不同制备方法对AlOOH结构和甲醇脱水性能的影响

采用完全液相、水热和沉淀法制备了4种不同的AlOOH催化剂, 选用工业AlOOH(SB粉)作为对照催化剂, 分别用XRD、NH₃-TPD-MS、FT-IR、氮物理吸附和热重分析等方法对催化剂进行了表征并将其用于固定床甲醇脱水制二甲醚反应。活性评价结果显示, 不同方法制备的AlOOH催化剂的甲醇脱水能力存在明显差异, 完全液相法制备的催化剂经焙烧除炭后活性高, 稳定性好, 特别是有良好的低温催化活性, 而沉淀法制备的催化剂活性低且稳定性差。表征结果发现, 与γ-Al₂O₃不同, AlOOH表面拥有强、弱两种酸性中心, 弱酸量相对较高的AlOOH催化剂具有强的甲醇脱水能力, 较多晶格缺陷和晶粒度适中的催化剂有利于甲醇脱水能力的提高。     

完全液相制备催化剂上合成二甲醚动力学研究

采用浆态床反应器,研究了用完全液相法制备的Cu-Zn-A l双功能催化剂上CO加氢直接合成二甲醚(DME)的反应动力学。按CO加氢先合成CH3OH,再由CH3OH脱水生成DME二步串联的反应机理,根据不同的中间产物及控制步骤分别建立了动力学模型,以反应物的平衡浓度代替逸度进行计算,最终选取的模型计算值和实验值吻合较好,说明采用L-H型动力学模型可以合理地描述催化剂表面的反应过程,模型参数计算结果表明,催化剂表面对CO2的弱吸附是该催化剂在浆态床中稳定性较好的主要原因之一。     

CO+H_2合成甲醇、二甲醚过程及其动力学研究——(Ⅱ) 动力学模型

本文研究了在Cu-Zn-Al和γ-Al_2O_3构成的复合催化剂上CO+H_2合成甲醇、二甲醚的本征动力学行为。在此复杂体系中,同时存在着CO+H_2合成甲醇、甲醇脱水生成二甲醚和水气变换三个反应。文中给出了表达这三个反应的动力学方程式,并通过数据拟合求出了动力学参数。模型的计算值与实验值相符较好。     

甲醇气相法脱水制二甲醚反应常压宏观动力学与催化剂粒内效率因子

研究了常压下甲醇气相法脱水生成二甲醚的宏观动力学,得到幂函数型动力学方程。推导了催化剂粒内效率因子的简化模型,用简化模型所得效率因子计算值与实验值吻合。     

Al2O3-HZSM-5催化甲醇脱水制二甲醚的反应动力学

采用机械混合法制备了不同组成的Al2O3-HZSM-5复合固体酸催化剂,采用N2吸附和x射线衍射（XRD）等对催化剂结构进行表征,考察了催化剂在甲醇脱水制二甲醚反应中的活性并研究其反应动力学。结果表明,添加质量分数为20％的Al2O3（20％）-HZSM-5复合固体酸催化剂具有较好的反应活性,在该催化剂上进行甲醇脱水制二甲醚的反应符合Rideal-Eley分子吸附机理,根据实验数据计算得到甲醇脱水反应的活化能为38.42kJ／mol,指前因子为1171.3min^-1。     

CO＋H2合成甲醇,二甲醚过程及其动力学研究：（Ⅱ）动力学研究

本文研究了在Ｃｕ－Ｚｎ－Ａｌ和γ－Ａｌ２Ｏ３构成的复合催化剂上ＣＯ＋Ｈ２合成甲醇、二甲醚的本征动力学行为，在此复杂体系中，同时存在着ＣＯ＋Ｈ２合成甲醇、甲醇脱水生成二甲醚和水气变换三个反应。文中给出了表达这三个反应的动力学方程式，并通过数据拟合求出了力学参数。模型的计算值与实验值相符较好。     

甲醇在耐高温磺酸树脂催化下的脱水反应动力学

为了开发反应精馏合成二甲醚新工艺,实验在2MPa(G)、120℃～155℃、初始甲醇摩尔分数100%～30%、液空速0.10mL/(min·g催化剂)～0.15mL/(min·g催化剂)条件下,以耐高温磺酸树脂作催化剂,在等温积分反应器内,系统地测定了甲醇脱水生成二甲醚的反应动力学数据。分别用L-H及E-R模型建立了反应动力学方程,并对实验数据进行了拟合。拟合结果表明:在实验范围内,按E-R模型拟合的反应动力学方程与实验结果更吻合。通过对动力学方程进行分析,发现随着反应温度的升高以及甲醇活度与水活度比值的增大,甲醇脱水反应速率都会增大。实验工作可为开发反应精馏合成二甲醚新工艺提供重要的反应动力学数据。     

甲醇气相脱水制二甲醚的催化剂

采用硝酸铝和氨水中和方法得到拟薄水铝石为原料,制备了甲醇制二甲醚催化剂。考察拟薄水铝石制备过程中的中和pH值、中和温度以及催化剂制备过程中的煅烧温度对甲醇气相脱水制二甲醚性能的影响。结果表明,当中和pH值在8.0±0.2、中和温度为50～60 ℃以及煅烧温度在550～600 ℃时得到的甲醇制二甲醚催化剂活性最高。通过在催化剂上添加SiO2、SO42?、PO43?等对甲醇脱水催化剂进行改性表明,改性后甲醇脱水催化剂活性有明显的提高。     

完全液相法制CuZnAl合成二甲醚浆状催化剂的催化性能

利用完全液相法制备了CuZnAl浆状催化剂,考察了反应温度、反应压力、搅拌速度、原料气组成等工艺条件, 以及催化剂中各组分配比对浆态床合成气一步法合成二甲醚反应过程的影响。结果表明, 利用完全液相法制备的催化剂在升温段和降温段活性保持稳定,随着反应时间的延长,催化剂活性呈现增长趋势,且其水煤气变换反应速率很快。Cu/Zn/Al摩尔比为1∶1∶2.09时催化剂的CO转化率与DME 选择性最好。     

甲醇气相羰化合成醋酸的反应机理及本征动力学

用浸渍法制备了负载型Ni-Mo-La/AC复合催化剂,并在平推流反应器中对甲醇气相羰基化催化反应进行了动力学数据的测定.实验证明,醋酸甲酯是甲醇气相羰基化反应的中间产物,醋酸显示连串反应最终产物的特征由醋酸甲酯水解生成;二甲醚通过甲醇脱水生成,碘甲烷和活性炭共同对该反应起催化作用,二甲醚可进一步羰化生成醋酸甲酯;甲烷由...     

Synthesis of AlOOH slurry catalyst and catalytic activity for methanol dehydration to dimethyl ether

AlOOH slurry catalysts were prepared by complete liquid-phase technology from aluminum iso-propoxide (AIP). Dehydration of methanol to dimethyl ether (DME) over these catalysts was investigated in slurry reactor. The catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption, temperature-programmed desorption of ammonia (NH₃–TPD). The results showed that the slurry catalysts had high specific surface area and pore volume, and the specific surface area and the strength of weak acidic sites were influenced considerably by the molar ratio of H₂O/AIP and HNO₃/AIP. Activity tests indicated that AlOOH slurry catalysts had excellent catalytic activity and stability in slurry reactor for the dehydration of methanol to dimethyl ether, and the activity correlated well with the strength of weak acidic sites of catalysts, which can be controlled by changing the H₂O/AIP and HNO₃/AIP molar ratios. The average methanol conversion at even stage reaches nearly 80% and DME selectivity almost 100% over CAT-P1 catalyst. No deactivation was found during the reaction of 500 h. It is also expected that CAT-P1 becomes a promising methanol dehydration catalyst for the STD process based on CuZuAl methanol synthesis catalyst.     

Liquid phase methanol and dimethyl ether synthesis from syngas

The Liquid Phase Methanol Synthesis (LPMeOH^TM) process has been investigated in our laboratories since 1982The reaction chemistry of liquid phase methanol synthesis over commercial Cu/ZnO/Al₂O₃ catalysts, established for diverse feed gas conditions including H₂-rich, CO-rich, CO₂-rich, and CO-free environments, is predominantly based on the CO₂ hydrogenation reaction and the forward water-gas shift reactionImportant aspects of the liquid phase methanol synthesis investigated in this in-depth study include global kinetic rate expressions, external mass transfer mechanisms and rates, correlation for the overall gas-to-liquid mass transfer rate coefficient, computation of the multicomponent phase equilibrium and prediction of the ultimate and isolated chemical equilibrium compositions, thermal stability analysis of the liquid phase methanol synthesis reactor, investigation of pore diffusion in the methanol catalyst, and elucidation of catalyst deactivation/regenerationThese studies were conducted in a mechanically agitated slurry reactor as well as in a liquid entrained reactorA novel liquid phase process for co-production of dimethyl ether (DME) and methanol has also been developedThe process is based on dual-catalytic synthesis in a single reactor stage, where the methanol synthesis and water gas shift reactions takes place over Cu/ZnO/Al₂O₃ catalysts and the in-situ methanol dehydration reaction takes place over -Al₂O₃ catalystCo-production of DME and methanol can increase the single-stage reactor productivity by as much as 80%. By varying the mass ratios of methanol synthesis catalyst to methanol dehydration catalyst, it is possible to co-produce DME and methanol in any fixed proportion, from 5% DME to 95% DMEAlso, dual catalysts exhibit higher activity, and more importantly these activities are sustained for a longer catalyst on-stream life by alleviating catalyst deactivation.     

Dehydration of Methanol to Dimethyl Ether by Catalytic Distillation

The kinetics of liquid catalytic dehydration of methanol over an ion exchange resin (Amberlyst 35) has been determined for the temperature range 343 to 403 K using a batch reactor. The experimental data are described well by an Eley‐Rideal type kinetic expression, for which the surface reaction is the rate‐determining step. A catalytic distillation process for methanol dehydration to dimethyl ether (DME) has been modeled using the experimentally determined kinetic data. The results were incorporated into the rate‐controlled reaction mode for RadFrac, a part of the commercial simulation program Aspen Plus. It was shown that synthesis of high purity DME can be achieved using a single catalytic distillation column. Thus there is significant potential for reduction of overall capital cost for a plant for methanol dehydration to DME when compared to conventional production facilities that involve separate reaction and distillation processes.     

The Structure Properties of CuZnAl Slurry Catalysts Prepared by a Complete Liquid-Phase Method and its Catalytic Performance for DME Synthesis from Syngas

Four CuZnAl slurry catalysts with different contents of Al were directly prepared from the solution of these metal salts to catalyst slurry by a complete liquid-phase method. The structure properties of the catalysts were characterized by XRD, BET, XPS, FTIR, and their catalytic performances for the single-step synthesis of Dimethyl ether (DME) from syngas were evaluated in a slurry reactor of 250 mL with a mechanical magnetic agitator. The results indicate the main phase existed in the catalysts are Cu, Cu₂O, ZnO and boehmite (AlOOH) and the structures of pore and surface are comparable with those of the commercial methanol synthesis catalysts. Activity tests show that the slurry catalysts are quite effective for the single-step synthesis of DME from syngas. Among them, the catalyst with 2.09 mol% Al is best, whose DME selectivity reaches 93.08%. All of the catalysts prepared by the novel method exhibit good stability during the reaction time investigated for 18 days.     

Modeling the low-temperature synthesis of dimethyl ether from methanol

The low-temperature catalytic dehydration of methanol to dimethyl ether (DME) has been analyzed. Efficient sulfocationic catalysts for the liquid-phase dehydration of methanol within a temperature range of 90–150°C and polyoxide catalysts for the gas-phase dehydration of methanol within a temperature range of 130–220°C have been selected. Kinetic models of these reactions are constructed, and their constants are determined from the results of kinetic experiments. The constructed models are shown to be adequate to experiment. The selected catalysts open additional opportunities for intensifying the processes of DME synthesis from methanol and syngas, abruptly reducing the primecost of the target product, dimethyl ether.     

浆态床合成二甲醚用CuZnAlSi催化剂的完全液相法制备及表征

采用完全液相法制备了不同SiO₂含量的二甲醚(DME)合成CuZnAlSi双功能催化剂,并在浆态床反应器中评价其催化反应活性,通过in-situ XPS、XRD、BET、NH₃-TPD等方法对其物理化学性能进行研究。结果表明,CuZnAl催化剂中加入SiO₂组分,能够促进活性组分Cu的分散,并通过与AlOOH的作用调变催化剂的孔结构和表面酸性,从而提高催化剂在DME合成反应中的活性。准原位 XPS表征结果显示,还原后的催化剂表面Cu⁰和ZnO共同构成DME合成反应中的甲醇合成活性中心。SiO₂的加入可能导致Cu、Zn和Al组分间的相互作用减弱,催化剂稳定性降低。     

用C301/P-γ-Al_2O_3催化剂合成二甲醚的动力学研究

以磷改性C301/P-γ-Al2O3为双功能催化剂,在CO/H2=1.325,温度210~300℃,压力2~4.3 MPa,空速600~1800 mL/(h.g催化剂)的条件下,进行浆态床二甲醚合成的动力学研究,并选取甲醇合成、甲醇脱水和水汽变换反应为3个独立反应,建立合成气制二甲醚的本征动力学模型。     

Direct dimethyl ether synthesis by spatial patterned catalyst arrangement: A modeling and simulation study

The effect of spatially patterned catalyst beds was investigated using direct dimethyl ether (DME) synthesis from synthesis gas as an example. A layered arrangement of methanol synthesis (MS) and dehydration catalyst was chosen and studied by numerical simulation under typical operating conditions for single‐step DME synthesis. It was revealed that catalyst layers significantly influence the DME productivity. With an increasing number of layers from two to 40, an increase in DME productivity was observed approaching the performance of a physical catalyst mixture for an infinite number of layers. The results prove that a physical mixture of MS and dehydration catalyst achieves the highest DME productivity under operating conditions chosen in this study. Essentially, the layered catalyst arrangement is comparable to a cascade model of the two‐step process, which is less efficient in terms of DME yield than the single‐step process. However, the layered catalyst arrangement could be beneficial for other reaction systems. © 2012 American Institute of Chemical Engineers AIChE J, 00: 000–000, 2012