非铂燃料电池电催化剂研究进展

商业铂碳催化剂价格高昂,开发非铂材料是推进燃料电池商业化的关键一步。本文首先介绍了燃料电池氧还原反应电催化剂的研究背景,接着分别介绍了非贵金属、非金属以及复合材料的催化剂,并对各类催化剂的活性位点和催化机理进行了简要的评述。其中,过渡金属的氮碳化物成本低廉,具有较高的催化活性以及优异的稳定性,是最有望替代贵金属Pt的一类催化剂。杂原子的掺杂能够改变碳材料的表面电荷分布,提升碳材料的催化活性。将过渡金属的氮碳化物和特殊结构的碳材料有效结合,可以设计出具有双功能的复合材料。最后,针对非铂催化剂存在的问题进行了分析并提出了今后工作的几个方向,为今后非铂电催化剂的研究提供参考。高活性高稳定性的非铂催化剂是未来该领域的重点研究方向。     

溶胶-凝胶工艺制备非氧化物超细粉体的研究现状

非氧化物材料因具有高熔点、高强度及优良的化学稳定性等优点而受到研究人员的普遍关注。综述了溶胶-凝胶(sol-gel)工艺制备非氧化物超细粉体的研究现状,总结了sol-gel工艺制备非氧化物超细粉体的优缺点,并提出了该技术今后潜在的发展方向。     

钙钛矿氧化物催化研究进展

简要介绍了钙钛矿氧化物的结构及优点。着重阐述了近年来钙钛矿氧化物催化剂在环境催化(NO_x消除、碳烟燃烧等)、电催化、光催化领域的应用及催化改性研究。简要分析了钙钛矿氧化催化剂在当前应用中存在的问题,并对钙钛矿氧化物催化剂今后的研究方向进行展望,期望为钙钛矿氧化物催化剂催化性能改进提供思路及方法。     

钙钛矿氧化物催化研究进展

简要介绍了钙钛矿氧化物的结构及优点。着重阐述了近年来钙钛矿氧化物催化剂在环境催化(NO_x消除、碳烟燃烧等)、电催化、光催化领域的应用及催化改性研究。简要分析了钙钛矿氧化催化剂在当前应用中存在的问题,并对钙钛矿氧化物催化剂今后的研究方向进行展望,期望为钙钛矿氧化物催化剂催化性能改进提供思路及方法。     

正庚烷异构化催化剂研究进展

阐述了当前正庚烷异构化所用的负载型催化剂和过渡金属碳化物和氧化物催化剂的研究进展,对催化剂性能的影响因素及对策进行了分析与讨论。正庚烷异构化催化剂中,研究较多的是以SAPO、HZSM-5和Y、B型分子筛为载体的贵金属催化剂,其中SAPO分子筛载体的性能较优,Pt比Pd具有更好的催化性能,非贵金属／分子筛催化剂的活性比贵金属／分子筛催化剂相差较大。过渡金属Mo、W的碳化物和氧化物也具有较好的正庚烷异构化性能,与碳氧化物或碳化物相比,部分还原氧化物催化正庚烷异构化活性和选择性要高得多,其活性甚至高于传统的Pt/USY双功能催化剂。展望了正庚烷异构化催化剂的研究方向和意义。     

多酸材料在燃油脱硫中的研究进展

多酸材料具备独特的酸性和氧化还原性能,在油品氧化脱硫领域得到广泛关注。本文综述了多酸材料在油品催化氧化脱硫领域的研究进展,详细叙述了多酸离子液体催化剂和以金属有机框架、氧化物、碳材料等为载体的负载型多酸催化剂的特点及其催化氧化燃油中多种有机硫化物的脱硫效果。将多酸与离子液体或其他载体结合后不仅能有效增强多酸的催化活性,而且可提高催化剂的热稳定性与重复利用性。本文对各类载体的特点及发展前景进行了详细比较,并对其研究现状进行了梳理。最后对多酸材料在氧化脱硫领域的发展方向提出了展望,指出了具有良好催化活性、循环性能及经济适用性强的多酸材料是未来的研究方向。     

钼基加氢脱硫催化剂的制备及应用研究进展

以钼在加氢脱硫(HDS)中的应用为线索,按催化剂结构不同,简介了负载型催化剂和非负载型催化剂的制备方法,总结了钼基加氢脱硫催化剂的应用进展。对于负载型钼基催化剂,按照载体不同,从单一氧化物载体、复合氧化物载体、分子筛载体和碳材料载体角度总结了催化剂在加氢脱硫中的应用。负载型催化剂虽然应用广泛,但其活性组分受载体限制。而非负载型催化剂可以有效提高活性组分含量,具有更高的催化活性。按照催化剂组成不同,总结了近年来单金属型、双金属型和多金属型非负载型催化剂在加氢脱硫中的应用。     

钼基加氢脱硫催化剂的制备及应用研究进展

以钼在加氢脱硫(HDS)中的应用为线索,按催化剂结构不同,简介了负载型催化剂和非负载型催化剂的制备方法,总结了钼基加氢脱硫催化剂的应用进展。对于负载型钼基催化剂,按照载体不同,从单一氧化物载体、复合氧化物载体、分子筛载体和碳材料载体角度总结了催化剂在加氢脱硫中的应用。负载型催化剂虽然应用广泛,但其活性组分受载体限制。而非负载型催化剂可以有效提高活性组分含量,具有更高的催化活性。按照催化剂组成不同,总结了近年来单金属型、双金属型和多金属型非负载型催化剂在加氢脱硫中的应用。     

SCR脱除NO_x催化剂的研究进展

NO_x排放对人体和环境造成较大危害。SCR脱硝技术已成为减少NO_x排放的主流技术,在SCR脱硝技术中催化剂占有重要作用,开发出具有高活性、高稳定性和高寿命的催化剂至关重要。阐述了金属氧化物载体、分子筛载体以及碳载体催化剂的选择性催化还原法脱除NO_x的研究进展,对SCR脱硝催化剂研究领域存在的问题进行探讨,并展望了今后研究方向。     

负载钯及非钯型Suzuki偶联反应催化剂体系的研究进展

Suzuki偶联反应是现代有机合成化学中构筑碳碳键的最有效方法之一。传统的Suzuki反应催化剂主要是Pd(PPh3)4、Pd(OAc)2等均相催化剂。这类催化剂的活性较高,但其价格高、化学稳定性较差、难以与反应液分离和回收再利用等缺点也是不容忽视的。近年来,人们开发了一系列具有不同的钯材料载体(碳材料、高分子材料以及无机材料等)的非均相催化剂体系,以及基于Ni、Cu、Mn等过渡金属的新型催化体系。这些新型的催化剂体系的发展有效地解决了上述均相催化剂的不足。综述了近来Suzuki反应在负载催化剂和非钯催化剂方面的研究进展。     

挥发性有机化合物催化燃烧用铂基催化剂的研究进展

负载型Pt催化剂由于具有高活性和良好的稳定性,被广泛应用于挥发性有机化合物(VOCs)的催化完全氧化反应中。系统阐述了载体种类、第二金属组分、催化剂预处理、颗粒尺寸等对催化剂反应活性和稳定性的影响,还概述了Pt催化剂对VOCs完全氧化的催化机理及动力学模型。最后,指出了负载型Pt催化剂今后的发展方向。     

中孔碳负载Pt催化剂用于抗氧剂7PPD合成反应

以纳米氧化锌为模板剂,酚醛树脂为碳源,通过硬模板法制备了中孔碳,并以其为载体制备了Pt/MC催化剂,通过BET、SEM、ICP、TEM等表征手段对中孔碳及其负载的Pt/MC催化剂进行表征。结果表明,可以通过模板剂有效调控中孔碳的比表面积和孔结构。将制备的Pt/MC催化剂用于抗氧剂7PPD合成反应,对比普通Pt/AC催化剂,p-ADPA的转化率由97.5%提高至100%,7PPD选择性由94.5%提高至99.5%,催化剂的稳定性明显提高。通过CO化学吸附、ICP、BET等对新鲜和使用十次后的催化剂进行表征,结果表明,催化剂载体的孔结构是影响催化剂稳定性的重要因素,平均孔径较小时,7PPD等大分子尺寸的分子容易堵塞孔道;平均孔径较大时,孔壁较薄,催化剂使用过程中容易磨损,活性组分流失。     

Development of Mn-based perovskite materials: Chemical structure and applications

In this article, we summarize current progress on the bulk and surface characteristics of Mn-containing perovskite oxides known for their good catalytic activity in atmospheric pollutant abatement. These materials are emphasized as serious alternatives for noble metal-based catalysts (Pt, Rh, Pd) in many catalytic applications particularly in automotive exhaust catalytic converters, mainly due to their low cost, good thermal stability at high temperature and ease of preparation compared to supported noble metal catalysts. The success of such materials is mainly related to Mn³⁺ and Mn⁴⁺ mixed valence and the resulted point defects formed after incorporation of a large variety of metals with different size and charge in the perovskite structure. These parameters could also affect the Mn reducibility and oxygen species mobility considered as one of the most determining factors in catalytic activity. The effect of perovskite metallic composition on the surface Mn oxidation state and relative cations segregation as well as applications of Mn-containing perovskite oxides as catalysts for several deep oxidation reactions at low and high temperatures are presented. Particular attention is devoted to the solution combustion synthesis for Mn-containing perovskite catalysts due to its time and energy saving characteristics and high surface areas of the obtained products. These advantages open new attractive opportunities for the use of this economic process to prepare supported perovskite oxide catalysts with the aim to better control morphology and stability of both surface catalyst and supports.     

离子液体体系制备高分散碳载Pt催化剂

用离子液体做溶剂制备碳载Pt催化剂,透射电镜结果表明,用离子液体做溶剂制备的催化剂Pt/C(A),活性组分Pt粒径小,分散的非常均匀。用这种方法制备的Pt/C(A)催化剂对乙二醇的阳极电氧化具有很高的电催化活性和稳定性。     

Dispersion of supported platinum catalysts in Oxygen

Further experimental evidences of redispersion on supported platinum catalysts studied by means of TPR, TPD and cyclohexene hydrogenation reaction. Pt/r-Al₂O₃ exhibits stronger interaction between the metal oxide and the support as compared with Pt/SiO₂ and Pt/TiO₂. The formation of surface complex is enhanced as oxidation temperature increases. The TPD spectrum of hydrogen on Pt/TiO₂ shifts to higher temperature upon reduction at high temperature and shifts again to its original position upon oxidation. Shift of TPD spectrum does not appear in other catalysts. The suggested mechanism for redispersion is the spreading of platinum oxide and trapping of migrating species.     

Selective oxidation of CO in hydrogen atmosphere on Pt–Fe catalysts supported on zeolite P-based materials

The catalytic properties of Pt supported on zeolite P (ZP)-based materials for the preferential CO oxidation in hydrogen atmosphere under mild conditions (from room temperature to 150 °C), have been investigated. Pt catalysts (1–4 wt%) supported on a zeolitized pumice support (Z-PM) have been prepared. A series of bimetallic Pt–Fe on ZP, having 2 wt% Pt and different Fe loading (0.5–4 wt%), have been also prepared and used as model catalysts. A detailed characterization of the catalysts has been carried out by means of surface area and porosity measurements, X-ray diffraction, scanning electron microscopy and transmission electron microscopy in order to investigate the morphological and microstructural properties of both support and catalytic system. Pt/Z-PM exhibited complete CO conversion with 55 % selectivity at temperatures as low as 50 °C, with no noticeable degradation of the catalytic performances, indicating that the Fe content present as an impurity in the zeolitized pumice support allows to obtain catalysts characterized by high activity and stability. On the basis of the characterization and kinetic tests, hypotheses on the role of Fe promoter have been formulated.     

载体对Pd和Pt催化剂加氢脱硫反应性能的影响

以质量分数为0.8%的二苯并噻吩(DBT)的十氢萘溶液为模型化合物,考察了SiO_2,Si-MCM-41和Al-MCM-41负载的Pd和Pt催化剂加氢脱硫(HDs)反应性能,并与传统的γ-Al_2O_3负载的催化剂进行了对比.反应结果表明,负载型Pd和Pt催化剂在DBT的HDS反应中表现出不同的反应特点.Pd催化剂具有较高的加氢反应路径(HYD)选择性,而Pt催化剂则表现出较高的直接脱硫路径(DDS)选择性.载体结构和表面酸性显著影响其负载的Pd和Pt贵金属催化剂的HDS活性以及HYD选择性和稳定性.提高载体比表面积和酸性有利于提高负载型贵金属催化剂HYD选择性.Al-MCM-41具有规整的介孔结构、较高比表面积和较强酸性,其负载的Pd和Pt催化剂表现出较高的HYD选择性和稳定性.研究还发现,催化剂加氢裂化反应活性随载体酸性的提高而增加.     

Carbon nanotube supported platinum catalysts for the ozonation of oxalic acid in aqueous solutions

Ozonation of oxalic acid in the presence of carbon nanotube (CNT) supported platinum (Pt/CNT) catalyst in aqueous solution was studied. The activity and stability of Pt/CNT, the influence of preparation conditions on Pt/CNT activity and the ozonation mechanism of oxalic acid with Pt/CNT were investigated. It was found that Pt/CNT was more active for oxalic acid removal and more resistant to ozonation compared with the case of activated carbon supported Pt catalyst. The Pt loading, reduction temperature and pyrolysis atmosphere significantly influenced the Pt/CNT activity, especially for pyrolysis atmosphere. By means of X-ray diffraction and X-ray photoelectron spectroscopy analysis, the aggregation of Pt and the existence of chemisorbed oxygen with Pt were found when the Pt/CNT catalyst was prepared by calcination, which are unfavorable for its performance. The CNT was oxidized and some acidic groups were generated in calcination, which also cause a decrease of Pt/CNT activity. A free radical mechanism was proposed which involves ozone decomposition and hydrogen peroxide formation for oxalic acid degradation on Pt/CNT. The redox couple of Pt_red/Pt_ox was suggested to be crucial for the improvement of CNT activity. The Pt/CNT has a good stability after five re-uses without any leaching of Pt.     

乙炔氢氯化金基无汞催化剂的研究进展

乙炔氢氯化无汞催化剂对我国煤基聚氯乙烯（PVC）工业实现绿色可持续发展具有重要意义，金基催化剂因其优良的催化性能而受到广泛的关注。本文从金基催化剂产业化应用存在成本高、稳定性差等问题出发，全面阐述了金基催化剂的反应和失活机理。从活性组分、载体等因素对催化性能的影响出发，概述了多年来金基催化剂的研究进展，重点总结了研究者们从改进活性组分和载体方面入手，使催化剂性能不断提升至工业化应用所做的工作。最后展望了金基催化剂的发展前景，并提出应深入研究内在反应机理，以简化制备及再生过程，探索低成本高效无汞催化剂及其工程化问题是该领域的研究重点。     

Nanoengineering catalyst supports via layer-by-layer surface functionalization

Recent progress in the layer-by-layer surface modification of oxides for the preparation of highly active and stable gold nanocatalysts is briefly reviewed. Through a layer-by-layer surface modification approach, the surfaces of various catalyst supports including both porous and nonporous silica materials and TiO₂ nanoparticles were modified with monolayers or multilayers of distinct metal oxide ultra-thin films. The surface-modified materials were used as supports for Au nanoparticles, resulting in highly active nanocatalysts for low-temperature CO oxidation. Good stability against sintering under high-temperature treatment was achieved for a number of the Au catalysts through surface modification of the support material. The surface modification of supports can be a viable route to control both the composition and structure of support and nanoparticle interfaces, thereby tailoring the stability and activity of the supported catalyst systems.