Coking of Catalysts: Mechanisms,Models, and Influence

Kinetics and Catalysis - This review considers the mechanism of multilayered coke formation on catalysts of various types and analyzes its possible variants. A detailed derivation of equations of...     

Ni-V-O催化剂的合成、表征及其催化性能

制备了Ni3V2O8, Ni2V2O7, NiV2O6催化剂, 进行了XRD, BET, H2-TPR, XPS和电导等表征, 并测试了这三种结构催化剂对丙烷氧化脱氢制丙烯反应的催化性能, 分析了影响催化性能的因素. 实验结果表明, 当丙烷的转化率为10%时, 在p-型半导体Ni3V2O8和Ni2V2O7催化剂上丙烯的选择性为69.13%和70.21%, 而在n-型半导体NiV2O6上, 丙烯的选择性为64.41%, 表明p-型半导体Ni3V2O8和Ni2V2O7的催化性能优于n-型半导体NiV2O6的催化性能. XPS实验结果表明, 这可能与p-型半导体正钒酸镍(Ni3V2O8)和焦钒酸镍(Ni2V2O7)催化剂表面含较多O-氧物种和V4+有关.     

石墨烯基单原子催化剂的合成、表征及分析

单原子催化剂具有配位数低、配位环境特殊、原子利用率极高和催化位点高度均一等优点,是沟通均相和异相催化剂之间的桥梁,有助于更好地认识催化反应的本质。本文综述了近年来国内外石墨烯基单原子催化剂的多种合成方法,包括原子层沉积法、浸渍-煅烧法、缺陷捕获法、配位锚定法和其他新颖方法的制备过程、合成原理和表征。在此基础上,本文对石墨烯基金属单原子催化剂在催化方面的性能进行阐述和分析,以期为单原子催化剂制备提供指导和参考。     

Activity,Selectivity, Decay and Long-Term Behaviour of Amination Catalysts

A survey of the activity and selectivity of several catalysts for the amination of long-chain aliphatic alcohols with dimethylamine is given. The best results were obtained with Cu-catalysts whose long-term behaviour was investigated. The main reasons for catalyst decay are the irreversible adsorption of dimerization products and the thermal diffusive fusion of Cu-crystallites.     

Homobimetallic Ruthenium-Ethylene,Vinylidene, Allenylidene,and Indenylidene Catalysts for Olefin Metathesis

Summary: Following the discovery of bimetallic ruthenium scaffold ( 1 ), two new homobimetallic ruthenium-N-heterocyclic carbene complexes ( 2 , 3 ) were synthesized and found highly suitable for promoting ROMP, RCM, and CM reactions. Results from this study indicated that the ethylene ligand was highly labile and that adding a small amount of a terminal alkyne to the reaction media had a beneficial influence on the metathetical activity. These observations prompted us to further investigate the role of the alkyne co-catalyst. Thus, homobimetallic ruthenium-arene complexes bearing vinylidene ( 4 , 5 ), allenylidene ( 6 ), and indenylidene ( 7 ) ligands were prepared from complex 1 and propargyl alcohol derivatives. Their catalytic activities were probed in several types of olefin metathesis reactions, and they were found valuable intermediates for the safe and efficient one-pot synthesis of the Hoveya–Grubbs isopropoxybenzylidene catalyst ( 8 ).     

Na-W-Mn/SiO2催化剂表面甲烷脉冲反应Ⅱ. 多组分Na、 W、 Mn/SiO2催化剂

制备了多组分Na,W,Mn/SiO2催化剂，在ITD（Ion Trap Detector)装置上进行了催化剂表面晶格氧脱附前后的甲烷恒温脉冲反应（CH4－CTPR）。研究结果表明，Na-W/SiO2催化剂表面晶格氧，具有较高的CH4转化率和C2烃选择性，并对C2H6的生成起着重要的作用，Na-Mn/SiO2催化剂表面晶格氧，也具有较高的CH4转化率和C2烃选择性，但对C2H6的形成有一定的诱导期；W－Mn/SiO2催化剂表面晶格氧，对CH4的转化和CO2的生成具有很高初活性，但对C2烃的选择性较低；Na-W-Mn/SiO2催化剂表面晶格氧，具有很高的CH4转化率和C2烃定向选择性，这是由于Na,W,Mn各组分协同作用的结果。     

直接甲醇燃料电池的阳极和阴极催化剂

直接甲醇燃料电池(DMFC)由于其结构简单、能量密度高、易携带、无污染等优点,成为燃料电池未来发展的方向。阳极和阴极催化剂的活性和稳定性是决定DMFC性能、寿命和成本的关键。然而,商业催化剂铂(Pt)的低储量和高成本限制了DMFC的广泛应用,同时,非铂类催化剂的活性和稳定性还需要进一步提高,以达到商业化应用的要求。本文综述了近年来国内外DMFC阳极和阴极催化剂的最新研究进展。首先,对于阳极甲醇氧化催化剂,分别对Pt基催化剂的改性和非Pt类催化剂的研究进展进行了详细介绍;其次,概述了Pt基阴极氧还原催化剂的改性和非Pt阴极催化剂的发展现状;此外,对于催化剂与载体的强相互作用产生的协同效应进行了总结论述;最后,对直接甲醇燃料电池阳极和阴极催化剂的发展前景进行了展望。     

TiO2-supported Single-atom Catalysts: Synthesis,Structure, and Application

In recent years, single-atom catalysts(SACs) have attracted increasing attention in catalysis. However, their stability is considerably challenging. As a result, fine-tuning the interaction of metal single atoms(SA) with different types of supports has emerged as an effective strategy for improving their thermal and chemical stabilities. Owing to its non-toxicity, cost-effectiveness, high abundance, and excellent stability, as well as presence of rich, tunable, and reliable anchor sites for metal SA, TiO₂ has been extensively explored as a superior support for SACs. In this review, recent advances of TiO₂-supported SACs(M₁/TiO₂) are discussed, and synthetic strategies, structure elucidation, and catalytic applications are summarized. First, the recently developed synthetic strategies for M₁/TiO₂arehighlighted and summarized, identifying the major challenges for the precise fabrication of M₁/TiO₂. Subsequently, key characterization techniques for the structure identification of M₁/TiO₂are discussed. Next, catalytic applications of M₁/TiO₂ are highlighted, viz. photocatalysis, electrocatalysis, and thermocatalysis. In addition, the mechanism via geometric structures and electronic states of metal centers facilitate catalytic reactions is outlined. Finally, opportunities and challenges of M₁/TiO₂ in catalysis are discussed, which may inspire the future development of M₁/TiO₂ for multifunctional catalytic applications.     

Design, Synthesis, and In Situ Characterization of New Solid Catalysts

The precise atomic architecture of the catalytically active center is the central topic of the approach presented herein to the design of solid-state catalysts. A wide range of new catalysts may be designed that effect regioselective, shape-selective, and enantioselective conversions, as well as producing high-performance catalysts for the isomerization and hydrogenation of alkenes and the terminal oxidation of alkanes. All the new catalysts described are either microporous or mesoporous solids that have the dual advantages of possessing large specific surfaces and being amenable to delicate structural and compositional variation.     

Ti-Co-SBA-15的制备、表征及其选择氧化催化性能

以钛酸丁酯为钛源,分子筛SBA-15为载体,采用水热法合成了一系列不同载钛量的Ti-SBA-15分子筛,用浸渍法将钴负载于其骨架结构上,得到Ti-Co-SBA-15催化剂。采用X射线、N2吸附-脱附、漫反射紫外-可见光谱和傅里叶变换红外光谱等方法对样品进行了表征,并考察了催化剂在温和条件下对叔丁基甲苯氧气氧化反应中的催化性能。结果表明,所制备的催化剂样品具有较大的比表面积和孔径,钛、钴以四配位体存在,具有较高的催化活性和选择性,可获得较高的对叔丁基苯甲醛收率。     

One-Pot Reactions with Sol-Gel Entrapped Catalysts, Acids and Bases

Silica sol-gel entrapped acids, bases and organometallic catalysts are used successfully in one-pot reactions without interfering with each other. Both physically and covalently entrapped acids and bases were employed in these processes, including polystyrene sulfonic acid, 1-propane sulfonic acid, molybdosilicic acid (SiO₂-MoO₃), poly[(vinylbenzyltrimethyl)ammonium] hydroxide and 1,5,7-triazabicyclo[4.4.0]decene. The entrapped metal-based catalysts are Rh₂Co₂(CO)₁₂ and RuCl₂(PPh₃)₃. The one-pot reactions carried out with these heterogenized reagents and catalysts include formation of alkenes under acidic and basic conditions, C—C bond formation by condensation reactions with an -carbon to a carbonyl, hydroformylation and hydrogenation.     

聚乙二醇(PEG)支撑的有机合成反应、试剂和催化剂

综述了近年来聚乙二醇支撑的有机合成反应、试剂和催化剂的研究进展。参考文献30篇。     

Ni-P非晶合金催化剂的制备、结构和性能

超细非晶态合金ＭＰ或ＭＢ(Ｍ=Ｎｉ,Ｃｏ,Ｆｅ)的高比表面和结构不规整性使其表现出催化加氢的高活性和选择性,有可能成为新型石油化工加氢催化剂[1-3].其制备主要有物理和化学两类方法[3-5].从提高催化活性角度,化学还原法是最为优越的方法.ＮｉＢ催化活性明显高于ＮｉＰ...     

固载化试剂和催化剂及其在液相组合合成中的应用

固载化试剂、催化剂及清洁树脂在液相合成中的应用, 极大地方便了液相合成的后处理, 提高了工作效率, 为液相平行组合合成提供了基础. 重点综述了近年来固载化试剂和催化剂在液相组合合成及多步液相合成中应用进展情况.     

Ti-Co-SBA-15的制备、表征及其选择氧化催化性能

以钛酸丁酯为钛源,分子筛SBA-15为载体,采用水热法合成了一系列不同载钛量的Ti-SBA-15分子筛,用浸渍法将钴负载于其骨架结构上,得到Ti-Co-SBA-15催化剂。采用X射线、N₂吸附-脱附、漫反射紫外-可见光谱和傅里叶变换红外光谱等方法对样品进行了表征,并考察了催化剂在温和条件下对叔丁基甲苯氧气氧化反应中的催化性能。结果表明,所制备的催化剂样品具有较大的比表面积和孔径,钛、钴以四配位体存在,具有较高的催化活性和选择性,可获得较高的对叔丁基苯甲醛收率。     

Na-W-Mn/SiO2催化剂表面甲烷脉冲反应Ⅰ.单组分Na/、W/、Mn/SiO2催化剂

制备了单组分Na/、 W/、 Mn/SiO2催化剂, 在ITD(Ion Trap Detector)装置上进行了催化剂表面晶格氧脱附前后的甲烷恒温脉冲反应(CH4-CTPR). 研究结果表明, Na/SiO2表面晶格氧具有一定的C2烃选择性, 并能强烈抑制CO2的生成; W/SiO2表面晶格氧对C2烃的选择性较差, 但对COx具有高的选择性; Mn/SiO2表面的晶格氧对C2H4和CO具有高选择性, 而较深部位的晶格氧则对C2H6和CO2具有高的选择性.     

CeO2负载的Cu, Ir和Pd催化剂上的醇转移脱氢反应

 研究了CeO2负载的Cu, Ir和Pd催化剂上的醇转移脱氢反应. 利用催化剂体系脱氢和加氢功能的偶合,在较温和的反应条件下实现了二级脂肪醇的高选择性转移脱氢. 其中, Ir/CeO2催化剂表现出较高的催化活性,其TOF值达16.0 h-1.     

具有纳米结构的钒磷氧催化剂的制备、表征及合成机理

在采用有机相法制备钒磷氧 (VPO) 催化剂前驱体的过程中, 添加铋盐、二甲基亚砜 (DMSO) 和聚乙二醇, 制得了一系列催化剂, 并将其用于正丁烷选择氧化反应. 结果表明, 当 V:Bi:DMSO 摩尔比 = 1:0.0035:0.1 时, VPO 催化剂上的顺酐摩尔收率最高, 达 55.1%. 低温氮气吸附、X 射线衍射、扫描电子显微镜、X 射线能谱和傅里叶变换红外光谱表征结果表明, 该催化剂的比表面积达到 38.2 m2/g, 有沿 (200) 晶面的择优取向, Bi 原子取代 V 原子, 形成固溶体, 引起 P 在表面富集, 生成了大量具有纳米尺度的催化剂颗粒. 三种助剂在催化剂前驱体形成过程中协同作用, 降低了前驱体晶体成核过程的表面能, 加速了 VOHPO4·0.5H2O 的形核速率, 阻抑了前驱体颗粒的聚集长大, 形成了稳定的纳米颗粒.