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.     

负载型金属催化剂上合成气制甲醇反应体系的耐硫性

<正> 研究了共沉淀法制备的系列金属负载型催化剂合成气制甲醇反应性能,考察了催化剂上合成甲醇反应体系的耐硫性能。结果表明,Cu/ZnO催化剂显示出较好的甲醇合成反应性能,但该反应在含硫气氛下迅速失活;Pd/CeO_2催化剂体现出良好的甲     

基于CuAl-LDH载体制备高分散Cu/ZnO/Al2O3催化剂及其催化性能

通过沉积沉淀法制备了以层状CuAl-LDH为载体负载不同Cu/Zn比例的前体,经热处理得到CuZnAl-LDO复合催化剂,应用于合成气制甲醇反应。采用电感耦合等离子体发射光谱（ICP）、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、N₂O化学吸附、N₂吸脱附、透射电镜（TEM）和X射线光电子能谱技术（XPS）等手段对前体及催化剂进行表征,考察了水滑石的限域效应和金属-载体相互作用对催化剂活性及稳定性的影响。结果发现：由于水滑石特殊的层状结构,具有较大比表面积和丰富孔道结构,促进了Cu物种的分散,有利于催化剂表面对CO和H₂的吸附,增加了Cu、Zn之间的相互作用,提高了催化剂的催化活性。在水滑石前体拓扑转变过程中,层板羟基和水脱除后形成的粗糙表面对所负载的Cu活性物种起到限域作用,抑制了Cu的迁移和团聚。其中,Cu_0.6Zn_0.3Al_0.1-LDO催化剂催化合成甲醇的时空收率达到883mg/(g?h),且反应120h后仅下降2.8%,较共沉淀制备催化剂失活速率降低了81%,表现出较好的催化活性及稳定性。     

Cu/SiO2催化剂在醋酸甲酯加氢制乙醇反应中失活比较

采用固定床微型反应器考察Cu/ZnO和Cu/SiO₂催化剂在醋酸甲酯加氢制乙醇反应中的稳定性,分别反应1 000 h和750 h后,Cu/ZnO和Cu/SiO2催化剂均失活。采用物理吸附、DTG、原位XRD和H₂-TPR等对失活前后Cu/ZnO和Cu/SiO₂催化剂进行比较。结果表明,Cu/ZnO和Cu/SiO₂催化剂在醋酸甲酯加氢制乙醇反应中失活机理不同,Cu/ZnO 催化剂失活的主要原因是Cu晶粒长大,催化剂上ZnO晶粒同时长大;Cu/SiO₂催化剂失活主要原因是积炭物种对催化剂孔道的堵塞和对活性位的覆盖。     

甲醇水蒸汽制氢低铜催化剂制备及其性能

采用浸溃法制备了具有较低铜含量的甲醇水蒸汽转化制氢Cu/ZnO2/ZrO2/Al203催化剂,并用X射线衍射(XRD)表征其性能,考察了Zr含量对催化活性的影响,优选出Cu/Zn/Al/Zr物质的量比为1/1/5.6/0.2的Cu1Zn1Al5.6Zr0.2催化剂.对比实验表明,Cu1zn1Al5.6Zr0.2用于甲醇水蒸汽转化制氢反应活性与工业催化剂相当,二氧化碳选择性高于工业催化剂: Cu1Zn1Al5.6Zr0.2催化剂中CuO质量含量仅为16.87%,只有工业催化剂的三分之一.正交实验表明,Cu1Zn1 AJ5.6Zr0.2催化剂较为适宜的反应条件为:温度245℃,水/醇比1.5,液体质量空速2 h-1.经100 h连续实验,Cu1 Zn1 Al5.6 Zr0.2催化剂对甲醇蒸汽转化反应活性稳定在90%左右.     

焙烧温度对Cu/Zn/Al催化剂超临界甲醇中木质素液化的影响

采用共沉淀法制备类层柱Cu/Zn/Al水滑石,经焙烧制备Cu/Zn/Al催化剂。考察了焙烧温度对催化剂在超临界甲醇中木质素催化液化活性及稳定性的影响。结果表明,500℃焙烧时水滑石分解较为完全,析出的ZnO和ZnAl2O4尖晶石相对析出的CuO纳米粒子起到良好的隔离和稳定作用;在340℃、80 mg木质素、30 mg催化剂、4 mL甲醇反应3 h条件下进行重复性实验,500℃焙烧催化剂表现出良好的活性和稳定性。     

垃圾焚烧脱硝催化剂钙镁失活与活性恢复特性

以国内某垃圾焚烧电厂失活选择性催化还原(SCR)脱硝催化剂为研究对象,针对Ca、Mg失活因素进行失活特性研究,同时探讨垃圾焚烧失活催化剂的活性恢复方法与原理。对新催化剂、失活催化剂和再生催化剂样品进行脱硝性能对比测试。利用扫描电子显微镜(SEM)、N₂吸附-脱附和X射线荧光光谱(XRF)表征催化剂样品的表面结构和化学组成;进行X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)测试,分析失活和再生催化剂的化学形态变化;采用NH₃程序升温脱附(NH₃-TPD)和H₂程序升温还原(H₂-TPR)研究催化剂的酸性位点变化和氧化还原特性。结果表明,由于受到Ca、Mg等失活因素的影响,失活催化剂脱硝性能大幅下降,300～350℃温度区间内的脱硝效率从新催化剂的95%以上下降到80%左右;利用“EDTA清洗+活性物质负载”方法再生后的催化剂脱硝能力明显恢复,RegCat样品在300～350℃温度区间的脱硝效率可恢复至新催化剂水平。Ca、Mg在催化剂表面形成性质稳定的硫酸盐,同时消耗大...     

氧化铈负载铼催化甲醇制甲酸甲酯稳定性研究

以高铼酸铵和氧化铈为原料,通过浸渍法合成了一种甲醇选择氧化制甲酸甲酯催化剂。对催化材料进行了热重-差热(TG-DTG),X射线衍射(XRD)和扫描电子显微镜(SEM)等技术表征;同时研究了甲醇在该催化剂上选择氧化制甲酸甲酯的反应活性和稳定性。结果表明,氧化铈负载铼催化剂表现出良好的催化甲醇选择氧化制甲酸甲酯的活性和选择性。稳定性实验结果表明24小时没有明显失活。     

多孔ZnO-SnO_2异质结构的制备及气敏特性研究

本研究采用溶剂热法制备了SnO_2介孔球,并以此为基础,将ZnO纳米颗粒负载到其表面,最终制备了ZnO/SnO_2异质结构。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和比表面测试(BET)对产物的晶体结构、微观形貌、元素化合态和孔结构进行了表征。气敏性能测试表明,多孔ZnO/SnO_2异质结构对三乙胺具有优异的气敏性能,对100 ppm三乙胺,灵敏度为88. 4,响应和恢复时间分别为12 s和15 s。此外,该材料对三乙胺表现出优异的选择性。从材料的多孔结构和异质结构能带匹配两方面对多孔ZnO/SnO2异质结构的作用机理进行了分析。     

合成列管式反应器催化剂钝化工艺优化

甲醇合成工序采用的是铜基催化剂,主要成分CuO/ZnO/Al_2O_3,特点是活性好,单程转化率高;选择性好,杂质只有微量的二甲醚、甲酸甲酯、乙醇等,易得到高纯度的精甲醇;耐高温性差,对硫敏感。随着催化剂的使用,催化剂会发生失活,如热失活、中毒失活、污染失活、强度下降等,降低甲醇的产量和质量,增加能耗,同时也会增加副产物含量,增加精馏的负荷,进而影响精甲醇的产品质量。     

Hydrogen production from steam reforming of methanol over CuO/ZnO/Al2O3 catalysts: Catalytic performance and kinetic modeling

A series of CuO/ZnO/Al_2O_3, CuO/ZnO/ZrO_2/Al_2O_3 and CuO/ZnO/CeO_2/Al_2O_3 catalysts were prepared by coprecipitation and characterized by N_2 adsorption, XRD, TPR, N_2O titration and HRTEM. The catalytic performances of these catalysts for the steam reforming of methanol were evaluated in a laboratory-scale fixed-bed reactor at 0.1 MPa and temperatures between 473 and 543 K. The results showed that the catalytic activity depended greatly on the catalyst reducibility and the specific surface area of Cu. An approximate linear correlation between the catalytic activity and the Cu surface area was found for all catalysts investigated in this study.Compared to CuO/ZnO/Al_2O_3, the ZrO_2-doped CuO/ZnO/Al_2O_3 exhibited higher activity and selectivity to CO,while the CeO_2-doped catalyst displayed lower activity and selectivity. Finally, an intrinsic kinetic study was carried out over a screened CuO/ZnO/CeO_2/Al_2O_3 catalyst in the absence of internal and external mass transfer effects. A good agreement was observed between the model-derived effluent concentrations of CO(CO_2) and the experimental data. The activation energies for the reactions of methanol-steam reforming, water-gas shift and methanol decomposition over CuO/ZnO/CeO_2/Al_2O_3 were 93.1, 85.1 and 116.5 k J·mol~(-1), respectively.     

含CO2合成气低温合成甲醇的研究

以含CO₂的合成气为原料,Cu-Zn基催化剂,醇溶剂,低温、低压（443 K、3.0 MPa）下合成甲醇。考察了时间、溶剂和催化剂对反应的影响。结果表明,随着反应时间的增加,碳的总转化率、甲醇选择性及收率均逐渐增加;醇溶剂参与反应,但并不被消耗,起到助催化作用,且2-丁醇溶剂表现出较高的反应活性;ZnO、Y₂O₃、La₂O₃、MgO和Al₂O₃作为载体制得的Cu/M_xO_y催化剂,Cu/ZnO呈现出较高的反应活性;稀土元素La作为助剂,能提高Cu-Zn基催化剂的活性,当使用n(Cu)∶n(Zn+La)=1∶1,且n(Zn)∶n(La)=3∶2的Cu/ZnO/La2O3催化剂进行甲醇合成反应时,碳总转化率、甲醇的选择性和收率均高于Cu/ZnO催化剂。     

Active sites in Cu/ZnO/ZrO2 catalysts for methanol synthesis from CO/H2

Among various Cu/ZnO/ZrO₂ catalysts with the Cu/Zn ratio of 3/7, the one with 15 wt.% of ZrO₂ obtains the best activity for methanol synthesis by hydrogenation of CO. The TPR, TPO and XPS analyses reveal that a new copper oxide phase is formed in the calcined Cu/ZnO/ZrO₂ catalysts by the dissolution of zirconium ions in copper oxide. In addition, the Cu/ZnO/ZrO₂ catalyst with 15 wt.% of ZrO₂ turns out to contain the largest amount of the new copper oxide phase. When the Cu/ZnO/ZrO₂ catalysts is reduced, the Cu²⁺ species present in the ZrO₂ lattice is transformed to Cu⁺ species. This leads to the speculation that the addition of ZrO₂ to Cu/ZnO catalysts gives rise to the formation of Cu⁺ species, which is related to the methanol synthesis activity of Cu/ZnO/ZrO₂ catalyst in addition to Cu metal particles. Consequently, the ratio of Cu⁺/Cu⁰ is an important factor for the specific activity of Cu/ZnO/ZrO₂ catalyst for methanol synthesis.     

发泡镍负载CuO/ZnO/Al2O3对甲醇水蒸汽重整的催化作用

以三维网状多孔发泡镍为载体，制备了负载CuO/ZnO/Al₂O₃的催化剂，研究了催化剂对甲醇水蒸汽重整制氢气的催化作用，考察了催化剂的制备方法、重整反应温度、催化反应器液体空速对催化反应以及催化剂稳定性的影响。结果表明，通过预先在发泡镍上包覆一层Al₂O₃，能够提高催化剂负载的均匀性，所制备的催化剂具有很好的低温初活性和选择性。在反应温度为220 ℃，液体空速为7.2 h^-1的条件下，甲醇初始转化率为98.36%，CO₂选择性为98.4%，产品气中CO摩尔分数为0.41%。通过40 h的连续实验，甲醇转化率始终维持在80%以上，产品气中CO摩尔分数保持在0.5%，CO2的选择性维持在98%。     

TPR and infrared measurements with cu/zno/al2o3 based catalysts for the synthesis of methanol and higher alcohols from co + h2

The influence of different promoters (CeO₂, MnO_x, K₂CO₃) on various properties of a standard coprecipitated Cu/ZnO/Al₂O₃ catalyst has been examined. The catalysts prepared were characterized by Cu surface area, PTIR and TPR measurements. It was found that addition of K₂CO₃ reduced the Cu surface area by about 30%, whereas the Cu surface area did not decrease with addition of the other promoters. The reduction behaviour was affected by the addition of K₂CO₃ as well as by MnO_x, but not by CeO₂. The cause of these effects is possibly an electronic interaction between the promoter and Cu ions.The effect of the different promoters on the activity and selectivity has also been studied. The K₂CO₃ promoted catalyst has an optimum selectivity to higher alcohols at 280 °C; addition of Mn made the catalyst more selective towards methanol. At 300 °C, the Ce promoted catalyst had a high selectivity to methanol and iso-butanol. The promoting effect of the additives may be caused by stabilization of the surface intermediates leading to alcohols. Infrared measurements of adsorbed CO or adsorbed methanol on materials with and without K did not, however, provide any evidence for a difference in reaction mechanism.     

Ignition of methanol partial oxidation over supported platinum catalyst

Supported platinum catalysts were prepared by precipitation of H₂PtCl₆ on powders of different metal oxides. Catalytic activity of the prepared catalysts was tested with reaction of partial oxidation of methanol (POM) for hydrogen production. Most of the prepared catalysts can ignite POM at the ambient temperature. The conversion of methanol and the selectivity of hydrogen and carbon monoxide, however, increased with the reaction temperature and varied with the kind of support and platinum loading. A 1 wt% Pt/ZnO catalyst exhibited optimized methanol conversion and selectivity at a low reaction temperature of 150 °C. The reactor may reach this temperature within 2 min after a start of the exothermic reaction.     

载体表面羟基种类对DMO加氢用Cu/SiO2催化剂性能的影响

通过程序升温焙烧改变气相纳米二氧化硅表面的羟基含量及种类,并以其为载体,采用蒸氨法制备了Cu/SiO₂催化剂,使用比表面积测试（BET）、傅里叶变换红外光谱（FTIR）、漫反射傅里叶变换红外光谱（DRIFT）、X射线衍射（XRD）、透射电子显微镜（TEM）、H₂程序升温还原（H₂-TPR）、NH₃/CO₂程序升温脱附（NH₃/CO₂-TPD）、X射线光电子能谱（XPS）、俄歇电子能谱（AES）等方法研究了Cu/SiO₂催化剂的结构和酸碱性,采用固定床反应器在低温（448K）、低压（1.5MPa）的反应条件下进行草酸二甲酯加氢制备乙二醇的反应,评价其催化活性。结果表明,高温焙烧二氧化硅载体可显著改变后续合成Cu/SiO₂催化剂的结构并降低其酸碱性,对提高乙二醇选择性和降低草酸二甲酯加氢过程中醇类或醚类副产物的选择性具有明显的促进作用。但同时该过程会导致催化剂的活性降低,载体焙烧（473K）后合成的催化剂均需要提高氢酯比方能获得最佳反应结果。其中经873K焙烧的二氧化硅制备的Cu/SiO₂-4催化剂,在最佳反应条件下乙二醇的选择性由低温焙烧后的92%左右提升到97%以上,草酸二甲酯转化率保持在100%。     

Hydrogenation of carbon dioxide to methanol over palladium-promoted Cu/ZnO/A12O3 catalysts

The effect of Pd on a Cu/ZnO/A1₂O₃ catalyst for methanol synthesis from CO₂/H₂ has been investigated. Activities of impregnated catalysts and physical mixtures were studied in an internal recycle reactor under 5 MPa, 250°C and a range of conversions. In all cases, the promotion of methanol production was greater at higher flow rates (lower conversions). The promotion achieved by use of Pd/A1₂O₃+ Cu/ZnO/Al₂O₃ physical mixtures was found to increase with Pd content. Greater promotion was observed over the Pd impregnated Cu/ZnO/Al₂O₃ catalysts, although this was insensitive to the particular Pd loadings used. The results are consistent with the proposal that hydrogen spillover is responsible for the observed promotion. The effectiveness of Pd as a promoter for the reduction of CuO in the catalysts was studied by TPR and was found to be related to the level of promotion in methanol production.