CO_2制备甲醇催化剂研究进展

通过将CO2有效转化为甲醇,真正实现"跨越油气时代"进入"甲醇时代"。通常CO2加氢合成甲醇所用催化剂主要是铜基催化剂,添加其他金属元素或助剂以提高铜基催化剂催化性能。介绍CO2制备甲醇催化剂早期的研究,综述近年来有关CO2制备甲醇催化剂研究进展,新研发的镍-镓结构催化剂可在低压(常压)下将CO2转化为甲醇,比传统的铜-锌-铝催化剂更有效,更多产甲醇。介绍CO2与水反应合成甲醇反应所用催化剂以及光催化还原CO2生成甲醇的新思路和新途径。     

Paper-structured fiber composites impregnated with platinum nanoparticles synthesized on a carbon fiber matrix for catalytic reduction of nitrogen oxides

Platinum nanoparticles (PtNPs) were synthesized on surface-activated carbon fibers with high thermal conductivity, and paper-structured composites were fabricated by a papermaking technique, using the PtNPs-supported carbon fibers and ceramic fibers as matrix materials. As-prepared materials, denoted paper-structured PtNPs catalyst, possessed a unique porous microstructure derived from entangled inorganic fiber networks on which PtNPs were well dispersed. In catalytic reduction of nitrogen oxides (NO_X) in the presence of methane (CH₄), both of which are model exhaust gas components of combustion engines, paper-structured PtNPs catalyst demonstrated excellent NO_X and CH₄ removal efficiency and rapid thermal responsiveness by comparison with the PtNPs-supported carbon fibers, commercial Pt catalyst powders and a monolithic Pt-loaded honeycomb. These features of the new catalyst material are thought to arise from synergistic effects of the highly active PtNPs in association with the unique paper-like microstructure, in promoting effective transfer of heat and reactants to the active sites of the Pt nanocatalysts. The paper-structured PtNPs catalyst with paper-like practical utility is expected to be a promising catalytic material for efficient NO_X gas purification.     

Cu/ZnO/Zn-Al水滑石催化剂的制备及在富CO_2合成气制甲醇反应中的催化性能

传统Cu/ZnO/Al_2O_3(CZA)甲醇合成催化剂在富CO_2合成气制甲醇反应中的性能不高。为了提高CZA催化剂的性能,采用并流沉淀-水热老化法制备Zn-Al水滑石(Zn-Al-HT)载体,与Cu-Zn母体复合得到Cu-ZnO/Zn-Al-HT(HCZA)催化剂。对载体以及催化剂进行表征,考察不同水滑石含量的HCZAx(x=1~4)催化剂在富CO_2合成气制甲醇反应中的催化性能,并在HCZA3催化剂上进行120h稳定性试验。结果表明,还原态催化剂上Cu比表面积越大,催化剂上总碳转化率越高;催化剂中Zn-Al-HT相含量越高,液相有机相中甲醇含量越高;HCZA3催化剂具有良好的催化稳定性。     

能源化工与催化固定床一步法制二甲醚催化剂性能

采用固定床反应装置,以共沉淀法制备甲醇催化剂和一步法合成二甲醚催化剂,采用BET、XRD和SEM对催化剂进行表征。在反应压力2.5 MPa、反应温度260 ℃和空速(500~900) h^-1条件下,催化剂催化活性最好,其中,CO转化率≥90%,二甲醚收率≥60%,二甲醚选择性≥65%。     

In situ combustion synthesis of structured Cu-Ce-O and Cu-Mn-O catalysts for the production and purification of hydrogen

The combustion method was employed for the in situ synthesis of nanocrystalline Cu-Ce-O and Cu-Mn-O catalyst layers on Al metal foam, without the need of binder or additional calcination steps. Copper-manganese spinel oxides have been proposed as a catalytic system for hydrogen production via methanol steam reforming, while CuO-CeO₂ catalysts have been successfully examined for CO removal from reformed fuels via selective oxidation. In this work, the performance of these catalysts supported on Al metal foam has been investigated in the reactions of methanol reforming and selective CO oxidation. The Cu-Ce-O foam catalyst exhibited similar catalytic performance to the one of the powder catalyst in the selective oxidation of CO. The performance of the Cu-Mn-O foam catalyst in the steam reforming of methanol was inferior to the one of the powder catalyst at intermediate conversion levels, but almost complete conversion of methanol was obtained at the same temperature with both foam and powder catalysts.     

甲醇氧化制甲醛铁钼催化剂研究

采用共沉淀法制备了不同Mo与Fe原子比的甲醇氧化制甲醛催化剂,在常压固定床反应器上对催化剂进行活性评价,采用BET、XRD和TEM对制备的催化剂进行表征。结果表明, Mo与Fe原子比为2.2~2.8时,催化剂具有较好的活性,(400~450) ℃焙烧的催化剂具有良好的比表面积、适宜的孔容和孔径,形成了较为稳定的MoO₃和Fe2(MoO₄)₃晶相,使催化剂具有更高的活性和选择性。对甲醇氧化制甲醛反应进行研究,结果表明,在反应温度(265~315) ℃,空速(8 500~13 000) h^-1时,甲醇转化率>98%,甲醛收率>93%, 500 h长周期考核,催化剂表现出良好的活性和稳定性。     

Autothermal reforming and water–gas shift double bed reactor for H2 production from ethanol

The present work reports the improvement in the H₂ production from the autothermal reforming of ethanol (ATR) through the addition of a second water–gas shift (WGS) catalytic bed in the same reactor. Thus, three Ni catalysts (ca. 10, 15 and 20%, w/w) supported on Yttria-stabilized zirconia (YSZ) were synthesized for the ATR process and characterized by atomic absorption spectrophotometry (AA), temperature-programmed reduction (TPR), X-ray diffraction (XRD) and N₂ adsorption/desorption. A commercial water–gas shift (WGS) Fe–Cr catalyst was employed for the double bed reactor configuration. The synthesized Ni based catalysts presented almost complete conversion of ethanol at low temperatures (below 400 °C) compatible with the WGS process. The addition of a second WGS bed in the same reactor, which works with an additional amount of water, led to a higher production of H₂ and to an important removal of the CO coming from the ATR process. Therefore, the proposed compact reactor configuration shows potential for the simultaneous production and purification of H₂ from ethanol.     

载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响

用PVP保护乙醇还原法制备了一系列Au-Pd/MOx(M=Zn、Ce、Fe、Ti、Cr和Al)双金属催化剂,考察了不同载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响,用XRD、TG、TPD、TPR和TPH等对催化剂进行了表征。结果表明,载体对催化剂性能有较大影响,与钛、铬和铝氧化物载体相比,448K时偏碱性的锌、铈和铁氧化物载体负载的Au-Pd催化剂的甲醇转化率均在80.0%以上,催化剂积碳量降低。其中以Au-Pd/ZnO催化剂的效果最好,523K时甲醇转化率和氢气选择性分别为99.0%和45.6%,反应20h后积碳量仅为0.0232g/gcat.。     

On the isopropylation of naphthalene over zeolite catalysts in the high-pressure fixed-bed flow reactor

Catalytic performances of various dealuminated mordenite catalysts for the isopropylation of naphthalene by isopropyl alcohol with decalin or cyclohexane as a solvent were investigated in a high-pressure fixed-bed flow reactor. It was found that dealumination of H-mordenite could substantially improve the catalytic conversion, selectivity and stability. The catalyst with steam treatment at 700 °C followed by acid leaching was revealed to exhibit high and comparatively stable conversion of ca. 37% with the high 2,6-/2,7-DIPN ratio of ca. 3. Reaction conditions, such as reaction temperature, pressure, space velocity and solvent, could significantly influence the catalytic performance, except for the 2,6-/2,7-DIPN ratio. The catalytic behavior is discussed in relation with catalyst porosity and acidity.     

A Highly Effective Pt and H3PW12O40 Modified Zirconium Oxide Metal–Acid Bifunctional Catalyst for Skeletal Isomerization: Preparation, Characterization and Catalytic Behavior Study

A series of metal–acid bifunctional catalysts with varying quantities of platinum and tungstophosphoric acid (TPA) supported on zirconium oxide were prepared by co-impregnation method. In skeletal isomerization of n-pentane using catalyst with 1% Pt and 30% TPA loadings the conversion of the reactant which was close to the equilibrium conversion reached ca. 65% and the selectivity towards the product was as high as ca. 97% at atmospheric pressure and relatively low reaction temperature (200 °C). The phase structure, chemical structure, surface physicochemical properties, surface element oxidation states and hydrogen reduction behavior of the catalysts were well-characterized via XRD, FT-IR, N₂ adsorption–desorption determination (BET), XPS and TPR. The effects of Pt and TPA loadings, calcination temperature, reaction temperature and weight hourly space velocity (WHSV) on the catalytic performance were investigated. In addition, a long period catalytic stability test of the catalyst with optimal Pt and TPA loadings was carried out, which indicated that the bifunctional catalyst was in possession of good stability in skeletal isomerization along with high catalytic activity under the experimental conditions.     

Methanol steam reforming over paper-like composites of Cu/ZnO catalyst and ceramic fiber

Copper–zinc oxide catalyst powders were successfully prepared into paper-like composites, called catalyst paper in this study, using ceramic fibers as the carrier matrix of the catalyst. A papermaking technique with a dual polyelectrolyte retention system was used. Catalyst particles were supported on the ceramic fiber networks tailored in the catalyst paper having various types of pores. Pieces of catalyst paper were subjected to methanol steam reforming (MSR) to produce hydrogen gas for fuel cell applications. They demonstrated a higher performance for methanol conversion and hydrogen production in the MSR reaction than commercial Cu/ZnO catalyst pellets, exhibiting an efficacy equivalent to that of the original catalyst powders. The concentration of carbon monoxide, which acts as a catalytic poison for fuel electrode catalysts, decreased remarkably, without any carbon monoxide reduction system. Moreover, the porous structure of catalyst paper influenced the MSR efficiency. It was assumed that the macropores ca. 20 μm in diameter greatly contributed to the MSR performance, rather than the mesopores on the catalyst surfaces. Thus, the porous, flexible and easy-to-handle catalyst paper is a promising material for practical MSR applications.     

Production of synthesis gas by autothermal reforming of iso-octane and toluene over metal modified Ni-based catalyst

The reforming process of gasoline is an attractive technique for fuel processor or hydrogen station applications. We investigated catalytic autothermal reforming (ATR) of iso-octane and toluene over transition metal supported catalysts. The catalysts were prepared by an incipient wetness impregnation method and characterized by N₂ physisorption, XRD, and TEM techniques before and after the reaction. Many of the tested catalysts displayed reasonably good activity towards the reforming reactions of iso-octane. Especially, Ni/Fe/MgO/Al₂O₃ catalyst showed more activity than the other catalysts tested in this study including commercial HT catalyst. Ni/Fe/MgO/Al₂O₃ catalyst showed good stability for 700 h in the ATR of iso-octane. No major change was observed in catalytic activity in ATR of iso-octane or in the structure of catalyst. Since iso-octane, toluene are surrogates of gasoline, Ni/Fe/MgO/Al₂O₃ catalyst can be considered as ATR catalyst for gasoline fuel processor and hydrogen station systems.     

Catalytic dehydration of methanol to dimethyl ether over mordenite catalysts

The conversion of methanol to dimethyl ether was carried out over various commercial mordenite and ion-exchanged catalysts to evaluate the catalytic performance of mordenite catalysts with different pore structures and acidities. These catalysts were compared for their catalytic properties in a fixed-bed reactor at 1 atm, 573 K and LHSV of 2.84 h^− 1. The catalysts were characterized by BET, ICP, NH₃-TPD, XRD, TGA and FT-IR techniques. The ion-exchanged mordenite showed higher activity, selectivity and good stability in dehydration of methanol due to the addition of medium acid sites. Also, the effect of water on catalyst deactivation was investigated over two selected catalysts in order to develop a suitable catalyst for synthesis of dimethyl ether. It was found that the H-mordenite catalyst supplied by Süd-chemie Co., (MCDH-1) was more active and less deactivated than another one in a feed containing 20 wt.% water.     

Hydrogen production by oxidative methanol reforming with various oxidants over Cu-based catalysts

In order to improve the start-up property of a small hydrogen producer with a micro methanol reformer, oxidative methanol reforming (OMR) with various oxidants over copper-based catalysts was examined. The addition of Fe to a Cu/ZnO/Al₂O₃ catalyst resulted in higher catalyst durability, with a slight improvement in catalytic activity, for OMR with air. However, the addition of larger amounts of Fe inhibited further improvement of catalytic performance, possibly due to the formation of less active CuFe₂O₄ spinel in the catalyst. The production of hydrogen by OMR with hydrogen peroxide as an alternative oxidant, which has the potential to provide concentrated hydrogen without nitrogen dilution, was also considered. It was found that hydrogen peroxide is an effective oxidant for OMR over copper-based catalysts due to its ability to suppress CO formation and its improving effect on methanol conversion.     

用于低温液相合成甲醇的Cu/MgO/ZnO催化剂

采用并流共沉淀法制备了不同Cu:(Mg+Zn)及Mg:Zn摩尔比的铜基催化剂Cu/MgO/ZnO,用于低温液相甲醇的合成,并对比了Cu/ZnO及Cu/MgO催化剂,分析了催化剂中载体MgO的作用. 结果表明,MgO的引入有利于催化剂中Cu+的生成并均匀分散在载体中,可提高催化剂的催化活性. 以合成气CO+H2为原料,在443 K和5.0 MPa条件下,采用液体石蜡作溶剂,考察了催化剂的催化性能. 结果表明,Cu/MgO/ZnO催化剂的活性优于Cu/ZnO和Cu/MgO催化剂,且当Cu:Mg:Zn=2:1:1时催化性能最好,此时合成气中CO的转化率为63.56%,甲醇的选择性为99.09%,时空收率为5.413 mol/(kg×h). 分析了Cu/MgO催化剂在高温反应条件下的失活现象,认为铜烧结是其失活的主要原因.     

Polymer-supported N-heterocyclic carbene-iron(III) catalyst and its application to dehydration of fructose into 5-hydroxymethyl-2-furfural

Polymer-supported NHC–metal catalysts were prepared from chloromethyl polystyrene resin via two-step reaction. Metals were loaded into 1.6 – 16 mol% of total imidazolium and the remaining imidazolium chloride salt provided ionic liquid moiety. The formation of metal complex with the polymer-supported NHC ligand was analyzed by ATR FT-IR, XRD, and XPS. The synthesized polymer-supported NHC–metal catalysts were applied to the dehydration of fructose into HMF. The environmentally benign and inexpensive polymer-supported NHC–Fe^III catalyst showed good catalytic activity and yielded HMF at 73% (with a conversion of 97%). It could also be reused without significant loss of catalytic activity.     

Ba–ZnO catalysts for soybean oil transesterification

The transesterification of soybean oil to biodiesel using Ba–ZnO as a solid catalyst was investigated. The Ba–ZnO sample with loading of 2.5 mmol/g Ba on ZnO and being calcined at 873 K for 5 h, was found to be the optimum catalyst, which could exhibit the highest basicity and the best catalytic activity for the reaction. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 12:1 molar ratio of methanol to oil and a catalyst amount of 6 wt.%, the conversion of soybean oil was 95.8%. Furthermore, XRD, XPS, DTA–TG and the Hammett indicator method were employed for the catalyst characterizations, and the relation between the catalytic efficiency and the basicity of the catalysts was also discussed.     

Synthesis of modified catalyst and stabilization of CuO/NH4‐ZSM‐5 for conversion of methanol to gasoline

In this article, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over CuO/ NH₄‐ZSM‐5(3,5,7,9%) catalysts prepared via sono‐chemistry methods. In order to improve, copper oxide can be used as a booster on NH₄‐ZSM‐5 this catalyst property. Accordingly, the conversion process of Methanol to Gasoline (MTG) was conducted under a pressure of 1 atm and temperature of 400°C by a fixed‐bed reactor on copper oxide catalysts which were prepared based on synthetic NH₄‐ZSM‐5. The synthetic catalyst was investigated by such analyses as BET, XRD, FT‐IR, and SEM. Formation of copper oxide phase and proper distribution of copper oxide were proven on the basic level of using XRD analysis. BET analysis showed the reduction in catalyst level and SEM images depicted the proper distribution of particles. The present investigation is to study the effect of CuO loading on NH4‐ZSM‐5 support for conversion of methanol to gasoline range hydrocarbons. A series of CuO/ NH4‐ZSM‐5 catalysts were prepared, characterized, and experimented for their performance on methanol conversion and hydrocarbon yield.     

Catalytic performance of sulfate-grafted graphene oxide for esterification of acetic acid with methanol

Graphene oxide possesses tremendous mechanical and electronic properties in combination with large surface area and accessible active sites leading to the development of novel innovative heterogeneous catalysts. The present study elaborates the catalytic activity of graphene oxide, enhanced by grafting active sulfate groups on its surface to result as a superior catalyst. The catalyst was evaluated in the model acetic acid esterification reaction with methanol in terms of acid conversion. Catalysts consisting of varied sulfate concentrations and calcination time were synthesized and optimized for its best catalytic activity. The prepared catalysts (GO-SO₄) were characterized using XRD, FT-IR, SEM-EDS, XPS, and BET. A 44% enhancement in catalyst activity was observed using sulfate-grafted graphene oxide (GO-SO₄) catalyst over bare GO due to the synergistic effect of sulfate ions. The catalyst can be separated out by simple filtration. Further, the influence of operating process parameters including catalyst loading, and the reaction temperature was evaluated toward the maximum acid conversion. In addition, the detailed kinetic study was also done in this system using Pseudo-homogeneous model.     

助剂对二氧化碳加氢合成甲醇催化剂性能的影响

采用并流共沉淀方法制备了CuO-ZnO-ZrO2催化剂,并以金属氧化物为助剂对其进行了改性,在固定窗连续流动反应装置上考察了Ag2O和La2O32种助剂对CuO-ZnO-ZrO2催化剂催化CO2加氢合成甲醇反应性能的影响,及不同La2O3含量的CuO-ZnO-ZrO2的催化性能,采用X射线衍射(XRD)、H2-程序升温还原(H2-TPR)等方法对催化剂进行了表征。实验结果表明Ag2O和La2O3都可以提高CuO-ZnO-ZrO2催化剂的活性,而且添加6%La2O3(文中均指质量分数)的催化剂催化效果最好。添加Ag2O的催化剂中Ag作为活性中心参与CO2加氢合成甲醇的反应;对于La2O3改性的CuO-ZnO-ZrO2催化剂,适量La2O3有利于提高催化剂中CuO和ZnO的分散度。