions, showing a high stability of the gold catalyst supported on titania-doped silica.     

铌酸的催化应用

铌酸和含铌化合物独特酸性和热稳定性,广泛的应用催化领域中。铌酸可直接作为固体催化剂,应用于水解、酯化、缩合、烷基化等反应中;铌酸也作为载体负载金属,应用于F-T合成、氧化反应和加氢等反应中;含铌化合物也可作为负载型催化剂,负载到不同类型的载体上;含铌化合物也作为助剂或光催化剂,广泛地应用于催化多种化学反应。铌类催化剂具有催化活性高、选择性好和使用寿命长等优点。研究开发新型铌类催化剂具有良好的应用前景。     

In situ combustion synthesis of structured Cu-Ce-O and Cu-Mn-O catalysts for the production and purification of hydrogen

The combustion method was employed for the in situ synthesis of nanocrystalline Cu-Ce-O and Cu-Mn-O catalyst layers on Al metal foam, without the need of binder or additional calcination steps. Copper-manganese spinel oxides have been proposed as a catalytic system for hydrogen production via methanol steam reforming, while CuO-CeO₂ catalysts have been successfully examined for CO removal from reformed fuels via selective oxidation. In this work, the performance of these catalysts supported on Al metal foam has been investigated in the reactions of methanol reforming and selective CO oxidation. The Cu-Ce-O foam catalyst exhibited similar catalytic performance to the one of the powder catalyst in the selective oxidation of CO. The performance of the Cu-Mn-O foam catalyst in the steam reforming of methanol was inferior to the one of the powder catalyst at intermediate conversion levels, but almost complete conversion of methanol was obtained at the same temperature with both foam and powder catalysts.     

PtAu/ZrO_2催化甘油选择性制备乳酸

采用溶胶-沉积法制备了Pt Au/ZrO_2系列催化剂,在惰性气体气氛下用于催化甘油选择性制备乳酸。研究不同反应温度下,不同单金属负载和不同比例Pt Au双金属负载催化剂的催化活性以及不同气氛下催化剂重复使用性能,对催化剂进行BET、AAS和TEM等表征。结果表明,在浓度1.1 mol·L-1甘油水溶液10 m L、(1∶1)Pt Au/ZrO_2催化剂用量0.132 g、反应温度160℃、氮气压力1.4 MPa和反应时间6 h条件下,甘油转化率90%,乳酸选择性93.7%。催化剂重复使用性能实验验证了氧气气氛下催化剂活性保持良好。     

Gold supported on carbon nanotubes for the selective oxidation of glycerol

Gold nanoparticles were supported on multi-walled carbon nanotubes (MWCNTs) by different methods and tested in the selective oxidation of glycerol under basic conditions, with the main purpose of evaluating the effect of the preparation technique on the activity and selectivity. The catalytic performances largely depended on the gold crystallite size. The sol immobilization method was the most suitable technique to prepare gold supported on carbon nanotubes. The use of MWCNTs as support for Au nanoparticles resulted in the oxidation of the secondary hydroxyl group, and therefore, a remarkable high dihydroxyacetone selectivity of about 60% is obtained independently of the preparation method used. A possible explanation based on the peculiar characteristics of the support is proposed. It was also concluded that dihydroxyacetone in the final mixture can be stabilized by lowering the pH to about 3.     

Rational approach to polymer-supported catalysts: synergy between catalytic reaction mechanism and polymer design

Supported catalysis is emerging as a cornerstone of transition metal catalysis, as environmental awareness necessitates "green" methodologies and transition metal resources become scarcer and more expensive. Although these supported systems are quite useful, especially in their capacity for transition metal catalyst recycling and recovery, higher activity and selectivity have been elusive compared with nonsupported catalysts. This Account describes recent developments in polymer-supported metal-salen complexes, which often surpass nonsupported analogues in catalytic activity and selectivity, demonstrating the effectiveness of a systematic, logical approach to designing supported catalysts from a detailed understanding of the catalytic reaction mechanism. Over the past few decades, a large number of transition metal complex catalysts have been supported on a variety of materials ranging from polymers to mesoporous silica. In particular, soluble polymer supports are advantageous because of the development of controlled and living polymerization methods that are tolerant to a wide variety of functional groups, including controlled radical polymerizations and ring-opening metathesis polymerization. These methods allow for tuning the density and structure of the catalyst sites along the polymer chain, thereby enabling the development of structure-property relationships between a catalyst and its polymer support. The fine-tuning of the catalyst-support interface, in combination with a detailed understanding of catalytic reaction mechanisms, not only permits the generation of reusable and recyclable polymer-supported catalysts but also facilitates the design and realization of supported catalysts that are significantly more active and selective than their nonsupported counterparts. These superior supported catalysts are accessible through the optimization of four basic variables in their design: (i) polymer backbone rigidity, (ii) the nature of the linker, (iii) catalyst site density, and (iv) the nature of the catalyst attachment. Herein, we describe the design of polymer supports tuned to enhance the catalytic activity or decrease, or even eliminate, decomposition pathways of salen-based transition metal catalysts that follow either a monometallic or a bimetallic reaction mechanism. These findings result in the creation of some of the most active and selective salen catalysts in the literature.