MgFeMn-HTLcs的制备、改性及其CO加氢性能

采用沉淀-水热法制备了系列不同Mg/Fe/Mn配比的MgFeMn-HTLcs类水滑石前体,经焙烧、浸渍法K改性用于CO加氢制烯烃反应。采用XRD、SEM、TG、N₂吸附-脱附、H₂-TPR、XPS等手段对催化剂进行了表征。结果表明,制备的Mg-Fe-Mn前体均具有类水滑石层状结构,Mn的添加使结晶度下降;焙烧后,Mg-Fe样品主要生成MgO,Mg-Fe-Mn样品生成Mg₂MnO₄、MgO和MgFe₂O₄物相;反应后主要为MgCO₃和FeCO₃混合物相,伴随FeO-MnO和Fe_xC_y的生成;与K/Mg-Fe样品相比,Mn的加入进一步促进了Fe的分散,使得Fe₂O₃到Fe₃O₄还原度增加,其供电子效应促使Fe电子结合能向低偏移。在CO加氢反应中,K/Mg-Fe-Mn催化剂均表现出较高的反应活性和烯烃选择性。其中,K/3Mg-1Fe-2Mn催化剂的效果较好,CH₄含量较低,O/P值达5.20,C₂⁼～C₄⁼质量分数为43.03%。     

钴基催化剂合成长链烃的选择性控制

F－T反应产物具有广泛的碳数分布，近年来，F－T合成研究的重点转移到高选择性地合成重质烃（C5^ 以上）产物。综述了钴基催化剂应用于F－T反应合成长链烃中链增长途径和F－T合成选择性的关系，从理论上评述了能有效提高长链烃选择性的制备催化剂的方法，指出了采用蛋壳型催化剂、添加合适的助剂及选择具有规整孔道分布的中孔载体材料均有利于提高F－T产物中长链烃的选择性。     

芳烃精制脱烯烃分子筛催化剂的研究

本研究以铝胶、硅铝胶及钛铝胶为粘合剂,以HY分子筛为主要活性组分制备了芳烃脱烯烃分子筛催化剂.采用NH3-TPD、BET、TG和活性评价等方法对催化剂的酸性、脱烯烃活性、失活原因及再生性能进行了研究.结果表明,含有不同粘合剂的HY分子筛催化剂的脱烯烃活性均明显高于工业使用的NC-01颗粒白土催化剂,分子筛催化剂表面具有较多的弱酸中心是其性能良好的重要原因.积碳是分子筛催化剂表面失活的主要原因,经焙烧再生处理后分子筛催化剂仍具有较好的脱烯烃性能.经823 K焙烧的硅铝胶质量分数为20%的分子筛催化剂具有较佳的反应性能.     

贫燃条件下净化汽车尾气中NO_x的金属氧化物催化剂的研究进展

综述了在贫燃条件下以碳氢化合物为还原剂,在金属氧化物催化剂催化下对NOX选择还原的研究进展,主要介绍了以Al2O3为载体的氧化物催化剂的组分和制备方法等对催化剂结构和催化性能的影响,对催化剂的抗二氧化硫和水的性能也做了介绍,然后指出了金属氧化物催化剂的发展方向。     

预硫化加氢催化剂钝化的研究进展

钝化是预硫化加氢催化剂的一个重要处理步骤,介绍了预硫化催化剂的气体钝化、含氧烃钝化和涂覆剂钝化3种工艺,以及预硫化催化剂钝化的应用和研究进展。经过上述钝化工艺处理后．有效抑制了催化剂的自热或自发燃烧的特性,使预硫化催化剂的运输、存放、保管变得简单安全,这对大规模推广使用器外预硫化催化剂有着重要的意义。     

高密度烃燃料挂式四氢双环戊二烯的研究进展

综述了由双环戊二烯加氢、异构化制备挂式四氢双环戊二烯的合成方法,概括了双环戊二烯加氢催化剂的种类,比较了几种催化剂的优缺点,并对连续式和间歇式加氢工艺发展现状进行了总结。对桥式四氢双环戊二烯异构化反应催化剂和Lewis酸催化反应过程及机理进行了介绍。提出了加氢及异构化催化剂的发展方向,并提出了改进挂式四氢双环戊二烯合成工艺的建议。     

低温氧化型过渡金属氧化物催化剂研究进展

汽车冷启动时催化剂床层温度低,尾气中的CO和烃类不能被传统三效催化剂有效消除。目前,非贵金属类的过渡金属氧化物催化剂用于CO和烃类的低温氧化受到了广泛关注。本文综述了近几年来国内外以Cu、Co和Mn的氧化物为主要代表的过渡金属氧化物上烃类和CO氧化的研究进展,对催化剂上界面氧空位参与氧化过程的反应机理进行了总结,展望了过渡金属氧化物催化剂用于CO和烃类低温氧化的未来研究趋势。     

A theory of ultradeep hydrodesulfurization of diesel in stacked‐bed reactors

Hydrodesulfurization catalysts have two types of active sites for hydrogenation and hydrogenolysis reactions. While hydrogenation sites are more active for desulfurizing refractory sulfur species, they are more susceptible to organonitrogen inhibition than hydrogenolysis sites. In contrast, hydrogenolysis sites are more resistant to organonitrogen inhibition but are less active for desulfurizing refractory sulfur species. This dichotomy is exploited to develop an ultradeep hydrodesulfurization stacked‐bed reactor comprising two catalysts of different characteristics. The performance of such a catalyst system can be superior or inferior to that of either catalyst alone. A mathematical model is constructed to predict the optimum stacking configuration for maximum synergies between the two catalysts. The best configuration provides the precise environment for the catalysts to reach their full potentials, resulting in the smallest reactor and minimum hydrogen consumption. Model predictions are consistent with experimental results. A selectivity‐activity diagram is developed for guiding the development of stacked‐bed catalyst systems. © 2017 American Institute of Chemical Engineers AIChE J, 64: 595–605, 2018     

催化裂化外取热器入口区域催化剂分布及优化研究

外取热器是维持催化裂化反应?再生系统热量平衡的关键设备,在其入口区域内催化剂质量呈现非均匀分布,加之入口管路内安装的调节阀门使催化剂流动出现偏流,影响其稳定运行。在一套大型冷模实验装置上,系统考察了入口区域催化剂质量分布特性和催化剂流动的偏流特性。结果表明,对于工业采用的初始入口结构,随入口管路内催化剂质量流率增大,催化剂质量周向分布非均匀性先增强后减弱,当Gs=230~620 kg/(m2?s), ug=0.2~0.35 m/s时,催化剂的质量周向分布均匀性最差;随入口管路内催化剂质量流率增大,催化剂流动偏流程度先增加后降低,在Gs=380~720 kg/(m2?s)时,催化剂流动偏流最显著;通过设计安装入口结构1和入口结构2,入口区域的催化剂质量分布均匀性得到了显著提升,催化剂流动偏流也被大幅弱化;入口结构2的优化效果更明显,其入口管路压降较初始入口结构升高约0.14 kPa。     

重整催化剂的抗硫性能研究进展

基于固体氧化物燃料电池(SOFC)的烃类原位重整供氢技术是重要的分布式和小型化制氢方案。传统镍基重整催化剂在烃类重整过程中,原料中微量的硫化物即可使催化剂中毒失活,严重时还可能造成巨大的安全隐患。本文梳理总结了催化剂硫中毒的机理,简述了天然气、液化石油气、液态烃重整原料中硫化物的组成和含量,重点分析了已报道的用于重整反应的抗硫催化剂并总结了有效可行的催化剂抗硫方案,并从重整制氢催化剂的硫中毒机理指导高效抗硫催化剂的开发。最后,文章指出,重整催化综合性能的提升、重整原料的预处理和重整反应器设计等综合抗硫策略也是重要的研究方向。     

Progress in the sulfur resistance of reforming catalysts

Hydrocarbon in-situ reforming hydrogen supply technology based on solid oxide fuel cell (SOFC) is an important distributed and miniaturized hydrogen production solution. Traditional nickel-based reforming catalysts often face sulfur poisoning during the reaction with trace amount of sulfur in the feedstock. In some cases, the existing sulfur may even cause severe safety risks. In this paper, the mechanisms of sulfur poisoning are summarized; the compositions and contents of sulfur species in natural gas, liquefied petroleum gas and liquid hydrocarbon are briefly described; the reported sulfur resistant catalysts for different reforming reactions are reviewed, and the effective and feasible solutions for developing sulfur-tolerant catalysts are summarized. The mechanisms of sulfur poisoning could guide the design of sulfur-resistant reforming catalyst with high performance. Finally, the paper reveals that the improvement of catalytic overall performance, the pretreatment of reforming feedstock and the design of reforming reactor and other comprehensive anti-sulfur strategies are also important research directions.     

烃类蒸汽转化催化剂表面改性的研究

本文介绍了烃类蒸汽转化催化剂表面改性的试验, 经表面改性后, 在不降低催化剂原有低温还原性及强度等性能的基础上, 其样品的初活性及活性稳定性明显提高, 试验达到了预期的目的。     

国内外蒸汽转化制氢催化剂及工艺进展

本文分别对烃类蒸汽转化制氢技术中涉及的原料、工艺、设备及催化剂等方面的国内外进展进行了讨论，评述了烃类蒸汽转化制氢技术的发展趋势并提出有关建议。     

芳烃蒸汽催化重整制氢研究进展

氢能是一种清洁的二次能源,具有绿色环保、零污染、零碳排放等优点。芳烃蒸汽重整制氢原料来源广、单位体积原料产氢量高,在重油焦油清除升级、便携式移动制氢等领域极具应用价值,其核心在于高性能催化剂的开发。文章首先从芳烃重整反应特性、反应网络、动力学模型构建和吸附解离等方面对其反应动力学及机理进行了概述,认为采用热力学理论计算、先进的原位表征技术和严密的逻辑论证实验等综合手段是加深反应动力学和机理认知的关键;其次,按照催化剂组成分类,评述了不同活性组分、载体及助剂的特点,基于镍基双金属活性组分的协同效应、钙钛矿载体的强储/释氧能力和碱性助剂的酸调控作用,指出碱性助剂改性的负载型镍基双金属钙钛矿催化剂是其发展方向。     

贫燃条件下汽车尾气净化新型催化剂--耐湿热双功能催化剂

由于汽车尾气对环境和人类的危害 ,开发和研制高效、高活性、高寿命、高抗毒性的尾气净化催化剂以净化大气是目前迫切需要解决的问题。本文综述了目前国际上由低碳烃催化还原催化剂的研究现状 ,分析了各种催化剂各自的优势和存在的问题 ,着重论述分析了双功能催化剂特性 ,并提出以湿热稳定性好的磷酸硅铝分子筛为载体研制贫燃条件下汽车尾气净化耐湿热双功能催化剂的新设想。     

高氮原料的催化裂化研究进展

从FCC催化剂碱氮中毒机理、含氮化合物的转化等角度分析了含氮化合物对催化裂化的不利影响.在此基础上,对目前已工业化和在研的各种高氮原料直接催化裂化技术进行了概述,展望了高氮原料催化裂化发展的方向.     

挥发性有机物催化燃烧消除的研究进展

介绍了近年来挥发性有机物(VOCs)的催化燃烧消除,特别是芳烃类、醇类、醛类、卤代烃类催化燃烧消除的研究进展,评述了用于各类VOCs催化燃烧消除催化剂的性能特点,对比、分析了不同催化反应条件下催化剂的性能差异,并对VOCs催化燃烧消除的研究发展方向进行了展望,以期对该领域的研究有所参考。     

Catalytic deoxygenation of fatty acids and their derivatives to hydrocarbon fuels via decarboxylation/decarbonylation

Fatty acids and their derivatives can be converted to renewable and carbon‐neutral fuel‐like hydrocarbons that are entirely fungible with fossil fuels. Typically, these hydrocarbon‐based biofuels are obtained through hydrotreating, a method which has the significant disadvantages of requiring problematic sulfided catalysts and high pressures of hydrogen. In recent years, decarboxylation/decarbonylation has been proposed as an alternative method, as this approach has the advantages of permitting the use of simpler catalysts and requiring less hydrogen than hydrotreating. In this contribution, the deoxygenation of fatty acids and their derivatives to fuel‐like hydrocarbons via decarboxylation/decarbonylation is critically reviewed. The main aspects discussed include the influence of the feed, catalyst, reactor system and reaction conditions on the decarboxylation/decarbonylation reaction, as well as the reaction mechanism and catalyst deactivation/regeneration. Copyright © 2012 Society of Chemical Industry     

Customizing the comonomer incorporation distribution in Ziegler–Natta-based LLDPE: Harnessing the influences of the titanation temperature during catalyst synthesis and of polymerization process parameters

The microstructure of linear low-density polyethylene (LLDPE) is strongly influenced by short-chain branches (SCBs) incorporated into the polymer backbone. Varying the number, distribution, and length of SCBs allows the properties of the resulting polymer to be tailored to meet specific requirements. Using Ziegler–Natta (ZN) catalysts for synthesis has disadvantages in terms of the comonomer incorporation distribution (CID) compared to, for instance, metallocene and post–metallocene catalysts. Nevertheless, ZN catalysts continue to be widely used, as many of the new generations of catalysts are more difficult to handle and cannot match the cheap cost of ZN catalysts. To improve this aspect of ZN catalysts, we investigated the influence of catalyst titanation temperature and polymerization process parameters on the CID. Our results show that it is possible to manipulate the process parameters of the present ZN catalyst system to yield a desired comonomer amount and CID in the polymer. Varying the titanation temperature clearly influenced the titanium content of the catalyst. Molecular-weight distribution analysis and deconvolution results indicate that changes in the amounts of comonomer incorporated and in the CID are directly related to the catalyst's active site that produces the lowest-molecular-weight fraction.     

Catalytic performance of Ag–Al2O3 catalyst for the selective catalytic reduction of NO by higher hydrocarbons

Silver–aluminum mixed oxide catalyst (Ag–Al₂O₃) prepared by the sol–gel method was studied for the selective reduction of NO by various alkanes in the presence of water vapor. As the carbon number of alkanes increases, the de-NO_x activity and water tolerance were markedly increased. In the case of n-octane as a reductant, the presence of water vapor markedly promoted NO reduction. The results of reaction studies and in situ IR experiment showed that the possible reasons for the promoting effect by water vapor are the inhibition of the n-octane oxidation by O₂ and the suppression of the poisoning effect caused by carboxylate and carbonate species. Among various alumina-supported transition metal catalysts, Ag–Al₂O₃ showed the highest activity for SCR by n-octane. Ag–Al₂O₃ showed higher NO conversion to N₂ and selectivity than alumina-supported Pt and Cu-ZSM-5 catalysts for the selective reduction of NO by n-octane and i-octane.