ZnSO_4和La_2O_3作共修饰剂单金属Ru催化剂上苯选择加氢制环己烯

用沉淀法制备了单金属纳米Ru(0)催化剂,考察了ZnSO4和La2O3作共修饰剂对该催化剂催化苯选择加氢制环己烯性能的影响,并用X射线衍射(XRD)、X射线荧光(XRF)光谱、X射线光电子能谱(XPS)、俄歇电子能谱(AES)、透射电镜(TEM)和N2物理吸附等手段对加氢前后催化剂进行了表征.结果表明,在ZnSO4存在下,随着添加碱性La2O3量的增加,ZnSO4水解生成的(Zn(OH)2)3(ZnSO4)(H2O)x(x=1,3)盐量增加,催化剂活性单调降低,环己烯选择性单调升高.当La2O3/Ru物质的量比为0.075时,Ru催化剂上苯转化率为77.6%,环己烯选择性和收率分别为75.2%和58.4%.且该催化体系具有良好的重复使用性能.传质计算结果表明,苯、环己烯和氢气的液-固扩散限制和孔内扩散限制都可忽略.因此,高环己烯选择性和收率的获得不能简单归结为物理效应,而与催化剂的结构和催化体系密切相关.根据实验结果,我们推测在化学吸附有(Zn(OH)2)3(ZnSO4)(H2O)x(x=1,3)盐的Ru(0)催化剂有两种活化苯的活性位:Ru0和Zn2+.因为Zn2+将部分电子转移给了Ru,Zn2+活化苯的能力比Ru0弱.同时由于Ru和Zn2+的原子半径接近,Zn2+可以覆盖一部分Ru0活性位,导致解离H2的Ru0活性位减少.这导致了Zn2+上活化的苯只能加氢生成环己烯和Ru(0)催化剂活性的降低.本文利用双活性位模型来解释Ru基催化剂上的苯加氢反应,并用Hückel分子轨道理论说明了该模型的合理性.     

Ru-[bmim]BF4 的制备及催化苯选择加氢反应性能

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)-水混合溶剂为介质,采用化学还原法制备了Ru-[bmim]BF4催化剂,并利用紫外-可见光谱、红外光谱、透射电镜、X射线衍射和X射线光电子能谱对催化剂进行了表征.结果表明,Ru在[bmim]BF4中分散较好,粒径~2nm,且离子液体中咪唑阳离子与部分Ru形成了金属卡宾配合物.利用苯选择加氢反应对该催化剂性能进行了评价,发现Ru-卡宾配合物存在时,催化剂活性较低,但环己烯选择性较高.在本文反应条件下,苯转化率为12.2%,环己烯选择性为40.5%.重复使用该催化剂时,由于Ru-卡宾配合物在反应中转变为Ru0,其催化活性增加,但环己烯选择性下降.继续多次使用该催化剂,其性能基本保持稳定.     

MIL-101限域Au纳米颗粒催化对硝基苯酚加氢反应

利用MIL-101有序纳米孔道的限域能力,制备出一系列尺寸较小且分散度均匀的Au纳米颗粒Au@MIL-101催化剂,通过X射线衍射、高分辨透射电子显微镜、物理吸附仪和原子发射光谱仪对该催化剂进行了表征.该催化剂在温和的反应条件下对对硝基苯酚加氢反应表现出良好的催化活性.     

MIL-100(Fe) Supported Pt−Co Nanoparticles as Active and Selective Heterogeneous Catalysts for Hydrogenation of 1,3-Butadiene

Superior catalytic performance for selective 1,3-butadiene (1,3-BD) hydrogenation can usually be achieved with supported bimetallic catalysts. In this work, Pt−Co nanoparticles and Pt nanoparticles supported on metal–organic framework MIL-100(Fe) catalysts (MIL=Materials of Institut Lavoisier, PtCo/MIL-100(Fe) and Pt/MIL-100(Fe)) were synthesized via a simple impregnation reduction method, and their catalytic performance was investigated for the hydrogenation of 1,3-BD. Pt1Co1/MIL-100(Fe) presented better catalytic performance than Pt/MIL-100(Fe), with significantly enhanced total butene selectivity. Moreover, the secondary hydrogenation of butenes was effectively inhibited after doping with Co. The Pt1Co1/MIL-100(Fe) catalyst displayed good stability in the 1,3-BD hydrogenation reaction. No significant catalyst deactivation was observed during 9 h of hydrogenation, but its catalytic activity gradually reduces for the next 17 h. Carbon deposition on Pt1Co1/MIL-100(Fe) is the reason for its deactivation in 1,3-BD hydrogenation reaction. The spent Pt1Co1/MIL-100(Fe) catalyst could be regenerated at 200 °C, and regenerated catalysts displayed the similar 1,3-BD conversion and butene selectivity with fresh catalysts. Moreover, the rate-determining step of this reaction was hydrogen dissociation. The outstanding activity and total butene selectivity of the Pt1Co1/MIL-100(Fe) catalyst illustrate that Pt−Co bimetallic catalysts are an ideal alternative for replacing mono-noble-metal-based catalysts in selective 1,3-BD hydrogenation reactions.     

A highly active multi‐usable palladium pyridylfluorene film‐based catalyst for C–C cross‐coupling reactions

The two terminal pyridyl nitrogen atoms of 2,7‐bis(4‐pyridyl)fluorene ( 1 ) were coordinated to Pd(II) ions to give self‐assembled, multilayer films using the layer‐by‐layer (LbL) method. The films were prepared by alternately dipping the substrate, pre‐coated with a polyethyleneimine layer, in aqueous solutions of PdCl₂ and ethanol solutions of 1 . The resulting films were characterized using UV–visible absorption spectroscopy, atomic force microscopy (AFM), X‐ray photoelectron spectroscopy, scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP‐AES). UV–visible spectra and SEM images show almost uniform growth of the film in a near ideal LbL manner. AFM images show that nanostructured aggregates of Pd(II) complexes form on the surface. With an increase in the number of Pd(II)/ 1 bilayers, more particulate aggregates are distributed on the surface. When released from the substrate, the Pd(II) complex nanostructure shows high catalytic activity for Suzuki–Miyaura and Mizoroki–Heck cross‐coupling reactions. The catalyst loading is as low as 9.1 × 10^?3 mol% Pd, as measured using ICP‐AES, and high turnover numbers of up to 1.08 × 10⁴ are obtained. Copyright © 2015 John Wiley & Sons, Ltd.     

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.     

Fe3O4改性的Ru/γ-Al2O3催化剂的原位液相加氢性能

采用分步浸渍法制备负载型Ru-Fe₃O₄/γ-Al₂O₃ 催化剂, 并利用透射电子显微镜(TEM)、X 射线衍射(XRD)、N₂吸附-脱附(BET)、傅里叶变换红外(FTIR)光谱与X射线光电子能谱(XPS)表征催化剂的纳米颗粒粒径分布、晶相组成、表面结构及吸附物种等性质. 将Ru-Fe₃O₄/γ-Al₂O₃催化剂用于3,4-二氯硝基苯选择性原位液相加氢反应, 考察了反应条件对催化活性的影响, 并讨论了不同制备条件下催化剂的稳定性能. 结果表明, 在473 K、液压3 MPa、原料质量分数2%, 乙醇/水体积比75:25 的反应条件下, 3,4-二氯硝基苯的转化率为100%, 3,4-二氯苯胺的选择性高达96.4%. Fe₃O₄含量对催化剂稳定性能有显著影响, 当Ru和Fe 的质量分数分别为2%和6%时, 催化剂可稳定200 h以上. 表面吸附CO与积碳是导致催化剂失活的主要原因, 以Fe₃O₄作为高效的助剂, 进行水汽转换(WGS)反应与费托合成(FTS)可移除CO, 而采用煅烧法去除表面积碳. 晶相变化与纳米颗粒的聚集可能导致催化剂部分失活, 其原因以及再生方法需进一步考察.     

Green synthesis of silver nanoparticles using Eucalyptus comadulensis leaves extract and its immobilization on magnetic nanocomposite (GO-Fe3O4/PAA/Ag) as a recoverable catalyst for degradation of organic dyes in water

The magnetically recyclable graphene oxide-Fe₃O₄/polyallylamine (PAA)/Ag nanocatalyst was prepared via a green route using Eucalyptus comadulensis leaves extract as both reducing and stabilizing agent. The catalytic activity of this nanocatalyst was investigated for the reduction reaction of methylene blue and methyl orange in the presence of NaBH₄ in aqueous medium at room temperature. The prepared nanocatalyst was characterized by different methods such as Fourier transformed infrared spectroscopy, X-ray diffraction, scanning electron microscopy–energy dispersive X–ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, transmission electron microscopy, and UV–visible spectroscopy. The results show that graphene oxide/PAA/Ag nanocatalyst has good activity and recyclability, and can be reused several times without major loss of activity in the reduction process. The apparent rate constants of the methyl orange (MO) and methylene blue (MB) were calculated to be 0.077 s⁻¹ (3 mg of catalyst) and 0.15 s⁻¹ (2 mg of catalyst), respectively.     

CuSO_4/TiO_2催化剂在氨选择性催化还原氮氧化物反应中的性能(英文)

氮氧化物(NO_x)是主要的大气污染物之一.氨气选择性催化还原法(NH_3-SCR)是目前去除固定源排放的氮氧化物的最有效方法,被广泛用于燃煤或者生物质的火电厂中.催化剂是NH_3-SCR法的核心,其中V_2O_5-WO_3/TiO_2催化剂是主要的商业SCR催化剂;但是V_2O_5有毒,对环境的影响很大;另外,该催化剂具有较高的SO_2氧化性能.因而研究者一直在探索新型的SCR催化剂.SO_2是燃煤电厂烟气中的典型气体之一,所以抗硫性能是催化剂的一个重要指标.在SCR反应条件下,SO_2和O_2容易与氧化物催化剂发生反应生成稳定性较高的硫酸盐,覆盖在催化剂表面从而引起催化剂失活.但已有研究发现,硫化会提高K中毒后的V_2O_5-WO_3/TiO_2催化剂的活性.并且,短时间的硫化可以明显提高CuO/Al_2O_3的NH_3-SCR活性.硫酸盐催化剂或许具有较低毒性和较高抗硫性能,应该是一种有前景的SCR催化剂.本文以商业纳米TiO_2为载体,采用湿式浸渍法制备了一系列的CuSO_4/TiO_2催化剂.在自制的活性评价装置上测试了样品的NH_3-SCR活性并且在340℃下连续24 h测试了SO_2、水蒸气及两者共同作用对催化剂活性的影响.使用N_2等温吸附-脱附、X射线衍射(XRD)、X射线光电子能谱(XPS)、H_2程序升温还原(H2-TPR)和NH_3程序升温脱附(NH_3-TPD)对催化剂进行了表征.另外,采用原位红外漫反射光谱研究了CuSO_4/TiO_2催化剂上的NH_3-SCR反应过程.N_2等温吸附-脱附结果表明,负载的CuSO_4没有明显改变载体的孔结构.而XRD结果仅显示锐钛矿TiO_2的衍射峰,说明CuSO_4在载体上有较好的分散度或者CuSO_4的含量低于检测限.XPS结果显示,催化剂中的铜主要以Cu~(2+)形式存在,硫主要以SO_4~(2-)形式存在,而氧主要以晶格氧和吸附氧两种形式存在,并且CuSO_4的存在会增加催化剂中吸附氧的含量.H_2-TPR结果表明,随着CuSO_4含量的增加,催化剂的氧化还原能力逐渐增强.NH_3-TPD结果表明,催化剂表面的酸性位数目随着样品中CuSO_4含量的增加而增加.纯TiO_2的NH_3-SCR活性很差,当温度从300℃增加到450℃时,最高NO_x转化率仅为32.7%.但当CuSO_4负载到TiO_2上以后,催化剂活性明显提高.在反应温度高于340℃时,CuSO_4/TiO_2催化剂的NO_x转化率在94%以上,与商业V_2O_5-WO_3/TiO_2催化剂相当,并且其N_2O生成量低于商业催化剂.不过,当温度低于340℃时,CuSO_4/TiO_2催化剂的NO_x转化率明显低于商业催化剂,说明CuSO_4/TiO_2催化剂的活性仍有待改善.连续24 h测试了SO_2、水蒸汽及两者的共同作用对CuSO_4/TiO_2催化剂活性的影响.结果显示,单独的水蒸气会导致活性轻微下降,但SO_2以及两者共同存在时对催化剂的活性基本没有影响.CuSO_4/TiO_2催化剂的NH_3吸附红外光谱表明,催化剂上存在Lewis和Bronsted两种酸性位,但Bronsted酸性位上的NH_4~+稳定性较差,280℃时即基本消失.在高温时,NH_3主要吸附在Lewis酸性位上且CuSO_4/TiO_2催化剂对NO_x的吸附能力较差,红外光谱未检测到NO_x的吸附峰.380℃下,当NO和O_2通入预吸附NH_3的催化剂样品时,属于Lewis酸性位上NH_3的红外峰明显下降,说明Lewis酸性位上吸附的NH_3参与了反应.CuSO_4/TiO_2显示出高的抗硫抗水性能和比较好的NH_3-SCR活性,应该是一种有应用前景的SCR催化剂.CuSO_4可以增加催化剂的酸性位数目和吸附氧量.根据原位红外漫反射结果,CuSO_4/TiO_2上的SCR反应遵循Eley-Rideal机理.气相的NO与吸附在Lewis酸性位上的NH_3反应生成N_2和H_2O或许是主要的反应途径,并且吸附氧可能会促进这个过程.     

Selective hydrogenation of monosubstituted alkenes by Pd nanoparticles embedded in polyelectrolyte films

Pd nanoparticles embedded in multilayer polyelectrolyte films can be easily prepared through layer-by-layer adsorption of poly(acrylic acid) (PAA) and poly(ethyleneimine)-Pd2+ (PEI-Pd(II)) complexes followed by reduction of Pd(II) with NaBH4. Transmission electron microscopy confirms the formation of Pd particles with diameters of 1-3 nm. Remarkably, [PAA/PEI-Pd(0)]3PAA films catalyze the hydrogenation of monosubstituted alkenes with turnover frequencies that are as much as 100-fold higher than turnover frequencies for hydrogenation of multiply substituted double bonds. Selectivities in the hydrogenation of monosubstituted over multisubstituted double bonds are higher than those of Wilkinson's catalyst. Moreover, the turnover frequency for the hydrogenation of allyl alcohol did not change when the catalyst was recycled three times. Intramolecular selectivity for the hydrogenation of monosubstituted alkenes also occurs when substrate molecules contain both mono and multiply substituted double bonds. The combination of the encapsulating polyelectrolyte film and small nanoparticles apparently results in hindered access of multiply substituted double bonds to catalytic sites.     

低浓度甲烷甲醇深度氧化Ag/La0.6Sr0.4MnO3催化剂

用柠檬酸溶胶－凝胶法制备钙钛矿型Ｌａ０．６Ｓｒ０．４ＭｎＯ３氧化物,并用Ａｇ对其进行修饰,制得Ａｇ／Ｌａ０．６Ｓｒ０．４ＭｎＯ３系列催化剂。结果表明,６％Ａｇ／Ｌａ０．６Ｓｒ０．４ＭｎＯ３催化剂上甲烷或甲醇氧化转化９５％时的反应温度Ｔ９５可低至７３５Ｋ（对ＣＨ４）或４２１Ｋ（对ＣＨ３ＯＨ）;适量Ａｇ的负载修饰并不改变催化剂基质氧化物Ｌａ０．６Ｓｒ０．４ＭｎＯ３的纳米级钙钛矿型结构;Ａｇ的掺杂诱使催     

ZnSO4和La2O3作共修饰剂单金属Ru催化剂上苯选择加氢制环己烯

用沉淀法制备了单金属纳米Ru（0）催化剂,考察了ZnSO₄和La₂O₃作共修饰剂对该催化剂催化苯选择加氢制环己烯性能的影响,并用X射线衍射（XRD）、X射线荧光（XRF）光谱、X射线光电子能谱（XPS）、俄歇电子能谱（AES）、透射电镜（TEM）和N₂物理吸附等手段对加氢前后催化剂进行了表征. 结果表明,在ZnSO₄存在下,随着添加碱性La₂O₃量的增加,ZnSO₄水解生成的（Zn（OH）₂）₃（ZnSO₄）（H₂O）_x（x=1,3）盐量增加,催化剂活性单调降低,环己烯选择性单调升高. 当La₂O₃/Ru 物质的量比为0.075 时,Ru催化剂上苯转化率为77.6%,环己烯选择性和收率分别为75.2%和58.4%. 且该催化体系具有良好的重复使用性能. 传质计算结果表明,苯、环己烯和氢气的液-固扩散限制和孔内扩散限制都可忽略. 因此,高环己烯选择性和收率的获得不能简单归结为物理效应,而与催化剂的结构和催化体系密切相关. 根据实验结果,我们推测在化学吸附有（Zn（OH）₂）₃（ZnSO₄）（H₂O）_x（x=1,3）盐的Ru（0）催化剂有两种活化苯的活性位：Ru⁰和Zn²⁺. 因为Zn²⁺将部分电子转移给了Ru,Zn²⁺活化苯的能力比Ru⁰弱. 同时由于Ru和Zn²⁺的原子半径接近,Zn²⁺可以覆盖一部分Ru⁰活性位,导致解离H₂的Ru⁰活性位减少. 这导致了Zn²⁺上活化的苯只能加氢生成环己烯和Ru（0）催化剂活性的降低. 本文利用双活性位模型来解释Ru基催化剂上的苯加氢反应,并用Hückel分子轨道理论说明了该模型的合理性.     

均相苯乙酮加氢反应研究

合成了一种新的钌膦配合物[RuCl2(Dmpp)2en](Dmpp=4-(2，6-二甲氧吡啶基)二苯基膦，en=乙二胺)，对其结构进行了表征．系统研究了反应温度，氢气压力，底物和催化剂的比例，碱和催化剂的比例等反应条件对[RuCl2(Dmpp)2en]催化的芳香酮加氢反应活性的影响，证明其在苯乙酮加氢反应中具有很好的催化活性．     

两相体系中催化氢化丙烯腈制备丙腈

膦配体TPPTS(三-间磺酸钠-三苯基膦)的水溶性很好,有关其过渡金属配合物催化剂的应用与研究活跃。近年来,对丙烯腈C=C双键加氢的研究多集中在以钯为中心金属的多相催化体系上,已报道的有聚硅氧烷钯体系,膦酸锆负载钯体系,高分子负载钯．金属氧化物催化剂,SiO2负     

Self-assembled graphene/azo polyelectrolyte multilayer film and its application in electrochemical energy storage device

Graphene/azo polyelectrolyte multilayer films were fabricated through electrostatic layer-by-layer (LbL) self-assembly, and their performance as electrochemical capacitor electrode was investigated. Cationic azo polyelectrolyte (QP4VP-co-PCN) was synthesized through radical polymerization, postpolymerization azo coupling reaction, and quaternization. Negatively charged graphene nanosheets were prepared by a chemically modified method. The LbL films were obtained by alternately dipping a piece of the pretreated substrates in the QP4VP-co-PCN and nanosheet solutions. The processes were repeated until the films with required numbers of bilayers were obtained. The self-assembly and multilayer surface morphology were characterized by UV-vis spectroscopy, AFM, SEM, and TEM. The performance of the LbL films as electrochemical capacitor electrode was estimated using cyclic voltammetry. Results show that the graphene nanosheets are densely packed in the multilayers and form random graphene network. The azo polyelectrolyte cohesively interacts with the nanosheets in the multilayer structure, which prevents agglomeration of graphene nanosheets. The sheet resistance of the LbL films decreases with the increase of the layer numbers and reaches the stationary value of 1.0 × 10(6) Ω/square for the film with 15 bilayers. At a scanning rate of 50 mV/s, the LbL film with 9 bilayers shows a gravimetric specific capacitance of 49 F/g in 1.0 M Na(2)SO(4) solution. The LbL films developed in this work could be a promising type of the electrode materials for electric energy storage devices.     

Mn_xCo_(3-x)O_4复合氧化物及改性催化剂催化分解N_2O

用共沉淀法制备了一组不同组成的MnxCo3-xO4尖晶石型复合氧化物,表面负载碱金属助剂制备改性催化剂,用于催化分解N2O.用X射线衍射(XRD)、N2物理吸附(BET)、红外光谱(FTIR)、扫描电镜(SEM)、H2程序升温还原(H2-TPR)、X射线光电子能谱(XPS)等技术表征催化剂结构.考察了复合氧化物组成、碱金属助剂类型、钾前驱物等制备参数对催化剂结构和催化活性的影响.结果表明:添加助剂K、Cs降低了催化剂表面Co、Mn元素的电子结合能,弱化了Co—O和Mn—O键,有利于氧物种的脱除,提高了催化剂活性.优化出了活性较高的催化剂K/Mn0.4Co2.6O4(K2CO3),有氧无水、有氧有水气氛400℃连续反应50 h,N2O转化率分别保持100%和74.2%,催化剂稳定性较高.     

封装型Pt/SOD分子筛的合成及表征

基于封装型贵金属分子筛的合成,充分利用其择形性和氢溢流特性构建新型加氢催化剂,选定Pt作为活性组分,方钠石作为载体,通过水热合成法直接将金属前驱体Pt(NH_3)_4Cl_2引进SOD合成母液中进行晶化,合成了不同封装量的Pt/SOD分子筛。采用苯加氢反应测试样品的催化活性,并运用XRD、SEM、TEM和H_2-TPD对样品进行表征。结果表明,合成的不同封装量的Pt/SOD样品均具有良好的催化活性,与溢流氢受体HZSM-5间均具有良好的氢溢流效应。其中,当金属前驱体Pt(NH_3)_4Cl_2的用量为(Pt(NH_3)_4Cl_2)∶(Si-Algel)比为0.030 g/g时,所合成的Pt/SOD样品最佳,催化苯加氢反应的苯转化率可达54.38%。     

DRIFT Study on Cr2O3-SO42-/TiO2 Catalyst for Low Temperature Selective Catalytic Reduction of NO with NH3

Chromium oxides supported on TiO2 showed good activity for the selective catalytic reduction of NO by NH3.The catalytic activity of Cr2O3-SO42-/TiO2 catalyst was greatly enhanced by the addition of SO42-into TiO2 support.The catalyst surface properties were characterized with NH3-TPD（temperature programmed desorption） and H2-TPR（temperature programmed reduction）.The sulphate on the catalyst surface could enhance the acidity and redox of the catalyst obviously.The reaction mechanism on this catalyst was researched in detail by in situ diffuse reflectance Fourier transform infrared（FTIR） spectroscope.Eley-Rideal and Langmuir-Hinshelwood mechanism existed simultaneously for selective catalytic reduction（SCR） reaction of NO over Cr2O3-SO42-/TiO2 catalyst.     

可循环磁性Pt/Fe_3O_4-MCNT催化剂上的肉桂醛选择性加氢反应

采用多步法依次将制备的Fe3O4纳米颗粒和Pt纳米颗粒负载到多壁碳纳米管(MCNT)上得到Pt/Fe3O4-MCNT磁性催化剂,以X射线衍射(XRD)、透射电镜(TEM)、超导量子干涉磁强计(SQUID)和热重-差热分析(TG-DTA)对Pt/Fe3O4-MCNT磁性催化剂的结构和磁性质进行了表征。研究发现预制备的Fe3O4纳米颗粒与Pt纳米颗粒均匀地分散于MCNT上,新制备以及多次使用后的Pt/Fe3O4-MCNT室温下都具有良好的超顺磁性。研究了Pt/Fe3O4-MCNT磁性催化剂上的肉桂醛选择性加氢反应,结果显示催化剂具有良好的C=O加氢活性,肉桂醛转化率在50%左右时,肉桂醇选择性可达96%以上。尺寸均一的Pt粒子均匀的分散在催化剂上可能是催化剂具有良好的C=O加氢选择性的重要原因。在外加磁场作用下催化剂可以高效地从液相反应体系中分离,经多次循环使用后仍具有良好的催化性能。     

Ni2+在γ-Al2O3上的分散状态及负载型Ni/γ-Al2O3催化剂的α-蒎烯加氢活性

用X-射线衍射(XRD)、紫外-可见漫散射光谱(UV-Vis DRS)、程序升温还原(TPR)、CO化学吸附和微反测试等方法研究了Ni²⁺在γ-Al₂O₃上的分散状态和负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢催化活性。结果表明，当Ni²⁺负载量远低于其在γ-Al₂O₃载体表面分散容量时，Ni²⁺优先嵌入载体表面四面体空位，随着Ni²⁺负载量的增加，嵌入载体表面八面体空位Ni²⁺的比例增大。由于八面体Ni²⁺易被还原为金属态Ni⁰，NiO/γ-Al₂O₃样品的还原度随Ni²⁺负载量的增加而大幅度地增加，经氢还原所得Ni/γ-Al₂O₃催化剂的CO吸附量和α-蒎烯加氢催化活性大幅度增加。对La₂O₃助剂的作用进行了研究，结果表明分散在γ-Al₂O₃上的La³⁺物种可阻止Ni²⁺嵌入γ-Al₂O₃表面四面体空位，增大了八面体Ni²⁺物种所占比例，提高了催化剂的还原度，故Ni-La₂O₃/γ-Al₂O₃催化剂催化活性高于Ni/γ-Al₂O₃催化剂。