镍盐前驱体对Ni/C催化剂乙醇气相羰化活性的影响

采用等体积浸渍法制备了分别以乙酰丙酮镍、氯化镍、硝酸镍和醋酸镍为前驱体负载在活性炭上的四种催化剂。用BET、金属分散度、H2-TPR、CO-TPD和XRD等方法研究了四种催化剂的结构特点和乙醇气相羰化活性。结果表明,以醋酸镍制备的Ni/C催化剂的羰化活性最高,乙醇转化率和丙酸选择性分别为96.1%和95.7%,而以乙酰丙酮镍制备的Ni/C催化剂的羰化活性最低,乙醇转化率和丙酸选择性分别为68.9%和27.1%。这种活性的差异与镍盐前驱体和活性炭之间的相互作用强弱有着密切关系。醋酸镍组分与活性炭之间的相互作用较强,浸渍组分易在活性炭表面充分吸附,活性中心Ni0在240－340 ℃温度范围内对CO吸附量最大,还原后金属镍的分散度较好且晶粒较小。     

Support Modification of Supported Nickel Catalysts for Hydrogen Production by Auto-thermal Reforming of Ethanol

Recent progress on support modification of supported nickel catalysts for hydrogen production by auto-thermal reforming of ethanol was reported in this review. Nickel catalysts supported on various materials, including metal oxides and metal oxide-stabilized mesoporous zirconias, were prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. Various experimental measurements such as NH₃-TPD (temperature-programmed desorption) and TPR (temperature-programmed reduction) were carried out to elucidate the different catalytic performance of supported nickel catalysts. It was revealed that acid property of supporting materials served as one of the important factors determining the catalytic performance. Hydrogen yield over nickel catalysts supported on metal oxides showed a volcano-shaped curve with respect to acidity of the supports. Among the catalysts tested, Ni/ZrO₂ catalyst with an intermediate acidity exhibited a superior catalytic performance. It was also observed that reducibility of nickel catalysts supported on metal oxide-stabilized mesoporous zirconias played a key role in determining the catalytic performance in the auto-thermal reforming of ethanol for hydrogen production. Hydrogen yield over nickel catalysts supported on metal oxide-stabilized zirconias increased with increasing reducibility of the catalysts (with decreasing TPR peak temperature of the catalysts).     

NiO/LaMnO3催化剂用于乙醇水蒸气重整反应

采用柠檬酸络合-浸渍法制备了NiO/LaMnO3钙钛矿型复合氧化物催化剂并将其应用于乙醇水蒸汽重整制氢反应, 考察了NiO含量、焙烧温度对催化剂性能的影响, 采用XRD、TPR和热分析等手段对催化剂进行了表征. 结果表明, 该催化剂具有高活性、高选择性和良好的稳定性. 催化剂中的NiO含量和焙烧温度对催化性能有显著影响. 在原料气体积组成为20%(体积分数, φ) C2H5OH 和水以及80%(φ)N2, 其中水醇摩尔比为3:1, 空速为80000 mL·h-1·g-1 cat, 反应温度为400 ℃时, 15%(质量分数, w)的NiO/LaMnO3上, 乙醇转化率接近100%. 关联催化剂活性和TPR及XRD实验结果, 发现催化剂的高活性源于由催化剂前驱体中进入钙钛矿型复合氧化物晶格中的镍离子被还原所得的金属镍.     

改性硫酸钛催化合成丙酸酯

固体硫酸钛经不同的高温灼烧制得改性硫酸钛，用改性硫酸钛吸附吡啶后的IR光谱表征其表面酸性；用丙酸与多种醇反应考察其酯化催化活性。结果表明，改性硫酸钛表面存在明显的Broensted酸中心；对酯化反应的催化活性高、反应时间短、催化剂可重复使用多次。     

Hydrogen Production by Steam Reforming of Ethanol Over Mesoporous Ni–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZrO<Subscript>2</Subscript> Catalysts

This review paper reports the recent progress concerning the application of nickel–alumina–zirconia based catalysts to the ethanol steam reforming for hydrogen production. Several series of mesoporous nickel–alumina–zirconia based catalysts were prepared by an epoxide-initiated sol–gel method. The first series comprised Ni–Al₂O₃–ZrO₂ xerogel catalysts with diverse Zr/Al molar ratios. Chemical species maintained a well-dispersed state, while catalyst acidity decreased with increasing Zr/Al molar ratio. An optimal amount of Zr (Zr/Al molar ratio of 0.2) was required to achieve the highest hydrogen yield. In the second series, Ni–Al₂O₃–ZrO₂ xerogel catalysts with different Ni content were examined. Reducibility and nickel surface area of the catalysts could be modulated by changing nickel content. Ni–Al₂O₃–ZrO₂ catalyst with 15 wt% of nickel content showed the highest nickel surface area and the best catalytic performance. In the catalysts where copper was introduced as an additive (Cu–Ni–Al₂O₃–ZrO₂), it was found that nickel dispersion, nickel surface area, and ethanol adsorption capacity were enhanced at an appropriate amount of copper introduction, leading to a promising catalytic activity. Ni–Sr–Al₂O₃–ZrO₂ catalysts prepared by changing drying method were tested as well. Textural properties of Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst produced from supercritical drying were enhanced when compared to those of xerogel catalyst produced from conventional drying. Nickel dispersion and nickel surface area were higher on Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst, which led to higher hydrogen yield and catalyst stability over Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst.     

Turkish perlite supported nickel oxide as the heterogeneous acid catalyst for a series of Claisen–Schmidt condensation reactions

Potentially active and eco-friendly solid acid catalysts have been synthesized by loading different weight percentages (10, 15, and 50) of nickel oxide on thermally activated Turkish perlite through the deposition-precipitation method. Structural features of prepared catalysts were analyzed using BET surface area analysis, X-ray diffraction, scanning electron microscope (SEM), SEM-EDX, transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), pyridine adsorbed FT-IR, UV-Vis diffuse reflectance spectroscopy (DRS), and thermogravimetric analysis (TGA) techniques. Pyridine adsorbed FT-IR analysis confirmed the presence of the optimum amount of Bronsted acidic sites in a catalyst having 15 wt. % loading of nickel oxide, which was tested for catalyzing a series of Claisen–Schmidt condensation of cyclohexanone and aromatic aldehydes to produce good isolated yield (90%–93%) of 2,6-bis(substituted benzylidene)cyclohexanones, significantly used in anti-tumor and cytotoxic activities. The high catalytic efficiency of the chosen catalyst remains almost intact up to six reaction cycles. On higher wt. % loading of nickel oxide, crystallite size increases along with agglomeration of larger nickel oxide particles on catalyst surface resulting in pore blockage and poor catalytic activity. Loading of NiO on the surface of thermally activated Turkish perlite was confirmed by SEM-EDX analysis, and TEM observations show that the particle size of the preferred catalyst was less than 50 nm. Based on results drawn from XRD, FT-IR, pyridine adsorbed FT-IR, UV-Vis DRS studies, model structures were proposed for Turkish perlite and all prepared catalysts. During this work, the catalytic potential of the preferred catalyst was compared with other previously reported catalysts, and it showed appreciable results. The formed products were further confirmed by their melting point and ¹H-NMR analysis.     

Mesoporous Nickel–Alumina Catalysts for Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG)

Recent progress on the mesoporous nickel–alumina catalysts for hydrogen production by steam reforming of liquefied natural gas (LNG) was reported in this review. A number of mesoporous nickel–alumina composite catalysts were prepared by a single-step surfactant-templating method using cationic, anionic, and non-ionic surfactant as structure-directing agents for use in hydrogen production by steam reforming of LNG. For comparison, nickel catalysts supported on mesoporous aluminas were also prepared by an impregnation method. The effect of preparation method and surfactant identity on physicochemical properties and catalytic activities of mesoporous nickel–alumina catalysts in the steam reforming of LNG was investigated. Regardless of preparation method and surfactant identity, nickel oxide species were finely dispersed on the surface of mesoporous nickel–alumina catalysts through the formation of surface nickel aluminate phase. However, nickel dispersion and nickel surface area of mesoporous nickel–alumina catalysts were strongly affected by the preparation method and surfactant identity. It was found that nickel surface area of mesoporous nickel–alumina catalyst served as one of the important factors determining the catalytic performance in hydrogen production by steam reforming of LNG. Among the catalysts tested, a mesoporous nickel–alumina composite catalyst prepared by a single-step non-ionic surfactant-templating method exhibited the best catalytic performance due to its highest nickel surface area.     

镍负载量对乙醇水蒸气重整制氢催化性能和催化剂的影响

采用稳态实验对镍负载量对Ni/MgO催化剂在乙醇水蒸气重整反应的影响进行了研究。结果表明，在101.3kPa下，镍负载量越高，催化剂的活性越高。对于催化剂的选择性，存在一个最佳镍负载量为10%Ni/MgO。按选择性从大到小排序，不同镍负载量的催化剂为：10Ni/MgO>15Ni/MgO>12.5Ni/MgO>7.5Ni/MgO≈5Ni/MgO。热分析表明，焙烧过程中不同镍负载量的催化剂镍前体与载体前体之间发生的相互作用不同。XRD和TPR 表征结果显示，催化剂的晶体结构和还原特性也与催化剂上镍的负载量有关。焙烧过程中样品10Ni/MgO上镍前体与载体前体发生了两种相互作用, 并且其氧化态与其他催化剂相比具有特殊的结构和还原性。说明催化剂的选择性不仅受活性相Ni的影响而且受Ni活性相周围环境的影响。     

Ethanol steam reforming on Ni/Al2O3 catalysts: effect of the addition of Zn and Pt

Ni-based catalysts supported on Zn-modified alumina were investigated in the ethanol steam reforming reaction. A commercial γ-alumina was impregnated with different amounts of zinc nitrate (0, 2, 5, 10, 15, 20 wt.% on Zn basis), calcined, and then impregnated with nickel nitrate aqueous solutions. The samples were characterized by a number of techniques: N(2) adsorption at 77 K, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence (XRF), and temperature-programmed reduction (TPR). Their catalytic behavior in the ethanol steam reforming reaction was studied at 873 K, with a H(2)O/ethanol ratio of 5:1. Two effects of the presence of Zn were detected. On the one hand, zinc modifies the surface structure and the surface chemistry of the catalysts by formation of zinc aluminates, and on the other hand, zinc oxide can be reduced to metallic zinc under reaction conditions, thus modifying the catalytic properties of the active phase. The presence of Zn increases the ethanol conversion to gaseous compounds as compared with the catalyst supported on the Zn-free commercial alumina. The addition of a small amount of Pt (1 wt.%) causes a beneficial effect in the reaction. When Ni catalysts were used without a previous reduction treatment, ethylene was formed in high amounts; however, the Pt-Ni catalysts need no reduction pre-treatment to achieve high H(2) yields (close to 70%) and showed a high stability versus time on stream because of the control of the production of ethylene, a coke precursor.     

制备条件对用于甘油蒸汽重整反应Ni基催化剂性能的影响

研究了制备参数对用于甘油蒸汽重整反应的Ni基催化剂性能的影响。采用过量浸渍法、等体积浸渍法和改进的平衡沉积过滤(EDF)法制备了一系列Al2O3负载的8 wt%Ni催化剂,运用X射线衍射(XRD)、电感耦合等离子体光谱仪、N2吸附-脱附、扫描电镜(SEM)、透射电镜和H2程序升温还原(TPR)表征了催化剂的表面和体相性质;采用CHN分析仪和SEM表征了使用后催化剂以测定其表面沉积的碳及其形貌。结果表明,制备方法对所制催化剂的织构、结构和表面性质影响很大,导致氧化铝表面Ni物种的分散和种类的不同。即使XRD和TPR结果证实形成了铝酸镍晶相,但Ni/Al-edf催化剂中β峰的贡献大于其它两个催化剂的,表明在这种情况下铝酸镍更容易还原。在550 oC以上CO2选择性增加和CO选择性不变,表明Ni/Al-wet和Ni/Al-edf催化剂可成功催化水汽变换反应。另外,650oC时Ni/Al-edf催化剂上甘油生成气相产物的转化率、氢气产率以及烯丙醇、乙醛和乙酸选择性最高,且它在所有催化剂中的积炭量也最低。将催化剂结构性质、分散度和还原性与其催化性能相关联,发现EDF法制得的催化剂比表面积和活性相分散度更高,更易被还原,因而其活性和生成H2的选择性更高,也更抗积碳。     

Adsorption of ethanol on the modified ruthenium catalysts in alkaline media

Regularities of ethanol adsorption in alkaline medium on the surface of the monoruthenium Ru/C catalyst and systems promoted by nickel and vanadium oxides, Ru-VO _x /C and Ru-NiO _x /C, were studied by non-stationary voltammetry techniques. An analysis of the kinetic and concentration dependences of adsorption showed that an increase in the content of the promoting component in the bimetallic systems enhances the energy heterogeneity of the catalyst surface. The data on adsorption measurements were compared with the results of previous studies of the kinetics and depth of ethanol electrooxidation on the examined catalysts. The larger quantity of electricity consumed for the oxidation of adsorbed particles formed on the surface of the metallooxide systems corresponds to higher extents of electrooxidation and rate than those for the monoruthenium catalyst.     

溶胶-凝胶法制备Ni-SiO2催化剂的表征与性能

以正硅酸乙酯和硝酸镍为原料,采用溶胶-凝胶法,将硝酸镍分别溶于水和乙醇制得凝胶,分别经超临界干燥和常规干燥制备了一系列Ni-SiO2气凝胶和干凝胶催化剂,运用BET、XRD、TPR、IR、H2-TPD和活性评价等方法对催化剂的物理化学性质和催化间二硝基苯加氢性能进行研究.结果表明,Ni-SiO2气凝胶催化剂均具有较高的比表面积,但由于金属镍烧结导致活性比表面积较小,加氢性能较差;以乙醇为溶剂制备的干凝胶催化剂的镍物种分散度较高,但镍与载体之间的相互作用过强,致使催化剂的还原度降低,活性组分利用率下降;以水为溶剂制备的干凝胶催化剂具有较高的活性比表面积,表现出很高的催化活性和选择性.     

钇和柠檬酸对非负载磷化镍催化剂加氢脱硫性能的影响

采用传统程序升温(TPR)法制备了稀土金属钇(Y)或柠檬酸(CA)改性及Y和CA同时改性的非负载型Ni2P催化剂;采用X射线衍射(XRD)分析、N2吸附比表面积(BET)测定、CO化学吸附分析、X射线光电子能谱(XPS)和透射电子显微镜(TEM)对催化剂的结构和性质进行了表征;并考察了Y和CA对催化剂上进行的二苯并噻吩(DBT)加氢脱硫(HDS)反应性能的影响.结果表明,Y和CA均可促使非晶相NixPyOz向磷化镍活性相的转化,抑制Ni_5P_4杂晶相的形成,从而促进Ni2P活性相的生成;同时能够丰富催化剂的孔道,抑制催化剂表面磷的富集,得到更好的孔结构、更高的活性相分散度.Y或CA以及两者同时改性后的催化剂DBT转化率均明显高于Ni-P催化剂.各催化剂的HDS活性大小顺序为Y-Ni-P-CANi-P-CAY-Ni-PNi-P.在340℃,3.0 MPa,氢油体积比700,质量空速(WHSV)1.5 h-1的条件下,Y-Ni-P-CA催化剂的DBT转化率为97%,比Ni-P催化剂提高了约35%.     

Effects of Propionic Acid and pH on Ethanol Fermentation by Saccharomyces cerevisiae in Cassava Mash

The effects of propionic acid on ethanol and glycerol production by Saccharomyces cerevisiae in cassava mash were examined along with the influence of pH (4.0, 5.0, and 6.0) and of dissolved solids content (22%, 25%, and 27%). Inhibition by propionic acid increased as solids content increased and medium pH declined. Complete inhibition of ethanol fermentation was observed in mashes at pH 4.0 (60 mM propionic acid for 22% solids and 45 mM for 25% and 27%). Glycerol production linearly decreased with increased undissociated propionic acid concentration in all mashes at all pH levels, which partly contributed to increased final ethanol production when propionic acid concentration in mashes was low (≤ 30 mM).     

Sulfonated porous biomass-derived carbon with superior recyclability for synthesizing ethyl levulinate biofuel

The synthesis of ethyl levulinate (EL) via esterification of levulinic acid (LA) with ethanol, which can be derived from biomass, has become an attractive topic since EL can be applied in many fields, such as fuel additives for petroleum and biodiesel, food additives and fragrance. Herein, the sulfonated porous carbon catalysts derived from the rinds of corn stalk biomass wastes were prepared by using sulfuric acid and phosphoric acid as the sulfonating agent and activator, respectively. The preparation parameters were optimized based on the catalytic activity for LA esterification with ethanol and the acid density of the corresponding catalysts. Also, various reaction factors were optimized to improve the catalytic efficiency over the optimal sulfonated corn stalk-derived carbon (s-CSC). Under the conditions of reaction temperature 80 °C, catalyst dosage 5 wt%, ethanol-to-LA molar ratio 5.0:1 and reaction time 8 h, the LA conversion reached 94% and 93% catalyzed by s-CSC and the optimal porous catalyst (s-p-CSC), respectively. Noticeably, benefitting from the hierarchical porous structure with large surface area, s-p-CSC exhibited much better recyclability than s-CSC. This work offers a highly effective solid acid catalyst for the synthesis of biofuel.

     

Oxidation of Methanol and Other Low-Molecular-Weight Alcohols on the RuNi Catalysts in an Alkaline Environment

The results of investigations of the RuNi catalysts, which are designed for the electrooxidation of methanol and other low-molecular-weight alcohols in alkaline solutions, are presented. It is shown that the maximum catalytic activity in this reaction is exhibited by a catalyst, which was synthesized thermochemically on acetylene black AD100 containing 15 wt % RuNi at a 68 : 32 atomic ratio (in at. %) between the metals. The structure of the synthesized catalysts is studied by the methods of x-ray photoelectron spectroscopy and x-ray diffraction analysis (XRDA). The area of the metal surface is determined on the basis of the magnitude of the adsorption of CO from the voltammetric curves. An analysis of the data obtained in this work leads to the conclusion that ruthenium in the composition of the catalyst exists in metallic and partially oxidized states and nickel exists in the form of a nonstoichiometric oxide. In addition it is found that the insertion of nickel into the system leads, as follows from the XRDA data, to the dispersion of ruthenium and, as follows from the voltammetric curves, to a decrease in the specific surface area accessible to the adsorption of CO. This is probably connected with the decoration and blockade of a portion of the ruthenium surface by some nickel oxides. Data on the influence, which is exerted by the concentration of methanol, alkali, and temperature on the electrocatalytic activity of the AD100 + 15 wt % RuNi catalyst at a 68 : 32 atomic ratio (in at. %) between the components, are presented. Rates of the oxidation of methanol, ethanol, n-butanol, and ethylene glycol in identical conditions on the catalyst AD100 + 15 wt % RuNi (68 : 32 at. %) between the metals are compared with one another. The oxidation currents, which are observed at a potential of 0.3 V, are equal to 5.48, 2.67, 0.48, and 0.47 A per gram of the catalyst for ethanol, ethylene glycol, methanol, and n-butanol, respectively.__________Translated from Elektrokhimiya, Vol. 41, No. 7, 2005, pp. 829–839.Original Russian Text Copyright © 2005 by Tarasevich, Karichev, Bogdanovskaya, Kapustin, Lubnin, Osina.     

助剂对Ni/海泡石催化剂加氢性能的影响

以海泡石为载体,Ｎｉ为活性组,用浸渍法制备了一系列含不同助剂的Ｎｉ基海泡石催化剂,以ＣＯ２甲烷化及苯加氢为探针反应,研究了催化剂的活性及抗硫性能,用Ｈ２－ＴＰＤ、ＸＰＳ、活性表面积及活化能的测定等于段,对催化剂进行表征,并从热力学上探讨ＣＯ２甲烷化的适宜温度。实验结果表明,海泡石或助剂的加入,能使镍晶粒变小,增加活性镍的表面积以及使镍原子的电子云密度升高,从而提高了催化剂的活性和使用寿命。能使镍晶     

Ni／MgO／Al2O3催化剂中Ni前体对甲烷—二氧化碳重整反应活性的影响

考察了以硝酸镍、氯化镍、硫酸镍、醋酸镍及硝酸六氨合镍5种Ni盐制备的Ni/MgO/Al2O3催化剂在CO2与CH4重整制合成气反应中的催化活性,发现Ni前体对活性有明显的影响,以硝酸镍、醋酸镍、硝酸六氨合镍为前体制备的Ni催化剂,反应性较高;以硫酸镍为前体制备的Ni催化剂,可能由于硫中毒等原因而显示出很低的活性;以氯化镍为前体制备的 Ni催化剂,其活性与制备方法有关,未经烧而直接还原的催化剂显示出较好的活性,X－射线粉末衍射（XRD）、BET比表面积及反应后的积量测定结果表明,以硝酸镍、醋酸镍、硝酸六氨合镍为前体制备的Ni催化剂,表面分散性好,比表面积大,积炭量少。     

Simultaneous removal of ethanol, acetaldehyde and nitrogen oxides over V-Pd/γ-Al_2O_3-TiO_2 catalyst

V-Pd/γ-Al2O3-TiO2 catalysts with different vanadium contents were prepared by a combined sol-gel and impregnation method. X-ray diffraction (XRD), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and catalytic removal of ethanol, acetaldehyde and nitrogen oxides at low temperature (<300 ?C) were used to assess the properties of the catalysts. The results showed that the sample with 1wt% vanadium exhibited an excellent catalytic performance for simultaneous removal of ethanol, acetaldehyde and nitrogen oxides. The conversions of ethanol, acetaldehyde and nitrogen oxides at 250 ?C were 100%, 74.4% and 98.7%, respectively. V-Pd/γ-Al2O3-TiO2 catalyst with 1 wt% vanadium showed the largest surface area and higher dispersion of vanadium oxide on the catalyst surface, and possessed a larger mole fraction of V4+ species and unique PdO species on the surface, which can be attributed to the strong synergistic effect among palladium, vanadium and the carriers. The higher activity of V-Pd/γ-Al2O3-TiO2 catalyst is related to the V4+ and Pd2+ species on the surface, which might be favorable for the formation of active sites.     

无溶剂高度分散Ni/MCM-41催化剂的制备及其萘加氢性能

分别用机械研磨无溶剂法、添加柠檬酸无溶剂法制备了 Ni/MCM-41催化剂,对所制催化剂进行了分析表征,探究其萘加氢反应性能并与常规浸渍法进行了对比.与常规浸渍法相比,机械研磨无溶剂法所制催化剂的物理性质相近,金属镍分散度和萘加氢性能略有提高;添加柠檬酸无溶剂法则显著提升了催化剂的分散度和萘加氢性能,金属镍分散度由6....