Co/TiO2-SiO2催化剂上肉桂醛选择性加氢制备肉桂醇

采用等体积浸渍法制备了系列Co/TiO₂-SiO₂催化剂,用于肉桂醛选择性加氢制备肉桂醇反应体系。系统考察了钴含量、焙烧温度、还原温度、稀土助剂等参数变化对钴催化剂选择性加氢性能的影响。结果表明,钴催化剂的活性和选择性与其表面钴的晶粒度有一定关系,较大尺寸的钴物种对肉桂醛加氢有利。当Co含量为15%、焙烧温度和还原温度均为823 K时,催化剂表现出良好的加氢性能。稀土助剂La和Ce的引入能改善Co /TiO₂-SiO₂催化剂表面活性组分钴的分散度,提高了钴催化剂的加氢性能。     

焙烧温度对Co-Ru-ZrO2/γ-Al2O3F-T合成催化剂性能的影响

采用浸渍法制备钴基催化剂,考察了催化剂焙烧温度对其F-T合成反应性能和产物分布的影响。制备催化剂时,不对催化剂进行焙烧,Co物种容易还原,并可较好分散,催化剂具有较高的催化活性和重质烃选择性。较高温度下焙烧,Co物种和载体间的相互作用增强,形成难还原的铝酸钴化合物,同时氧化钴晶粒聚集或烧结,Co物种的还原程度下降,催化剂CO加氢活性降低,重质烃选择性下降。在原料气n(H₂)∶n(CO)=2.0、483 K、1.5 MPa和800 h^-1条件下,未焙烧、673 K和923 K焙烧的催化剂上进行F-T合成反应,CO的转化率分别为80.27%、78.41%和61.14%,重质烃的选择性C₅⁺分别为88.54%、88.57%和77.95%。较低焙烧温度有利于反应速率的提高和重质烃的合成,较高焙烧温度使CO加氢活性下降,有利于低碳烃的生成。     

TiO2复合氧化物的制备及其在加氢脱硫中的应用

对TiO₂、TiO₂-Al₂O₃、TiO₂-SiO₂和TiO₂-ZrO₂载体的制备技术及其在加氢脱硫中的应用进行了综述。研究表明，以TiO₂调变的Al₂O₃、SiO₂和ZrO₂载体能影响MoO₃与Al₂O₃、MoO₃与SiO₂及MoO₃与ZrO₂之间的相互作用，改善MoO₃在载体表面的分散，促进其还原，有利于提高催化剂表面活性组分的数量，提高催化剂的加氢脱硫活性。     

TiO2-SiO2复合氧化物的理化性质及其对柴油加氢精制性能的影响

采用溶胶-凝胶法结合CO₂超临界流体干燥技术制备了不同Ti/Si原子比的TiO₂-SiO₂复合氧化物（TS-n）,考察了Ti/Si原子比、焙烧温度对复合氧化物比表面积、孔结构、酸性及原子结合状态的影响,通过重油催化裂化柴油加氢精制反应考察了以TS-1、TS-4为载体的催化剂脱硫性能的差异.结果表明,TiO2经SiO2复合改性后,热稳定性和晶态稳定性大幅度提高;TiO₂-SiO₂复合氧化物的酸性及原子间的相互作用与Ti/Si原子比有直接的关系;载体的晶态组成及酸性和催化剂的酸性对催化剂的加氢脱硫性能有显著影响,复合氧化物中锐态型TiO₂的存在强化了载体与金属组分之间的相互作用,提高了催化剂的加氢脱硫活性,不同类型的酸性中心对柴油中不同类型的硫化物具有不同的脱除能力,Bronsted 酸中心较多的催化剂对结构简单的硫化物脱除能力强,Lewis酸中心较多的催化剂对结构复杂的硫化物有较好的脱除效果.     

V2O5/TiO2基SCR脱硝催化剂的制备及其催化性能

采用纳米TiO₂为催化剂载体原料,V₂O₅为催化剂,通过混合、球磨、干燥和焙烧等工艺制备选择性催化还原脱硝法催化剂,研究了催化剂的制备工艺和催化性能。通过差热分析研究催化剂的相变和烧结温度,通过模拟烟气分析装置表征催化剂的催化性能。结果表明,加入V₂O₅可以提高催化性能,以6%V₂O₅-94%TiO₂为配方的催化剂对NO的脱除率达97.5%,温度窗口为（300～420） ℃。     

VxTi复合氧化物催化剂用于二氧化碳气氛乙苯脱氢的研究

采用溶胶-凝胶法制备了以TiO₂为基体的VxTi复合氧化物催化剂,该催化剂用于乙苯二氧化碳低温氧化脱氢制苯乙烯反应。考察了活性组分含量和焙烧温度对催化剂活性的影响。结果表明,活性金属钒的添加有助于提高脱氢反应性能,但存在一适量值,摩尔分数超过5%,催化脱氢活性下降。通过XRD分析发现,不同焙烧温度制备的VxTi催化剂中TiO₂的晶相不同,随着温度的升高,TiO₂的晶相将由锐钛矿型转变为金红石晶相。TiO₂锐钛矿型晶相有利于苯乙烯选择性的提高,而金红石晶相则不利于催化剂的脱氢反应。     

Ni/SiO2催化剂的制备条件对催化间二硝基苯加氢反应性能的影响

将Ni/SiO₂催化剂应用于间二硝基苯加氢反应中,考察了该催化剂制备过程中焙烧温度和还原温度对其催化性能的影响,并通过BET、XRD、TEM、TPR等方法对催化剂进行了表征.结果表明,在实验研究范围内,随着焙烧温度的提高,Ni/SiO₂催化剂比表面积降低,NiO与载体SiO₂之间的相互作用逐渐增强,催化剂的还原温度明显提高,活性组分Ni的晶粒度增大,焙烧温度为773 K时催化剂具有最佳的催化反应性能,此时活性组分Ni以高分散状态存在.催化剂的还原温度对Ni/SiO₂催化剂的结构和催化性能影响显著,当还原温度较低时,活性组分还原不完全,催化剂活性较低;而还原温度太高会使活性组分烧结,导致催化剂活性明显降低;还原温度为723 K时催化剂表现出最佳的活性和选择性.     

Co-Fe/硅藻土催化剂上肉桂醛的选择加氢——反应性能的研究

在固定床反应器中对肉桂醛选择加氢制肉桂醇的反应性能进行了研究。考察了Co-Fe催化剂的活性和选择性;Co负载量、助剂Fe对催化剂选择加氢性能的影响;考察了反应温度、压力、H2的空速等对肉桂醛在催化剂上加氢性能的影响。结果表明,钴/硅藻土催化剂的最佳钴负载量为12%,助催化剂和主催化剂的最佳比为Fe/Co=0.20(mol/mol)。最佳反应温度为423 K,反应的压力越高越有利于催化反应,但压力大于4 MPa后,肉桂醛的转化率和肉桂醇的选择性提高幅度不大,宜控制在4 MPa左右。空速对肉桂醇的选择性影响不大,但空速越高肉桂醛的转化率越低,催化反应中宜控制较低的氢气空速为佳。     

MoP/TiO2-ZrO2催化剂制备及加氢脱氮性能考察

采用溶胶-凝胶法制备了TiO₂-ZrO₂复合载体,并用共浸渍法制备负载型MoP/TiO₂-ZrO₂催化剂,通过原位还原技术对催化剂进行还原处理后,在连续固定床反应器上进行活性评价。结果表明, TiO₂和ZrO₂物质的量比以及Mo负载量对催化剂活性有较大影响,当n(Ti)∶n(Zr)=4∶1和Mo负载质量分数为20%时,MoP/TiO₂-ZrO₂催化剂的加氢脱氮效果最好,并且TiO₂-ZrO₂复合载体比TiO₂-Al₂O₃复合载体的活性提高12.4个百分点。     

低含量Ni掺杂TiO2光催化剂及其在水溶液体系中的重复使用性能

利用溶胶-凝胶法制备了低含量Ni掺杂的TiO₂光催化剂粉体,考察了催化剂在甲基橙水溶液中的重复使用性能,并用XRD、XPS和N₂吸附-脱附等手段对催化剂进行了表征分析。结果表明,当掺杂Ni物质的量分数为0.3%和焙烧温度400 ℃时,制备的Ni/TiO₂的光催化降解甲基橙水溶液的活性高于纯TiO₂的光催化降解活性。Ni/TiO₂光催化剂在水溶液体系重复使用过程中,催化活性急剧下降,重复使用性能较差。Ni掺杂使TiO₂上产生具有较低结合能的低价钛离子如Ti^3＋,使表面缺陷（或氧空位）增加。比表面积和氧空位增加可能是Ni掺杂提高TiO₂光催化活性的主要原因。Ni流失可能是Ni/TiO₂在水溶液体系中重复使用性能较差的原因。     

Co-N-C催化剂的构筑及在亚砜催化氢化中的应用

利用N-乙酰-丙氨酸修饰改性的壳聚糖作为有机含氮配体，与钴离子配位形成前驱体，随后通过在不同温度下热解制备得到一系列的Co-N-C型催化剂（Co/CNAA-T）。通过多种表征手段，研究了热解温度对所制备的Co/CNAA-T催化剂的形貌、结构、组成的影响，认为Co-Nx位点是催化活性中心，并评价了Co/CNAA-T催化剂在甲基苯基亚砜催化氢化反应中的活性，探究了热处理温度对催化剂催化氢化性能的影响。其中，Co/CNAA-900在140oC、3MPa氢压下反应11个小时表现出最佳的催化活性，原料转化率达到了97.2%，选择性>99%。     

还原温度对Co/ZnO催化剂的F-T合成反应性能影响

采用沉淀-浸渍法制备Co/ZnO催化剂,研究还原温度对Co/ZnO催化剂F-T合成反应性能影响。结果表明,催化剂Co/ZnO适宜在较低温度还原,Co负载质量分数5%和10%的催化剂最佳还原温度分别为260 ℃和250 ℃。还原温度与催化剂活性之间的关系取决于Co/ZnO催化剂上Co的分布状态,氧化态Co以约50 nm的颗粒存在于ZnO表面,容易被氢还原。低温还原的Co基催化剂是浆态床F-T合成的良好催化剂。     

Co/γ-Al2O3催化乙酰丙酸加氢合成γ-戊内酯的研究

采用等体积浸渍法制备一系列Co负载量不同的Co/Al₂O₃催化剂,用于乙酰丙酸液相催化加氢制γ-戊内酯反应。采用X射线衍射仪和透射电镜对Co/Al₂O₃催化剂进行表征,考察Co负载量、反应温度、反应压力和催化剂用量等对乙酰丙酸液相催化加氢反应的影响。结果表明,在Co负载质量分数15%、反应温度140 ℃、反应压力4.0 MPa和催化剂用量为反应物总质量的20%条件下,以甲醇为溶剂,反应6 h,乙酰丙酸转化率100%,γ-戊内酯选择性80.4%。催化剂重复使用6次仍具有较好的催化性能。     

Temperature Programmed Hydrogenation of Toluene

Supported Ni, Co, Pt and Ir catalysts were studied by temperature programmed gas phase hydrogenation (TPH) of toluene to evaluate the performance of the catalysts and to obtain information about the applicability of temperature programming to hydrogenation studies. On all catalysts the reaction rate passed through a maximum as the temperature increased. The maximum reaction rate was reached at slightly lower temperatures with the Co catalyst than the Ni, Pt and Ir catalysts. This work demonstrates that TPH is a rapid method for evaluating the performance of hydrogenation catalysts and, combined with temperature programmed desorption, provides information on the reaction mechanism unobtainable from isothermal experiments.     

Highly active and selective CoCu/ZnO catalysts prepared by mild oxalic acid co-precipitation method in dimethyl oxalate hydrogenation

Novel CoCu/ZnO catalysts prepared by oxalic acid co-precipitation method have been systematically characterized focusing on the effect of calcination temperature on the structural evolution of the catalysts and the catalytic performance in dimethyl oxalate hydrogenation. The calcination temperature plays an important role in determining the physicochemical features of cobalt species and dispersion of copper species in the CoCu/ZnO catalysts. 100% dimethyl oxalate conversion and 93% selectivity to ethylene glycol could be obtained over the CoCu/ZnO catalyst calcined at 450 °C. High dispersion of Co species interacting with crystalline Cu contributed to the excellent catalytic performance.     

Reactivity of olefins in the hydrodesulfurization of FCC gasoline over CoMo sulfide catalyst

To achieve selective hydrodesulfurization (HDS) of fluid catalytic-cracked (FCC) gasoline for producing sulfur-free gasoline (S < 10 ppm), the reactivity of various olefins contained in FCC gasoline on CoMoP/Al₂O₃ sulfide catalysts was investigated. Isomerization of the CC double bond from the terminal position to an internal position was observed. The steric hindrance around the CC double bond suppresses the reactivity of olefin hydrogenation. The sulfidation temperature of the catalyst has a major influence on olefin hydrogenation active sites. Addition of the appropriate amount of cobalt (Co/Mo ratio approximately 0.6) contributes to the suppression of olefin hydrogenation at high reaction temperature (260 °C). From the comparison of catalytic performance and characterization of our CoMoP/Al₂O₃ catalyst with an analogous commercial catalyst, it is suggested that the hydrogenation of olefins depends not only on the state of the Mo CUS but also on the steric effects of both olefin structure and MoS₂ crystalline structure.     

Liquid phase hydrogenation of biomass-derived ethyl lactate to propane-1,2-diol over a highly active CoB amorphous catalyst

Amorphous CoB alloy catalysts were prepared using chemical reduction method by changing the concentration of cobalt acetate from 0.5 to 1.0 mol/L and examined for the liquid phase hydrogenation of ethyl lactate. The catalyst, prepared with cobalt acetate concentration being 0.75 mol/L, gave a 99.8% selectivity to propane-1,2-diol at a conversion of 98.3%. The catalysts were characterized by XRD, TEM, BET, H₂-TPD and XPS. For all the catalysts, Co was electron-rich whereas B electron-deficient, and B was rich on the surface. The change in the concentration of cobalt acetate results in different surface composition of B/Co, various types of Co active sites, and different distribution of particles, which have large influence on activity and selectivity of the catalyst.     

Hydrogenation of Sunflower Oil over M/SiO2 and M/Al2O3 (M = Ni,Pd, Pt,Co, Cu) Catalysts

This work is aimed at evaluating the performance of several catalysts in the partial hydrogenation of sunflower oil. The catalysts are composed of noble (Pd and Pt) and base metals (Ni, Co and Cu), supported on both silica and alumina. The following order can be proposed for the effect of the metal on the hydrogenation activity: Pd > Pt > Ni > Co > Cu. At a target iodine value of 70 (a typical value for oleomargarine), the production of trans isomers is minimum for supported nickel catalysts (25.7–32.4 %, depending on the operating conditions). Regarding the effect of the support, Al₂O₃ allows for more active catalysts based on noble metals (Pd and Pt) and Co, the effect being much more pronounced for Pt. Binary mixtures of catalysts have been studied, in order to strike a balance between catalyst activity and product distribution. The results evidence that Pd/Al₂O₃–Co/SiO₂ mixture has a good balance between activity and selectivity, and leads to a very low production of trans isomers (11.8 %) and a moderate amount of saturated stearic acid (13.5 %). Consequently, the utilization of cobalt‐based catalysts (or the addition of cobalt to other metallic catalysts) could be considered a promising alternative for the hydrogenation of edible oil.     

Tailoring of activity and selectivity using bimetallic catalyst in hydrogenation of succinic acid

The liquid phase hydrogenation of succinic acid (SA) to γ-butyrolactone (GBL) and 1,4-butanediol (BDO) was investigated using ruthenium–cobalt bimetallic catalysts in a semi-batch slurry reactor. The doping of ruthenium (up to 1%) with cobalt resulted in increase (3–4 times) in the overall hydrogenation activity indicating a strong synergistic effect. Ru–Co bimetallic catalyst also influenced the product distribution by promoting specific hydrogenation steps in the overall reaction scheme. Based on the observed catalyst activity results, a speculative reaction pathway for cobalt as well as for ruthenium–cobalt catalyzed hydrogenation of succinic acid has been proposed.