负载型铜基催化剂组分间相互作用及其催化性能

负载型铜基催化剂因其良好的催化性能和相对低廉的价格在诸多重要工业催化反应中得到广泛的应用.探讨负载型铜基催化剂中组分间的相互作用,有助于了解相关催化作用的本质,为现有催化剂的改进和新催化剂的设计提供科学依据.本文综述了近年来我们就CuO在不同载体上的分散、铜物种和载体的改性及其物理化学性质以及催化CO完全氧化、CO+NO和NH₃+NO+O₂反应性能等方面的研究进展.结果表明,CuO在多种氧化物载体表面的分散和所得负载型铜基催化剂的一些物理化学性质可参考“嵌入模型”得到解释,本文主要讨论了以CeO₂,Ce_xZr_1-xO₂和Mo₃-CeO₂为载体的一些铜基催化剂的组成-结构-性质间的关系.     

Preparation and formation of nickel-copper catalytic systems on various supports and commercial catalysts based on these systems

Based on the Ni-Cu system, catalysts were developed for low-and high-temperature industrial gas and waste gas purification. It was found that, regardless of the preparation procedure, the formation of a catalytically active structure occurred via the formation of a Ni-Cu solid solution at the stage of activation. The catalytic, physicochemical, and physicomechanical properties of NKO Ni-Cu catalysts can be purposefully regulated by changing the nature and concentration of a liquid reagent. A promoting effect of copper on the activation process and on the catalytic activity of a nickel catalytic system was found. The catalysts developed were commercialized. The catalysts were introduced into various processes of industrial gas and waste gas purification.     

Effect of textural characteristics on the catalytic performance of supported KCoMoS2 in the synthesis of higher alcohols from syngas

The influence of textural characteristics on the catalytic performance of supported KCoMoS₂ catalysts was explored to provide essential information for the design of better catalysts for the synthesis of higher alcohols (C₁–C₅) from syngas. Syngas conversion was carried out over KCoMoS₂ catalysts supported on various mesoporous (alumina and carbon-coated alumina) and microporous (two types of powdered activated carbons) materials. The experimental results show that catalysts supported over microporous materials exhibit higher catalytic activity in HAS from syngas than catalysts based on mesoporous materials.     

柴油车尾气排放PM2.5氧化消除催化剂的设计、制备与催化作用

柴油机尾气中的炭烟颗粒(PM2.5)已经引起了严重的环境污染问题,作为控制柴油车尾气中炭烟颗粒使用最有效和最经济的技术手段—催化净化技术成为当前研究的热点,而开发高效的催化剂是催化净化技术中最活跃、最重要的因素.本文总结了近年来柴油炭烟燃烧催化剂的最新研究进展,重点介绍了本研究组近年来在柴油炭烟氧化催化剂的设计、制备和催化作用机理方面的研究结果和进展,主要包括:低共熔点催化剂、纳米催化剂、三维有序大孔催化剂及三维有序大孔氧化物担载贵金属催化剂的最新研究进展,并报道了上述催化剂对炭烟燃烧的反应机理.最后,总结性地提出了目前炭烟催化燃烧中存在的主要问题和发展方向.     

An Overview of Heterogeneous Transition Metal-Based Catalysts for Cyclohexene Epoxidation Reaction

Cyclohexane epoxide, which contains highly active epoxy groups, plays a crucial role as an intermediate in the preparation of fine chemicals. However, controlling the epoxidation pathway of cyclohexene is challenging due to issues such as the allylic oxidation of cyclohexene and the ring opening of cyclohexane epoxide during the cyclohexene epoxidation process to form cyclohexane oxide. This review focuses on the structure-activity relationships and synthesis processes of various heterogeneous transition metal-based catalysts used in cyclohexene epoxidation reactions, including molybdenum(Mo)-based, tungsten(W)-based, vanadium(V)-based, titanium(Ti)-based, cobalt(Co)-based, and other catalysts. Initially, the mechanism of cyclohexene epoxidation by transition metal-based catalysts is examined from the perspective of catalytic active centers. Subsequently, the current research of cyclohexene epoxidation catalysts is summarized based on the perspective of catalyst support. Additionally, the differences between alkyl hydroperoxide, hydrogen peroxide (H₂O₂), and oxygen (O₂) as oxidants are analyzed. Finally, the main factors influencing catalytic performance are summarized, and reasonable suggestions for catalyst design are proposed. This work provides scientific support for the advancement of the olefin epoxidation industry.     

Influence of H-ZSM-5, Al-MCM-41 and acid hybrid ZSM-5/MCM-41 on polyethylene decomposition

Thermogravimetry (TG) and mass spectrometry (MS) combined techniques have been used to investigate the thermal degradation and catalytic decomposition of high-density polyethylene (HDPE) over solid acid catalysts as H-ZSM-5, Al-MCM-41 and a hybrid material with a bimodal pore size distribution (H-ZSM-5/Al-MCM-41). The silicon/aluminum ratio of all catalysts is 15. Both thermal and catalytic processes showed total conversion in a single mass loss step. Furthermore, the catalytic conversion presents average reduction of 27.4%, in the onset decomposition temperature. The kinetic parameters were calculated using non-isothermal method. These parameters do not indicate significant differences between the thermal and catalytic processes. Even though, the presence of the catalysts changes the reaction mechanism, from phase boundary controlled reaction to random nucleation mechanism. Important difference in distribution of evolved products was detected when several catalysts were used. However, in all cases the main products were alkanes (C₂, C₃ and C₄), alkenes (C₃ and C₄), dienes (C₄ and C₅) and traces of aromatic compounds.     

Nanostructured perovskite oxides as promising substitutes of noble metals catalysts for catalytic combustion of methane

In this review, we summarize the recent development of nanostructured perovskite oxide catalysts for methane combustion, and shed some light on the rational design of high efficient nanostructured perovskite catalysts via lattice oxygen activation, lattice oxygen mobility and materials morphology engineering.     

Sustainability of microporous polymers and their applications

Microporous polymers (MPs) are studied for their intriguing chemistry and physics as well as their potential application in catalytic transformations, gas-separation processes, water purification and so on. Here, we critically review MPs with respect to the sustainability aspects of their synthesis as well as their applications that have sustainable character. Some MPs have been synthesized from monomers derived from biomass resources, but there is certainly a large potential for further developments. There are also opportunities to improve the sustainability of MP synthesis in terms of the use of solvents, catalysts, and related aspects. The applications of MPs in processes related to sustainability depend upon multiple properties. A rich and flexible chemistry is important to applications as catalysts for, among other useful reactions, the photoreduction of CO₂ and selective oxidation. The (ultra)micropore volume of MPs are crucial in gas-separation applications such as CO₂ capture, and the chemisorption of CO₂ on MP-tethered alkylamines could offer a means to remove that gas from dilute mixtures. When it comes to the storage of H₂ and CH₄ in MPs for onboard use in fuel cell or biogas cars, volumetric capacity is paramount, meaning that the density of the MPs must be considered. Finally, for use in separation and purifications from liquid mixtures (aqueous or hydrocarbon-based), crosslinked MPs are more limited than the solution-processable MPs that can be more easily processed into films and membranes.     

Review of Acetic Acid Synthesis from Various Feedstocks Through Different Catalytic Processes

Acetic acid (AA) has been largely used with a wide range of applications such as a raw material for a synthesis of vinyl acetate monomer, cellulose acetate or acetate anhydrate, acetate ester and a solvent for a synthesis of terephthalic acid and so on. The present paper briefly summarizes the commercialized chemical processes with their Rh or Ir-based catalytic systems in a liquid-phase carbonylation reaction such as Monsanto, Cativa and Acetica processes. In addition, some alternative catalytic systems such as heterogeneous catalysts to produce AA by direct oxidation or indirect carbonylation of dimethyl ether through BP-SaaBre process in a gas-phase reaction to solve some problems such as a difficult separation of homogeneous catalysts in a corrosive reaction medium. Some home-made heterogeneous catalysts such as a rhodium incorporated graphitic carbon nitride (Rh-g-C₃N₄) and some heterogenized homogeneous catalysts using the supports of tungsten carbide, iron oxide or graphitic carbon nitride containing rhodium complexes were also introduced for the synthesis of AA through a liquid-phase methanol carbonylation reaction to effectively solve the leaching problem of active rhodium metal as well as to mitigate the separation problem of homogeneous catalysts.     

Pt-BaO催化剂的NOx储存-还原化学及结构-性能关系

NOx储存-还原(NSR)技术是目前稀燃汽车尾气中NOx消除的最有前景的催化技术之一,NSR催化过程中稀燃/富燃条件的交替运行、NSR催化剂上化学计量反应与催化反应的耦合赋予了NSR催化过程迥异于常规连续流动气固相催化反应的特点.本文首先介绍了目前人们对Pt-BaO催化剂上NSR基本化学过程的认识;在此基础上,结合本研...     

Electrocatalytic CO2 Reduction: from Discrete Molecular Catalysts to Their Integrated Catalytic Materials

Molecular catalysts (metal complexes), with molecularly defined uniform active sites and atomically precise structural tailorability allowing for regulating catalytic performance through metal- and ligand-centered engineering and elucidating reaction mechanisms via routine photoelectrochemical characterizations, have been increasingly explored for electrocatalytic CO₂ reduction (ECR). However, their poor stability and low catalytic current density are undesirable for practical applications. Heterogenizing discrete molecular catalysts can potentially surmount these issues, and the resulting integrated catalysts largely share catalytical properties with their discrete molecular counterparts, which bridge the gap between heterogeneous and homogeneous catalysis and combine their advantages. This minireview surveys advances in design and regulation of molecular catalysts such as porphyrin, phthalocyanine, and bipyridine-based metal complexes and their integrated catalytic materials for selective ECR.     

Recent advances in catalytic automotive emission control: Passive NO storage at low temperatures

In the practical applications, a high portion of the NO_x is emitted without purification in the cold start period of engine because the selective catalytic reduction (SCR) or NO_x storage and reduction (NSR) catalysts are not warmed up. Passive NO_x absorbers (PNA) were proposed earlier to store the NO_x at low temperatures and release the stored NO_x during warm-up period when the SCR and NSR catalysts downstream are functional, while this concept just attracted great interests recently to meet the extra stringent requirement of governmental emissions regulations. A plant of PNA catalysts, showing different NO adsorption/release characteristics, was disclosed. This review summarizes the recent progress in the development of PNA catalysts. The characteristics of NO adsorption/release on precious metal (i.e., Pt, Pd) loading Al₂O₃ support catalysts, CeO₂ support catalysts, and zeolite support catalysts are summarized and compared.     

Controlling the Selectivity of the Surface Plasmon Resonance Mediated Oxidation of p‐Aminothiophenol on Au Nanoparticles by Charge Transfer from UV‐excited TiO2

Although catalytic processes mediated by surface plasmon resonance (SPR) excitation have emerged as a new frontier in catalysis, the selectivity of these processes remains poorly understood. Here, the selectivity of the SPR‐mediated oxidation of p‐aminothiophenol (PATP) employing Au NPs as catalysts was controlled by the choice of catalysts (Au or TiO₂‐Au NPs) and by the modulation of the charge transfer from UV‐excited TiO₂ to Au. When Au NPs were employed as catalyst, the SPR‐mediated oxidation of PATP yielded p,p‐dimercaptobenzene (DMAB). When TiO₂‐Au NPs were employed as catalysts under both UV illumination and SPR excitation, p‐nitrophenol (PNTP) was formed from PATP in a single step. Interestingly, PNTP molecules were further reduced to DMAB after the UV illumination was removed. Our data show that control over charge‐transfer processes may play an important role to tune activity, product formation, and selectivity in SPR‐mediated catalytic processes.     

Cost-effectiveness analysis to assess commercial TiO2 photocatalysts for acetaldehyde degradation in air

In the commercialisation of photocatalytic air purifiers, the performance as well as the cost of the catalytic material plays an important role. Where most comparative studies only regard the photocatalytic activity as a decisive parameter, in this study both activity and cost are taken into account. Using a cost-effectiveness analysis, six different commercially available TiO₂-based catalysts are evaluated in terms of their activities in photocatalytic degradation of acetaldehyde as a model reaction for indoor air purification.     

柴油机尾气净化催化剂的最新研究进展

柴油机尾气排放的污染物已经引起了严重的环境污染问题,催化净化技术是柴油机尾气污染治理必不可少和最有效的处理技术之一,而高效催化剂的研制和开发是催化净化技术的核心.本文以柴油机尾气中最难处理的两种污染物NOx和碳烟颗粒(PM)的催化处理技术为主线,综述了NOx的催化还原(选择性催化还原(SCR)和贮存还原(NSR))催化剂、碳烟的催化燃烧催化剂、NOx和碳烟颗粒同时消除的催化剂及柴油机尾气四效催化剂的最新研究进展,并总结性地提出了目前该研究方向存在的主要问题和发展方向.     

Promotion effect of Au single-atom support graphene for CO oxidation

CO oxidation is a vital catalytic reaction for environmental purification, facing challenges due to the catalysts applied to oxidize CO are mainly rare and expensive noble catalysts. Since the high atomic availability, catalytic efficiency, and selectivity of single-atom catalysis, it has been widely studied and proven to be brilliant in CO oxidation. Au single-atom catalysts are regarded as excellent single-atom catalysts in oxidizing CO, whose progress is limited by the indistinct understanding of the reaction mechanism and role of the active atom. Hence, DFT calculation was used to investigate CO oxidation processes, active mechanisms, and the role of Au single-atom. Graphene involving prominent physical and chemical properties was selected as a model supporter. The single-atom support graphene materials exhibit better CO oxidation activities than pristine graphene, among which CO oxidation property on Au/GP is the highest with a 0.38 eV rate-determining barrier following ER mechanism. The outstanding performances including excellent electronic structures, adsorption properties, and strong activation of intermediate products contribute to the high CO oxidation activity of Au/GP, and the Au single-atom is the active center. Our work provides a novel guide for single-atom catalytic CO oxidation, accelerating the development of single-atom catalysis.     

Plasmonic photothermal catalysis for solar-to-fuel conversion: current status and prospects

Solar-to-fuel conversion through photocatalytic processes is regarded as promising technology with the potential to reduce reliance on dwindling reserves of fossil fuels and to support the sustainable development of our society. However, conventional semiconductor-based photocatalytic systems suffer from unsatisfactory reaction efficiencies due to limited light harvesting abilities. Recent pioneering work from several groups, including ours, has demonstrated that visible and infrared light can be utilized by plasmonic catalysts not only to induce local heating but also to generate energetic hot carriers for initiating surface catalytic reactions and/or modulating the reaction pathways, resulting in synergistically promoted solar-to-fuel conversion efficiencies. In this perspective, we focus primarily on plasmon-mediated catalysis for thermodynamically uphill reactions converting CO₂ and/or H₂O into value-added products. We first introduce two types of mechanism and their applications by which reactions on plasmonic nanostructures can be initiated: either by photo-induced hot carriers (plasmonic photocatalysis) or by light-excited phonons (photothermal catalysis). Then, we emphasize examples where the hot carriers and phonon modes act in concert to contribute to the reaction (plasmonic photothermal catalysis), with special attention given to the design concepts and reaction mechanisms of the catalysts. We discuss challenges and future opportunities relating to plasmonic photothermal processes, aiming to promote an understanding of underlying mechanisms and provide guidelines for the rational design and construction of plasmonic catalysts for highly efficient solar-to-fuel conversion.

Hot carrier activation and photothermal heat can be constructively coupled using plasmonic photothermal catalysts for synergistically promoted solar-to-fuel conversion efficiency.     

金属卟啉类超分子催化剂*

金属卟啉类超分子催化剂是超分子催化研究领域的重要内容之一,其关键环节是以金属卟啉为基础构建超分子微反应器,使反应活性中心处在一个特定的微环境中,从而实现高的催化效率和选择性。本文分别从超分子催化剂母体结构构筑（借助环糊精、模板等）和催化应用（模拟细胞色素P-450系列酶、光电催化等）的角度详细评述了近年来金属卟啉类超分子催化剂的设计、结构及催化作用的研究进展,并对该研究领域的前景进行了展望。     

Phosphomolybdic heteropolycompounds as oxidation catalysts. Effect of transition metals as counter-ions

Phosphomolybdic compounds were first described as active catalysts in heterogeneous catalytic reactions some twenty-five years ago. Research on these catalysts underwent a huge acceleration when an industrial application in the oxidation of methacrolein to methacrylic acid was reported. They were later developed with success as catalysts for the oxidative dehydrogenation of isobutyric acid into methacrylic acid for which they surpass in many aspects the FePO catalysts. More recently phosphomolybdic catalysts were shown to be very efficient for the oxidation of light alkanes. The structure of these ionic solids with discrete cations and anions can be defined at the molecular level of the heteropolyanion 〚PMo₁₂O₄₀〛^3–, this feature makes them attractive for fundamental studies on catalytic reaction mechanism or catalytic site visualization. In the latter case they represent a unique model of a mixed oxide cluster that can be advantageously used to design new catalysts. Starting from the acid H₃〚PMo₁₂O₄₀〛 two substitution types leading to important modifications of the catalytic properties are possible: (i) the substitution of protons with counter-cations, (ii) the substitution of molybdenum in the anions. This review addresses the effect of transition metals substituting protons on both catalytic and physicochemical properties. It will focus on the influence of iron, copper and vanadyl directly introduced as counter-cations and that of vanadium initially substituting molybdenum in the anion but which moves out due to a partial rebuilding of the anions under catalytic reaction conditions. These transition metals have important and complex effects and have been widely studied. In both cases alkaline metals substituting protons have been also studied.     

Uncovering the synergistic photocatalytic behavior of bimetallic molecular catalysts

Bimetallic catalysts usually exhibit better performance than monometallic catalysts due to synergistic effect. However, there is a lack of exploring the synergistic effect on catalytic performance caused by the introduction of inactive metal ion. In this work, we design a molecular model system that can precisely regulate the metal site number and catalytic property. When these molecular metal compounds are used as homogeneous catalysts for photocatalytic CO₂ reduction, the dinuclear heterometallic CuNi-L² shows the highest CO₂-to-CO conversion, which is 2.1 and 3.0 times higher than that of dinuclear homometallic Ni₂-L² and mononuclear Ni-L¹. Density functional theory calculations demonstrate that, in CuNi-L², the introduction of inactive Cu^II is easier to promote the photo-generated electrons transferring to the coupled active Ni^II site to achieve the highest activity. In addition, this work also provides insights to design and construct more efficient bimetallic catalysts in future.