生物质合成气调变方式对其合成甲醇的影响

对生物质气、工业合成气、重整后生物质气及配氢后生物质气4种合成气进行了合成甲醇的研究. 发现甲醇产率顺序为工业合成气>重整生物质气>配氢生物质气>生物质气,生物质气合成甲醇产率较低主要是因为其为富CO2体系. 实验同时发现(H2-CO2)/(CO+CO2)比值在1.5~2之间时,(H2-CO2)/(CO+CO2)比值对液相产物中甲醇选择性没有明显影响. 液相产物中甲醇选择性随CO2含量上升而下降.     

HZSM-5硅铝比对生物质合成气合成二甲醚的影响

以不同硅铝比的HZSM-5分子筛为甲醇脱水活性组分,采用共沉淀沉积法制备合成二甲醚的双功能催化剂Cu-ZnO-Al2O3/HZSM-5,在加压固定床反应装置上进行了生物质合成气合成二甲醚的研究。考察了不同硅铝比的HZSM-5对生物质合成气合成二甲醚的影响。结果表明,随着硅铝比的增加,催化剂的酸性降低,使得CO的转化率降低。当硅铝比为38时,双功能催化剂具有较好的活性和选择性。     

生物质热化学转化合成二甲醚

在鼓泡流化床反应器内，采用空气-水蒸汽气化松木粉制备了富氢燃气，在下游的固定床重整反应器内，通过添加沼气重整富氢燃气，调变化学当量比，制备了含氮的生物质合成气. 在Cu-Zn-Al/HZSM-5催化剂上，对生物质合成气一步法合成二甲醚进行了实验研究. 在280℃, 4 MPa, 1000~4000 h-1的条件下，CO的单程转化率达到67%，单位质量催化剂的最大二甲醚时空收率0.358 g/(g×h) [DME/(催化剂×h)]；通过添加沼气重整，90%以上的生物质碳转化为合成气，二甲醚的最大产量为0.244 kg/kg (DME/生物质).     

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。     

助剂对微波辐射制备浆态床合成甲醇铜基催化剂性能影响

采用并流共沉淀法,在微波辐射老化的条件下,制备了CuO/ZnO/Al2O3/X（X=ZrO2,Fe2O3,MnO2）四元铜基合成甲醇催化剂,考察了第四组分元素对催化剂前驱体物相组成及浆态床合成甲醇性能的影响。通过XRD,TG,EDS等对催化剂及其前驱体的微观结构进行了表征。结果发现,助剂Zr、Fe、Mn的加入均不同程度的促进了Cu,Zn组分间的相互作用,有利于活性物相绿铜锌矿及锌孔雀石的生成。与CuO/ZnO/Al2O3三元催化剂相比,助剂ZrO2、Fe2O3、MnO2的加入均提高了催化剂合成甲醇的活性。其中ZrO2对铜基催化剂活性影响较大,CO转化率从43.51%提高到了59.18%,提高了36%;甲醇时空收率从256.9 mg/（gcat·h）提高到了372.8 mg/（gcat·h）,提高了45%。     

流化床甲醇合成催化剂的制备及其性能

采用碳酸钠共沉淀法制备了5种不同组成的铜基甲醇合成催化剂,并对其进行了活性评价和形貌及抗磨损性能表征. 结果表明,氧化锆可使催化剂的耐磨损强度显著提高,磨损指数(AJI)可达0.056;催化剂的活性和稳定性较好,CO转化率约40%,260℃高温下长达50 h基本不失活. 氧化铝与铜锌发生复合使催化剂的活性显著下降,CO转化率仅有10%,对催化剂的强度提高作用不明显,AJI值达0.103. 组成为铜锌锆的催化剂较适用于流化床中甲醇的合成.     

生物质合成气合成二甲醚的研究

在加压固定床反应装置上进行了生物质合成气合成二甲醚(DME)的研究.采用机械混合法制备二甲醚合成双功能催化剂.考察了组成为V(H_2):V(CO):V(CO_2):V(CH_4)=52:24:23:1的生物质合成气在不同反应温度、空速、压力下对合成二甲醚反应的影响.同时进行了102 h的催化剂的稳定性实验.结果表明,在260-300℃范围内,随反应温度的升高,CO转化率和二甲醚的选择性均先增大后减小;随反应压力的升高,CO转化率和二甲醚选择性都随之升高;原料气中高浓度的CO_2可导致铜基催化剂较快的失活.     

镍镓催化剂实现CO2常压制甲醇

3月4日,美国斯坦福大学和丹麦技术大学的科学家宣布,他们发现一种镍镓催化剂,可在常压下使氢和二氧化碳转化为甲醇,产率与传统的催化剂相当,且副反应更少。研究人员经过一系列催化剂的合成和测试后,发现Ni5Ga3特别具有活性和选择性,并可在低压下工作,与传统的Cu/ZnO/Al2O3催化剂相比,具有相似或较高的甲醇产率,并可大大降低CO的生成。他们认为,这是向CO2制甲醇小规模低压设施迈进的第一步。目前,甲醇多通过合成气(CO、CO2和H2)在高压(50~100 bar)下经Cu/ZnO/Al2O3催化生产。     

PtCoK/Al2O3催化剂涂层选择性氧化脱除富氢气氛中的CO

富氢气体中选择性氧化脱除CO是去除重整气中少量CO的有效方法。该文考察了K/Pt摩尔比对PtCoK/Al2O3催化剂涂层的影响。研究发现,适量K的添加能显著提高催化剂涂层的CO去除能力,最优K/Pt摩尔比是1～1.5,超过这个配比,CO脱除能力降低。将进口气氛中O2的体积分数从1%提高到1.5%,可提高CO转化率,但是对应的CO2选择性有所下降。富氢气中同时含有H2O和CO2对催化剂涂层活性影响微弱。连续反应100 h后,PtCoK/Al2O3催化剂涂层上CO转化率几乎未降低,催化剂涂层非常稳定,表明该催化剂涂层具有较强的工业化应用前景。     

净化气补CO_2提高甲醇合成转化率的技术改造

针对解化化工公司因低温甲醇洗出口净化气中的CO2含量偏低,影响甲醇合成转化率及粗甲醇产量的问题,进行了技术改造。通过将合成氨厂低温甲醇洗装置出CO2再生塔的CO2送入甲醇合成工段低温甲醇洗净化气管,达到提高入甲醇合成塔合成气中CO2含量的目的。运行结果表明,净化气补入CO2后,甲醇合成塔合成气中CO2体积分数提高至3%,甲醇合成转化率提高了4%,粗甲醇耗净化气量明显下降。     

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。     

改进共沉淀法制Cu基甲醇催化剂

采用传统共沉淀法和加表面活性剂改进共沉淀法制备了两种超细 Cu/ Zn O/ Al2 O3 催化剂 ,并应用 XRD,TEM对催化剂的结构和形貌进行了表征 ,同时用流动固定床微型反应器在3.0 MPa和体积空速 760 0 h-1下考察了其催化合成气合成甲醇的活性 .结果表明 ,改进共沉淀法制备的超细 Cu/ Zn O/ Al2 O3 催化剂具有比传统共沉淀法制备的催化剂更细的粒径和更高的催化活性 .同时从理论上对表面活性剂的作用机制进行了讨论 .     

Fischer-Tropsch synthesis and the generation of DME in situ

Ternary physical mixtures comprised a Fischer-Tropsch catalyst, a methanol synthesis catalyst and a zeolite employed in the hydrocarbon synthesis from syngas. Two Fe-based catalysts (i.e., one promoted by K and the other by Ru), two HY zeolites with different acidities, a commercial HZSM-5 and Cu/ZnO/Al₂O₃ (methanol synthesis catalyst) were used in these systems. The main products obtained were dimethyl ether, methanol and hydrocarbons. First of all, it was observed that by adding Cu/ZnO/Al₂O₃ catalyst to a binary physical mixture comprised of a Fischer-Tropsch catalyst and HZSM-5, the CO conversion increases more than 20 times. Second, during the reaction transient period the dimethyl ether selectivity decreases as the conversion increases. Third, the hydrocarbons synthesized followed the ASF distribution in the C₁-C₁₂ range and finally, it was also verified that the Y zeolites and the Fischer-Tropsch synthesis catalyst promoted by Ru generated the most active physical mixtures. The results showed that the role of zeolites in the ternary physical mixture is only associated with the dimethyl ether synthesis. The following reaction pathway was suggested: first, methanol is synthesized from syngas using Cu/ZnO/Al₂O₃ catalyst; after that, this alcohol is dehydrated by an acid catalyst generating DME; and lastly, DME initiates Fischer-Tropsch synthesis, which is then propagated by CO.     

Investigating the effect of metal oxide additives on the properties of Cu/ZnO/Al2O3 catalysts in methanol synthesis from syngas using factorial experimental design

The Cu/ZnO/Al₂O₃ catalysts, prepared by co-precipitation method, have been modified by adding small amount of Mn, Mg, Zr, Cr, Ba, W and Ce oxides using design of experiments (1/16 full factorial design). The structure and morphology of catalysts were studied by X-ray diffraction (XRD) and BET. Performance of the prepared catalysts for CO/CO₂ hydrogenation to methanol was evaluated by using a stainless steel fixed-bed reactor at 5 MPa and 513 K. The oxide additives were found to influence the catalytic activity, dispersion of Cu, Cu crystallite size, surface composition of catalyst and stability of catalysts during their operations. The results showed that the Mn and Zr promoted catalysts have high performance for methanol synthesis from syngas.     

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。     

Development of sulfur tolerant catalysts for the synthesis of high quality transportation fuels

In this paper, results concerning the development of sulfur tolerant catalysts for Fischer–Tropsch synthesis (FTS), C₂₊ alcohol synthesis, methanol and/or DME synthesis are presented. In the FTS reaction on Fe using H₂-rich syngas such as the biomass-derived syngas, the composition of catalyst pretreatment gas and the addition of MnO on Fe had strong impacts on its sulfur resistance as well as activity. Especially the Fe/MnO catalyst pretreated with CO showed a much lower deactivation rate and a higher FTS activity than an Fe/Cu/K catalyst in the presence of H₂S. For C₂₊ alcohol synthesis a novel preparation method was developed for a highly active MoS₂-based catalyst that is well known as the sulfur tolerant catalyst. Besides some metal sulfides were found to show higher CO hydrogenation activities than MoS₂. In particular, both Rh and Pd sulfides were active and selective for the methanol synthesis. Modified Pd sulfide catalyst, i.e. sulfided Ca/Pd/SiO₂, showed an activity that was about 60% of that of a Cu/ZnO/Al₂O₃ catalyst in the absence of H₂S. This catalyst preserved 35% of the initial activity even in the presence of H₂S. The sulfided Ca/Pd/SiO₂ mixed with γ-Al₂O₃ was also available for in situ DME synthesis in the presence of H₂S.     

Promotional SMSI Effect on Supported Palladium Catalysts for Methanol Synthesis

High-temperature reduction (HTR) of palladium catalysts supported on some reducible oxides, such as Pd/CeO₂, and Pd/TiO₂ catalysts, led to a strong metal-support interaction (SMSI), which was found to be the main reason for their high and stable activity for methanol synthesis from hydrogenation of carbon dioxide. But low-temperature-reduced (LTR) catalysts exhibited high methane selectivity and were oxidized to PdO quickly in the same reaction. Besides palladium, platinum exhibited similar behavior for this reaction when supported on these reducible oxides. Mechanistic studies of the Pd/CeO₂ catalyst clarified the promotional role of the SMSI effect, and the spillover effect on the HTR Pd/CeO₂ catalyst. Carbon dioxide was decomposed on Ce₂O₃, which was attached to Pd, to form CO and surface oxygen species. The carbon monoxide formed was hydrogenated to methanol successively on the palladium surface while the surface oxygen species was hydrogenated to water by spillover hydrogen from the gas phase. A reaction model for the hydrogenation of carbon dioxide was suggested for both HTR and LTR Pd/CeO₂ catalysts. Methanol synthesis from syngas on the LTR or HTR Pd/CeO₂ catalysts was also conducted. Both alcohol and hydrocarbons were formed significantly on the HTR catalyst from syngas while methanol formed predominantly on the LTR catalyst. Characterization of these two catalysts elucidated the reaction performances.     

Higher alcohol synthesis reaction study using K- promoted ZnO catalysts. III

Recent results indicate that modified high- temperature, high- pressure, Zn/Cr spinel methanol synthesis catalysts consist primarily of ZnO at the catalyst surfaces. Nonpromoted and K- promoted ZnO powders, therefore, were tested for methanol and isobutanol production using a 1:1 H₂ and CO syngas feedstream at two operating pressures (6.9 and 10.3 MPa) and two reactor bed temperatures (400 and 440°C). No isobutanol formation occurs over the nonpromoted ZnO. The highest isobutanol production is obtained using a 1 wt% K-containing ZnO catalyst while operating the reactor at 440°C and 10.3 MPa, but the greatest hydrocarbon byproduct rate also is obtained under these conditions. Although the isobutanol product rates are lower than the best values presented in the literature, the product rate of isobutanol formation is limited by a lower surface area of the promoted ZnO catalysts in comparison to the Zn/Cr spinel catalysts. The ratio of the BET surface areas of the K/ZnO catalysts to the surface area of an alkali-modified, commercial Zn/Cr spinel catalyst is approximately 0.23. Comparison of the catalysts on a surface area basis could result in the promoted ZnO samples performing better than the alkali- promoted Zn/Cr spinel catalysts. Most importantly, this study demonstrates that the promoted ZnO is the active catalyst phase for this reaction and that the spinel structure is not required for high activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

合成气一步法合成二甲醚的催化剂研究

简述了现有的几种合成气一步法合成二甲醚的反应机理及动力学模型,并分别对双功能催化剂中的甲醇合成活性组分、甲醇脱水活性组分进行了研究,CuO／ZnO／Al2O3作为甲醇合成组分已经比较成熟,甲醇脱水活性组分以γ-AlO3、分子筛及其改性后产物最为常用。探讨了双功能催化剂的制备方法及改性方法的研究,这也将成为今后合成气一步法制二甲醚技术的研究热点。