Pd/Al2O3催化剂的制备及其在对氨基苯酚合成中的应用

用等体积浸渍法制备了Pd/Al2O3催化剂。采用ICP、XRD、HRTEM和XPS等对催化剂的组成和形貌进行表征。结果表明，Pd粒子均匀分布在Al₂O₃的表面，粒径约为5 nm。在对硝基苯酚催化加氢制备对氨基苯酚的反应中，对催化剂的催化性能进行了考察。Pd/Al₂O₃催化剂的催化活性随着Pd负载量的增大而增大；其与市售的骨架镍、纳米镍以及2%Pd/C相比，显现了优异的催化活性；Pd/Al₂O₃具有高的催化选择性；Pd/Al2O3的催化活性稳定性明显优于骨架镍；随着使用次数的增加，Pd/Al₂O₃的催化活性有所降低，这可能是因为Pd粒子的团聚。     

γ-Al2O3负载铜锌氧化物催化剂的N2O催化分解性能

以γ-Al₂O₃为载体,采用共浸渍法合成了负载量为35%（以CuO与ZnO总质量计）的CuZn金属氧化物催化剂,分别考察了金属助剂（Co、Ni,、Mg、Fe、Mn、Ba和Ce）对催化剂的影响。采用XRD、BET和H₂-TPR等方法对制备的催化剂进行表征,在微反装置上对催化剂的N₂O催化分解活性进行评价。结果表明,合成的CuZn氧化物催化剂均具有CuxZn_1-xAl₂O₄的类Co₃O₄尖晶石结构;加入金属助剂使催化剂的比表面积不同程度得到提高,催化剂的N₂O催化分解反应活性不仅与Cu³⁺还原为Cu²⁺的温度有关,还与晶粒尺度大小和催化剂比表面积等有关;其中,含金属助剂Ni的催化剂具有相对较高的N2O催化分解反应活性,其N₂O完全转化温度为567 ℃。除含金属助剂Ba催化剂以外,加入其他金属助剂有利于N₂O催化分解反应进行。     

ZrO2-Al2O3催化剂载体的制备及应用

ZrO₂-Al₂O₃复合载体具有独特的性能，当其作为催化剂载体时，可通过与活性组分的相互作用改变活性组分的分散状态及活性相结构，从而改善催化剂的催化性能。介绍了ZrO₂-Al₂O₃复合载体的制备以及组织结构、物相、表面酸性和与活性组分的相互作用等性能，并重点介绍了其在加氢脱硫反应中的应用。     

紫外拉曼光谱:破解催化剂技术瓶颈

<正>本刊讯大连化物所凝聚科学技术研究团队十几年的智慧和心血,研究的催化材料紫外拉曼光谱技术,破解了催化材料的若干关键技术难题,为突破国家建设急需、引领未来发展的关键材料和技术提供了重要技术支持。     

负载型Pt/Al2O3催化剂中铂的测定

利用Pt（Ⅳ）在盐酸介质中与过量的氯化亚锡形成黄色的氯铂酸锡络合物，采用紫外-可见分光光度计在403 nm处测定该络合物显色液的吸光度，然后通过换算因子计算出负载型Pt/Al₂O₃催化剂中的铂含量。方法简单、快捷、准确，回收率在97％以上，相对标准偏差在2.0％以内 。在选定的试验条件下，负载型Pt/Al₂O₃催化剂中的常见元素对测定铂含量无干扰，但NO^－₃的存在对测定有影响。     

改进的二步共沉淀法制备Cu/ZnO/Al2O3甲醇合成催化剂

采用改进的二步共沉淀法制备了Cu/ZnO/Al₂O₃甲醇合成催化剂。用XRD、SEM和BET等手段对催化剂结构和形貌进行了表征。采用流动固定床微型反应器在5.0 MPa和空速5 000 h^-1条件下,考察了其催化合成气合成甲醇的活性,并在同一条件下用一种工业催化剂做对比测试。结果表明,改进的二步法制备的甲醇合成催化剂结晶度较低,基本以无定形状态的固溶体形式存在,铜锌之间的协同作用大,催化剂粒度较小,尺寸分布较均匀,比表面积较大,催化剂单位面积活性达98.54 mg·m^-2。     

Pd/Al2O3催化剂上CH4选择性还原NO的研究

考察了Pd/Al₂O₃、In/Al₂O₃和Co/Al₂O₃对甲烷选择性还原NO的催化活性。结果表明，采用浸渍法制备的Pd/Al₂O₃、In/Al₂O₃和Co/Al₂O₃三种催化剂，在有氧气氛下，用CH₄作还原剂催化还原NO时，Pd/Al₂O₃催化剂的活性最佳，热稳定性好，在550 ℃，用CH₄选择还原NO，Pd/Al₂O₃催化剂表现出较强的催化能力，NO的转化率达到100%。在高空速实验中，该催化剂亦表现出较高的活性，其活性顺序为Pd/Al₂O₃>In/Al₂O₃>Co/Al₂O₃。实验研究了助催化剂、氧含量以及空速对Pd/Al₂O₃催化剂活性的影响。     

NiMo/ZrO2-Al2O3柴油深度加氢脱硫催化剂的研究

以ZrOCl₂·8H₂O和Al₂O₃为原料,采用包覆法制备了一系列不同ZrO₂含量的ZrO₂-Al₂O₃复合载体,并用等体积浸渍法负载活性金属,制备了相应的NiMo/ZrO₂-Al₂O₃加氢脱硫催化剂,以柴油为原料考察了催化剂的加氢脱硫活性,利用XRD、N₂吸附和UV-Vis DRS等技术对催化剂及载体的基本物性进行了表征。结果表明,在催化剂载体中引入适量的ZrO2,保持了Al₂O₃载体的孔道结构,降低了活性金属和载体的相互作用,有利于提高催化剂的柴油加氢脱硫活性,当载体中ZrO₂质量分数为10%时,催化剂表现出最高的催化活性,脱硫率达99.25%,产品中硫低于10 μg·g^－1,满足柴油欧-Ⅳ的硫含量标准。     

以RuCl3为前驱体的无氯Ru/Al2O3氨合成催化剂的制备

用等体积浸渍法制备了一种以RuCl₃作为钌母体，分别以γ-Al₂O₃和δ,θ-Al₂O₃为载体的负载型无氯Ru/Al₂O₃氨合成催化剂。该催化剂用水合肼还原，以Sm(NO)₃和Ba(NO₃)₂作助剂。催化剂各组分n(Ru)∶n(Ba)∶n(Sm)=1∶0.55∶1.6。用N₂物理吸附、XRD、XRF和CO化学吸附等方法对载体和催化剂进行表征。结果表明，以δ,θ-Al₂O₃为载体的催化剂，其氨合成活性高于以γ-Al₂O₃为载体的催化剂的活性；用水合肼还原并用热碱液和纯水洗涤的催化剂不残留Cl^-，Ru金属分散度高，其氨合成活性与用无氯钌前驱体制备并用H2还原的催化剂的活性相当，在压力10.0 MPa，空速10 000 h^-1的反应条件下，475 ℃转化率为81.2%，在500 ℃时转化率可以达到100%。而用H₂还原以RuCl₃作为钌母体的Ru/Al₂O₃催化剂时，因还原后催化剂上有Cl^-残留，其催化活性较低。     

新型Pt/Al2O3苯加氢催化剂研制

在模拟苯加氢制环己烷工业装置建成的催化剂原粒度活性评价装置上，研究气相苯加氢制环己烷的Pt/Al₂O₃催化剂，主要考察催化剂制备方法、Al₂O₃载体物化性能和不同竞争吸附剂对催化剂性能的影响，提出了苯加氢制环己烷最佳的催化剂推荐工艺操作条件。与参比样对比表明，研制的Pt/Al₂O₃苯加氢催化剂性能达到参比催化剂的水平，催化剂侧压强度明显高于参比催化剂。     

载体焙烧温度对Co/Al2O3催化剂F-T合成反应催化性能的影响

采用等体积浸渍法,以不同温度焙烧的Al2O3为载体制备Co/Al₂O₃催化剂,通过N₂物理吸附、X射线衍射和程序升温还原等方法对催化剂进行表征,并在固定床反应器中评价催化剂的F-T合成反应性能。结果表明,低温焙烧可获得较大比表面积的Al₂O₃载体,有利于提高活性组分的分散度,但增强了钴与载体之间的相互作用,降低催化剂活性和选择性。高温焙烧的Al2O3载体有利于提高C⁺₅选择性,尤其是柴油组分的选择性。     

锰前驱体对负载型氧化锰催化剂脱硝性能的影响

分别以醋酸锰、醋酸锰-硫酸锰以及硫酸锰为前驱体,采用浸渍法制备Mn/Al₂O₃催化剂,考察其SCR脱硝活性和耐硫性能。采用BET、XRD、FT-IR、H₂-TPR和NH₃-TPD等对催化剂进行表征。结果表明,锰前驱体不同,导致催化剂晶型、比表面积存在显著差异;硫酸锰的加入使催化剂表面总酸量和酸强度上升。与单独的醋酸锰和硫酸锰相比,醋酸锰-硫酸锰复合前驱体制备的催化剂可以提高催化剂在（300~450） ℃的NO转化率,且原料气中SO₂体积分数为0.2%时,脱硝率下降幅度最小,耐硫性能最好。因此,采用醋酸锰-硫酸锰复合前驱体制备催化剂,可以提高催化剂在高温区的脱硝活性和抗硫性能。     

Vanadia layers supported on TiO2/SiO2 mixed oxides — An ESR and Raman investigation

ESR and Raman spectroscopy have been used to characterize monolayers of vanadia, which had been immobilized on titania and on a 20% TiO₂/80% SiO₂ mixed oxide support from a vanadyl alkoxide precursor. Characteristic vibrations observed in the Raman spectrum, as well as UV-visible reflection data, indicate that the most abundant vanadia species on the surface consists of disordered polymeric arrays: the central vanadium ion is surrounded by the tightly bound vanadyl oxygen, four oxygen ions in the basal plane, and a distant sixth oxygen ligand in bridging position to the support. From the ESR spectra the principal values ofg andA tensors are obtained, and their dependence on the support material and on the vanadia loading is investigated. Comparison with TPR measurements indicates that for structurally and chemically similar catalysts, the ESR-derived deviationg = g – g _e from the free electrong value provides a useful measure of the V=O bond strength.     

FeCrAl金属壁载PdZn/Al2O3催化剂上甲醇水蒸汽重整制氢

采用等体积浸渍法制备了不同Pd负载量和不同Pd与Zn物质的量比的PdZn/Al<,2>O<,3>甲醇水蒸汽重整颗粒催化剂,结果表明,Pd负载质量分数9.25%和n(Pd):n(Zn)=0.24的催化剂表现出较佳的催化性能.XRD表征表明,由于生成了较大的Pd-Zn合金粒子,从而有利于甲醇重整反应的进行.制备了金属壁载型...     

The influence of the preparing conditions of SiO2 supported Cp2ZrCl2 catalyst on ethylene polymerization

In this work, ethylene was polymerized by using Cp₂ZrCl₂ supported on silica pretreated with methylaluminoxane (MAO) as the catalyst system. The influence of the conditions for the preparation of the heterogeneous catalyst, such as temperature, washing method of the catalytic solid, MAO and metallocene concentration in the support treatment, time of MAO, and metallocene immobilization on the support, type of alkylaluminum used in the support pretreatment, and calcination temperature of the support were investigated. Aluminum and zirconium content fixed on the silica surface were determined by inductively coupled plasma emission spectroscopy. Polymer characteristics were determined by gel permeation chromatography and differential scanning calorimetry. According to the results, the activity of some supported catalysts were far higher than with the homogeneous system. Moreover, polyethylene with very high molecular weights were also obtained and with molecular weight distribution larger than those produced with the homogeneous precursor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2054–2061, 2002     

Effect of SO2 on NOx reduction by ethanol over Ag/Al2O3 catalyst

A new Ag/Al₂O₃ catalyst for removing NO_x in diesel engine exhaust gas was developed. The influence of SO₂ on the reduction of lean NO_x by ethanol over the Ag/Al₂O₃ catalyst was evaluated in simulated diesel exhaust and characterized using TPD, XRD, XPS, SEM and BET measurements. The Ag/Al₂O₃ catalyst was highly active for the reduction of NO_x with ethanol in the presence of SO₂ although the reduction of NO_x is suppressed at lower temperatures. The activity for NO_x reduction is high even on the Ag/Al₂O₃ catalyst exposed to a SO₂ (200 ppm)/O₂ (10%)/H₂O (10%) flow for 20 h at 723 K and comparable to that on the fresh Ag/Al₂O₃ catalyst. No crystallized Ag metal and Ag compounds were formed by the SO₂/O₂/H₂O exposure. On the other hand, crystallized Ag₂SO₄ was easily formed when the Ag/Al₂O₃ catalyst was exposed to a SO₂ (200 ppm)/O₂ (10%)/NO (800 ppm)/H₂O (10%) flow for 10 h at 723 K. XRD, SEM and XPS studies showed that the formation of crystallized Ag₂SO₄ results in growing of Ag particles in larger size and lowering the surface content of Ag particles. In addition, the specific surface area of the Ag/Al₂O₃ catalyst decreases from 221 to 193 m²/g. Although the dispersion of Ag particles was decreased by the formation of Ag₂SO₄, the activity for the reduction of lean NO_x was, remarkably, not affected. This suggests that the Ag–alumina sites created by the Ag₂SO₄ formation are still active for the lean catalytic reduction of NO_x. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigation of La3+-modified Al2O3supported CeO2

X-ray photoelectron spectroscopy measurements indicate that the Ce³⁺ fraction in Al₂O₃-supported CeO₂ can be decreased by the incorporation of La³⁺. If La³⁺ is incorporated into the Al₂O₃ before CeO₂ is added, a higher CeO₂ dispersion and a greater range of reversible reducibility of the CeO₂ may also be obtained. These changes offer potential for improvement in the oxygen storage capacity provided by CeO₂ in three-way catalysts.     

少量掺杂Al2O3、SiO2的Mg-PSZ陶瓷材料的液相烧结

通过在Mg-PSZ陶瓷材料中少量掺杂Al2O3或SiO2,可使材料在较低温度(≤1550℃)下实现液相烧结,使材料的烧结温度大幅度降低.随Al2O3、SiO2掺杂量摩尔分数在1%～4%范围内增加,材料中m-ZrO2相组成增加,相应的烧结密度降低.所形成的镁铝尖晶石相多分布于ZrO2晶粒间,而形成的镁橄榄石相多镶嵌于ZrO2晶粒内.     

Preparation of alumina supported molybdena catalysts by new slurry impregnation method: MoO3/Al2O3 sulfide hydrodesulfurization catalyst

A new slurry impregnation method (SIM) of the preparation of a catalyst or catalyst precursor MoO₃/Al₂O₃ is described. Aqueous slurry of powdered MoO₃ is mixed with alumina extradátes and the mixture is refluxed. A low solubility of MoO₃ is sufficient for transport of MoO₃ from powder form via solution to the surface of the support. The catalysts were tested by hydrodesulfurization of thiophene at 1.6 MPa and 280–400°C. Their activity was similar to the activity of industrial and laboratory MoO₃/Al₂O₃ samples prepared by conventional impregnation with solution of ammonium heptamolybdate. The advantage of the SIM method is that calcination, producing nitrogeneous waste gases, is not required and that all deposited molybdenum species are adsorbed and not precipitated.     

Partial oxidation of ethane over K2MoO4/SiO2 and potassium promoted MoO3/SiO2 catalyst

Silica supported K₂MoO₄ and potassium-promoted MoO₃ were used as catalysts for the partial oxidation of ethane in fix-bed continuous-flow reactor at 770–823 K using N₂O as oxidant. The main products of the oxidation reaction were ethylene, acetaldehyde, CO and CO₂. Addition of various compounds of potassium to the MoO₃/SiO₂ greatly enhanced the conversion of ethane and influenced the product distribution. The highest rate and selectivity for acetaldehyde formation was found on a K₂MoO₄/SiO₂ catalyst.