低碳烷烃脱氢Pt系催化剂的研究进展

低碳烷烃脱氢Pt系催化剂由于活性较高且对环境友好等优点而被广泛研究。从催化剂的助剂、载体以及制备方法三个方面,综述了近五年的低碳烷烃脱氢Pt系催化剂的研究进展,并对Pt系催化剂未来的研究方向进行了展望。     

低碳烷烃脱氢催化剂的研究进展

叙述了低碳烷烃脱氢研究的发展现状。介绍了低碳烷烃脱氢的方法,包括无氧脱氢法和有氧脱氢法。用于低碳烷烃脱氢的Pt基催化剂主要缺点是稳定性差、选择性低。分别介绍了Pt基催化剂的活性组分、载体及不同助剂添加对Pt-Sn催化剂性能的影响。简单介绍了铬系催化剂以及国外低碳烷烃脱氢的技术工艺。最后对低碳烷烃脱氢催化剂的发展趋势做了展望。     

丁烷脱氢工艺及催化剂研究进展

C₄烯烃作为石油化工和聚合物行业的基础原料被广泛用于合成橡胶、塑料和特种燃料等的生产。由低碳烷烃向C₄烯烃的转化,不仅可以有效缓解我国低碳烯烃紧缺的难题,而且可以大大提升低碳烷烃的附加值。综述近年来国内外丁烷催化脱氢的技术现状与研究进展,重点论述正丁烷脱氢反应的机理、催化剂活性组分、载体及助剂对催化脱氢性能的影响,概述脱氢催化剂的失活原因,并对丁烷脱氢催化剂的研究前景进行展望。     

丙烷CO_2氧化脱氢制丙烯研究进展

丙烷氧化脱氢反应不受热力学平衡限制,焓变小于零,为放热反应,可节省能源。但氧化脱氢制丙烯因为有O2存在,导致丙烷和丙烯深度氧化,使丙烯选择性下降。可通过以下途径改进:(1)通过添加助剂或改变活性组分限制丙烯的深度氧化;(2)改变反应气氛,用氧化性较弱的氧化剂(如CO2和N2O等)代替O2。近年来,在低碳烷烃脱氢领域以CO2为氧化剂的研究较多,CO2可以避免深度氧化。综述在丙烷氧化脱氢反应中通过引入CO2,将丙烷直接脱氢反应与逆水煤气反应进行偶合,打破了丙烷直接脱氢反应平衡,消除积炭,提高催化剂稳定性,推动反应向生成丙烯的方向进行,丙烯收率提高;在低温(270℃)区域,副反应可提高丙烷CO2氧化脱氢反应的丙烯平衡收率,丙烷二氧化碳脱氢反应的催化剂体系主要包括铬系催化剂、镓系催化剂、钒系催化剂及其他催化剂。     

低碳烷烃催化脱氢催化剂的专利概况及Pt系催化剂发展路线

介绍了低碳烷烃催化脱氢领域Pt系催化剂和Cr系催化剂的专利概况,重点分析了UOP、BASF、中国石化、法国石油研究院和康菲石油等跨国石油公司的Pt系催化剂的发展路线,以期给研发方向提供启示。同时指出国内公司也应及时跟踪该领域的最新研究进展,做好专利布局。     

低碳烷烃催化转化制取低碳烯烃反应工艺的研究进展

低碳烷烃催化转化制取低碳烯烃可以大大提高低碳烷烃的附加值,因此,受到石油化工和催化领域的广泛关注。对近年来国内外有关低碳烷烃选择氧化制烯烃、低碳烷烃催化裂解制烯烃以及低碳烷烃催化脱氢制烯烃等催化反应过程的催化剂体系、反应工艺流程和催化反应器的设计等方面的研究进展进行评述,并对该领域的研究发展方向作了展望。     

低碳烷烃脱氢催化剂流化特性与耐磨性能

将相对廉价的低碳烷烃经催化脱氢转变成高附加值的烯烃,并副产大量氢气,是石化资源高效转化与利用的有效途径。本研究针对自主研发的PBD型低碳烷烃脱氢催化剂,分别从催化剂密度、粒径分布及最小流化速度等多个方面进行了流化特性研究。结果表明,PBD型催化剂具有适宜的粒径分布与颗粒密度,属于Geldart A类颗粒,完全适用于循环流化床脱氢装置。此外,PBD型催化剂的磨耗率仅0.27%,是国内同类型催化剂磨耗率的1/8~1/4,可有望大幅度减少工业装置中催化剂的消耗量。     

低碳烷烃循环流化床脱氢工艺条件优化

针对PBD型脱氢催化剂,采用循环流化床中试装置对低碳烷烃(丙烷、异丁烷、正丁烷)单独脱氢以及不同配比混合低碳烷烃进行了较为系统的工艺条件优化研究。结果表明,反应温度和空速对低碳烷烃脱氢过程的影响至关重要,不同脱氢原料具有不同的适宜操作工况,其中丙烷脱氢在600℃和1 700 h~(-1)条件下,转化率为39%,丙烯收率达33%;异丁烷脱氢在580℃和1 700 h~(-1)条件下,转化率为48%,异丁烯收率为45%;正丁烷脱氢在580℃和1 700 h~(-1)条件下,转化率为40%,丁烯收率高达32%。PBD型催化剂对于不同配比混合低碳烷烃具有较高的催化活性。最终获得的不同脱氢原料适宜的操作工况下,可以为循环流化床低碳烷烃脱氢装置的工程设计与放大和工业装置的生产调优提供基础数据与理论支持。     

长链正构烷烃脱氢铂、锡、锂高效催化剂的研究

<正> 一、前言长链正构烷烃脱氢生产烯烃是国外七十年代才成熟的工艺方法。原料为分子筛脱腊腊油,我国此石油馏份丰富、质量高,是一种较理想的生产烯烃原料。它有利于自石油资源来解决烯烃来源合成洗涤剂的安排。我国为发展合成洗涤剂的生产,于一九七三年从美国环球油品公司(uop)引进年产5万吨烷基苯的生产装置,现已投产。为解决对脱氢催化剂的需要,取代uop DEH—5型脱氢催化剂,我厂承担了轻工部下达的此项研究任务。本研究工作的目的为赶超世界水平,进一步提高催化剂的性能,采用油柱成型担体系统的研究基础上,积极开展铂、锡、锂催化剂的研制,在脱氢过程和脱氢催化剂方面进行了大量研究工作。用C_(10-13)馏份正构烷烃为原料考察它们的脱氢性能。经过上百次试验与多次改进,研制出性能更好的烷烃脱氢铂、锡、锂催化剂。以正构烷烃C_(10-13)馏份     

CO2在低碳烷烃催化转化中的综合利用

对近年来CO2用于甲烷重整,甲烷氧化偶联,低碳烷烃脱氢制烯烃,脱氢芳构化等方面的工作进行了评述.指出开发高活性催化剂,有效活化碳氢键与碳氧键,增加催化剂的稳定性是未来工业应用中的核心问题.     

Pt0.02Sn0.003Mg0.06 on γ-alumina: a stable catalyst for oxidative dehydrogenation of ethane

The advantages of two-step oxidative dehydrogenation as an alternative method for manufacturing small alkenes are outlined. In a nutshell, the process is based on separating the gaseous oxygen and hydrocarbon feeds in time. In the first step, alkanes are dehydrogenated in the presence of a solid oxygen carrier (without gaseous oxygen). Subsequently, the carrier is reoxidised using a gaseous feed. This process requires a dehydrogenation catalyst that is selective and stable under severe redox cycling. In search for such a catalyst, we prepare and study various platinum/tin catalysts supported on alumina. The catalysts are doped with either magnesia or potassium oxide. The activity, selectivity, and stability of these catalysts in the dehydrogenation of ethane to ethylene are then investigated under severe redox cycling conditions (600 °C and 10% (v/v) oxygen in the regeneration step). Pt_0.02Sn_0.003Mg_0.06 is found to be the most stable combination. The catalysts’ dispersion and the metal–support interactions are studied using transmission electron microscopy (TEM) and temperature-programmed hydrogen desorption (TPD). The effects of the (earth)alkali promoter and the interaction between the metal catalyst and support are discussed.     

Dehydrocyclization of Alkanes Over Zeolite-Supported Metal Catalysts: Monofunctional or Bifunctional Route

The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C₆₊ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the cycloalkanes into aromatics (1,5 ring closure to a lesser extent also contributes to aromatic production); or dehydrogenation of the alkanes into olefins, dienes, and trienes followed by thermal ring closure. Zeolites were found most suitable as support for preparing catalysts more active and more selective in the alkane aromatization. In addition catalysts based on noble metals supported on zeolite appeared more resistant against deactivation by coke. In this review the aromatization of hexane, heptane, and octane over Pt-zeolite catalysts is discussed in detail. Comparisons between different zeolite structures and different dehydrogenation sites are given. In particular a critical analysis of the results and interpretation concerning Pt-KL catalysts strongly suggests that the exceptional high selectivity towards aromatization of n-hexane exhibited by Pt-KL could not be explained by only the nest or constraint effect exerted by the channel dimension and morphology, not by only the terminal cracking properties, not by only the partial electron transfer from the zeolite support to the Pt particles, and not by only the Pt particle size. Zeolite structure also affects the aromatic product distribution, in particular when the alkane contains more than 7 carbon atoms. It is shown how Pt on medium-pore zeolites such as In-ZSM-5, silicalites will favor the aromatization of C₈ alkane isomers into ethylbenzene-styrene with respect to other C₈ aromatics. Aromatization of light alkanes, C₂-C₅, requires the increase of the hydrocarbon chain length up to 6 carbon atoms and higher, followed by cyclization reaction. Recently new processes to convert C₂-C₅ alkanes into aromatics have been disclosed, M2-forming from Mobil, Cyclar from BP-UOP, and Aroforming from IFP-Saluted. In general these processes use bifunctional catalysts possessing a dehydrogenating and an acid function. The catalysts consist of a metal ion or metal oxide supported on a microporous acid solid. In this review we analyze the results concerning mainly platinum supported on pentasil-type zeolite. It is shown that althoug Pt has better dehydrogenating properties as compared with gallium and zinc, the efficiency of catalysts based on Pt-ZSM-5 for light alkane aromatization is less because undersirable reactions such as hydrogenolysis and ethene (olefins) hydrogenation occur on the platinum surface, resulting in the production of unreactive alkanes, CH₂, C₂H₆. These drawbacks could be partially suppressed by alloying Pt and by increasing the reaction temperature.     

Dehydrocyclization of Alkanes Over Zeolite-Supported Metal Catalysts: Monofunctional or Bifunctional Route

The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C₆₊ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the cycloalkanes into aromatics (1,5 ring closure to a lesser extent also contributes to aromatic production); or dehydrogenation of the alkanes into olefins, dienes, and trienes followed by thermal ring closure. Zeolites were found most suitable as support for preparing catalysts more active and more selective in the alkane aromatization. In addition catalysts based on noble metals supported on zeolite appeared more resistant against deactivation by coke. In this review the aromatization of hexane, heptane, and octane over Pt-zeolite catalysts is discussed in detail. Comparisons between different zeolite structures and different dehydrogenation sites are given. In particular a critical analysis of the results and interpretation concerning Pt-KL catalysts strongly suggests that the exceptional high selectivity towards aromatization of n-hexane exhibited by Pt-KL could not be explained by only the nest or constraint effect exerted by the channel dimension and morphology, not by only the terminal cracking properties, not by only the partial electron transfer from the zeolite support to the Pt particles, and not by only the Pt particle size. Zeolite structure also affects the aromatic product distribution, in particular when the alkane contains more than 7 carbon atoms. It is shown how Pt on medium-pore zeolites such as In-ZSM-5, silicalites will favor the aromatization of C₈ alkane isomers into ethylbenzene-styrene with respect to other C₈ aromatics. Aromatization of light alkanes, C₂-C₅, requires the increase of the hydrocarbon chain length up to 6 carbon atoms and higher, followed by cyclization reaction. Recently new processes to convert C₂-C₅ alkanes into aromatics have been disclosed, M2-forming from Mobil, Cyclar from BP-UOP, and Aroforming from IFP-Saluted. In general these processes use bifunctional catalysts possessing a dehydrogenating and an acid function. The catalysts consist of a metal ion or metal oxide supported on a microporous acid solid. In this review we analyze the results concerning mainly platinum supported on pentasil-type zeolite. It is shown that althoug Pt has better dehydrogenating properties as compared with gallium and zinc, the efficiency of catalysts based on Pt-ZSM-5 for light alkane aromatization is less because undersirable reactions such as hydrogenolysis and ethene (olefins) hydrogenation occur on the platinum surface, resulting in the production of unreactive alkanes, CH₂, C₂H₆. These drawbacks could be partially suppressed by alloying Pt and by increasing the reaction temperature.     

Catalytic behaviour of Pt or Pd metal nanoparticles–zeolite bifunctional catalysts for n-pentane hydroisomerization

Bifunctional catalysts based on acidified Mordenite or ZSM-5 and platinum or palladium as metal function, were tested for n-pentane hydroisomerization. Two methods were used to introduce platinum: wetness impregnation and microemulsion; palladium was introduced via an organometallic complex. A lower catalytic activity was obtained for palladium catalyst in comparison with platinum samples which is explained by the lower activity of Pd in the dehydrogenation reaction step. Different catalytic behaviour of systems based on Mordenite and ZSM-5 was attributed to zeolite pore structure. The uncompleted removal of surfactant during calcination could explain the lower activity showed by catalysts prepared by microemulsion.     

丙烷脱氢制丙烯催化剂中国专利技术进展

介绍了近几年丙烷脱氢制丙烯催化剂中国专利技术,分别论述了铂系催化剂、铬系催化剂和其它催化剂专利技术进展,对丙烷脱氢制丙烯催化剂的发展方向进行了推测。     

Characterization and catalytic activity of Al2O3-supported Pt-Co catalysts

A series of Pt-Co supported on γ-alumina have been prepared from acetylacetonate precursors with 2 wt% as total metal loading and different atomic contents. The catalysts were characterized by hydrogen chemisorption, TPR, TEM, XPS and they were tested in two different reactions: methylcyclohexane dehydrogenation and n-butane hydrogenolysis. The results have shown that platinum is in reduced state and cobalt is mainly in an oxidized state. Additionally, TEM results evidence an increase in the particle size as cobalt content is increased, in agreement with chemisorption results. Monometallic platinum and cobalt supported catalysts showed large differences in the dehydrogenation of methylcyclohexane, while the bimetallic catalysts have activities in the same order of magnitude with respect to the pure platinum catalyst. In n-butane hydrogenolysis all the catalysts show a large decrease in activity compared to other, previously studied Pt-based bimetallic catalysts. This revised version was published online in July 2006 with corrections to the Cover Date.     

铂催化硅氢加成反应研究进展

硅氢加成反应是合成有机硅材料最重要的途径之一,铂催化剂作为其应用最广的催化剂,具有重要的意义。本文首先介绍了硅氢加成反应机理的研究现状;分析了聚合物长链段铂配合物、含多个铂原子铂簇化合物及N-杂环卡宾铂配合物均相铂催化剂的研究进展,致力于改善均相催化剂催化选择性差、催化活性难以控制等缺点;分别阐述了不同铂催化剂载体如无机二氧化硅、炭载体、金属氧化物、有机高分子、固载液等作为铂催化剂载体的优点,负载铂催化剂具有可回收、产物选择性好的优点,有效解决了工业上铂损失的问题;最后对铂催化硅氢加成反应的发展趋势进行了展望分析,铂负载能力的提高、铂负载催化剂的分离、硅氢加成反应的原理、催化范围的扩大等均是今后研究的重要方向。     

Cu系催化剂在催化反应中的研究进展

Cu是常用的金属催化剂,具有加氢、脱氢和氧化等催化性能,铜基催化剂在化学工业中应用广泛。主要介绍了铜基催化剂在甲醇水蒸汽重整制氢、CO催化氧化消除、合成甲醇、草酸二甲酯加氢合成乙二醇、乙醇脱氢制乙酸乙酯等领域的研究进展。     

Surface organometallic chemistry on metals in water: Chemical modification of platinum catalyst surface by reaction with hydrosoluble organotin complexes: application to the selective dehydrogenation of isobutane to isobutene

Surface organo-metallic chemistry on metals can be a new route to generate supported bimetallic catalysts. According to previous works on Pt–Sn catalysts, the reaction of tetra n-butyl-tin on the reduced platinum surface leads to well-defined bimetallic catalysts which are very active and selective in the dehydrogenation of isobutane into isobutene. The presence of tin not only isolates the surface platinum atoms from each other (EXAFS) and thus prevents a fast deactivation by decreasing the processes of C–C bond cleavage but also favors the regeneration processes under air. So far the catalyst preparations were carried out either in the gas phase or in organic solution (e.g. heptane). However, in order to meet the industrial criteria of process simplicity, there is a need to carry out such catalyst preparation in water.

In this work, Pt–Sn/Al₂O₃ and Pt–Sn/SiO₂ catalysts was prepared by reacting tris n-butyl-tin hydroxide on the platinum surface, in water solution under atmospheric pressure of hydrogen. The kinetics of the reaction was followed by measuring the amount of butane evolved as a function of time. The solids obtained were characterized by CO, O₂ or H₂ chemisorption and electron microscopy (CTEM and EDAX). Clearly, the (n-Bu)₃Sn(OH) reacts selectively on the platinum surface and not with the support, with evolution of butane, leading to a bimetallic catalyst where the platinum atoms are isolated from each other by the tin atoms. Very high selectivities (>95%) and activities were obtained for the reaction of isobutane dehydrogenation into isobutene and it was concluded that surface organo-metallic chemistry on metal in water can be an alternative route to prepare well-defined supported bimetallic Pt–Sn catalysts.     

催化合成咔唑的研究进展

综述了催化合成咔唑的研究进展。介绍了有关负载钯和雷尼镍催化剂在脱氢反应中的理论与实验研究,阐述了以1,2,3,4-四氢咔唑为原料,经催化脱氢反应得到咔唑的具体条件,脱氢的效率与催化剂的用量和种类、溶剂的种类以及反应条件等有关。以廉价原料二苯胺合成咔唑,反应由负载钯或铂催化剂催化;2-氨基联苯可经催化氧化反应或贵金属催化的偶联反应得到合成咔唑,这两条路线是制备咔唑的重要途径。