Effect of preparation methods of aluminum emulsions on catalytic performance of copper-based catalysts for methanol synthesis from syngas

Various Cu/ZnO/Al2O3 catalysts have been synthesized by different aluminum emulsions as aluminum sources and their pertormances tor methanol synthesis from syngas have been investigated. The influences of preparation methods of aluminum emulsions on physicochemical and catalytic properties of catalysts were studied by XRD, SEM, XPS,N2 adsorption-desorption techniques and methanol synthesis from syngas. The preparation methods of aluminum emulsions were found to influence the catalytic activity, CuO crystallite size, surface area and Cu0 surface area and reduction process. The results show that the catalyst CN using the aluminum source prepared by addition the ammonia into the aluminum nitrate （NP） exhibited the best catalytic performance for methanol synthesis from syngas.

Dynamic Kinetics of Methanol Synthesis over a Commercial Copper-Based Catalyst

Adsorption, surface reaction and process dynamics on the surface of a commercial copper-based catalyst for methanol synthesis from CO/CO2/H2 were systematically studied by means of temperature programmed desorption (TPD), temperature programmed surface reaction (TPSR), in-situ Fourier transform-inferred spec-troscopy(FTIR) and stimulus-response techniques. As a part of results, an elementary step sequence was suggested and a group of ordinary differential equations (ODEs) for describing transient conversations relevant to all species on the catalyst surface and in the gas phase in a micro-fixed-bed reactor was derived. The values of the parameters referred to dynamic kinetics were estimated by fitting the solution of the ODEs with the transient response data obtained by the stimulus-response technique with a FTIR analyzer as an on-line detector.

Effect of CeO_(2)on Activity of Catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)for Synthesis of Methanol

The size of the nanoparticles and the number of oxygen vacancies have a significant effect on the catalytic activity of copper-based catalysts used for the synthesis of methanol from syngas.In this study,the authors prepared a series of catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)(CZAC)with CuO particles of different sizes and varying number of oxygen vacancies on the surface by changing the added volume of CeO2 by using the co-precipitation method.The properties of the catalysts were characterized and their activity was evaluated by using high-pressure fixed-bed reaction equipment.The results showed that the addition of CeO_(2)to CuO/ZnO/Al_(2)O_(3)not only influenced the size of the CuO particles and metal-metal interactions,but also had an effect on the concentrations of oxygen vacancies and strongly basic sites.The presence of CuO particles of small sizes and a large numbers of oxygen vacancies on the surface of the catalyst were beneficial to its activity for the synthesis of methanol.The catalyst CZAC,when modified by 5%of CeO_(2),recorded CuO particles of the smallest size(8.9 nm),strong intermetallic interactions,and the highest concentrations of oxygen vacancies and strongly basic sites.It also exhibited the highest catalytic activity,with a space-time yield of methanol of 0.315 g/(h·g)that was higher than that of the enterprise RK-5 catalyst[0.215 g/(h·g)].

Characterization and performance of Cu/ZnO/Al_2O_3 catalysts prepared via decomposition of M(Cu,Zn)-ammonia complexes under sub-atmospheric pressure for methanol synthesis from H_2 and CO_2

Methanol synthesis from hydrogenation of CO2 is investigated over Cu/ZnO/Al2O3 catalysts prepared by decomposition of M（Cu,Zn）-ammonia complexes （DMAC） at various temperatures.The catalysts were characterized in detail,including X-ray diffraction,N2 adsorption-desorption,N2O chemisorption,temperature-programmed reduction and evolved gas analyses.The influences of DMAC temperature,reaction temperature and specific Cu surface area on catalytic performance are investigated.It is considered that the aurichalcite phase in the precursor plays a key role in improving the physiochemical properties and activities of the final catalysts.The catalyst from rich-aurichalcite precursor exhibits large specific Cu surface area and high space time yield of methanol （212 g/（Lcat·h）;T=513 K,p=3MPa,SV=12000 h-1）.

Synthesis of dimethyl carbonate by gas-phase oxidative carbonylation of methanol in the presence of solid catalyst I. Catalyst preparation and catalytic Properties

The gas-phase synthesis of dimethyl carbonate (DMC) from methanol, carbon monoxide and oXygen has here Studied in a flow system at atomspheric Pressure. A series of Catalyst used in this reaCtion have been prepared and evaluated. The influence of trivared carbon supporters, alkaline metal Promoters and operation conditions on DMC opthesis reaction has been discussed. Under the conditions of 130℃, CO/O2=1 .96, SV=3340h-1, the space-time yield (STY) of DMC over PdCl2-CuCl2-CH3COOK/ac. catalyst is 217g/l-cat h,which is higher than what is published in the literatUre so far.

A sulfur-tolerant Pd/CeO_2 catalyst for methanol synthesis from syngas

The catalytic activity of ceria-supported Pd for selective hydrogenation of CO is well preserved in the presence of 30 ppm H2S due to the parallel oxidation of sulfur by CeO2 under standard methanol synthesis conditions. The bifunctional nature of this catalyst opens a route for the conversion of sulfur-contaminated gas streams such as the integrated gasification combined cycle syngas or biogas into liquid fuels if desulfurization by conventional means is not practical.

Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas:Effect of copper content

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.

Study on Highly Active Catalysts and a Once-Through Process for Methanol Synthesis from Syngas

Highly active CNT-promoted co-precipitated Cu-ZnO-Al_2O_3 catalysts,symbolized as Cu_iZn_jAl_k-x%CNTs, were prepared, and their catalytic activity for once-throughmethanol synthesis from syngas was investigated. The results illustrated that, under the reactionconditions (at 493 K, 5.0 MPa, the volume ratio of H_2/CO/CO_2/N_2= 62/30/5/3, GHSV= 4000 h^(-1),the observed single-pass CO-conversion and methanol-STY over a Cu_6Zn_3Al_1-12.5%CNTs catalystreached 64% and 1210 mg/(h-g), which was about 68% and 66% higher than those (38% and 730 mg/(h·g))over the corresponding CNT-free catalyst, Cu-6Zn_3Al_1, respectively. The characteristic studies ofthe catalysts revealed that appropriate incorporation of a minor amount of the CNTs into theCu_iZn_jAl_k brought about little change in the apparent activation energy of the methanol synthesisreaction, however, led to a considerable increase in the catalyst's active Cu surface area andpronouncedly enhanced the stationary-state concentration of active hydrogen-adspecies on the surfaceof the functioning catalyst, which would be favorable to increasing the rate of the COhydro-genation reactions. Moreover, the operation temperature for methanol synthesis over theCNT-promoted catalysts can be 10-20 degrees lower than that over the corresponding CNT-free contrastsystem, which would contribute considerably to an increase in equilibrium CO-conversion andCH_3OH-yield.

New Rh-ZnO/Carbon Nanotubes Catalyst for Methanol Synthesis

A new catalyst for methanol synthesis, ZnO-promoted rhodium supported on carbon nanotubes, was developed. It was found that the Rh-ZnO/CNTs catalyst had high activity of 411.4 mg CH3OH/g/cat/h and selectivity of 96.7 % for methanol at 1 MPa and 523 K. The activity of this catalyst is much higher than that of NC 207 catalyst at the same reaction conditions. It was suggested that the multi-walled structure CNTs favored both the couple transfer of the proton and electron over the surface of the catalyst and the uptake of hydrogen which was favorable to methanol synthesis.

Activity of Catalyst for Liquid Phase Methanol Synthesis

the effects of reduction procedure, reaction temperature andcomposition of feed gas on the activity of a CuO-ZnO-Al_2O_3 catalystfor liquid phase methanol synthesis were studied. An optimizedprocedure different from conventional ones was developed to obtainhigher activity and better stability of the catalyst. Both CO andCO_2 in the feed gas were found to be necessary to maintain theactivity of catalyst in the synthesis process. Reaction temperaturewas limited up to 523 K, otherwise the catalyst will be deactivatedrapidly.

The Effect of Rare Earth on the Activity of Methanol Synthesis Catalyst

In this paper several rare earth oxides were added into methanol synthesis catalyst by solid-mixing method to improve the activity of methanol synthesis catalyst. Nd2O3, CeO2, La2O3 and Sm2O3 decrease the catalyst activity, while Pr2O3, Gd2O3 and Eu2O3 increase the methanol yield.

NC310 Catalyst for Methanol Synthesis Developed by SINOPEC Research Institute of Nanjing Chemical Company

The NC310 type catalyst for methanol synthesis developedby the SINOPEC Research Institute of NanjingChemical Company has passed the appraisal of researchachievements organized by the Science and TechnologyDivision of the Sinopec Corp. The group of specialistsattending the appraisal meeting has recognized that thiscatalyst has reached the internationally advanced level interms of its overall catalytic performance.

A review of C_1 chemistry synthesis using yttrium-stabilized zirconia catalyst

C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making such products, such as acetic acid, dimethyl ether, and alcohol. Catalytic syngas processing is currently done at high temperatures and pressures, conditions that could be unfavorable for the life of the catalyst. Another issue of C1 chemistry is related to the methane-initiated process. It has been known that direct methane conversions are still suffering from low yields and selectivity of products resulting in unprofitable ways to produce products, such as higher hydrocarbons, methanol, and so on. However, many experts and researchers are still trying to find the best method to overcome these barriers, for example, by finding the best catalyst to reduce the high-energy barrier of the reactions and conduct only selective catalyst-surface reactions. The appli- cation of Yttria-Stabilized Zirconia （YSZ） and its combination with other metals for catalyzing purposes are increasing. The existence of an interesting site that acts as oxygen store could be the main reason for it. Moreover, formation of intermediate species on the surface of YSZ also contributes significantly in increasing the production of some specific products. Understanding the phenomena happening inside could be necessary. In this article, the use of YSZ for some C1 chemistry reactions was discussed and reviewed.

One-Pot Synthesis of Dimethyl Carbonate over Basic Zeolite Catalysts

One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best catalytic performance for DMC production. That the desilication of zeolite structure resulted in a hierarchical porosity of Beta, leading to more amount of KOH can be loaded on the surface of zeolite and therefore enhancing the base strength of the catalyst was proposed to be the reason for improved catalytic performance.

不同表面结构氧化铟催化CO_(2)加氢制甲醇的反应机理

IN_(2)O_(3)对CO_(2)加氢合成甲醇具有较好的催化活性,为了进一步阐明IN_(2)O_(3)的失活机理与甲醇合成的构效关系,选择了立方晶相IN_(2)O_(3)的不同表面,采用密度泛函理论(DFT)研究了H_(2)还原无氧空位的IN_(2)O_(3)完美表面生成氧空位的反应机理,模拟了IN_(2)O_(3)催化剂在氢气作用下失活形成In团簇的微观过程。选择抗烧结性较好的IN_(2)O_(3)(111)阶梯表面,研究了CO_(2)的吸附活化以及甲醇生成的反应机理。结果表明:随着IN_(2)O_(3)表面氧空位数目的增加,H_(2)还原IN_(2)O_(3)的反应能垒升高,H_(2)解离成为氧空位生成的限速步骤;带有缺陷的IN_(2)O_(3)(111)阶梯表面具有较好的反应活性和抗烧结性能;CO_(2)加氢生成HCOO^(*)的反应路径是甲醇合成的优势路线,其中,bi-HCOO^(*)加氢生成bi-H_(2)CO^(*)并同时脱氧填补氧空位的过程为反应的限速步骤。

180×10^(4)t/a甲醇装置合成催化剂国产化应用探析

国内大型甲醇装置主要采用国外甲醇合成工艺包和催化剂,不利于我国现代煤化工技术的长期稳定发展。中国神华煤制油化工有限公司首次在一个产能180×10^(4)t/a的甲醇装置中实现了国产甲醇合成催化剂的应用。对比分析了国外某甲醇合成催化剂(M催化剂)和国内某甲醇合成催化剂(C催化剂)的物化参数、升温还原过程及生产运行情况。结果表明,与M催化剂相比,C催化剂的优点在于活性高(尤其是低温活性突出)、稳定性强、气体单程转化率高,以及副产物和结蜡较少。此外,C催化剂较M催化剂具有更好的节能降耗效果,在设定条件(电价格0.3 CNY/(kW·h)、水价格0.15 CNY/t和蒸汽价格100 CNY/t)下,使用C催化剂可节约667.8×10^(4)CNY/a左右。目前,C催化剂在该装置中已稳定运行超过1年,装置生产负荷接近110%。

CO-CO_(2)体系制备氘代甲醇催化剂的合成与改性

作为一种重要的化工原料和氘代中间体,氘代甲醇(CD3OD)广泛用于核磁共振试剂、氘代药物中间体和光电材料改性,但其在CO-CO_(2)体系的催化合成效率仍有待提高。本研究采用浸渍法掺杂稀土元素对CuO/ZnO/Al_(2)O_(3)(CZA)催化剂进行改性,评价了其在CO-CO_(2)体系加D2制氘代甲醇的催化性能,并表征了催化剂。结果表明,稀土元素成功掺杂并均匀分散于CZA催化剂中,La和Ce的掺入能有效提高催化剂的比表面积和孔容,增加表面CuO的数量;而Pr的掺入降低了催化剂活性。其中,CZA-3%La催化剂具有最大的比表面积(46.69m^(2)/g)和最大的孔容(0.26cm^(3)/g),催化活性最好,其氘代甲醇时空产率相比CZA催化剂提高了7.96%。稀土掺杂改性的CZA催化剂对提升CO-CO_(2)体系合成氘代甲醇的反应效率有重要意义。

分步沉淀法制备铜锌基甲醇合成催化剂及其性能研究

铜锌完全共沉淀方法是制备铜锌基甲醇合成催化剂的常用方法,然而该方法难以实现对催化剂表面铜-氧化锌交界面活性位点的构筑调控。为了解决这一问题,采用分步沉淀法,在催化剂整体锌含量一定的前提下,将催化剂的锌组分一部分与铜共沉淀形成内核,一部分在外包覆形成表面铜-氧化锌交界面位点,并研究了不同锌包覆比例对催化剂性能的影响。分别采用X射线衍射(XRD)、N2吸/脱附、X射线光电子能谱(XPS)和H2程序升温还原(H2-TPR)等方法对催化剂的晶粒尺寸、孔道结构、金属价态、电子结构和还原能力等进行了表征分析。结果表明,采用分步沉淀法合成的催化剂比共沉淀法合成的催化剂具有更小的晶粒尺寸、更丰富的孔道结构、更强的铜锌相互作用、更稳定的低价铜位点以及更强的还原能力。甲醇合成性能结果显示,在250℃、5.0 MPa和空速10000 h-1的条件下,锌包覆比例为25%时,催化剂的甲醇合成初活性和耐热后活性达到最优。相比于共沉淀法合成的催化剂,其初活性和耐热后活性分别提升了6%和13%。锌包覆比例为50%时,催化剂的耐热后活性衰退率最低,仅为共沉淀法合成的催化剂的66%。分步沉淀法合成的催化剂的活性和耐热性能均有大幅度提升,该方法实现了对甲醇合成催化剂表面活性位点的有效调控,从而成功提升了铜锌基甲醇合成催化剂的活性和热稳定性。

前体元素含量及物相组成对甲醇合成催化剂性能的影响

基于共沉淀法制备了不同n(Cu)∶n(Zn)的Cu/ZnO/Al_(2)O_(3)催化剂,采用XRD、FTIR和N2吸附-脱附等手段对二元前体及催化剂进行表征,并将催化剂用于合成气制甲醇反应,研究了二元前体的物相随n(Cu)∶n(Zn)的演变规律,分析了二元前体元素含量及物相组成对催化剂晶粒尺寸、织构性质和活性的影响。实验结果表明,Zn含量增加使得二元前体物相发生由锌孔雀石到锌孔雀石和绿铜锌矿混合相再到绿铜锌矿的结构转变;二元前体的物相组成同时反映了催化剂中Cu/Zn的相对含量,并影响焙烧后催化剂的晶粒大小和织构特征,进而影响催化剂的性能;当二元前体为锌孔雀石和绿铜锌矿混合相且锌孔雀石物相占比较高时,能够获得晶粒较小、比表面积和孔体积较大的催化剂。此时,催化剂的性能最佳,甲醇时空收率达1.45 g/(mL·h),活性衰减率为11.7%,具有较好的应用价值。

RK-05型甲醇合成催化剂的工业应用

简单介绍了甲醇合成工艺流程,从单位体积催化剂甲醇产量、生产负荷、合成塔压差、床层温度、转化率五个方面介绍了两批RK-05型甲醇合成催化剂的工业应用情况,结果表明:RK-05型甲醇合成催化剂在使用的初期、中期阶段具有床层温度分布均匀、生产负荷稳步提升、催化剂转化率比较稳定、甲醇产量较好等特点。