Cu-Ni双金属催化剂上CO2的加氢反应

采用真空浸渍法,制备了Ｃｕ－Ｎｉ双金属催化剂（引入Ｃｕ前,Ｎｉ以不同的状态存在）,在连续流动微型反应装置上测试各催化剂的ＣＯ２加氢性能,并用ＸＲＤ方法对催化剂进行了表征。实验发现,与Ｃｕ／ＡＩ２Ｏ３催化剂相比,Ｃｕ－Ｎｉ／ＡＩ２Ｏ３催化剂上ＣＯ２逆变换反应的活性因Ｎｉ的存在而受到抑制,Ｃｕ引入前处于氧化态的Ｎｉ,对所制得的Ｃｕ－Ｎｉ催化剂上ＣＯ生成的抑制更为明显,Ｃｕ－Ｎｉ－Ｉ２Ｏ３双金属催化剂表     

Co-Fe/Al2O3 Nanocomposite Catalysts of the Process of CO2 Hydrogenation

Theoretical and Experimental Chemistry - Effective catalysts of CO2 hydrogenation towards methane were obtained by impregnation of aluminum oxide with cobalt and iron nitrates. The catalysts have...     

助剂促进的Rh-Fe/Al_2O_3催化剂上CO加氢制乙醇反应性能

考察了Fe,Rh载量以及助剂对Rh-Fe/Al2O3催化剂上合成气制乙醇反应性能的影响.结果表明,随着Fe载量的增加,甲醇选择性持续上升伴随着甲烷选择性的持续下降,而乙醇选择性有最优值.助剂的添加或多或少促进了甲醇耦合、CO插入和解离的活性,或抑制了催化剂加氢能力,使得乙醇选择性有所上升,甲醇选择性有所下降,而烃类选择性变化不大.随着CO加氢反应的进行,Rh-Fe/Al2O3催化剂上烃类选择性逐渐下降,但甲醇的生成活性逐渐上升,而乙醇选择性和生成活性逐渐下降;然而,助剂的添加并未提高催化剂的稳定性.这可能是由于在反应过程中Fe物种逐渐被合成气还原使得乙醇生成活性位数量逐渐减少所致.     

Co/Al2O3催化剂上3-甲基-2-丁烯醛选择性加氢反应

3-甲基-2-丁烯醛(3-MeCal)是一种典型的α,β-不饱和醛,其C=O加氢产物3-甲基-2-丁烯醇(3-MeCol)作为重要的有机中间体,在医药、香料、农药等生产领域有着广泛的应用.我们采用沉积沉淀法制备了Co/Al2O3催化剂,将其应用于3-MeCal液相选择性加氢反应中,考察了反应温度、H2初始压力、催化剂焙烧温度和还原温度对3-MeCal选择性加氢反应的影响.发现反应温度为80℃,H2初始压力为1×106Pa下,加氢反应效果良好.通过H2-TPR与XRD表征了焙烧温度对催化剂的影响,发现适当焙烧温度能增强Co物种与载体Al2O3间作用力.焙烧温度为600℃,还原温度为550℃下制备的催化剂反应48 min后转化率为23.0%,3-MeCol选择性达到88.6%.制备的Co/Al2O3催化剂具有良好的磁性,在外磁场作用下可与液相反应体系实现高效分离,循环使用3次后,催化性能没有明显下降,表现出良好的循环使用性能.     

CO Hydrogenation by K-Promoted Coprecipitated Co/Al2O3

Effect of K promotion on the CO hydrogenation activity and selectivity of coprecipitated Co/Al₂O₃ has been studied. K addition is found to lower total activity while enhancing C₂-C₄ olefins selectivity; kinetic data indicate that the reaction mechanism is not affected.     

Pd/Al2O3催化剂催化毛竹与聚乙烯共裂解反应研究

我们采用等体积浸渍法制备了Al2O3负载贵金属Pd系列催化剂,分别在N2和H2气氛下,研究了不同Pd负载量的催化剂对毛竹和低密度聚乙烯(LDPE)混合物的催化裂解性能.实验结果表明:Pd的负载量为1.0%时,Pd/Al2O3催化剂在两种气氛下活性均较好,在H2气氛下所得到的油品中烯烃含量较低,异链烷烃和环烷烃含量较高,油品的收率和质量均明显优于在N2气氛下所得到的油品.XRD表征发现,Pd负载量为1.0%的催化剂上,Pd在Al2O3载体上生成了晶形,表明金属钯有利于毛竹和LDPE共裂解生成液体产物.     

用射频等离子体技术制备乙炔选择加氢催化剂及其性能研究

 采用射频等离子体技术制备了α－Al2O3（MgO修饰）负载钯催化剂，以乙炔选择加氢为模型反应考察了制备方法、钯含量、助剂种类及反应温度对催化剂性能的影响．结果表明，采用等离子体技术制备的催化剂具有催化活性及乙烯选择性高、操作简便和工艺流程短等优点，在50℃下反应时乙炔转化率可达100％，乙烯选择性可达71．3％，而且在反应20h后催化剂样品仍保持有高活性．CeO2助剂的加入能改善催化剂的催化性能．     

超声浸渍法制备Pd/Al2O3催化剂及其催化蒽醌加氢性能

 以球形 γ-Al2O3 和 θ-Al2O3 为载体,分别采用超声浸渍和普通浸渍方法制备了Pd含量为0.3%的负载型催化剂,并将其用于蒽醌加氢反应. 采用X射线衍射、 N2吸附和透射电镜等手段对催化剂的理化性质和孔结构进行了分析,考察了浸渍方法对催化剂活性金属分散度的影响. 结果表明,与普通浸渍法相比,超声浸渍法制备的负载型Pd催化剂金属分散度明显提高,因而对蒽醌加氢反应表现出较高的催化活性. 以960 ℃焙烧的球θ-Al2O3 为载体,通过超声浸渍制备的负载型Pd催化剂具有较高的Pd分散度和较大的孔径,在蒽醌加氢反应中对反应物的扩散阻力较小,因而表现出更高的催化活性,而且反应中催化剂的稳定性良好.     

Oscillatory formation of CO hydrogenation products on Pd/Al2O3

Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, p. 384, May–June, 1990.     

Pt-Ir/Al2O3催化剂催化2-氧-4-苯基丁酸乙酯不对称加氢

用浸渍法制备了一系列γ-Al2O3负载的Pt、Ir单金属及不同Pt/Ir比例的双金属催化剂,在辛可尼定修饰下用于对2-氧-4-苯基丁酸乙酯不对称加氢合成(R)-2-羟基-4-苯基丁酸乙酯反应.运用XRD、TEM、TPR、XPS、UV-Vis等表征手段,对催化剂的物化性质进行了研究,并对Pt、Ir金属表面辛可尼定手性诱导机理进行了初步探讨.结果表明,金属组分在催化剂上分散均匀,无团聚现象,平均粒径为3～4 nm;Pt-Ir/γ-Al2O3上Pt、Ir组分以单质形式存在;Ir作为低活性物种,在Pt/γ-Al2O3催化剂掺杂Ir组分遮盖和稀释了催化剂表面总体Pt活性位点数目,降低了Pt-Ir/γ-Al2O3催化剂加氢性能.辛可尼定在Pt、Ir表面的不同吸附行为(吸附方式、吸附强度、吸附构象)影响EOPB不对称加氢活性和对映选择性.     

Al2O3 Effect on the Catalytic Activity of Cu-ZnO-Al2O3-SiO2 Catalysts for Dimethyl Ether Synthesis from CO2 Hydrogenation

The effect of Al2O3 on the Cu-ZnO-Al2O3-SiO2 catalysts prepared by a pseudo sol-gel method has been investigated and these catalysts were characterized by XRD, H2-TPR, XPS, NH3-TPD and CO2- TPD techniques. As revealed by XRD and H2-TPR, the added alumina produces high dispersion of CuO and makes the reduction of CuO difficult. XPS analysis detects a remarkably high Al^3＋ enrichment at the surface of calcined samples, along with a decrease of Eb of Cu 2p3/2, which confirms the Cu-Al interaction. Another important role of Al203 would be to incorporate into the SiO2 structure to form the acid-base sites for ether formation. The reaction results shows that the addition of Al2O3 exhibits a promoting effect on the CO2 conversion only when its content is below 1.4%, and an optimal DME selectivity is obtained when 4.0%Al2O3 is added, indicating a better ＇synergistic effect＇ is present between the methanol forming component and the acidic component in bifunctional catalysts. Possible relationship between the catalytic activity and the Cu-Al interaction as well as the surface acidity is discussed.     

二氧化碳在Pd/SiO2和La-Pd/SiO2上的催化氢化反应

对CO₂在附载型Pd催化剂上的氢化反应的研究迄今报道不多^[1,2],且都在加压条件下进行,对常压下助催剂如何改善Pd的催化行为未见报道。本文探讨了Pd/SiO₂催化剂,未加与掺加助催剂La(NO₃)₃后,其Pd粒大小、CO₂的吸附性能及CO₂/H₂催化活性等方面都有显著差异。     

负载型Pd/TiO2和Pd-Ag/TiO2催化剂的乙炔选择性加氢催化性能

利用程序升温还原(TPR)、X-射线衍射(XRD)、CO吸附-红外光谱(CO-IR)、电子顺磁共振(EPR)和微型催化反应评价等手段, 研究了负载Pd/γ-Al2O3, Pd/TiO2和Pd-Ag/TiO2催化剂的结构和乙炔选择性加氢催化性能. 结果表明, Pd/TiO2催化剂具有较Pd/γ-Al2O3催化剂更优良的乙炔选择性加氢催化性能, 这与Pd-TiO2之间的强相互作用密切相关. Pd-TiO2之间的强相互作用不仅使负载型钯金属催化剂具有较高的乙炔加氢催化选择性, 而且具有较高的乙炔加氢催化活性. Pd/TiO2催化剂中添加Ag 组分后, Pd金属可促进Ag+的还原并可能形成Pd-Ag合金, 催化剂的乙烯选择性虽有所增加, 但乙炔转化率和乙烯收率下降.     

Au/MOx/Al2O3催化剂催化CO低温氧化

 采用沉积沉淀法，将金负载在复合氧化物载体MOx/Al2O3上，制备得到了Au/MOx/Al2O3催化剂的活性要高于Au/Al2O3催化剂。Au/FeOx/Al2O3催化剂能够在低于223K的温度下实现CO完全催化氧化。TEM图象分析表明，纳米级高分散的金颗粒是金催化剂高活性的前提，但载体的选择，以及复合氧化物载体中过渡金属氧化物的选择，也会对金催化剂的活性产生明显的影响。     

PdIn/Al2O3 Intermetallic Catalyst: Structure and Catalytic Characteristics in Selective Hydrogenation of Acetylene

Kinetics and Catalysis - The structure and catalytic characteristics of a bimetallic catalyst containing Pd1In1 nanoparticles deposited on the surface of γ-Al2O3 were studied. The formation of...     

La2O3对Pd/Al2O3催化蒽醌氢化制H2O2性能的影响

 采用湿浸法制备了用于蒽醌氢化制H2O2的La2O3促进的Pd/Al2O3催化剂,并考察了不同La2O3含量对催化性能的影响. 采用XRD,N2物理吸附,CO2-TPD,H2-O2滴定和电子探针等技术对催化剂进行了表征. 结果表明,加入适量的La2O3能够抑制高温焙烧时Al2O3晶粒的长大,增大催化剂的比表面积,提高金属Pd的分散度,增强载体表面碱性,提高催化剂表面的Pd浓度,减小Pd层厚度,从而提高催化剂的氢化活性. 加入La2O3可使催化剂的Pd负载量由0.281%降至0.188%,而催化剂活性提高了44%.     

A Highly Selective Cr2O3/nano-ZSM-5 Bifunctional Catalysts for CO2 Hydrogenation to Aromatics

Russian Journal of Applied Chemistry - The direct conversion of CO2 to aromatics is an effective strategy for simultaneously achieving carbon neutrality and its resource utilization. However, it is...     

Unravelling the Promotional Effect of La2O3 in Pt/La-TiO2 Catalysts for CO2 Hydrogenation

This work reports the preparation of a La₂O₃-modified Pt/TiO₂ (Pt/La-TiO₂) hybrid through an excess-solution impregnation method and its application for CO₂ hydrogenation catalysis. The Pt/La-TiO₂ catalyst is characterized by XRD, H₂ temperature-programmed reduction (TPR), TEM, X-ray photoelectron spectroscopy (XPS), Raman, EPR, and N₂ sorption measurements. The Pt/La-TiO₂ composite starts to catalyze the CO₂ conversion reaction at 220 °C, which is 30 °C lower than the Pt/TiO₂ catalyst. The generation of CH₄ and CO of Pt/La-TiO₂ is 1.6 and 1.4 times greater than that of Pt/TiO₂. The CO₂ temperature-programmed desorption (TPD) analysis confirms the strengthened CO₂ adsorption on Pt/La-TiO₂. Moreover, the in situ FTIR experiments demonstrate that the enhanced CO₂ adsorption of Pt/La-TiO₂ facilitates the formation of the active Pt–CO intermediate and subsequently boosts the evolution of CH₄ and CO. The cycling tests reveal that Pt/La-TiO₂ shows reinforced stability for the CO₂ hydrogenation reaction because the La species can prevent Pt nanoparticles (NPs) from sintering. This work may provide some guidance on the development new rare-metal-modified hybrid catalysts for CO₂ fixation.