过渡金属对分子筛担载Pd催化剂上CO氧化性能影响

分别采用共浸和连续浸渍法制备了一系列添加过渡金属的Pd-M-Ox-NaZSM-5(M=Cr，Mn，Fe，Co，Ni，Cu，Zn，Mo，Zr等)负载型催化剂．以CO氧化为探针反应，考察了不同制备方法对CO氧化性能影响，结果表明共浸法制备的各催化剂其活性明显优于连续浸渍法．详细考察了反应温度、Fe含量、氢气预还原、空速以及水蒸气等对共浸Pd-Fe-Ox-NaZSM-5催化剂上CO氧化行为影响，并应用XRD和XPS等手段对催化剂体相结构和表面状态进行了表征．结果表明：加入Fe2O3可明显提高Pd/NaZSM-5催化剂活性，且催化CO氧化的转化率随反应温度及Fe含量增加而增加；空速增加以及H2预还原作用导致Pd-Fe-Ox-NaZSM-5活性有所降低；催化剂对水蒸气较为敏感．XRD测试结果表明催化剂中Pd组分处于较高分散状态，以红铁矿形式存在的Fe2O3的引入，促进了Pd物种在NaZSM-5载体上的分散．表面XPS分析证实Fe2O3与Pd物种间存在较强的相互协同作用，且催化剂表面Pd物种处于较高氧化状态．Pd的高分散及其与Fe2O3的相互协同作用是共浸催化剂具有高活性的关键因素．     

用于苯催化燃烧的Cu-Mn-O/Ce/γ-Al_2O_3-TiO_2催化剂

采用不同的浸渍法制备了负载型催化剂Cu-Mn-O/Ce/γ-Al2O3-TiO2,应用X射线粉末衍射(XRD)、低温液氮吸附(BET)、H2程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等测试技术对催化剂进行了表征。在200～500℃考察了催化剂催化燃烧较高浓度的苯(体积分数为3.6%)反应中的催化性能。结果表明,15%CuMn2Ox/Al2O3-TiO2催化剂(CuMn2Ox质量分数为15%)在300℃苯的转化率达到79%,其低温催化活性明显高于单独负载氧化铜或氧化锰的催化剂。而采用共浸渍法制备的催化剂15%CuMn2Ox-15%CeO2/Al2O3-TiO2在300℃苯的转化率达81%,其催化活性明显高于分步浸渍法制备的催化剂。CeO2的添加更利于提高共浸渍法制备的催化剂中各活性组分的分散度和相互作用。     

浸渍溶液pH值对Co/TiO2催化剂F-T反应性能的影响

Fischer—Tropsch合成（简称F—T合成）是煤和天然气转化制取液体燃料的重要途径，催化剂的研制与开发是该过程实现工业化的关键步骤。钻基催化剂以其较高的加氢反应活性、较高的长链烃选择性和较低的水煤气变换活性而成为F—T合成中最有前途的催化体系之一。钴基催化剂的制备通常采用浸渍法。除了能够提高催化剂的比表面积和分散度，载体可以与金属发生相互作用而改变活性金属组分的结构组成、电子状态等，从而影响催化剂的催化反应性能。TiO2作为F—T合成的载体近年来受到普遍的关注。文献[7，8]是针对TiO2载体的低表面有针对性地添加无机氧化物黏接剂，提高金属钴的负载量，从而改进催化剂的反应性能；或者是添加助剂及第二金属组分以提高催化剂分散与还原性能。本文通过调节浸渍液pH值控制钻钛的相互作用并与催化剂反应性能关联，以期为催化剂制备条件的选择提供参考。     

Pd catalysts supported on modified Zr0.5Al0.5O1.75 used for lean-burn natural gas vehicles exhaust purification

Composite supports Zr0.5Al0.5O1.75 modified by metal oxides,such as La2O3,ZnO,Y2O3 or BaO,were prepared by co-precipitation method,and palladium catalysts supported on the modified composite supports were prepared by impregnation method.Their properties were characterized by X-ray diffraction(XRD),NH3 temperature-programmed desorption(NH3-TPD),H2 temperature-programmed reduction(H2-TPR),N2 adsorption/desorption,and CO-chemisorption.The catalytic activity and the resistance to water poisoning of the prepared Pd catalysts were tested in a simulated exhaust gas from lean-burn natural gas vehicles with and without water vapor.The results demonstrated that the modified supports had an apparent effect on the performance of Pd catalysts,compared with the Pd catalyst supported on the unmodified ZrAl.The addition of ZnO or Y2O3 promoted the conversion of CH4.In the absence of water vapor,Pd/ZnZrAl exhibited the best activity for CH4 conversion with the light-off temperature(T50) of 275℃ and the complete conversion temperature(T90) of 314℃,respectively.However,in the presence of water vapor,Pd/YZrAl was the best one over which the light-off temperature(T50) of methane was 339℃ and the complete conversion temperature(T90) was 371℃.These results indicated that Pd catalyst supported on the modified composite ZrAl support showed excellent catalytic activity at low temperature and high resistance to H2O poisoning for the exhaust purification of lean-burn natural gas vehicles.     

Hydrodehalogenation of 4-chlorophenol and 4-bromophenol over Pd–Fe/Al2O3: influence of catalyst reduction conditions

The reduction of monometallic Pd/Al₂O₃ and bimetallic PdFe/Al₂O₃ catalysts produced by co-impregnation or sequential impregnation of the support with metal salts was possible not only under high temperature hydrogen treatment but also at 30 °C under the action of aqueous phenol solution and hydrogen. According to the XPS data, both reduction routes provided sufficient degrees of Pd reduction required for fast hydrodehalogenation of 4-chlorophenol and 4-bromophenol to phenol in aqueous solutions. The degree of Pd reduction was higher in the co-impregnated bimetallic PdFe catalyst, which was more efficient in transformation of 4-bromophenol; the bimetallic catalysts were more stable than the monometallic Pd one in the conversion of 4-chlorophenol.     

铈对低负载Pd/Al2O3催化剂加氢丙烯腈的改性效应

钯基催化剂对烯烃及烯烃类衍生物有很好的加氢活性。但钯催化剂价格昂贵，单一的钯容易中毒失活，研究表明：掺入稀土氧化物能够提高钯催化剂在载体上的分散度，增大其氧化及氢化活性，提高催化剂的寿命及稳定性。但稀土助剂对双键选择性加氢影响的研究却很少有报     

整体式Pd/La_2O_3-Al_2O_3和Pd/CeO_2-ZrO_2-Y_2O_3催化剂上汽油车尾气净化性能的比较

采用共沉淀法制备了耐高温高比表面积的La2O3-Al2O3(LA)材料和CeO2-ZrO2-Y2O3(CZY)储氧材料,并用浸渍法制备了整体式Pd/LA和Pd/CZY汽油车尾气净化三效催化剂,考察了它们的三效催化性能和空燃比性能,并单独通过水煤气变换和CO氧化反应性能的考察,探讨了两种催化剂空燃比窗口扩大的原因.结果表明,Pd/CZY催化剂三效窗口明显较宽,且催化氧化CO的性能明显更优;对于CO+NO反应,Pd/CZY催化剂的活性较高.当反应中逐步通入O2后,抑制了该反应的进行,但CO氧化的转化率升高,而NO转化率降低,直至CO+NO反应完全被抑制,表明CO氧化反应对于抑制催化剂在NO贫燃方向的窗口具有一定的作用.另外,Pd/CZY催化剂上对于水煤气变换反应性能明显优于Pd/LA催化剂,在一定温度下逐步通入O2后,不会抑制水煤气变换反应的发生;当逐步通入NO时,可以促进水煤气变换反应的进行,表明Pd/CZY催化剂在富燃时对扩展CO转化窗口的性能明显优于Pd/LA催化剂.     

含钯类水滑石衍生复合氧化物Pd/M3AlO(M=Mg,Co, Ni,Cu, Zn)催化剂上氯苯的催化氧化

采用共沉淀法制备了系列含Pd类水滑石材料, 类水滑石基体为M3Al-HT (M=Mg, Co, Ni, Cu, Zn), 经焙烧制备出含Pd类水滑石衍生复合氧化物催化剂. 通过X射线衍射(XRD), 热重-差热分析(TG-DTG), H2程序升温还原(H2-TPR), O2程序升温脱附(O2-TPD)和N2吸脱附等表征技术手段研究了不同二价金属元素对含Pd类水滑石衍生复合氧化物催化剂物理化学性质及其对挥发性有机污染物氯苯催化氧化性能的影响. XRD和TG-DTG结果表明, 不同二价金属元素, 除Cu外, 都能形成类水滑石层状结构, Pd在不同类水滑石前驱物中均能良好分散. 不同的二价金属元素对催化剂性能的影响不同, 其中Pd/Co3AlO催化剂表现出最高的氯苯催化氧化活性, 其起燃温度和全转化温度分别为182和283 ℃. H2-TPR和O2-TPD测试表明, Pd和类水滑石衍生复合氧化物存在着协同作用, Pd的引入促进了复合氧化物的还原, 从而影响氧化物的氧化还原性能. Pd/M3AlO系列催化剂的活性主要受催化剂的氧化还原性能及其表面活性氧物种的影响.     

Cr2O3-Co3O4／SiO2对十八醇氧化生成十八酸反应的催化性能

 制备了一系列不同Cr／Co比例的Cr2O3－Co3O4／SiO2催化剂，并用XRD，FT－IR和BET等手段对催化剂进行了表征；考察了催化剂对十八醇氧化生成十八酸反应的催化性能，及反应条件（反应温度和反应时间）对催化性能的影响，确定了最佳反应条件．结果表明，金属硝酸盐在773K焙烧后转变成相应的氧化物并负载于二氧化硅上．Cr2O3－Co3O4／SiO2催化剂对十八醇氧化反应有很高的催化活性，十八酸选择性最高可达99．93％，收率可达52．44％．Cr2O3－Co3O4／SiO2催化剂的活性明显高于单一的Cr2O3／SiO2或Co3O4／SiO2催化剂     

Effects of impregnation sequence on the microstructure and performances of Cu-Co based catalysts for the synthesis of higher alcohols

Silica-supported CuCo catalysts were prepared by impregnation method with different impregnation sequence for higher alcohols synthesis. These catalysts were characterized by H2-TPR, XRD, N2 adsorption, XPS techniques and CO selective hydrogenation reaction measurement. The effects of impregnation sequence on the structure and performance of catalysts were investigated, and there were important influences on the selectivity to higher alcohols. There was a strong synergistic effect between copper and cobalt for the co-impregnated sample. The CuCo/SiO2 catalyst prepared by co- impregnation showed a better yield of total alcohols, and a higher selectivity to total alcohols which reached 51.5%.     

制备方法对Co-MOR催化剂CH4选择还原NO性能的影响

采用离子交换法、浸渍法制备一系列的Co-MOR 催化剂, 并将其用于CH₄选择性催化还原 NO_x(CH₄-SCR)反应. 运用X 射线衍射(XRD)、X 射线荧光光谱(XRF)、扫描电子显微镜(SEM)、紫外-拉曼(UVRaman)光谱、X射线光电子能谱(XPS)、NO程序升温脱附(NO-TPD)等手段对催化剂进行了表征. 结果表明, 浸渍法制备的催化剂, Co以Co₃O₄形式存在; 而离子交换法制备的催化剂, Co以离子形式进入丝光沸石(MOR)骨架之中, 在催化剂上形成更多的Co²⁺和[Co-O-Co]²⁺, 形成更均匀NO吸附中心和CH₄-SCR反应活性中心. 催化剂活性评价表明离子交换法制备的催化剂具有更宽的活性温度区间, Co(0.30)-MOR 催化剂在327-450℃温度范围内NO转化率大于50%.     

CeO2-ZrO2-La2O3-Al2O3 composite oxide and its supported palladium catalyst for the treatment of exhaust of natural gas engined vehicles

Composite supports CeO2-ZrO2-Al2O3 (CZA) and CeO2-ZrO2-Al2O3-La2O3 (CZALa) were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles (NGVs) operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction (XRD) and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperature-programmed reduction (H2-TPR) and oxygen storage capacity (OSC) measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. The catalysts reported in this work also have significant potential in industrial application because of their high performance and low cost.     

准“原位”XPS技术研究加氢精制催化剂的硫化过程

用准“原位”XPS技术研究了Mo/Al_2O_3、Mo/TiO_2-Al_2O_3、CO/Al_2O_3、CO/TiO_2-Al_2O_3、Co-Mo-Al_2O_3和Co-Mo/TiO_2-Al_2O_3等催化剂的硫化过程．结果表明：对以Al_2O_3为载体的催化剂，当Mo或Co载量较低(分别低于0.05 gMoO_3/gAl_2O_3或0.03gCoO/gAl_2O_3)时，没有Mo或Co硫化物的生成，而以TiO_2改性的Al_2O_3为载体的催化剂，Mo/TiO_2-Al_2O_3催化剂的硫化较Mo/Al_2O_3容易得多, 表现为在较低温度下，负载在TiO_2改性Al_2O_3载体上的MoO_3，能很快硫化并达到相当大的硫化度, 对Co/Al_2O_3催化剂而言，即使在较高温度400 ℃时，载体上高分散的CoO物种仍难以硫化；而Co_3O_4微晶的硫化却容易得多, 载体用TiO_2改性，并不影响高分散形态的CoO催化剂的硫化，却明显地影响Co_3O_4微晶的硫化．噻吩加氢脱硫(HDS)的活性测量指出，对Co-Mo/Al_2O_3和Co-Mo/TiO_2-Al_2O_3催化剂而言，HDS活性和硫化度之间存在着良好的相关性．并用TiO_2改性载体，可以增加Co-Mo催化剂的HDS活性和硫化度.     

Au-Cu/Co3O4双金属催化剂上乙烯完全催化氧化性能

以共沉淀法制得的Co₃O₄为载体, 采用两步法负载Au和Cu制得了一系列Au-Cu/Co₃O₄双金属催化剂, 考察了Au-Cu/Co₃O₄双金属催化剂完全催化氧化乙烯的性能, 并通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、H₂程序升温还原(H₂-TPR)和O₂程序升温脱附(O₂-TPD)对催化剂进行了表征. 活性测试结果表明: 负载型Au-Cu/Co₃O₄双金属催化剂的催化性能优于单一金属催化剂Au/Co₃O₄, 并且在Au负载量为4% (w, 质量分数)时, 与AuCu/Co₃O₄和Au₃Cu/Co₃O₄催化剂相比, AuCu₃/Co₃O₄催化剂的催化活性较好, 0 ℃时可催化转化15.3%的乙烯为CO₂和H₂O, 120 ℃时100%催化转化乙烯. XRD和HRTEM表明, AuCu₃/Co₃O₄催化剂中有Au-Cu合金相的生成, 而Au₃Cu/Co₃O₄催化剂中Cu主要以氧化物的形式存在. Au和Cu之间产生相互作用, 使活性相金属的粒径降低. H₂-TPR和O₂-TPD分析结果表明, AuCu₃/Co₃O₄催化剂具有较强的低温可还原能力和可提供的大量表面活性吸附氧物种, 促进了乙烯的完全催化氧化.     

Co—Mo／Al2O3催化剂的微结构

B_(302Q)型Co-Mo/Al_2O_3催化剂在制备过程中要经过一高温区,活性组分Co、Mo会与载体Al_2O_3发生反应,生成无活性的CoAl_2O_4,CoMoO_4和低活性的CO_9S_8。而活性相MoS_2晶化程度加快,使催化剂活性降低。不过B_(302Q)比C_(25-2-02)(美国),SKK(丹麦)及     

铜钼组分对γ-Al2O3负载镍催化剂脂肪酸甲酯加氢脱氧性能的影响

制备一系列包含或不包含铜、钼组分的Ni/γ-Al₂O₃催化剂,并对其进行表征和性能测试。考察了铜、钼负载量,浸渍顺序（包括连续浸渍和共浸渍）,反应条件对脂肪酸甲酯加氢脱氧反应性能的影响。根据TG数据,使用过的20Ni-6Cu/γ-Al₂O₃催化剂其热失重小于20Ni/γ-Al₂O₃催化剂,这表明,铜的引入能够有效抑制反应过程中催化剂表面的积炭行为。对于20Ni-6Cu/γ-Al₂O₃和20Ni-6Cu-nMo/γ-Al₂O₃（n=2、5、8和12）催化剂,NH₃-TPD分析结果显示,钼物相的引入对载体γ-Al₂O₃的酸性位有着显著影响,当钼负载量达到5%时,可以观察到一个新的酸位对应于中强酸位。铜和钼修饰过的催化剂其催化性能要高于Ni/γ-Al₂O₃催化剂。从XPS的分析可以看出,催化剂中的铜主要以正二价形式存在,钼主要以正四价和正六价形式存在,而且不同的浸渍顺序会影响催化剂表面活性组分的实际含量。此外,脂肪酸甲酯的转化率和烷烃产品的收率也和所制备出来的催化剂的浸渍顺序有关。在所有的催化剂中,使用连续浸渍（先浸渍镍铜组分、浸渍钼组分）所制备的三金属20Ni-6Cu-5Mo/γ-Al₂O₃催化剂展现了优异的催化性能。在适宜的反应条件下（350 ℃,2.5 MPa,WSHV=2.0 h^-1,H₂/oil ratio=1250 mL/mL）,脂肪酸甲酯的转化率和烷烃产品的收率分别达到98.4%和94.2%。     

(CeO_2-ZrO_2-Al_2O_3)-(La_2O_3-Al_2O_3)复合氧化物负载的Pd密偶催化剂:载体焙烧温度的影响

采用同时共沉淀法制备了(CeO2-ZrO2-Al2O3)-(La2O3-Al2O3)新型复合氧化物(CZA-LA),考察了焙烧温度对CZA-LA负载的Pd密偶催化剂的影响,并采用N2吸附-脱附法和X射线衍射对其进行了表征.结果表明,随着焙烧温度的升高,尽管CZA-LA样品的比表面积降低,但即使在1000°C焙烧5h后,其比表面积仍能保持在122m2/g左右;另外,CZA-LA样品的孔体积降低幅度不大,当在700℃及更高温度下焙烧后基本上保持稳定.以不同温度焙烧5h后的样品为载体,采用等体积浸渍法制备了一系列整体式Pd/CZA-LA密偶催化剂(Pd含量2.0g/L).催化剂对消除模拟汽油车尾气中C3H8活性测试结果表明,各新鲜催化剂的活性相差不大,均具有较低的起燃温度T50和完全转化温度T90.当催化剂经老化处理后,以1000°C焙烧的载体负载的Pd催化剂活性最高,T50和T90分别为310和341℃,ΔT仅为31℃,仅比新鲜催化剂的高7℃.可见,该催化剂表现出优异的催化活性和抗老化性能,可以满足欧Ⅳ及更高标准的用于汽油车尾气净化的密偶催化剂的性能要求.     

Influence of CeO2 and La2O3 on properties of palladium catalysts used for emission control of natural gas vehicles

Pd/YZ-Al2O3 (Y and Zr modified Al2O3, and hereafter, labelled as Al) catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy (XPS), NO-temperature programmed desorption (NO-TPD), N2-adsorption/desorption (Brunauer-Emmet-Teller BET method), X-ray diffraction (XRD) and CO-chemisorption. Catalytic activities for CH4, CO and NO conversion were tested in a gas mixture simulated the emissions from natural gas vehicles (NGVs) operated under stoichiometric conditions. The results indicated that all catalysts exhibited excellent catalytic performances for CH4 and CO oxidation and the promoting effect of CeO2 or La2O3 was significant for NO conversion. XPS results showed that the electron density around Pd was increased by CeO2 and/or La2O3, the binding energy of Pd 3d decreased as the order: Pd/Al>Pd/Ce/Al>Pd/La/Al>Pd/CeLa/Al. The electron-rich Pd showed Rh-like catalytic properties which exhibited good activity for the reduction of NO. NO-TPD results showed that the addition of CeO2 and/or La2O3 increased NO adsorption on surface, and promoted the conversion of NO.     

几种方法制备的H3PW12O40/SiO2催化剂的结构和催化性能

 针对H3PW12O40(HPW)的比表面积小和不易回收利用等缺点,分别采用浸渍法、溶胶-凝胶法和以离子液体为模板剂的溶胶-凝胶法制备了HPW/SiO2催化剂,采用傅里叶变换红外光谱、 X射线衍射、 N2物理吸附和吸附氨的程序升温脱附等技术对催化剂样品进行了表征,并考察了其对苯硝化反应的催化性能. 结果表明,所制备的催化剂样品都保持了HPW原有的Keggin结构. 浸渍法制备的催化剂的比表面积(475.2 m2/g)较小,使用4次后硝基苯的收率由82.4%下降到70.7%; 溶胶-凝胶法制备的催化剂的比表面积(498.6 m2/g)居中,使用4次后硝基苯的收率由85.1%下降到79.6%; 以［emim］BF4离子液体为模板剂,采用溶胶-凝胶法制备的催化剂含有介孔结构,比表面积(558.5 m2/g)最高,使用4次后硝基苯的收率由84.7%下降到79.9%. 不同方法制备的HPW/SiO2催化剂具有较高的催化苯硝化反应活性和较好的稳定性.     

Cu改性ZIF-67衍生的Co3O4/C催化剂的CO-SCR脱硝特性

采用CO气体对NO进行选择性催化还原(CO-SCR)是一种有前景的脱硝技术.目前已报道的CO-SCR催化剂的脱硝特性主要是在无氧条件下开展的研究,考虑到实际应用情况,探究一种在有氧环境中具有较高脱硝效率的催化剂是很有必要的.作为一种新型功能性材料的金属有机骨架是脱硝催化剂的优良载体,其中ZIFs系列具有优良的性能.引入Cu对ZIF-67衍生的Co₃O₄/C进行改性,通过浸渍法在载体上负载铜后,热解氧化获得一系列CuO_x/Co₃O₄/C催化剂.利用ICP、 SEM、 XRD、 TEM、 TGA、 XPS、 BET和H₂-TPR等技术对催化剂的物理化学性质进行表征,结果表明,由于Cu的引入增加了表面的氧空位,改善了氧化还原能力,进而提高了催化剂脱硝活性.在制备的一系列催化剂中, 8.0 CuO_x/Co₃O₄/C在300℃时即可达到约95%NO转化率,并且其N₂选择性也达到9...