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XPS在有机/无机复合载体型催化剂制备中的应用 总被引:1,自引:0,他引:1
以聚丙烯接枝马来酸酐聚合物及SiO2为载体,以3-氨基三乙氧基硅烷为偶联剂,制备了有机/无机复合载体。将此载体经MAO处理后负载TiCl4制得负载型催化剂。用光电子能谱追踪了负载催化剂的制备过程,结果表明,在复合载体催化剂中存在两种可能的活性中心。 相似文献
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正庚烷在β沸石负载的磷钨杂多酸催化剂上加氢异构化 总被引:2,自引:0,他引:2
制备了系列含微量Pt(0.4%)的负载型磷钨杂多酸(PW)催化剂,采用Hβ或通过水热和盐酸联合脱铝的Hβ沸石作为催化剂载体,并在微型常压固定床催化反应器上考察了所制备的催化剂在正庚烷临氢异构化反应中的催化性能。结果表明,Pt及PW能够高度分散在催化剂载体表面;PW负载量及载体的水热处理温度和时间都显著影响催化剂的转化率和选择性,与未负载杂多酸的催化剂相比,负载杂多酸后的催化剂的正庚烷转化率有大幅度提高,异构化产物有所下降,但仍保持较高的异构化选择性。 相似文献
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负载型碱催化剂的制备及其在酯交换和醇、胺羰化反应中应用 总被引:3,自引:0,他引:3
以三乙胺和甲醇钠为活性碱组分,以A,X和Y型分子筛及硅胶和有机高聚物担体为载体制备了负载型碱性催化剂。考察了催化剂在甲醇和二乙胺羰化以及酯交换反应中的活性,并考察了催化剂制备过程中多种因素对活性的影响,结果表明,在催化剂制备过程中,溶剂和制备方法对催化剂活性的影响较大,而载体粒度的影响较小,在适当的条件下,上述载体能较好地负载有机碱三乙胺和甲醇钠,所得负载型碱性催化剂在环氧丙烷作用下具有较高的甲醇和二乙胺羰化催化活性及酯交换催化活性。 相似文献
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挥发性有机物(VOCs)的排放对自然环境、人类健康产生了严重危害,吸附法和催化氧化法是治理VOCs的有效方法.沸石分子筛含有丰富的微孔,比表面积大,且含有较多的酸位点,具有一定的催化活性,十分适合作为催化剂载体材料,被广泛应用于分离、吸附及催化等领域.本文综述了不同沸石分子筛吸附去除及沸石基负载型催化剂催化氧化去除烷烃、芳香烃、醛类、酮类、酸类、酯类、醇类及氯代烃等VOCs的研究进展.分析表明,沸石吸附剂的孔道结构、硅铝比、表面物理化学性质,VOCs种类、极性、亲水性,对沸石分子筛吸附性能影响较大;沸石载体表面酸碱度,催化剂活性组分种类、分散性,VOCs种类等是影响负载型催化剂催化活性的重要因素;沸石载体和活性组分之间存在协同作用,赋予了负载型催化剂优异的催化活性.沸石负载贵金属催化剂对各类VOCs的催化氧化性能优于沸石负载金属氧化物催化剂,但贵金属价格昂贵,成本较高,通过合理设计多组分金属氧化物催化剂,可显著提高负载型催化剂的催化活性.此外,本文对沸石分子筛及其负载型催化剂去除VOCs的未来研究方向进行了展望. 相似文献
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介绍了以活性炭为载体的负载型杂多酸催化剂的研究进展,包括制备方法、影响负载量的因素、负载催化剂的性质、吸附模型和脱附作用。总结了杂多酸在活性炭上的吸附形态研究以及杂多酸与活性炭表面含氧基团的化学键合作用的研究成果,展望了该催化剂未来的研究方向。 相似文献
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近年来,单原子催化剂因其较高的催化活性和选择性等优点而受到了人们的广泛关注.我们综述了以C, Si, Ti, Al为基底的单原子催化剂的制备方法,并对以不同材料基底制备单原子催化剂的制备方法、形成机理及优势特点进行了比较.通过对单原子制备、表征方法及催化活性的概述,以期对制备单原子催化剂提供一定的借鉴和指导.研究表明,单原子催化剂的制备已从贵金属单原子催化剂向过渡金属单原子催化剂进行了转变.单原子催化剂的基底也不再仅仅局限于单一的形式.这些转变为单原子催化剂向传统催化领域迈进提供了可能.我们同时也对单原子催化剂在工业上的应用进行了介绍. 相似文献
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《应用有机金属化学》2017,31(12)
In this paper a novel simple method for preparing two different catalysts with various‐valences copper was reported. Carbon nanofibers supported copper‐cuprous oxide nanoparticles (Cu‐Cu2O NPs/CNFs) and copper oxide nanoparticles (CuO NPs/CNFs) through electrospinning, adsorption and reduction in the high‐pressure hydrogenation and the high‐temperature calcination methods. These catalysts were investigated by a series of characterizations and were applied in reaction in nitrogen atmosphere, which had a good catalytic activity and selectivity of benzaldehyde for the reaction. Above all, the new study has been certified clearly, in which Cu‐Cu2O NPs/CNFs and CuO NPs/CNFs composite catalysts enhanced the generation of benzaldehydeand the excellent catalytic properties were exhibited. 相似文献
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综述了用于燃料电池中氧还原反应(ORR)的石墨烯衍生物负载的各种纳米催化剂的最新进展。介绍了用于表征石墨烯基电催化剂的常规电化学技术以及石墨烯基电催化剂最新的研究进展。负载于还原氧化石墨烯(RGO)上的Pt催化剂的电化学活性和稳定性均得到显著提高。其它贵金属催化剂,如Pd, Au和Ag也表现出较高的催化活性。当以RGO或少层石墨烯为载体时, Pd催化剂的稳定性提高。讨论了氧化石墨烯负载Au或Ag催化剂的合成方法。另外,以N4螯合络合物形式存在的非贵过渡金属可降低氧的电化学性能。 Fe和Co是可替代的廉价ORR催化剂。在大多数情况下,这些催化剂稳定性和耐受性的问题均可得到解决,但其整体性能还很难超越Pt/C催化剂。 相似文献
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Najmeh Bashiri Sayed Javid Royaee Morteza Sohrabi 《Research on Chemical Intermediates》2018,44(1):217-229
Global warming, fossil fuel depletion and fuel price increases have motivated scientists to search for methods for the storage and reduction of the amount of greenhouse gases, especially CO2. The hydrogenation process has been introduced as an emerging method of CO2 capture and convertion into value-added products. In this study, new types of catalysts are introduced for CO2 hydrogenation and are compared based on catalytic activity and product selectivity. The physical properties of the samples are specified using BET. Iron catalysts supported on γ-Al2O3 with different metal promoters (X = Ni, K, Mn, Cu) are prepared through the impregnation method. Moreover, Fe–Ni catalysts supported on HZSM5-Al2O3 and Ce–Al2O3 are synthesized. Samples are reduced by pure H2 and involved in hydrogenation reaction in a fixed bed reactor (H2/CO2 = 3, total pressure = 10 MPa, temperature = 523 K, GHSV = 2000, 1250 nml/min). All catalysts provide high conversion in hydrogenation reactions and the results illustrate that the selectivity of light hydrocarbons is higher than that of methane and CO. It is found that Ni has a promoting effect on the conversion fluctuations throughout the reaction with 66.13% conversion. Using combined supported catalysts leads to enhancing catalytic performance. When Fe–Ni/γ–Al2O3—HZSM5 is utilized, CO2 conversion is 81.66% and the stability of the Fe–Ni catalyst supported on Al2O3 and Ce–Al2O3 furthey improves. 相似文献
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Asymmetric catalysis plays an important role in present-day production of pharmaceuticals. It can be predicted that enantioselective catalysis will dominate in the future, replacing conventional stoichiometric methods. Heterogeneous catalysts offer several advantages compared to their homogeneous counterparts. In the present review mechanisms of asymmetric heterogeneous catalysis are discussed and the different ways of chirality transfer are addressed. Enantioselection is possible over chiral supports and chiral metals exhibiting intrinsic chirality, as well as over modified metal supported catalysts. The interactions between a reactant and a modifier are very specific being critical for achieving high enantioselectivities. 相似文献