Cu/Zn/Al/Zr纳米纤维催化剂上的CO2加氢合成甲醇过程

A highly active Cu/Zn/Al/Zr fibrous catalyst was developed for methanol synthesis from CO₂ hydrogenation.Various factors that affect the activity of the catalyst,including the reaction temperature,pressure and space velocity,were investigated.The kinetic parameters in Graaf’s kinetic model for methanol synthesis were obtained.A quasistable economical process for CO₂ hydrogenation through CO circulation was simulated and higher methanol yield was obtained.     

A Cu/Zn/Al/Zr Fibrous Catalyst that is an Improved CO<Subscript>2</Subscript> Hydrogenation to Methanol Catalyst

A series of Cu/Zn/Al/Zr CO₂ hydrogenation to methanol catalysts containing different ratios of Al/Zr were prepared using a co-precipitation procedure. SEM, TEM, and XRD characterization showed that all the catalysts comprised crystallites in a fibrous structure and their Cu/Zn crystallite dispersions were better than that of a commercial (COM) catalyst. It is suggested that the high dispersion and stability of the Cu/Zn crystallites due to the fibrous structure enhanced CO₂ hydrogenation, and the added Zr component further improved the catalyst. A 5% Zr addition gave a methanol space time yield 80% higher than that on the COM catalyst.     

CO2 Hydrogenation to Methanol Over Cu/ZnO/Al2O3 Catalysts Prepared by a Novel Gel-Network-Coprecipitation Method

A novel gel-network-coprecipitation process has been developed to prepare ultrafine Cu/ZnO/Al₂O₃ catalysts for methanol synthesis from CO₂ hydrogenation. It is demonstrated that the gel-network-coprecipitation method can allow the preparation of the ultrafine Cu/ZnO/Al₂O₃ catalysts by homogeneous coprecipitation of the metal nitrate salts in the gel network formed by gelatin solution, which makes the metallic copper in the reduced catalyst exist in much smaller crystallite size and exhibit a much higher metallic copper-specific surface area. The effect of the gel concentration of gelatin on the structure, morphology and catalytic properties of the Cu/ZnO/Al₂O₃ catalysts for methanol synthesis from hydrogenation of carbon dioxide was investigated. The Cu/ZnO/Al₂O₃ catalysts prepared by the gel-network-coprecipitation method exhibit a high catalytic activity and selectivity in CO₂ hydrogenation to methanol.     

胶溶剂对完全液相法制备的Cu/Zn/Al催化剂结构和性能的影响

采用完全液相法制备了Cu/Zn/Al浆状催化剂,考察了胶溶剂HNO3用量对催化性能的影响。结果表明,适量的胶溶剂HNO3用量可以减小Cu0晶粒度,提高催化剂的活性;胶溶剂的用量可以改变催化剂各组分之间的相互作用,过多的HNO3会导致催化剂活性的降低。     

载体氧化铝的粒径对对硝基苯酚加氢催化剂Ni/Al2O3的影响

The catalytic hydrogenation ofp-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/A12O3 catalyst,but little influence on the selectivity. At a comparable amount of Ni loading,the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/A12O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.     

CO Hydrogenation to Light Alkenes Over Mn/Fe Catalysts Prepared by Coprecipitation and Sol-gel Methods

CO hydrogenation to light alkenes was carried out on manganese promoted iron catalysts prepared by coprecipitation and sol-gel techniques. Addition of manganese in the range of 1–4 mol.% by means of coprecipitation could improve notably the percentage of C₂⁼~C₄⁼ in the products, but it was not so efficient when the sol-gel method was employed. XRD and H₂-TPR measurements showed that the catalyst samples giving high C₂⁼~C₄⁼ yields possessed ultrafine particles in the form of pure α-(Fe_1-xMn_x)₂O₃, and high quality in lowering the reduction temperature of the iron oxide. Furthermore, these samples displayed deep extent of carburization and different surface procedures to the others in the tests of Temperature Programmed Surface Carburization (TPSC). The different surface procedures of these samples were considered to have close relationship with the evolving of surface oxygen. It was also suggested that for the catalysts with high C₂⁼~C₄⁼ yields, the turnover rate of the active site could be kept at a relatively high level due to the improved reducing and carburizing capabilities. Consequently, there would be a large number of sites for CO adsorption/dissociation and an enhanced carburization environment on the catalyst surface, so that the process of hydrogenation could be suppressed relatively to a low level. As a result, the percentage of the light alkenes in the products could be raised.     

Cu/Zn比对CuO/ZnO/ZrO_2催化CO_2加氢合成甲醇性能的影响

研究了不同Cu/Zn摩尔比对CO2加氢合成甲醇催化性能的影响。采用草酸凝胶共沉淀法制备了一系列不同Cu/Zn摩尔比的Cu O/Zn O/Zr O2催化剂,考察不同温度及Cu/Zn摩尔比对催化性能的影响,并结合X射线衍射(XRD)、N2物理吸附、程序升温还原(H2-TPR)和程序升温脱附(H2/CO2-TPD)技术对催化剂的结构和性质进行表征。结果表明:适宜的Cu/Zn摩尔比可以提高催化剂的反应性能。在513 K,2.0 MPa,n(H2)/n(CO2)=3/1和GHSV=4 800 h-1反应条件下,当R(Cu/Zn)=4时,Cu O/Zn O/Zr O2催化剂反应性能最好,CO2转化率高达17.8%,甲醇选择性高达67.8%。     

离子液体中催化香茅醛一锅合成薄荷醇

研究制备了Cu/ZrO2-SiO2双载体催化剂,并在离子液体介质中研究香茅醛催化加氢合成薄荷醇反应。结果表明：离子液体中的阳离子与香茅醛分子中的羰基形成氢键,使香茅醛更容易异构化为胡异薄荷醇,提高了催化剂选择性;特别是可调节酸度的[bmim][AlmCln]离子液体,有效提供香茅醛的异构化所需的路易斯酸条件,在竞争性加...     

甲醇水蒸汽转化制氢Cu1Zn1Al3.2催化剂研究

采用浸渍法制备了一系列CuxZnyAlz催化剂,考察了催化剂焙烧温度和组成对甲醇水蒸汽转化制氢反应性能的影响, 用TG-DTA、XRD和SEM等方法对催化剂性能进行了表征.结果表明:400℃焙烧、Cu/Zn/Al配比(摩尔)为1:1:3.2时,制备的Cu1Zn1Al3.2催化剂具有良好催化性能;Cu1Zn1Al3.2催化剂较为适宜的反应工艺条件为:反应温度240～250℃,水/醇比1.1～1.3,液体质量空速1～2 h-1;甲醇转化率达到100%,二氧化碳选择性大于97%.本研究制备的Cu1Zn1Al3.2催化剂中CuO 含量仅为24.53%(质量),约为通常共沉淀法制备的Cu/Zn/Al催化剂的CuO 含量的50%,但Cu1Zn1Al3.2催化剂对甲醇水蒸汽转化制氢反应性能与共沉淀法相当.为甲醇水蒸汽转化制氢技术用于燃料电池用氢和中小规模制氢过程提供依据.     

机械研磨燃烧法制备Cu/ZnO/Al2O3甲醇合成催化剂

引言Cu/ZnO/Al2O3催化剂近年来广泛应用于低压甲醇合成、二甲醚合成和水煤气变换等领域[1-2],该催化体系具有活性高、使用寿命长、反应温度及     

Effect of Pd on Cu-Zn Catalysts for the Hydrogenation of CO2 to Methanol: Stabilization of Cu Metal Against CO2 Oxidation

A palladium–copper–zinc catalyst (PdO:CuO:ZnO=2:28:70), prepared by sequential precipitation of the respective cations, was tested in the hydrogenation of CO₂ at high pressure (conditions: 60 bar, CO₂:H₂=1:3 (molar), W/F=0.0675 kg h/m³, 453-513 K). The methanol yield was improved on using this Pd-containing catalyst at all temperatures with respect to the reference copper–zinc catalyst (CuO:ZnO=30:70). This improvement was not due to an additional effect in which palladium was acting as an independent catalytic site but was caused by a synergetic effect of Pd on the active Cu sites. This effect was explained in terms of hydrogen spillover and an increased stability against CO₂ oxidation of the surface copper. Therefore, the present contribution not only supports previous literature findings concerning the hydrogen spillover mechanism but also resulted in a complementary view regarding the role of palladium in Pd-modified CuO-ZnO-based catalysts.     

Cu/ZnO/Al_2O_3催化剂用于醋酸仲丁酯加氢制备仲丁醇联产乙醇

采用固定床反应器,研究共沉淀法制备的Cu/ZnO/Al_2O_3催化剂用于醋酸仲丁酯催化加氢制备仲丁醇联产乙醇的催化性能,并考察反应温度、氢酯物质的量比、反应压力和空速对反应的影响。结果表明,Cu/ZnO/Al_2O_3催化剂表现出优良的催化性能,在反应温度210℃、氢酯物质的量比15、反应压力4.0MPa和空速1.0h-1条件下,醋酸仲丁酯转化率大于99%,仲丁醇选择性大于99%,乙醇选择性大于97%。推测Cu/ZnO/Al_2O_3催化剂上醋酸仲丁酯加氢制备仲丁醇联产乙醇的反应网络,仲丁醇与乙醇的脱氢反应和脱水反应、烯烃饱和加氢反应和酯交换反应是该体系在Cu/ZnO/Al_2O_3催化剂上存在的主要副反应。     

电沉积Al/Fe/Cu多层薄膜的固态扩散研究

采用AlCl3-NaCl熔融盐镀铝、FeSO4溶液镀铁、CuSO4溶液镀铜得到了结构完整、界面清晰的Al／Fe/Cu多层薄膜。研究了电流密度、时间、温度对镀铝层性能及电流效率的影响。采用X-射线衍射仪对该多层薄膜热处理前后进行了表征，并用金相显微镜对其结构与形貌进行了分析。结果表明，该多层薄膜致密均匀且各层之间结合力良好；通过热处理后得到了一面心立方结构的新相，该新相基本结构与Cu大致相同，且多层薄膜中铁铜质量比越低，越有利于该新相的生成。     

活性形貌对CuO/ZnO/Al2O3催化加氢反应的影响

以硝酸铜、硝酸锌等为原料,采用沉淀-沉积法制备了载体是介孔Al_2O_3的CuO/ZnO/Al_2O_3催化剂,通过改变焙烧时间可得到不同活性组分形貌(团簇球状和棒状)的催化剂,并用于CO/CO_2加氢反应。通过XRD、BET、N_2吸附-脱附、TEM、H_2-TPR、CO_2-TPD、NH_3-TPD和FTIR对催化剂进行了表征与测试。结果表明,活性组分(CuO/ZnO)形貌的改变影响了催化剂的Cu O晶粒尺寸、比表面积、孔径及其还原性能,且对催化剂的酸性位点和碱性位点的相对数量影响较大。团簇球状催化剂中活性组分的分散度高、易还原、碱性位多、酸性位少,有利于甲醇的生成;而棒状催化剂中孔道不均匀、碱性位少、酸性位多,更有利于二甲醚(DME)的生成。活性测试结果表明,团簇球状催化剂表现出高甲醇选择性(95.05%)和低DME选择性(4.18%);棒状催化剂的产物选择性与团簇球状相反,表现出高DME选择性(75.41%)和低甲醇选择性(12.81%)。     

载体氧化铝的粒径对对硝基苯酚加氢催化剂Ni/Al2O3的影响

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.     

Co/SiO2 catalysts prepared from Co2(CO)8 for CO hydrogenation into alcohols and hydrocarbons: characterization by magnetic methods and temperature-programmed hydrogenation

The hydrogenation of carbon monoxide over Co/SiO₂ catalysts obtained by reduction of precursors prepared by the reaction of dicobaltoctacarbonyl with silica gives rise to a mixture of alcohols and hydrocarbons. The chain growth probability for hydrocarbon synthesis is similar to that observed over conventional catalysts prepared by the ammonia method (=0.74) with a comparable metal dispersion (metal particle size 4 nm). Alcohol formation yields a smaller chain growth probability (=0.42). Magnetic measurements have shown that in the latter catalyst, small cobalt clusters (1 nm) are likely to be present together with the cobalt particles (4 nm), this observation reconciles apparently conflicting results from the literature. It has been speculated that alcohol formation might be related to the presence of these clusters according to a concerted mechanism. Furthermore, the observation of large amounts of acetates by temperature-programmed hydrogenation, not detected in hydrocarbon selective catalysts, suggests that they may play a role in ethanol synthesis.     

不同硅铝比ZSM-5负载铁基催化剂二氧化碳加氢性能

CO₂加氢在铁基催化剂上直接制取高附加值化学品是实现其资源化利用的重要途径。通过等体积浸渍法制备了不同硅铝比（25,70,150）的ZSM-5负载的铁基催化剂,考察硅铝比对铁基催化剂上CO₂加氢性能的影响。结果表明,随着硅铝比的升高,催化剂活性先升高后降低,最优化硅铝比为70。CO₂-DRIFTS和CO₂-TPD结果显示,硅铝比为70的ZSM-5载体制备的催化剂具有较多且较强的表面碱性位,促进CO₂分子的活化解离。通过H₂-TPR、XRD、Raman等表征揭示了催化剂结构的演变过程。还原后催化剂的活性金属以单质Fe形式存在,反应过程中单质Fe向Fe₃O₄和FeC_x物种转化。不同硅铝比配位环境影响Fe与C的相互作用,影响FeC_x的生成,从而影响CO₂加氢的活性和选择性。     

Vapor-Phase Alkylation of Toluene with Isopropanol over Mg/Al, Ni/Al and Cu/Al Hydrotalcites (Layered Double Hydroxide)

Vapor-phase isopropylation of toluene has been carried out over Mg/Al, Ni/Al and Cu/Al calcined hydrotalcites (CHTs). Reaction conditions were optimized for alkylation by varying temperature, weight hourly space velocity and reactant mole ratio. Side-chain alkylation is found to be more predominant than ring alkylation over Mg/Al CHT, while Ni/Al and Cu/Al CHTs favored ring alkylation. The main products were isobutylbenzene and cymene. The combined participation of acidic and basic sites of the materials is found to be crucial for both side-chain and ring alkylation of toluene with isopropanol. An X-ray diffraction pattern of the resulting oxide indicates a diffuse MgO structure. The incorporation of small amounts of Al³⁺ to MgO generates new surface Lewis acid--base pair sites.     

Nanosized Pd/Pt and Pd/Rh Catalysts for Naphthalene Hydrogenation and Hydrogenolysis/Ring-opening

Pd/Rh and Pd/Pt catalysts supported on two different mesoporous materials – a Zr-doped MCM-41-type silica [Si/Zr = 5 w/w (SiZr)] and a commercial silica-alumina [Si/Al = 40:60 w/w (SiAl)] – were prepared by incipient wetness impregnation using nanosized suspensions of alloy particles prepared by polyol-mediated synthesis in diethylene glycol (DEG). The catalytic behaviour of these catalysts was investigated in the hydrogenation and hydrogenolysis/ring-opening of naphthalene at 6.0 MPa, by checking the role of both the main reaction conditions (temperature, contact time and H₂/naphthalene molar ratio) and increasing amounts of dibenzothiophene (DBT). The catalysts supported on SiAl showed higher activity than catalysts supported on SiZr, thus suggesting that activity is favoured by higher acidity of the support and/or higher interaction of the nanosized metal particles with the support. While using the SiZr support, weaker metal-support interactions took place by forming catalysts with bigger metal and/or metal oxide particles. Besides, the catalyst with lowest noble-metal content (0.3 wt.%) (SiAl-0.3Pd/Pt-5) had the greatest acidity and metal surface and, consequently, the highest activity. Furthermore, it exhibited a good thiotolerance in presence of increasing amounts of DBT in the feed, thus maintaining a high catalytic activity in the hydrogenation of naphthalene, although with decreased yield in trans- and cis-decalin (decahydronaphthalene or DeHN) and high-molecular-weight compounds (H.M.W.), with a corresponding increased yield in the partially hydrogenated tetralin (tetrahydronaphthalene or TeHN).     

The interaction of sulfur with Cu/Pt(111) and Zn/Pt(111) surfaces: copper-promoted sulfidation of platinum

The interaction of sulfur with Pt(111), Zn/Pt(111) and Cu/Pt(111) has been examined using X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), and thermal desorption mass spectroscopy (TDS). At temperatures between 300 and 600 K, the exposure of Pt(111) to S₂ gas produces a chemisorbed layer of sulfurwithout the formation of bulk sulfides. Exposure of S₂ to a Zn/Pt(111) alloy, at room temperature, results in a breakdown of the alloy and formation of a zinc-sulfide film on Pt(111). Further S₂ exposure at 550 K sulfidizes the remaining metallic zincwithout affecting platinum. For the Cu/Pt(111) surface alloy, on the other hand, exposure to S₂2 at 550 K leads to sulfidation of the platinum. Platinum can effectively compete for sulfur atoms bonded to copper but not for those bonded to zinc. The reaction of S₂ gas with Cu/Pt(111) surfaces produces copper sulfides that promote the sulfidation of Pt by providing surface sites for the dissociation of S₂, and by favoring the diffusion of S into the bulk of the system.