Pt,Ru和Pd助剂对F-T合成中Co/γ-Al2O3催化剂性能的影响

 采用浸渍法制备了添加贵金属Pt,Ru和Pd助剂的Co/γ-Al2O3催化剂,并考察了它们在F-T合成反应中的催化性能. 结果表明,添加贵金属助剂可以显著提高Co/γ-Al2O3催化剂的催化活性. XRD和TPR表征结果表明,贵金属助剂不但可以使催化剂的金属分散度增加,而且可以通过氢溢流促进催化剂表面活性相的Co3O4以及与载体Al2O3有相互作用的非活性相钴氧化物物种的还原,从而改善催化剂的还原性能. TPSR结果进一步表明,添加贵金属助剂后催化剂对CO的吸附解离能力增强,从而使吸附态CO的加氢活性提高.     

助剂CeO2对Co/Al2O3催化剂上F-T合成反应性能的影响

 在用于F－T合成的Co／Al2O3催化剂中加入少量助剂,能够提高CO转化率和C5＋烃选择性．主要考察了助剂CeO2添加量和催化剂焙烧温度等因素对F－T合成反应的影响,并通过程序升温还原、程序升温氧化及X射线衍射等手段对催化剂进行了表征．结果表明,在Co／Al2O3催化剂中加入少量CeO2（n（Ce）／n（Co）＝0．1～0．14）,能够有效提高催化剂的催化活性和C5＋烃选择性;焙烧温度则以相反的趋势控制F－T反应活性和链增长几率;助剂的加入降低了催化剂的起始还原温度,改善了催化剂的还原性能．但是,催化剂的积碳量有所增加,经10h反应后,催化剂上存在两种类型的积碳．     

助剂对Co／HMS催化剂结构和F-T合成性能的影响

详细研究了钍、锆、锗及铈助剂对钴质量分数为15％的Co／HMS催化剂结构、 F-T合成CO转化率、CO2选择性及烃分布的影响,结果表明：钍能适当提高F-T合成 活性,且低温下具有较强的链增长能力;锆、锗、铈降低了催化剂CO转化率,催化 剂加氢能力变强,导致低碳烃增加较快,汽柴油馏分段减低,相应的链增长能力降 低,并以锰和铈较为明显;XRD,TPR及TG表征表明：锆和铈可提高催化剂Co还原度 ,但F-T合成反应时金属Co易披氧化,反应中金属Co量明显减少,CO转化率降低, 并以铈最为显著;Th助催化剂Co还原度稍有减低,Co分散度高于Co／HMS,且反应 中金属Co较为稳定,Co转化率得以提高;添加Mn助剂后,催化剂难以还原,反应中 活性相金属Co量较小,CO转化率较低．     

助剂镍/钴对磷化钨催化剂加氢精制性能的影响

在共浸渍法制备磷化钨／γ-Al2O3催化剂基础上，分别加人1％、3％、5％、7％和9％(占活性组分比例)的助剂镍或钴，制得负载30％含助剂镍／钴磷化钨／γ-Al2O3系列催化剂，考察了助剂及其加人比例对催化剂加氢脱硫和加氢脱氮性能的影响．结果表明，加人适当比例的助剂镍或钴，有利于提高磷化钨／γ-Al2O3催化剂的加氢脱硫活性，当助剂含量分别为5％镍或7％钴时，催化剂的噻吩加氢脱硫率最高；助剂镍对磷化钨／γ-Al2O3催化剂的加氢脱氮反应不利，而加人适当比例助剂钴有利于提高催化剂加氢脱氮活性，当助剂钴含量为5％时，催化剂吡啶加氢脱氮率最高．温度对磷化钨／γ-Al2O3催化剂加氢精制性能有一定影响，高温有利于加氢脱硫反应，低温有利于加氢脱氮反应．     

噻吩加氢脱硫和四氢萘催化加氢反应中的载体和助剂的影响

 为了更好地认识加氢脱硫和催化加氢反应中的载体影响和助剂效应，在同样的催化剂制备方法及反应条件下，研究了噻吩加氢脱硫（HDS）和四氢萘催化加氢（HYD）反应．结果表明，对于无助剂的Mo和W催化剂，载体对催化活性的影响顺序为TiO2－Al2O3＞ZrO2＞Al2O3．助剂的添加改变了催化剂活性顺序．Ni助剂催化剂的活性明显高于Co助剂催化剂．ZrO2担载的添加Ni的Mo和W催化剂分别获得了最佳的HDS和HYD活性．然而，添加Pt的Mo和W催化剂其HDS和HYD活性仅是Pt与Mo（W）二者的加和，Pt与Mo（W）之间没有协同效应．先将担载的Mo和W预硫化再将助剂引入体系的催化剂制备方法可以避免Ni和Co过早硫化形成类硫化镍（或硫化钴）物相，与采用螯合物分子方法制备的催化剂间有一定的相似性．     

贵金属对钴基催化剂上肉桂醛选择加氢反应的影响

 研究了贵金属改性的Co／γ－Al2O3催化剂上的肉桂醛选择加氢反应．结果表明，通过Pt，Pd和Ru贵金属改性，提高了催化剂的活性，但只有Pt改性的催化剂具有较高的选择性．w（Pt）＜0．5％时，催化剂的活性随着Pt含量的增加呈直线升高，当w（Pt）＝0．5％时，催化剂活性可提高近5倍，但催化剂的选择性变化很小．XRD结果表明，催化剂经还原后，γ－Al2O3上的钴主要为α－Co0．TPR结果表明，Pt的加入提高了Co3O4的还原性能，且Pt含量越高，Co3O4的还原温度越低．XPS结果表明，Pt改性的催化剂样品，其Co3O4大部分被还原为Co0．由于Pt与Co具有协同效应，故Pt改性的Co／γ－Al2O3催化剂既具有较高的活性，又具有很高的选择性．     

含钴铜镍类水滑石焙烧产物催化分解N2O的研究

 合成了含Co，Cu和Ni的M／Mg－Al－HTL类水滑石，并将其焙烧产物用于N2O催化分解反应．实验结果表明，Co／Mg－Al－HTL对N2O分解反应的催化活性明显高于Cu／Mg－Al－HTL和Ni／Mg－Al－HTL的活性．在保持样品中Al含量不变的条件下，催化活性随着Co含量的增加及Mg含量的减少而升高，各催化剂的活性顺序为：Co／Al－HTL＞Co／Mg－Al－HTL＞Cu／Mg－Al－HTL＞Ni／Mg－Al－HTL．在此基础上，进一步考察了Co／Al－HTL中Co／Al原子比调变对催化剂活性的影响．对含Co类水滑石及其焙烧产物进行了XRF，XRD和N2O－TPD表征．结果表明，含Co类水滑石具有典型的水滑石结构，其高温焙烧产物都含尖晶石相．由于尖晶石相中Co－O－Al活性中心的作用，含Co类水滑石对N2O分解反应表现出较高的催化活性．随着Co／Al原子比的增大，含Co类水滑石焙烧产物的尖晶石相特征更加突出，Co－O－Al活性中心数目随之增多，催化剂的活性也相应升高．     

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     

氧化铝对Fe－Cu－Zn－K－Al低碳醇合成催化剂性能的影响

 采用N2吸咐，TPR和XRD等表征手段对高温熔融法制备的Fe－Cu－Zn－K－Al催化剂中氧化铝的作用进行了研究．结果表明，当比表面积低于4．0m2／g时，催化剂性能受比表面积的影响非常明显．少量的Al2O3即可有效地增加催化剂的比表面积，提高醇的收率和C2＋OH的选择性；大量的Al2O3虽然能使催化剂的比表面积有所增加，但醇的收率和C2＋OH选择性却显著降低．这是Fe－Cu－Zn－K－Al催化剂中Al2O3同时具有物理作用和化学作用所致．物理作用能有效地增加还原后催化剂的比表面积，提高金属利用率，分散催化剂的活性组分，使其更容易还原，进而提高催化剂活性和选择性．化学作用影响到催化剂的电子性质，从而导致催化剂的活性和选择性降低．TPR和XRD结果表明，在Fe－Cu－Zn－K－Al催化剂中，助剂Al2O3的作用随着其含量的变化而有所不同．当Al2O3含量较低时，其物理作用是主要的；随着Al2O3含量的增加，其化学作用更为明显，甚至导致新物相AlFeO3生成，进而影响催化剂的催化性能．     

Co/γ-Al_2O_3催化剂上肉桂醛的选择加氢──反应性能的考察

研究了γ－Al2O3负载的Co／γ－Al2O3催化剂上肉桂醛的选择加氢反应．反应结果表明,以CoCl2作为前驱物的Co／γ－Al2O3催化剂的选择性要高于以Co（NO3）2作为前驱物的Co／γ－Al2O3催化剂,而活性则正好相反．当钴的负载量小于9％时,随着钴负载量的增加,催化剂的活性和选择性随之增加,当钴的负载量大于9％时,随着钴负载量的增加,Co／γ－Al2O3催化剂的活性略有增加,而生成肉桂醇的选择性变化也很小,认为9％的钴负载量是催化剂反应活性和选择性的一个阈值．在所选定的范围内,反应温度和压力对肉桂醛加氢的选择性几乎没有影响．     

费-托合成Co/ZrO2-Al2O3催化剂反应性能的研究

以ZrOCl2·6H2O和AlCl3为原料，采用共沉淀方法制得一系列不同ZrO2质量分数的ZrO2-Al2O3混合氧化物载体；并以该混合氧化物为载体，采用初湿浸渍法制得钴质量分数为12％的Co/ZrO2-Al2O3催化剂。XRD、NH3-TPD、TPR和原位IR等表征结果表明，随着混合载体中ZrO2质量分数的增加，载体比表面积先增加后减少，混合载体的平均孔径则小于单一氧化物ZrO2和Al2O3的平均孔径。ZrO2和Al2O3载体混合后会导致氧化物的比表面积和酸性增大并且有新的物相生成。当混合氧化物用作载体时，能够抑制载体表面金属钴的分散，改变催化剂的还原行为，降低催化剂对CO物种的吸附能力。CO加氢反应表明，与单一金属氧化物相比，钴负载ZrO2-Al2O3混合氧化物催化剂的加氢活性和重质烃选择性有所降低。     

Fischer-Tropsch synthesis on anchored Co/Nb2O5/Al2O3 catalysts: the nature of the surface and the effect on chain growth

A series of Co/x%Nb2O5/Al2O3 catalysts were prepared by anchoring niobia on an Al2O3 support at different niobia concentrations. Characterization of the structure and nature of surface active sites was attempted in order to correlate the CO hydrogenation activity of these systems with those of the Co/Al2O3 and Co/Nb2O5 catalysts. The effect of the reduction temperature on the CO hydrogenation activity and selectivity was studied, showing that interaction of cobalt and niobia surface species favored the selectivity for hydrocarbon chain growth. However, this effect is less pronounced on the niobia-promoted Co/Al2O3 compared to Co/Nb2O5 catalysts. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) results on Co/x%Nb2O5/Al2O3 showed prevailing amounts of Co2+ and Co3+ after calcination and reduction at 573 K, while, after reduction at 773 K, besides metallic cobalt, the Co2+ species still remains in contact with alumina, even for higher niobia loading. It seems that during this process formation and destruction of new interfaces involving Co0-NbOx sites takes place. Results suggest that Co0, Co0-Co2+, and Co0-NbOx are the active sites at the surface. The relative abundance of Co2+ species affects greatly the performance of the catalysts. DRIFTS and selectivity results suggest that these sites might be responsible for the reaction chain growth and therefore for the drastic change in the selectivity of CH4 and C5+ hydrocarbons mainly on the Co/Nb2O5 catalyst. DRIFTS results on Co/Nb2O5/Al2O3 showed the formation of -C=C- and -CH3- besides CHxO species. With increasing reduction temperature, the -C=C- species disappear while -CH3- fragments increased markedly, suggesting the formation of increasing amounts of hydrocarbons with higher chain length.     

焙烧温度对柴油车氧化催化剂Pt-Pd-（x）ZrO2/Ce0.3Zr0.7O2-Al2O3性能的影响

制备了氧化铝、铈锆固溶体复合氧化物负载铂、钯的双金属催化剂Pt-Pd/ Ce0.3Zr0.7O2-Al2O3,并添加3% ZrO2助剂改性,用于柴油车尾气中CO、HC和NO的催化氧化,其中贵金属负载量仅为0.68 wt%。考察了制备过程中焙烧温度对催化剂性能的影响。催化剂活性评价结果表明,与未添加ZrO2的催化剂比较。添加ZrO2明显提高了催化剂的低温氧化活性,而且焙烧温度对催化剂的氧化性能有较大影响。焙烧温度为800 ?C时,CO和C3H6的起燃温度最低,分别为168、189 ?C,焙烧温度为700 ?C时,NO转化为NO2的转化率最高,最大转化率为36%,具有较好的热稳定性。通过XRD、N2吸附-脱附、CO化学吸附、XPS、H2-TPR等表征手段考察了催化剂物理化学性质随焙烧温度的变化情况,并分析了与催化剂活性之间的关系,得到贵金属分散度、表面化学吸附氧含量、催化剂的还原性质对氧化性能有重要影响,发挥协同作用。进而可以通过优化焙烧温度提升柴油车氧化催化剂性能,对提高工业应用柴油车尾气后处理系统的净化效率有重要意义。     

助剂对Cu-Mn复合氧化物整体式催化剂催化低浓度甲烷燃烧反应性能的影响

以堇青石蜂窝陶瓷(COR)为载体,采用浸渍法制备了Cu-Mn-O/A12O3/COR,Cu-Mn-Ce-O/Al2O3/COR,Cu-Mn-Zr-O/Al2O3/COR,Cu-Mn-La-O/A12O3/COR和Cu-Mn-Ce-Zr-O/Al2O3/COR5种Cu-Mn复合氧化物整体式催化剂,用于低浓度甲烷催化燃烧反...     

Effect of barium on reducibility and activity for cobalt-based Fischer-Tropsch synthesis catalysts

Barium modified Co/Al2O3 catalysts were prepared by incipient wetness impregnation. The catalysts were characterized by XRD, TPD and DRIFTS. The catalytic activity for Fischer-Tropsch synthesis was measured in a continuously stirred tank reactor. It was found that small amounts of BaO (≤ 2 wt%) improved the cobalt reducibility, which led to more cobalt active sites on the catalyst surface, and then resulted in higher CO conversion and C5+ selectivity. However, for the catalysts with high BaO loadings negative effects on the catalytic activity and selectivity for high hydrocarbons were observed because of low cobalt reducibility.     

Methane reforming With CO2 to syngas over CeO2-promoted Ni/Al2O3-ZrO2 catalysts Prepared Via a direct sol-gel process

CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure. TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support. There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable. The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts. The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst. The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.     

纳米二氧化锆催化剂上一氧化碳加氢合成异丁烯

 考察了纳米ZrO2的制备方法及Al2O3和KOH助剂的添加对ZrO2催化\r\nCO加氢合成异丁烯反应的影响．纳米ZrO2的制备方法对ZrO2的物理性质\r\n和催化性能有较大的影响．用超临界流体干燥法干燥并在流动N2气氛中\r\n焙烧制得的ZrO2催化剂对异丁烯具有较高的选择性．Al2O3和KOH助剂表\r\n现出非常优良的助剂效应，在大幅度提高催化剂对i－C4烃选择性的同\r\n时保持了和ZrO2同样高的催化活性．催化剂的酸碱性表征结果表明，酸\r\n碱性对催化剂的催化性能影响很大，催化剂上适宜的酸碱数量和酸碱比\r\n例是影响其催化CO加氢合成异丁烯性能的非常重要的因素．     

Effect of cobalt and its adding sequence on the catalytic performance of MoO3/Al2O3 toward sulfur-resistant methanation

The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method and characterized by N₂-adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and laser Raman spectroscopy (LRS). The conversions of CO for Mo-Co/Al, Co-Mo/Al and CoMo/Al catalysts were 59.7%, 54.3% and 53.9%, respectively. Among these catalysts, the Mo-Co/Al catalyst prepared stepwisely by impregnating Mo precursor firstly showed the best catalytic performance. Meanwhile, the conversions of CO were 48.9% for Mo/Al catalyst and 10.5% for Co/Al catalyst. The addition of cobalt species could improve the catalytic activity of Mo/Al catalyst. The N₂-adsorption results showed that Co-Mo/Al catalyst had the smallest specific surface area among these catalysts. CoMoO₄ species in CoMo/Al catalyst were detected with XRD, TPR and LRS. Moreover, crystal MoS₂ which was reported to be less active than amorphous MoS₂ was found in both Co-Mo/Al and CoMo/Al catalysts. Mo-Co/Al catalyst showed the best catalytic performance as it had an appropriate surface structure, i.e., no crystal MoS₂ and very little CoMoO₄ species.     

Applied magnetic field rejects the coating of ferromagnetic carbon from the surface of ferromagnetic cobalt: RAPET of CoZr2(acac)2(OiPr)8

We present the results of the RAPET (reaction under autogenic pressure at elevated temperatures) dissociation of CoZr(2)(acac)(2)(O(i)Pr)(8) at 700 degrees C in a closed Swagelok cell under an applied magnetic field of 10 T. It produces a mixture of carbon-coated and noncoated metastable ZrO(2) nanoparticles, bare metallic Co nanoparticles, and bare carbon. The same reaction in the absence of a magnetic field produces spherical Co and ZrO(2) particles in sizes ranging from 11 to 16 nm and exhibiting, at room temperature, metastable phases: fcc for cobalt and a tetragonal phase for zirconia. The metastable phases of Co and ZrO(2) are manifested because of a carbon shell of approximately 4 nm thickness anchored to their surfaces. The effect of an applied magnetic field to synthesize morphologically different, but structurally the same, products is the key topic of the present paper.     

铂基催化剂用于柴油烃氧化

The catalytic performance of Pt-based catalysts for the total oxidation of hydrocarbons was investigated.The activity of supported Pt catalysts(Pt/Al2O3,Pt/ZrO2,Pt/TiO2,and Pt/H-ZSM-5)depends on the metal oxide support.Pt/Al2O3 showed the highest catalytic activity when the catalysts were aged at 750°C for 50 h in air.The activity of Pt/Al2O3 was dependent on the valence state of the Pt surface.Pt/Al2O3 with the Pt surface in the metallic state was more active than with the surface in the cationic state.The surface density of acid and basic sites on the Al2O3 support controlled the valence state of the Pt surface and stability of the Pt particles in the highly dispersed state,respectively.