金属负载型有序介孔碳催化剂的制备及应用研究进展

在金属负载型有序介孔碳催化剂的制备工艺过程中,合成比表面积高、孔道结构规整、活性组分高度分散以及粒径尺寸小的催化剂是当前研究的热点,常用的制备方法有浸渍法、化学还原法、一步合成法及共组装合成法等。通过对介孔碳载体改性并采用不同的制备方法调控活性金属在有序介孔碳载体中的粒径及分散度,可提高其在工业废水处理、电化学、催化、储氢等领域的性能。     

高分散Ni/Al_2O_3催化剂的制备及其裂解汽油一段加氢性能

通过调整载体酸性、在活性组分负载过程中添加助剂、络合剂等方法制备Ni/Al2O3催化剂。采用XRD、TPR等技术表征了催化剂活性组分的分散度和还原度,并进行了催化剂性能的评价。结果表明通过调整载体酸性、添加助剂、络合剂的方式可以实现对催化剂中活性组分分散度的调变,提高催化剂加氢活性、稳定性及选择性能。     

负载活性组分对载体孔结构的影响

采用BET法测定了负载不同量丙烷脱氢制丙烯铬基催化剂、贵金属系催化剂载体的比表面积、孔结构等数据;采用压汞法测定了负载不同量乙烯氧化制环氧乙烷银催化剂载体的比表面积、孔结构等数据。随着活性组分负载量增加,负载铬基催化剂载体的孔容、比表面积持续降低;负载贵金属系催化剂的载体,由于活性组分负载量较低,载体的孔结构等数据几乎没有变化;负载银催化剂的载体与未负载活性组分的载体相比,其孔容降低13%。     

丙烷氧化脱氢制丙烯的钒基介孔催化材料研究进展

介绍了近年来丙烷氧化脱氢催化技术的最新研究进展,针对其中应用最广泛的钒基介孔催化剂,对其反应机理、载体性能和制备方法进行了综述,并比较了不同催化体系的丙烷氧化脱氢性能,提出了改善钒基介孔催化剂催化活性与选择性的途径。通过比较已经报道的同类研究结果,着重阐述了载体的孔结构对于氧化脱氢过程的影响,比表面积和孔径的优化对于提高催化剂的活性组分分散度以及活性位的数量效果明显。今后研究应着重提高催化剂孔道结构在高温下的稳定性以及使用寿命。     

合成条件对Pt负载γ-Al2O3催化剂在邻苯基苯酚合成中催化性能的影响

采用浸渍法制备了以γ-Al2O3为载体,Pt为活性组分的负载型催化剂,考察了不同制备条件对负载型贵金属催化剂在合成邻苯基苯酚中脱氢活性的影响.结果表明,浸渍液中活性组分的浓度、浸渍时间、有无竞争剂等对活性组分Pt在载体上的分散度有一定的影响,从而影响脱氢催化剂的活性.     

FCC柴油芳烃选择性开环催化剂研究进展

选择性开环技术可以使芳烃转换成单环烷烃或链烷烃化合物,极大地提高了柴油的清洁度和十六烷值,该技术的核心是开发具有加氢和开环性能的双功能催化剂。本文综述了近年来国内外催化裂化(FCC)柴油芳烃选择性开环催化剂的研究进展,重点讨论了催化剂载体、活性金属及制备方法3个方面对加氢开环反应性能的影响。分析表明载体的酸性和孔道结构、负载活性金属的类型(包括非贵金属和贵金属)及不同的制备方法对催化性能有极大影响。最后对柴油芳烃选择性开环催化剂的研究提出了一些建议,指出今后研究的重点是开发具有适宜酸性和孔结构的新型载体及能够保持活性和稳定性的活性金属组分并加强该领域反应机理的研究。     

提高柴油加氢精制催化剂活性的方法

依据过渡金属硫化物催化剂的活性相理论及加氢脱硫、脱芳反应的历程,综述了各种提高柴油加氢精制催化剂性能的方法--使用高加氢能力的活性组分、引入中等强度酸中心、减弱活性组分与载体间的相互作用以及提高活性组分的分散度;介绍了相关的国内外最新研究进展,指出研究开发高比表面积、中等酸性的介孔载体和既能提高活性组分分散度又不增强活性组分与载体间相互作用的新型催化剂制备方法是提高柴油加氢精制催化剂性能的主要途径.     

活性炭负载钌基氨合成催化剂的制备

利用浸渍法制备了活性炭负载钌基氨合成催化剂,讨论了影响钌分散度与氨合成催化活性的若干因素. 研究发现,若活性炭载体具有较大的比表面和较好的孔结构将有利于活性组分的分散. 同时,在浸渍之前,样品需在100～200 ℃干燥6～8 h. 催化剂各组分浸渍后对载体的表面结构影响不同,实验发现,Ba的添加可能为Ru的分散提供了合适的表面,而K主要填充于载体中孔并和Ru充分接触,并为Ru提供电子.同时要控制母体钌水溶液的pH值,并选用合适的浸渍顺序,方能达到较好的效果.     

介孔炭的应用研究进展

介绍了介孔炭在吸附、催化、模板材料及其他领域的应用现状及发展趋势。介孔炭作为吸附材料,在生物、环保、储能领域有了一定的应用。介孔炭作为新兴的催化剂载体,在电化学领域、石油化工领域、有机及无机化学领域的研究较多,指出进一步分析其特性,提高催化剂活性组分的分散性,简化工艺,降低成本是介孔炭在该领域的研究重点。同时也介绍了介孔炭作为模板材料及纳米反应器的探索性研究。     

加氢精制催化剂的制备及在石油化工中的应用

目前,加氢精制催化剂在化工业是比较常用的催化剂,但其大多数为负载型催化剂。负载型催化剂的活性在随着相关理论及制备技术的进步而日益提高。但是,负载型催化剂也有自身的局限性,载体比表面积和孔体积是影响其有效活性的金属负载量的主要原因,因此催化剂活性的提高受到一定的约束。非负载型催化剂的活性组分含量高,原因是其不用载体,它具有活性密度大,加氢脱硫、脱氮和芳烃饱和能力强的优点。本文先对非负载型加氢精制催化剂的制备进行了分析,然后对非负载型加氢精制催化剂在石油化工中的应用进行了探讨。     

正丁烷脱氢异构制异丁烯的研究进展

正丁烷脱氢异构制异丁烯是提高正丁烷利用率和增产异丁烯的重要途径。对正丁烷脱氢异构制异丁烯的反应热力学进行分析,从热力学角度指出制约反应的关键因素,总结正丁烷脱氢异构制异丁烯反应中各催化体系的研究现状,提出催化剂的研发要点和催化剂研发过程中要解决的关键问题。在传统过渡金属双功能型催化剂中,通过加入助剂等方式提高脱氢活性组分的分散度并降低其聚集度,通过调变载体的酸性和孔道结构等方式提高载体的异构性能,即合理调节脱氢活性位和载体异构性能之间的匹配是传统过渡金属双功能型催化剂研发的关键。在新型催化剂中,探索在缓和条件下制备高比表面积和合适孔道结构的氮化物、碳化物和碳氧化合物的方法是新型催化剂研发的关键。     

Propane oxidative dehydrogenation over vanadia catalysts supported on mesoporous silicas with varying pore structure and size

The structural characteristics and the performance of vanadia catalysts (0.7–8 wt.% V) supported on mesoporous (MCM-41, HMS, MCF, SBA-15), microporous (silicalite) and non-porous (SiO₂) silicas in oxidative dehydrogenation of propane were investigated. The structure of vanadia species, the redox and the acidic properties of the catalysts were studied using in situ Raman spectroscopy, TPD- NH₃ and H₂-TPR. The only vanadia species detected on the surface of HMS and MCM-41 for V loadings up to 8 wt.% were isolated monovanadates indicating high vanadia dispersion. Additional bands ascribed to V₂O₅ nanoparticles were evidenced in the case of SBA-15 and MCF supported catalysts while these bands were the only ones identified on the surface of the catalysts supported on silicalite and non-porous silica. The catalysts supported on mesoporous HMS and MCM-41 materials showed the best performance achieving high propane conversions (35–40%) with relatively high propene selectivities (35–47%). Lower activity due to the lower degree of vanadia dispersion, caused by the partial destruction of the pore structure was observed for the SBA-15 and MCF supported catalysts. The degree of dispersion of the V species on the catalyst surface and not the pore size and structure of the mesoporous support or the acidity/reducibility characteristics mainly determine the catalytic activity towards propene production. In addition, it was shown that the pore structure and size of the mesoporous supports did not have any significant effect in the turnover rates (TOF values) of propane conversion (and propene formation at low propane conversion, below ca. 10%). However, the highest propene yield (up to 19%) and stable catalytic behavior was attained for catalysts supported on HMS mesoporous silica, and especially for those combining framework mesoporosity and textural porosity (voids between primary nanoparticles).     

非金属碳基丙烷直接脱氢制丙烯催化剂研究进展

采用绿色可持续的催化剂替代传统贵金属或过渡金属催化剂是目前工业催化领域研究的重要方向。作为绿色催化剂中的重要成员之一,多孔碳基材料由于其独特的孔道结构、较大的比表面积、丰富的表面含氧官能团以及良好的导电性和抗腐蚀性,被广泛应用于生物、医药、电池和化工领域。近年来,非金属碳基催化剂被发现是一种良好的丙烷脱氢催化剂,具有替代传统Pt基和Cr基催化剂的应用前景,得到广泛关注。一般而言,碳基催化剂的催化活性与其表面性质和孔道结构有很大关系:(1)碳材料表面的含氧官能团、杂原子和缺陷位点等可以作为活性中心,活化丙烷分子中的碳氢键,实现脱氢的目的;(2)碳材料的孔道结构和电子特性等会影响反应物丙烷和反应产物丙烯分子的扩散和传质,进而影响碳基催化剂在丙烷脱氢反应中的活性、选择性和稳定性。综述近年来丙烷直接脱氢制丙烯碳基催化剂的研究进展,详细比较不同碳材料之间的优缺点和性能差异,系统讨论碳材料的活性位点和物化性质对其催化性能的影响,并对未来碳基丙烷脱氢催化剂的发展方向和应用前景进行展望。     

氮掺杂碳材料的制备及其在催化领域中的应用

氮掺杂碳材料以其独特的性质在催化研究领域具有广泛的应用。氮掺杂过程可引入缺陷位及氮物种,改善催化剂的物理化学性质、酸碱性和浸润性,并与活性物种产生相互作用,提升催化性能。本文从氮掺杂碳材料的制备及其在催化领域中的应用展开综述。常见的氮掺杂碳材料主要利用含氮前驱体,通过后合成法、原位合成法、催化生长法和模板法进行制备。通过改变前驱体种类、处理条件等制备参数,可实现孔道结构、氮物种类型、氮物种掺杂量及其与活性物种相互作用等性质的调变。开发大规模经济环保的制备方法,推动对缺陷构筑以及氮物种与活性组分相互作用机制的研究,是未来重要的研究方向。氮掺杂碳材料在催化领域表现出优越的性能,有望成为催化剂开发的前瞻领域,推动相关工业技术的进步。     

钌炭催化剂的制备及其在芳环加氢反应中的应用

芳环加氢反应是最重要的合成反应之一,钌炭催化剂在芳环加氢反应中具有优异的催化性能。综述钌炭催化剂的制备方法和载体性质对钌炭催化剂的影响以及钌炭催化剂在苯、苯甲酸和对苯二甲酸二甲酯等芳环加氢反应中的应用进展。负载型钌炭催化剂的制备方法主要有浸渍法、沉淀法和升华法,超声辅助浸渍法可将大部分钌纳米粒子引入到炭载体的孔道内部,得到限域型负载钌炭催化剂。而镶嵌式钌炭催化剂主要是指通过原位炭化的方法将钌粒子部分镶嵌在炭的孔壁上,一步得到钌炭催化剂,其制备方法主要有软模板剂法和硬模板剂法。除制备方法外,炭的骨架结构、表面性质及氮掺杂对钌炭催化剂的性能影响也较大。镶嵌式钌炭催化剂具有钌纳米粒子和炭载体之间的相互作用强、催化剂抗流失及烧结性能好,在芳环加氢反应中表现出卓越的催化性能和稳定性。随着新制备技术的出现,新型镶嵌式钌炭催化剂将可能实现产业化。     

A comparative study on catalytic performances of chromium incorporated and supported mesoporous MSU-x catalysts for the oxidehydrogenation of ethane to ethylene with carbon dioxide

Two kinds of Cr-based mesoporous materials, Cr incorporated and supported silicate MSU-1, were synthesized at room temperature and characterized with XRD, N₂ adsorption–desorption, FT-IR, DR UV–vis and H₂-TPR techniques. Both Cr-based catalysts exhibited similar mesoporous channels and textural properties. The catalytic performances of two catalysts for the oxidative dehydrogenation of ethane to ethylene with CO₂ were investigated. They both showed high activities, providing 58.0 and 68.1% ethane conversion and 53.4 and 55.6% ethylene yield at 700 °C, respectively. The catalysts were prone to deactivate in the reaction but could be partially regenerated by oxygen. Cr species formed in high oxidation state were reduced during the reaction. It was proposed that these high-valent Cr species were responsible for the high activities of catalysts.     

A novel catalyst system based on quadruple silicoaluminophosphate and aluminosilicate zeolites for FCC gasoline upgrading

To develop a novel catalyst system that has excellent olefin reduction capability for FCC gasoline without loss in octane number, different catalysts supported on multiple composite carriers consisting of SAPO-11, Hβ, HMOR and HZSM-5 were prepared and their catalytic performances for FCC gasoline upgrading were assessed in the present investigation. The pore structure and acidity of the catalysts were characterized by N₂ adsorption and pyridine adsorption FTIR, respectively. Based on the results obtained over the catalysts supported on binary-zeolite carriers (Hβ/HZSM-5, HMOR/HZSM-5 and SAPO-11/HZSM-5) using FCC gasoline as the feedstock, various multiple-zeolite supported catalysts were developed from different combinations of the binary-zeolite systems. It was found that the SAPO-11/HMOR/β/ZSM-5 quadruple composite zeolite supported catalyst gave higher liquid yield, improved gasoline RON, and lower coke deposit amount for the hydro-upgrading of FCC gasoline and thus can be considered as a potential catalyst system. A comprehensive analysis based on the catalytic activities and acidity measurements revealed that acid strength and acid type were two very important factors influencing hydroisomerization and aromatization activities, and the difference in catalyst acid strength determined which factor predominates.     

不同高岭土系黏土性质及在催化裂化催化剂中的应用

随着原料油重质化、劣质化程度逐渐增高,催化裂化催化剂基质不仅需要保证催化剂有良好的磨损性能和流化性能,还需要具有适当的孔和一定的酸性对原料油中的大分子进行预裂化。半合成催化裂化催化剂中的高岭土系黏土对催化剂性能有重要影响。高岭土可直接或经酸、碱改性作为催化剂基质,也可通过原位晶化技术合成分子筛或含有Y型分子筛的催化剂。累托石通过交联反应可以合成层柱分子筛用于催化裂化催化剂制备。埃洛石因其管状结构,作为基质时催化剂具有孔体积和比表面积大及活性高的特点。对催化裂化催化剂中高岭土系黏土结构、改性方法及在催化裂化催化剂中应用进行综述,并对今后高岭土在催化裂化催化剂中的研究方向进行展望。     

Efficient catalysts with controlled porous structure obtained by anodic oxidation under spark-discharge

The anodic oxidation under spark discharge (ANOF technique) is presented as a promising alternative for the preparation of catalytic oxide layers on metallic supports. The influence of the substrate (Al, Ti, and Mg), electrolyte composition and the treatment time to obtain egg-shell catalysts with tailor-made properties for the effective oxydehydrogenation (ODH) of cyclohexane to cyclohexene is studied. Chromium, molybdenum and nickel were chosen as precursors for active species in order to obtain catalysts able to perform the substrate oxidation by electrophilic (chromium oxide), nucleophilic (molybdena) or both kind of oxygen species (nickel oxide). It was found that compared to nickel oxide, the chromium oxide containing egg-shell catalyst was less selective while the molybdenum oxide showed very high selectivity, but lower activity. The intrinsic activity of nickel containing egg-shell catalysts is an order of magnitude higher than that of a classic alumina supported nickel oxide catalyst obtained by impregnation. The selectivity to the intermediate cyclohexene is also favored on the egg-shell catalyst with a regular pore structure. Moreover, the selectivity performance of the catalysts can be improved by designing catalysts with shorter pores.