Methanol synthesis over Cu/SiO2 catalysts

The rates of CO and CO/CO₂ hydrogenation at 4.2 MPa and 523 K are reported for a series of Cu/SiO₂ catalysts containing 2 to 88 wt.% Cu. These catalysts were prepared on a variety of silica sources using several different Cu deposition techniques. In CO/CO₂ hydrogenation, the rate of methanol formation is proportional to the exposed Cu surface area of the reduced catalyst precursor, as determined by N₂O frontal chromatography. The observed rate, 4.2×10^–3 mole CH₃OH/Cu site-sec, is within a factor of three of the rates reported by others over Cu/ZnO and Cu/ZnO/Al₂O₃ catalysts under comparable conditions. These results suggest that the ZnO component is only a moderate promoter in methanol synthesis. Hydrogenation of CO over these catalysts also gives methanol with high selectivity, but the synthesis rate is not proportional to the Cu surface area. This implies that another type of site, either alone or in cooperation with Cu, is involved in the synthesis of methanol from CO.     

Nafion/SiO2催化合成环己烯

应用新型固体酸催化剂 Nafion/Si O2 作为环己醇的脱水剂 ,成功地制备了环己烯 ,并对催化剂用量、反应温度和反应时间等对脱水反应的影响进行了探讨 ,实验结果表明 :Nafion/Si O2 是环己醇脱水制备环己烯的良好催化剂 ,且反应时间短 ,后处理容易 ,催化剂用量少 ,可重复使用 ,收率高。脱水反应的最佳工艺条件为 :催化剂用量为环己醇质量的 8% ,反应温度为 1 70°C,反应时间为0 .8h。     

Cu/SiO2催化剂上草酸二甲酯加氢反应的研究

对草酸二甲酯气相催化加氢反应体系进行了热力学分析和实验研究,考查了Cu／SiO2催化剂的最佳活化温度,对影响产物组成的因素和分布规律进行了讨论。结果表明,催化剂的适宜还原温度为523～623K;低氢酯比低压和高溶剂比有利于乙醇酸甲酯的生成;提高氢酯比或反应压力可以提高乙二醇的选择性,氢酯比和反应压力的适宜组合均能得到较好的草酸二甲酯转化率和乙二醇选择性。产物组成随草酸二甲酯转化率增加呈一定的变化规律,可根据市场需求调整产物结构,获得最佳的经济效益。     

甲醇合成铜基催化剂末期运行优化分析

在刚开始进行甲醇的合成生产时候,会经常面临开车以及停车的现象,具有复杂的工况以及比较大的操作变化,这样一来就非常容易造成氢碳之间的比例不符合规定,而且有毒物质所积累的时间也会比较长。一般来说,当甲醇合成催化剂处于生产末期的时候,其热点的温度会相应地有所下降,造成甲醇的产量降低。主要讨论了如何实现对于气体组分的有效控制,例如对于一氧化碳或者二氧化碳的有效控制,此外,还讨论了面对惰性气体的相对含量比较高的情况下通过对汽包的压力大小进行控制将合成塔的相对温度降低,从而可以有效地延长催化剂的使用寿命。     

介孔CuO-ZnO/SiO_2催化剂用于二氧化碳加氢合成甲醇的研究

采用原位溶胶-凝胶法制备了介孔CuO-ZnO/SiO_2催化剂,考察了表面活性剂类型和焙烧温度对催化剂结构和催化性能的影响。以二氧化碳加氢合成甲醇为探针反应,并结合TG-DTG、BET表征手段对催化剂结构和性能进行了分析。结果表明,采用CTAB为表面活性剂并经450℃焙烧所得的介孔CuO-ZnO/SiO_2催化剂具有高的比表面积和最佳的催化性能;反应条件250℃、3.0 MPa时,该催化剂的CO_2转化率、甲醇选择性分别为21.6%和35.6%。     

Hydrogen Generation from CO2 Reforming of Biomass-Derived Methanol on Ni/SiO2 Catalyst

Topics in Catalysis - CO2 reforming of methanol for producing hydrogen was experimentally carried out in a fixed-bed reactor on 10%Ni/SiO2. The 10%Ni/SiO2 was completely reduced during H2...     

载体对Cu-Mn甲醇合成催化剂性能的影响

实验证实ＣｕＭｎ甲醇合成催化剂的载体采用ＳｉＯ２比Ａｌ２Ｏ３性能更好，并探讨了催化过程的原理。     

SiO_2载体对Cu/SiO_2催化剂在仲丁醇脱氢中催化性能的影响

采用B,D,F,H 4种不同理化性质的二氧化硅微球作为Cu/Si O2催化剂的载体,等体积浸渍法制备Cu/Si O2催化剂,并对制备的催化剂进行了表征和活性评价。通过BET法、程序升温还原法(TPR)对所得催化剂进行表征,采用仲丁醇脱氢作为探针反应,介绍了不同载体、不同理化性质对催化剂催化性能的影响。结果表明:不同载体具有不同的理化性质,这些理化性质会影响催化剂在仲丁醇脱氢反应中的活性,F型载体为较好的负载纳米铜颗粒的载体。     

硅胶负载磷钨酸催化剂上金刚烷的制备

采用过量浸渍法制备了一系列硅胶（SiO2）负载磷钨酸（PW）催化剂,考察了催化剂在桥式四氢双环戊二烯（endo-TCD）异构化制备金刚烷反应中的催化性能,并采用XRD、N2吸附和NH3-TPD等手段对催化剂的物化性质进行了表征。结果表明,当PW负载量为40%时,PW仍能在SiO2表面高度分散;随着PW负载量的增加,催化剂的酸量增加,负载量为40%时酸量最大,负载量进一步增大,酸量下降,40% PW/SiO2表现出最高的催化活性。采用40% PW/SiO2为催化剂,考察了各种反应条件对催化性能的影响。实验结果发现,适宜的反应条件为：催化剂活化温度200℃,反应温度260℃,反应时间3h,初始压力1.1MPa。当催化剂与原料的质量比为0.7,溶剂环己烷与原料的摩尔比为5.0时,endo-TCD的转化率达到99.5%,金刚烷的收率达到24.7%。     

1800kt／a甲醇装置合成催化剂运行总结

结合神华包头煤化工分公司煤制甲醇合成工艺,介绍Katalc051-9型甲醇合成催化剂升温还原、生产运行、钝化等各个阶段的情况,并指出其在运行等阶段存在的问题及解决措施。     

制备方法对铜基甲醇合成催化剂的影响

采用了表面活性剂-模板法、柠檬酸溶胶-凝胶法及共沉淀法三种制备方法在其余条件相同的情况下制备了一系列催化剂,并采用XRD、H2TPR、CO2TPD、BET等表征手段对它们进行了表征,并对三种催化剂进行了CO2加氢活性评价,结果表明利用柠檬酸溶胶-凝胶法制备的催化剂具有更高的铜分散度,且在活性评价中具有更高的CO2转化率及较高的甲醇选择性。     

二氧化碳和丙烯直接合成甲基丙烯酸Ni2(OCH3)2/SiO2催化剂的研究

采用表面改性法制备了负载型Ni2(OCH3)2／SiO2双核金属甲氧基配合物催化剂,利用IR、DSC、TPD和微反技术对催化剂的表面结构、化学吸附性质和催化活性进行了研究。结果表明,负载型双核金属甲氧基配合物Ni2(OCH3)2／SiO2中Ni^2 与载体SiO2表面O^2-以双齿配位形式键合;二氧化碳在催化剂表面存在桥式吸附态和甲氧碳酸酯基物种两种吸附态,丙烯则只有一种吸附态;在适宜反应条件下,CO2和丙烯在Ni2(OCH3)2／SiO2催化剂上可以高选择性地合成甲基丙烯酸,反应物分子共吸附于催化剂表面同一活性单元以及羧酸根与丙烯解离吸附态的形成是反应顺利进行关键因素．     

The Effects of SiO2/Al2O3 and H2O/Al2O3 Molar Ratios on SAPO-34 Catalyst in the Methanol to Olefin Process

Silicon - Informed through synthesis and characterization of NH 3 TPD, BET techniques, the current study investigated the right contribution of silicon and water content on a 9 sample SAPO-34...     

200kt/a焦炉气制甲醇装置合成催化剂升温还原过程简介

介绍200kt/a焦炉气制甲醇装置合成塔结构及催化剂装填情况,催化剂升温还原过程,导气及低负荷运行状况。     

一步法合成吲哚的Ag/SiO2催化剂

以硝酸银为活性相前体,以SiO2为载体,并加入硝酸钙、硝酸锌、硝酸镁等助剂,采用等体积浸渍法和焙烧-还原法制备Ag／SiO2-ZnO—MgO—CaO催化剂,并对吲哚合成条件进行考察。     

Preparation of Cu/ZnO/M2O3 (M = Al, Cr) Catalyst to Stabilize Cu/ZnO Catalyst in Methanol Dehydrogenation

ZnO reducibility in three component catalysts was monitored in a methanol stream by a microbalance. The ZnO in the Cu/ZnO is reduced in the methanol stream from ca 500 K, but the addition of a third component to Cu/ZnO can suppress the reduction of ZnO. The Cu/ZnO/Cr₂O₃ prepared from a hydrotalcite-like precursor shows high stability in methanol dehydrogenation. The high stability of Cu/ZnO/Cr₂O₃ is due to the stabilization of ZnO by formation of ZnCr₂O₄ even in the reduced condition.     

Methanol Synthesis from Carbon Monoxide and Hydrogen over Ceria-Supported Copper Catalyst Prepared by a Coprecipitation Method

High catalytic activity in the synthesis of methanol from carbon monoxide and hydrogen can be produced with ceria-supported copper catalysts prepared by a coprecipitation method. The activity at 468 K is comparable with that produced with commercial copper-zinc catalysts at 503-523 K, while it is still unstable. Although the reaction atmosphere is reductive, metallic copper particles on cerium oxide are oxidized during the reaction and the catalyst is activated. Hence, formation of the copper oxide species is indispensable for the appearance of the high catalytic activity.     

联醇催化剂和合成甲醇催化剂的研制

介绍了LC210型联醇催化剂和LC308型合成甲醇催化剂的特点和性能,分析了工艺条件对催化剂性能的影响,对技术经济指标和经济效益进行了总结。     

Simultaneous MS-IR Studies of Surface Formate Reactivity Under Methanol Synthesis Conditions on Cu/SiO<Subscript>2</Subscript>

The coverages and surface lifetimes of copper-bound formates on Cu/SiO₂ catalysts, and the steady-state rates of reverse water-gas shift and methanol synthesis have been measured simultaneously by mass (MS) and infrared (IR) spectroscopies under a variety of elevated pressure conditions at temperatures between 140 and 160 °C. DCOO lifetimes under steady state catalytic conditions in CO₂:D₂ atmospheres were measured by ¹²C–¹³C isotope transients (SSITKA). The values range from 220 s at 160 °C to 660 s at 140 °C. The catalytic rates of both reverse water gas shift (RWGS) and methanol synthesis are ~100-fold slower than this formate removal rate back to CO₂ + 1/2 H₂, and thus they do not significantly influence the formate lifetime or coverage at steady state. The formate coverage is instead determined by formate’s rapid production/decomposition equilibrium with gas phase CO₂ + H₂. The results are consistent with formate being an intermediate in methanol synthesis, but with the rate-controlling step being after formate production (for example, its further hydrogenation to methoxy). A 2–3 fold shorter life time (faster decomposition rate) was observed for formate under reactions conditions, with both D₂ and CO₂ present, than in pure Ar or D₂ + Ar alone. This effect, due in part to the effects of the coadsorbates produced under reaction conditions, illustrates the importance of using in situ techniques in the study of catalytic mechanisms. The carbon which appears in the methanol product spends a longer time on the surface than the formate species, 1.8 times as long at 140 °C. The additional delay on the surface is attributed in part to readsorption of methanol on the catalyst, thus obscuring the mechanistic link between formate and methanol.