多相催化体系的反应机理和失活模式(英文)

Solving the problem of catalyst deactivation is essential in process design. To do this, various aspects of the kinetics of processes with catalyst deactivation, and their different mechanisms, are discussed. Catalyst deactivation often cannot be avoided, but more knowledge on its mechanism can help to find kinetic means to reduce its harmful consequences. When deactivation is caused by coke, the generation of coke precursors is the determining step in the deactivation kinetics. Different types of deactivation were distinguished that lead to different evolution of the process. The phenomenon of non-uniform coking can be linked to catalyst surface non-uniformity. For the class of catalysts with more than one type of active sites, an explanation was suggested for the observed trends in the deactivation modes. For catalytic proc-esses using catalyst particles of industrial size, the influence of intraparticle diffusion resistance is important. The analysis showed that for a number of processes, the decrease of the reaction rate due to deactivation is less under diffusion control. For certain reaction mechanisms, there exist operation conditions where the rate of the process under diffusion control exceeds the rate in the kinetic control regime. A signifi-cant problem is the change of selectivity in the course of catalyst deactivation. The selectivity may either decrease or increase, and depends on the reaction mechanism during deactivation. The changes are larger when there is no diffusion resistance. The intentional poisoning of catalysts and its influence on catalyst activity and selectivity for the process of ethylene oxide production was discussed.     

A Promising MoOx—based Catalyst for n—Heptane lsomerization

The SiO2 and γ-A12O3 supported MoOx catalyst and a MoOx-SiO2 catalyst have been studied in a conventional fixed-bed flow reactor for n-alkanes isomerization. It is shown that the MoOx-SiO2 catalyst with SiO2 framework, in which the bulk MoOx phase is large enough to form typical mesoporous structure, is promising in terms of its advantages of both improved mechanical strength and high catalytic properties over the supported MoOx and bulk MoOx catalyst.     

Improved activity of Ni/MgAl_2O_4 for CO_2 methanation by the plasma decomposition

CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs to be improved. Dielectric barrier discharge(DBD) plasma, initiated at ambient condition and operated at ~150 °C,has been employed in this work for decomposition of nickel precursor to prepare Ni/Mg Al2O4. The plasma decomposition results in high dispersion, unique structure, enhanced reducibility of Ni particles and promoted catalyst-support interaction. An improved activity of CO2 methanation with a higher yield of methane has been achieved over the plasma decomposed catalyst, compared to the catalyst prepared thermally. For example, the methane yield of the plasma prepared catalyst is 71.8% at 300 °C but it is 62.9% over the thermal prepared catalyst. The catalyst characterization confirmed that CO2 methanation over the DBD plasma prepared catalyst follows pathway of CO methanation.     

Preparation of High Surface Area, Large Pore Volume Alumina by Using β-Cyclodextrin as a Non-surfactant Template

Alumina is widely used as a catalyst or catalyst support in many heterogeneous catalytic processes owing to its high surface area, superior chemical activity and low cost 1. In order to prepare the thermal-stable alumina with high surface area and large p…     

Regulation of mixed Ag valence state by non-thermal plasma for complete oxidation of formaldehyde

Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations. Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature range. The valence state of Ag is one of the key roles in formaldehyde catalytic oxidation.However, its effect on activity is still ambiguous. Non-thermal plasma and conventional calcination were employed to regulate Ag valence state in this study. Three Ag-Co/CeO₂ cataly...     

Role of nickel on vanadium poisoned FCC catalyst: A study of physiochemical properties

Active sites of Fluid catalytic cracking（FCC） catalyst are poisoned during operation in the FCC reactor due to causes including feedstock contaminant metals deposition.This leads to activity,selectivity and increasing coking problems,thereby raising concern to the refiner.This work investigated effect of nickel coexisting with vanadium in the FCC feedstock on the standard FCC catalyst during cracking process,in which destruction of active sites occurs as a result of the metals deposition.Laboratory simulated equilibrium catalysts（E-cats） were studied by XRD,FTIR spectroscopy,N₂ adsorption,solid state MAS-NMR,SEM and H₂-TPR.Results revealed that vanadium,above a certain concentration in the catalyst,under hydrothermal conditions,is highly detrimental to the catalyst’s structure and activity.Conversely,nickel hardly affects the catalyst structure,but its co-presence in the catalyst reduces destructive effects of vanadium.The mechanism of nickel inhibition of vanadium poisoning of the catalyst is discussed.     

Electrochemical Behavior of Methanol Influenced by Polyaniline Incorporated with Ferrocenesulfonic-carboxylic Acid

After the synthesis of polyaniline in the presence of ferrocenesulfoniccarboxylic acid, its influence on the electrochemical reaction of methanol was studied. The result indicates that the ferrocenyl in ferrocenesulfoniccarbexylic acid plays an important role in the electrocatalytic oxidation of methanol. CH3OH is adsorbed on PANI-Fc before its electrocatalytic oxidation. When the concentration of methanol is 2 mol/L, it begins to be oxidized. The effect of scan rate on the electrochemical reaction of methanol was also studied and 5 mV/s was favourable. It is another method to insert a metal catalyst in polyaniline without its electrodeposition.     

Cu(II)salen配合物催化三组分偶联反应合成炔丙胺(英文)

A one pot three‐component coupling reaction of phenylacetylene, aldehyde, and amine derivatives in the presence of Cu(II) Salen complex as an efficient heterogeneous catalyst under solvent‐free conditions is reported. The catalyst displayed high activity and afforded the corresponding propargylamines in good to excellent yields. This method provides a wide range of substrate applicability. The catalyst was reused several times without significant loss of its catalytic activity.     

Effect of diluent and reaction parameter on selective oxidation of propane over MoVTeNb catalyst using nanoflow catalytic reactor

The selective oxidation of propane to acrylic acid over an MoVTeNb mixed oxide catalyst, dried and calcined before reaction has been studied using high-throughput instrumentation, which is called nanoflow catalytic reactor. The effects of catalyst dilution on the catalytic performance of the MoVTeNb mixed oxide catalyst in selective oxidation of propane to acrylic acid were also investigated. The effects of some reaction parameters, such as gas hourly space velocity （GHSV） and reaction temperature, for selective oxidation of propane to acrylic acid over diluted MoVTeNb catalyst have also been studied. The configuration of the nanoflow is shown to be suitable for screen catalytic performance, and its operating conditions were mimicked closely to conventional laboratory as well as to industrial conditions. The results obtained provided very good reproducibility and it showed that preparation methods as well as reaction parameters can play significant roles in catalytic performance of these catalysts.     

Ingeniously designed Ni-Mo-S/ZnIn2S4 composite for multi-photocatalytic reaction systems

Molybdenum disulfide（Mo S2） with low cost, high activity and high earth abundance has been found to be a promising catalyst for the hydrogen evolution reaction（HER）, but its catalytic activity is considerably limited due to its inert basal planes. Here, through the combination of theory and experiment, we propose that doping Ni in Mo S2as catalyst can make it have excellent catalytic activity in different reaction systems. In the EY/TEOA system, the maximum hydrogen production rate of EY/Ni-Mo-S...     

再生气氛对HDN催化剂再生性能的影响

采用不同手段研究了催化剂反应前后及在Ｈ２Ｏ和Ｎ２介质中再生时催化剂性质和表面原子浓度及其颁的变化。ＢＥＴ结果表明，Ｎ２介质中再生，催化剂的孔径基本没有变化，而Ｈ２Ｏ介质中再生的催化剂孔径明显增大，化学组成分析结果说明，长期运转使用后的催化剂在２和Ｈ２Ｏ介质中再生后其活性组分均有少量流失。电子探针的结果表明，结炭后的催化剂活性组分很不均匀，在Ｎ２和Ｈ２Ｏ介质中再生后其分布得到了明显改善，但仍不如新鲜     

乙二醇单乙醚醋酸酯合成用固体催化剂的筛选及催化作用分析

采用自建动态酯化反应实验装置，通过色谱分析测定了不同催化剂上乙二醇单乙醚醋酸酯合成反应的转化率－时间关系曲线。根据多种催化剂的活性及寿命，筛选出一种较为理想的锆基催化剂。该催化剂在实验条件下，反应２ｈ，转化率达９７％，对目标产生的选择性为１００％。     

加压条件下MgO/BaCO_3催化剂在甲烷氧化偶联反应中的性能研究(英文)

在加压条件下（0.1~1.1MPa）考察了MgO／BaCO_3催化剂在甲烷氧化偶联反应中的性能,以及加压后该催化剂的失活。XRD谱图表明,在加压失活的MgO／BaCO_3催化剂表面有部分MgCO_3牛成,这是由于部分活性相MgO发生了转变：XPS表征结果表明,在加压失活后的MgO／BaCO_3催化剂中B3CO_3向表面富积,致使催化剂的表面活性相MgO的浓度相对降低和催化剂表面积降低。另外,在加压失活后的MgO／B3CO_3催化剂上表面活性氧物种的离子浓度大大降低,表面晶格氧的流动性及晶格氧参与甲烷转化的能力也大大减弱;另外,由于该失活催化剂表面结构的变化,由MgO和BaCO_3共同作用形成的强碱中心也消失了。     

渣油加氢转化催化剂初期结焦规律的研究

以孤岛减压渣油及其超临界流体萃取分馏所得的窄馏分为原料,采用齐鲁石化公司胜利炼油厂VRDS装置的主催化剂,在高压釜反应器内考察了渣油加氢转化催化剂的初期结焦规律。结果表明,焦炭的生成是一个动态过程,其产率和性质与反应体系的温度、时间、氢气初始压力及原料的性质密切相关;结焦催化剂的孔壁焦炭沉积和堵孔现象严重,导致其比表面积大大减小,孔分布向小孔范围迁移。     

渣油裂解催化剂的再生

在渣油的流化催化裂化(FCC)中,来自原料的重金属(Ni,Fe,V等)连续沉积在催化剂上,使后者的活性和选择性严重下降,积炭量增加。为使这些失效的催化剂再生,从60年代末就开始了脱除沉积金属的研究。所用方法都涉及硫化,氧化等反应,处理时间长,操作繁杂,危害环境。本文进行了以盐酸再生裂解催化剂的探索研究,以开发简便有效的脱金属方法。镍铁沉积的FCC催化剂的处理     

助催化剂对Fe1-xO基氨合成催化剂还原性能的影响

当助催化剂存在是地，Ｆｅ１－ｘＯ基催化剂的还原性能明显优于Ｆｅ３Ｏ４基催化剂，其原因是铝、钾、钙的氧化物对催化剂母体相Ｆｅ１－ｘＯ和Ｆｅ３Ｏ４还原性能的影响不同。由于Ａｌ＾３＋大量地进入Ｆｅ３Ｏ４的晶格而强烈地阻止Ｆｅ３Ｏ４的还原，只有少量的Ａｌ＾３＋能进入Ｆｅ１－ｘＯ晶格，因此对Ｆｅ１－ｘＯ的还原影响很小；     

银-磷催化剂催化乙二醇制乙二醛及其表面性质

用银－磷催化剂研究了原料气线速、空速、氧醇摩尔比、反应温度、乙二醇重量浓度对催化氧化乙二醇制乙二醛的反应活性的影响．结果表明，在相近的反应条件下，银－磷催化剂能使副产物ＣＯ２的产率从电解银的３０％降到１３．３％，而使乙二醛收率从５４％增至８１％．Ｘ射线光电子能谱表明，在银表面上形成了稳定的表面磷化合物并占据了一部分深度氧化的活性位，因而提高了反应的选择性．     

乙烯氧气法氧氯化反应中铜催化剂的研究

用微分固定床和沸腾床反应器考查了在乙烯氧气法氧氯化制二氯乙烷反应中,浸渍法制备的铜催化剂的反应活性及其应用的可能性,并与共沉淀法制备的铜催化剂进行了比较。用x射线衍射分析,程序升温还原和乙烯脉冲反应探讨了乙烯氧氯化催化剂的活性相结构与反应机理。     

A301氨合成催化剂的稳定性

合成氨工业是一个高能耗、高产值的产业,在化学工业中占有重要的地位.目前,合成氨工业的总趋势是朝着低(等)压、低能耗工艺方向发展,其核心技术之一是开发低(等)压、高活性的氨合成催化剂.七十年代以来国际上兴起了载钌催化剂的研究开发,目前已有工业化的报道[1].     

超高交联树脂催化剂对水溶液中孔雀绿的催化降解研究

通过磺酸铁酞菁(FePcS)与氯甲基化交联聚苯乙烯进行Friedel-Crafts反应,合成了一种新型光反应催化剂(命名为C-FePcS).在可见光的照射下,加入适量的H2O2,该催化剂能非常有效地降解难生物降解染料孔雀绿(MG).实验结果表明,脱色率近100%,总有机碳(TOC)的去除率达到72%,而且该催化剂对反应环境的pH值不敏感.最后对光催化降解的机理进行了合理的推测.