改性铝土矿载体负载Ru催化剂上的水煤气变换制氢

采用水热法对天然铝土矿进行改性,获得高比表面积的铝土矿(bauxite)载体.用等体积浸渍法制备了Ru含量为1.0%-4.0%(质量分数,下同)的Ru/bauxite催化剂和Ru含量为2.0%的Ru/Al2O3催化剂,以水煤气变换反应为探针反应,考察了催化剂性能.利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、低温N2物理吸附、H2程序升温还原(H2-TPR)以及CO程序升温脱附(CO-TPD)等对载体和催化剂样品进行表征.结果表明,不同Ru含量的Ru/bauxite催化剂具有优异的水煤气变换制氢性能,优于Ru/Al2O3催化剂.其原因是铝土矿本身含有的Fe2O3与负载的Ru之间发生了相互作用,降低了Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的水煤气变换反应性能.     

Fe2O3含量对Cu-Fe/铝土矿水煤气变换催化剂结构和性能的影响

利用具有高比表面积和介孔结构的改性铝土矿为载体,采用并流共沉淀法制备不同Fe₂O₃含量的Cu-Fe/铝土矿催化剂。以水煤气变换反应为探针反应,考察了催化剂性能。利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、H₂程序升温还原(H₂-TPR)、CO程序升温脱附(CO-TPD)和X射线光电子能谱(XPS)等对催化剂进行了表征。结果表明:负载的Fe₂O₃能显著提高CuO/改性铝土矿催化剂的水煤气变换活性特别是热稳定性能,且随负载的Fe₂O₃含量增加而提高,当负载量为20%时达到最佳。其原因是负载的Fe₂O₃和CuO之间发生了相互作用,形成了类似于CuFe₂O₄复合氧化物,且随负载的Fe₂O₃含量的增加而增强,这种相互作用同时促进了CuO和Fe₂O₃的还原,抑制了CuO的烧结,进而提高了催化剂的性能。     

焙烧温度对低温水煤气变换Au/Fe2O3催化剂性能的影响

采用改性沉积-沉淀法制备了系列低温水煤气变换Au/Fe2O3催化剂, 发现经300 ℃焙烧的样品具有较好的催化活性和稳定性. 并运用N2物理吸附、原位X 射线粉末衍射(in situ XRD)、程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等技术, 探讨焙烧温度对催化剂性能的影响机制, 同时对样品的失活原因进行了分析. 结果表明, 催化剂性能与焙烧温度引起的金和载体氧化铁的相互作用以及载体还原性质的变化密切相关. XPS表征结果说明, 尽管反应后在催化剂表面有碳酸盐或类碳酸盐物种生成, 但半定量分析表明这些物种的形成不是催化剂失活的主要原因;根据在低温水煤气变换反应过程中Au/Fe2O3催化剂的比表面积明显下降, 载体的结晶度也明显提高, 推断Au/Fe2O3催化剂载体的结构性质的变化才是其失活的主要原因.     

焙烧温度对低温水煤气变换Au/Fe2O3催化剂性能的影响

采用改性沉积-沉淀法制备了系列低温水煤气变换Au/Fe2O3催化剂,发现经300℃焙烧的样品具有较好的催化活性和稳定性.并运用N2物理吸附、原位X射线粉末衍射(in situ XRD)、程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等技术,探讨焙烧温度对催化剂性能的影响机制,同时对样品的失活原因进行了分析.结果表明,催化剂性能与焙烧温度引起的金和载体氧化铁的相互作用以及载体还原性质的变化密切相关.XPS表征结果说明,尽管反应后在催化剂表面有碳酸盐或类碳酸盐物种生成,但半定量分析表明这些物种的形成不是催化剂失活的主要原因;根据在低温水煤气变换反应过程中Au/Fe2O3催化剂的比表面积明显下降,载体的结晶度也明显提高,推断Au/Fe2O3催化剂载体的结构性质的变化才是其失活的主要原因.     

铜物种对Cu/Fe_2O_3水煤气变换反应催化剂性能的影响

采用共沉淀法制备了系列铜负载量不同的Cu/Fe2O3水煤气变换(WGS)催化剂,并考察了铜负载量对催化剂结构和水煤气变换反应性能的影响.结果表明,Cu/Fe2O3催化剂呈现出良好的水煤气反应性能,当CuO质量分数为20%时,催化剂的WGS性能最优,250°C时CO转化率高达97.2%,同时热稳定性也最好.运用X射线粉末衍射(XRD)、N2物理吸脱附和H2程序升温还原(H2-TPR)等手段对Cu/Fe2O3催化剂的物相、织构特征及还原性能进行了表征,结果表明,CuFe2O4物种的存在极大地改善了催化剂的还原性能和WGS反应活性.这是由于CuFe2O4特殊的尖晶石结构有利于Cu微晶的稳定;同时,CuFe2O4在低温下即被还原为单质铜,有利于促进催化剂体系中电子的转移.此外,通过(NH4)2CO3溶液处理,研究了独立相CuO对Cu/Fe2O3催化剂WGS反应性能的影响,结果发现,独立相CuO的存在,有利于H原子在各组分传递,从而促进催化剂的CuFe2O4的还原,改善Cu/Fe2O3催化剂的WGS反应性能.     

不同的沉淀剂对铁酸铜催化剂水煤气变换活性和热稳定性的影响(英文)

以氢氧化钾、碳酸钠和碳酸氢钠为沉淀剂,采用共沉淀法制备3种铁酸铜催化剂,并对其水煤气变换活性和热稳定性进行了评价。测试发现,以氢氧化钾为沉淀剂制得的催化剂表现出优异的水煤气变换活性。通过X射线粉末衍射仪(XRD)、N2物理吸附(N2-physisorption)、H2-程序升温还原(H2-TPR)、CO2-程序升温脱附(CO2-TPD)和循环伏安法(CV)等技术手段研究了不同的沉淀剂对催化剂的微观结构和表面性质的影响。结果发现,氢氧化钾能有效促进CuFe2O4的生成、抑制CuO和CuFe2O4晶格的长大、促使CuO在催化剂表面的较好分散、增强催化剂的还原能力、增加弱碱性位点的数量。它们显著改善了催化剂的催化活性和热稳定性。     

Pt/Ce0.6Zr0.4O2催化剂在水煤气变换反应中的电导研究

采用浸渍法制备了不同载体(Ce0.6Zr0.4O2,CeO2和ZrO2)负载的Pt基水煤气变换反应(WGSR)催化剂, 并对其进行了活性评价. 利用X射线衍射(XRD), 程序升温还原(TPR)和原位电导等技术对样品进行了表征. 结果表明, Ce0.6Zr0.4O2固溶体具有比CeO2更高的氧转移能力, 因此促进了Pt/Ce0.6Zr0.4O2催化剂的WGSR活性.     

沉淀温度对CuO/ZnO/Al2O3催化剂前驱体物相及催化水煤气变换反应活性的影响

 用X射线衍射、差热热重测定、程序升温还原、N2吸附、N2O滴定和常压微反活性评价技术考察了沉淀温度对CuO/ZnO/Al2O3系催化剂及其前驱体的物相和催化水煤气变换反应活性的影响. 结果表明,在沉淀温度为60～90 ℃时,催化剂前驱体中主要存在Cu2CO3(OH)2,(Cu,Zn)2CO3(OH)2和(Cu,Zn)6Al2(OH)16CO3·4H2O三种物相. 焙烧后的催化剂样品中形成了较多的CuO-ZnO固溶体,沉淀温度升高有利于CuO-ZnO固溶体的形成及催化剂活性的提高. 水煤气变换反应是一个非结构敏感型反应.     

Cr 助剂对 Fe 基催化剂结构和费托合成性能的影响

 采用 N2 吸附-脱附、X 射线衍射、穆斯堡尔谱、X 射线光电子能谱、程序升温还原和热重分析等技术研究了助剂 Cr 含量对 Fe 基费托合成催化剂的织构性质、还原行为以及物相变化的影响. 在 H2/CO = 2.0, 260~300 oC, 1.5 MPa 和 2 000 ml/(g•h) 条件下, 在固定床反应器中考察了 Cr 含量对 Fe 基催化剂费托合成反应活性和产物烃选择性的影响. 结果表明, 在氧化态催化剂中, Cr 助剂与 Fe 物相存在较强的相互作用, 形成固溶体相 α-(Cr1-xFex)2O3; 随着 Cr 含量的增加, 逐渐由单一的富 Fe 相 α-(Fe1-xCrx)2O3 向富 Fe 相和富 Cr 相 α-(Cr1-yFey)2O3 两相过渡. Fe-Cr 固溶体的生成显著抑制了催化剂的还原, 导致催化剂还原度降低, 因而催化剂活性下降. 同时, Cr 的添加提高了甲烷和轻质烃选择性, 但抑制了水煤气变换活性.     

La2O3对CuO/CeO2水煤气变换反应催化剂微观结构及催化性能的影响（英文）

以La2O3为助剂,采用共沉淀法制备了具有良好催化活性和热稳定性的CuO/CeO2-La2O3水煤气变换反应催化剂,其中,当La2O3含量为2wt%时,催化剂的催化性能最为优异.同时运用X射线衍射、N2吸附-脱附、Raman光谱、程序升温还原等手段,研究了不同含量的La2O3对CuO/CeO2催化剂微观结构及催化性能的影响.结果表明,La2O3助剂进入了载体CeO2的晶格并对CuO/CeO2催化剂的微观结构和催化性能产生了直接影响,适量La2O3的添加可以抑制CuO和CeO2晶格的长大、增强CuO与CeO2间的相互作用、提高催化剂的比表面积、促进CeO2载体中生成更多的氧空位,CuO/CeO2催化剂的催化活性和热稳定性也明显改善.     

铜物种对Cu/Fe2O3水煤气变换反应催化剂性能的影响

采用共沉淀法制备了系列铜负载量不同的Cu/Fe₂O₃水煤气变换(WGS)催化剂,并考察了铜负载量对催化剂结构和水煤气变换反应性能的影响. 结果表明,Cu/Fe₂O₃催化剂呈现出良好的水煤气反应性能,当CuO质量分数为20%时,催化剂的WGS性能最优,250 ℃时CO转化率高达97.2%,同时热稳定性也最好. 运用X射线粉末衍射(XRD)、N₂物理吸脱附和H₂程序升温还原(H₂-TPR)等手段对Cu/Fe₂O₃催化剂的物相、织构特征及还原性能进行了表征,结果表明,CuFe₂O₄物种的存在极大地改善了催化剂的还原性能和WGS反应活性. 这是由于CuFe₂O₄特殊的尖晶石结构有利于Cu微晶的稳定;同时,CuFe₂O₄在低温下即被还原为单质铜,有利于促进催化剂体系中电子的转移. 此外,通过(NH₄)₂CO₃溶液处理,研究了独立相CuO对Cu/Fe₂O₃催化剂WGS反应性能的影响,结果发现,独立相CuO的存在,有利于H原子在各组分传递,从而促进催化剂的CuFe₂O₄的还原,改善Cu/Fe₂O₃催化剂的WGS反应性能.     

Pt/CexZr1-xO2 催化剂在含硫合成气中催化水煤气变换反应活性

 采用浸渍法制备了 Pt/Ce_xZr_1-xO₂ 催化剂, 通过 X 射线衍射和程序升温还原等方法对催化剂进行了表征, 并在固定床反应器中评价了催化剂在合成气和含硫合成气中的水煤气变换活性. 结果表明, 铈锆固溶体的氧化还原能力强于 CeO₂, Zr 的掺杂明显改善了 CeO₂ 的孔道结构, 其担载的 Pt 催化剂具有更高的金属分散度, 因而活性更高. 两种催化剂在含硫合成气中的催化活性较无硫合成气中的均有所降低, 且 H₂S 浓度越大, 催化剂活性下降越多, 但这种因吸附硫而引起的失活是可逆的, 即催化剂重新暴露在无 H₂S 重整气的还原性气氛下活性能基本恢复.     

Influence of Calcination Temperature on Properties of Au/Fe2O3 Catalysts for Low Temperature Water Gas Shift Reaction

A series of Au/Fe₂O₃ catalysts for the water gas shift (WGS) reaction were prepared by modified deposition-precipitation method. The sample calcined at 300 °C showed higher catalytic activity and better stability than other samples. Using N₂ physisorption, in situ XRD, H₂-TPR, and XPS techniques, the influence of calcination temperature on properties of Au/Fe₂O₃ catalyst was explored, and the cause of deactivation was analyzed as well. The results showed that the catalytic behaviors were related to the interaction between Au and Fe₂O₃, and the reductive property of support, both of which were significantly affected by calcination temperature. Furthermore, according to the results of XPS, although stable carbonate and carbonyl surface species were found on the spent catalysts, the semiquantitative analysis of these species indicated that they were not the main cause of the deactivation. In fact, the deactivation of Au/Fe₂O₃ was sensitive to the structure change of support. During the water gas shift reaction, Fe₃O₄ particle would aggregate and crystallize leading to increase in the crystallinity of support and a significant reduction in the surface area of the catalysts, which resulted in the deactivation of Au/Fe₂O₃.     

Strong Metal–Support Interactions between Copper and Iron Oxide during the High‐Temperature Water‐Gas Shift Reaction

The commercial high‐temperature water‐gas shift (HT‐WGS) catalyst consists of CuO‐Cr₂O₃‐Fe₂O₃, where Cu functions as a chemical promoter to increase the catalytic activity, but its promotion mechanism is poorly understood. In this work, a series of iron‐based model catalysts were investigated with in situ or pseudo in situ characterization, steady‐state WGS reaction, and density function theory (DFT) calculations. For the first time, a strong metal‐support interaction (SMSI) between Cu and FeO_x was directly observed. During the WGS reaction, a thin FeO_x overlayer migrates onto the metallic Cu particles, creating a hybrid surface structure with Cu‐FeO_x interfaces. The synergistic interaction between Cu and FeO_x not only stabilizes the Cu clusters, but also provides new catalytic active sites that facilitate CO adsorption, H₂O dissociation, and WGS reaction. These new fundamental insights can potentially guide the rational design of improved iron‐based HT‐WGS catalysts.     

Selective Catalytic Reduction of NO with Propene over Au/Fe2O3/Al2O3 Catalysts

A series of Au/Fe₂O₃/Al₂O₃ catalysts were prepared by the homogeneous deposition-precipitation method. The catalytic activity of the catalyst samples for selective catalytic reduction of NO by propene under oxygen-rich atmosphere was evaluated. The results showed that 2%Au/10%Fe₂O₃/Al₂O₃ exhibited good low-temperature activity. The maximum of NO conversion reached 43% at 300 °C, while it was only 21% over the 2%Au/Al₂O₃ catalyst at the same temperature. The addition of 2% steam to the feed gas had little effect on the catalytic activity. X-ray diffraction results indicated that both Au and Fe₂O₃ particles were highly dispersed over Al₂O₃. H₂-temperature-programmed reduction results indicated that there was strong interaction between Au and Fe₂O₃, which made the reduction of Fe₂O₃ easy. The synergistic effect between Au and Fe₂O₃ was probably responsible for the good catalytic performance of the Au/Fe₂O₃/Al₂O₃ catalyst at low temperature.     

Monolith Manganese-Based Catalyst Supported on ZrO2-TiO2 for NH3-SCR Reaction at Low Temperature

Monolith catalysts were prepared using TiO₂ and ZrO₂-TiO₂ as supports with MnO₂ as active component and Fe₂O₃ as promoter. The catalytic activities at low temperature and stability at high temperature for selective catalytic reduction of NO_x with NH₃ (NH₃-SCR) in the presence of excessive O₂ were studied after the catalysts calcined at different temperatures. The catalysts were characterized by X-ray diffraction (XRD), specific surface area measurements (BET), oxygen storage capacity (OSC), and temperature programmed reduction (H₂-TPR). The results indicated that the catalyst supported on ZrO₂-TiO₂ had excellent stability at high temperature, and possessed high specific surface area and oxygen storage capacity, and had strong redox property. The results of the catalytic activities indicated that the monolith manganese-based catalyst using ZrO₂-TiO₂ as support had evidently improved the activity of NH₃-SCR reduction reaction at low temperature, and it showed great potential for practical application.     

Study of CuO/Ce0.8Zr0.2O2 catalysts for low-temperature CO oxidation

Summary Copper oxide catalysts supported on Ce_0.8Zr_0.2O₂ were prepared via an impregnation method and characterized by XRD and H₂-TPR techniques. The catalytic activity of the samples for low-temperature CO oxidation was investigated by means of a microreactor-GC system. The influence of calcination temperature, calcination time and different CuO content on the catalytic activity was studied. TPR analysis indicated that well-dispersed CuO was responsible for the low-temperature CO oxidation. The results of the investigation showed that the calcination temperature and CuO loadings had larger influence than the calcination time.     

Fe3O4修饰的Pt-Ru/C纳米催化剂的制备及其在无溶剂条件下邻氯硝基苯选择性加氢的催化性能

采用浸渍法制备了一系列Pt/Ru质量比不同的Fe₃O₄修饰的Pt-Ru/Fe₃O₄/C催化剂, 运用透射电镜(TEM)、能量弥散X射线谱(EDX)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)等手段对Pt-Ru/Fe₃O₄/C一系列催化剂进行了表征, 并考察了Pt/Ru质量比不同对催化剂Pt-Ru/Fe₃O₄/C在无溶剂条件下催化邻氯硝基苯(o-CNB)选择性加氢制备邻氯苯胺(o-CAN)催化性能的影响. 研究结果表明, 催化剂的催化活性和对目标产物的选择性跟活性组分Pt、Ru比例有关. 随着Pt/Ru比例的减小, 目标产物o-CAN的选择性有所升高, 然而反应物o-CNB的转化率有所下降. 当Pt/Ru的质量比为2时, o-CNB的转化率降为76.5%, 而目标产物o-CAN的选择性仍然为100%. 与此同时, 我们还对Pt-Ru/Fe₃O₄/C催化剂高的催化活性和目标产物的高选择性可能的原因进行了分析.     

甲醇重整反应中Pt/γ-Al2O3催化剂纳米Pt粒径与催化性能关系研究

利用硝基甲烷还原法在室温条件下得到了纳米Pt粒径可控的担载Pt/γ-Al₂O₃催化剂, 并利用甲醇重整反应为反应探针考察了Pt粒径与催化反应性能之间的关系, 发现催化反应的性能与担载贵金属颗粒粒径之间存在明显的相关性. 通过透射电镜(TEM)、X射线衍射(XRD)、程序升温还原(TPR)等测试手段对催化剂进行表征, 发现钠米Pt的粒径大小不但影响甲醇重整反应的活性, 同时也影响反应的选择性, 即催化剂的催化性能与担载贵金属粒径之间存在明显的尺度效应.