高分散度铜基甲醇合成催化剂的研究

高分散度铜基甲醇合成催化剂的研究李基涛高利珍张伟德陈明树（厦门大学化学系物理化学研究所３６１００５）７０年来甲醇合成催化剂被广泛关注，特别是６０年代后期英国ＩＣＩ公司发明低温低压铜基甲醇合成催化剂以来，人们对铜基甲醇合成催化剂的制备与表征进行了深入地...     

铜基催化剂上低温液相甲醇合成的研究

采用并流共沉淀法制备了Cu-ZnO、Cu-MgO、Cu-MnOx催化剂,用于合成气(H2/CO/CO2)为原料的低温液相甲醇合成。沉淀pH为7时制备的Cu-MnOx在170℃,5.0MPa条件下,乙醇为溶剂,碳酸钾为助剂,其碳转率可达62.4%,甲醇收率为33.6%,甲醇选择性为54%。铜基催化剂的H2-TPR表征结果显示Cu-MnOx催化剂的还原温度明显高于Cu-ZnO和Cu-MgO催化剂,利于Cu-MnOx催化剂预还原后生成较多Cu+,使得Cu-MnOx催化剂表现出最好的低温液相甲醇合成性能。Cu-MnOx催化剂催化下有较多碳链增长产物生成,可为低碳醇的合成提供参考。     

不同改性组分对Cu-ZnO基催化剂低温甲醇合成性能的影响

通过共沉淀法制备了Al、Zr和Ce改性的Cu-ZnO基低温甲醇合成催化剂,采用氮气物理吸附、H2-TPR、CO2-TPD、N2O滴定、XRD和TEM等技术对其进行了表征,并考察了改性组分和煅烧温度对其在170℃下合成气制甲醇催化性能的影响。结果表明,经Zr改性的Cu-ZnO基催化剂,其低温甲醇合成性能较好;随着煅烧温度的降低,Cu在催化剂表面的分散度逐渐变大、颗粒逐渐变小,所得到的催化剂其活性也较高;其中,未经煅烧的Cu-ZnO/ZrO2催化剂的活性最佳,其甲醇时空产率为106.02 g/(kg·h),选择性达87.04%。     

Cu/ZrO_2催化剂的结构及其CO_2加氢合成甲醇催化反应性能

采用低温氮气吸脱附、XRD、TPR、In-situ IR和XPS等表征手段,对分步沉淀法、浸渍沉淀法和固态反应法制备的CuO/ZrO2催化剂进行表征,同时考察了其CO2加氢合成甲醇反应性能。结果表明,制备方法对CuO/ZrO2的物理结构和还原性能影响很大,其中浸渍沉淀法制备的催化剂Cu与ZrO2相互作用最强,并显示了较高的CO2转化率和甲醇收率。Cu与ZrO相互作用的强弱直接影响CO加氢合成甲醇反应性能的优劣,而催化剂的比表面积不是影响反应性能的主导因素。     

Mo-Sn催化剂上甲醇低温氧化制甲缩醛

采用水热合成法制备了甲醇合成甲缩醛的新型Mo-Sn催化剂。该催化剂可以在低Mo含量时实现甲醇低温氧化高选择性制取甲缩醛。通过考察Mo含量对催化剂结构及甲醇低温氧化制甲缩醛性能的影响,发现Mo1Sn10催化剂在甲醇氧化中表现出了较好的催化性能,在140℃、常压反应条件下,甲醇转化率为14.2%,甲缩醛选择性达到了88.9%,并且反应过程中无COx生成。采用XRD、Raman、FT-IR、XPS、NH3-TPD及H2-TPR等表征手段对催化剂进行深入研究。结果表明,不同Mo含量的催化剂结构性能存在着明显的差别,较低含量Mo的存在更有利于Mo~(5+)及MoOx的生成,而由此引起的酸性及氧化还原性的变化是催化剂具有良好性能的重要原因。     

铜基合成甲醇催化剂的研究——Ⅰ.铜锌铝系催化剂中活性组份的研究

以CO-CO_2-H_2为合成气,在低温、低压下,测定了氧化铜,氧化锌、氧化铝及其组合样品的合成甲醇催化活性及热稳定性,并列出了它们的大小顺序。观察到氧化铜和氧化锌在合成甲醇反应中,对CO、CO_2转化显示不同的催化性能。铜、锌用适当方法制备,可显著改善其合成甲醇的催化性能,催化剂的活性和热稳定性的变化倾向一致。将催化剂的催化活性与山X-射线衍射、ESCA、俄歇电子能谱和BET等方法所获得的物化参数进行了关联。讨论了铜锌铝系催化剂用于合成甲醇的催化活性部位。认为有若干类型的活性部位分别存在于铜,氧化锌,相互邻近的铜和氧化锌、以及铜-氧化锌固溶体上。提出了铜锌铝系催化剂中,优良活性单元可能是由溶于氧化锌品格中的铜与其邻近的锌、氧离子以及氧缺位所构成的结构模型。     

改进型合成甲醇铜基催化剂NC208的低氢活化(英文)

用TPR、DTA和XRD方法研究了改进型合成甲醇铜基催化剂NC208,成功地建立了对该催化剂进行低氢活化的程序升温还原程序并把它用于工业生产,取得了很高的甲醇收率。     

酸-碱交替沉淀法铜基甲醇合成催化剂的优化制备与表征

采用酸-碱交替沉淀法制备了Cu基甲醇合成催化剂放大样(500 g), 并用X射线衍射、低温N2吸附和扫描电子显微镜等对催化剂进行了表征,系统考察了制备条件(搅拌速度、溶液滴加速度、盐和碱溶液浓度等)对催化剂性能的影响. 结果表明,采用酸-碱交替沉淀法制备的Cu基甲醇合成催化剂中, Cu和Zn组分以无定形的CuO-ZnO固溶体存在,使得CuO和ZnO的晶粒减小,导致催化剂的晶粒度较小,粒径尺寸分布较均匀,结晶度相对较低,有利于提高催化剂的比表面积. 采用酸-碱交替沉淀法制备的Cu基甲醇合成催化剂具有较高的Cu分散度和较大的Cu比表面积. 在优化条件下制备的催化剂的活性和耐热性均比国内外工业催化剂高.     

合成气催化转化的绿色化学

将Ru催化剂加工到2 4 nm就可以使费托合成的反应温度降低100 ℃而活性却达到传统Ru催化剂(200 ℃)的2～5倍. 这一成果迅速被国内能源公司买断,显示了原创的绿色能源技术在中国生机无限. 本文围绕甲醇、乙醇合成和铁基催化剂上的费托合成等讨论了发展液相低温的合成气转化新化学.     

甲醇低压羰基化合成醋酸的负载型催化剂体系

负载型催化剂体系是甲醇羰基化合成醋酸的重要研究方向。本文综述了用于甲醇羰基化合成醋酸的不同载体的催化剂体系的研究进展,其中包括聚合物、活性炭、无机氧化物及分子筛载体催化剂以及其他一些新型负载型催化剂体系。     

A New Method of Low Temperature Methanol Synthesis

Low temperature methanol synthesis is a promising technique for the practical methanol industry. New developments of a new kind of low temperature methanol synthesis were reviewed, including the effects of feed gas, reaction solvent, supercritical media and catalyst modification. The reaction mechanism and kinetics were also summarized primarily. Carbon dioxide played an important role in this new kind of low temperature methanol synthesis. It reacted with hydrogen adsorbed on catalyst surface to form HCOOM, an important reaction intermediate. Alcohol solvent in the low temperature methanol synthesis performed not only a media, but also a homogeneous catalyst. The reaction of the adsorbed formate species with alcohol on Cu/ZnO catalyst surface proceeded according to the Rideal mechanism rather than Langmuir–Hinshelwood mechanism to form alkyl formate. The formation of alkyl formate from alcohol solvent and hydrogenation of such an alkyl formate were the key steps in low temperature methanol synthesis reaction. These results provided new insights into low temperature methanol synthesis.     

二氧化碳和甲醇直接合成碳酸二甲酯的研究进展

碳酸二甲酯是一种重要的绿色化工原料,二氧化碳和甲醇直接合成碳酸二甲酯是一种绿色合成方法.本文介绍了近年来此方法的催化剂及其催化机理研究的进展,讨论了不同催化体系设计的理论基础和催化剂的作用机理,并对助催化剂和吸水剂以及反应条件对催化剂活性和选择性的影响进行了评述.     

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_X 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_X catalysts, and accordingly, the Cu/ZnO_0.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.     

CO_2在Fe-Zn-M/HY复合催化剂上加氢合成异丁烷的研究(英文)

对ＣＯ_２在Ｆｅ－Ｚｎ－Ｍ（Ｍ＝Ｚｒ,Ａｌ,Ｇａ和Ｃｒ）／ＨＹ复合催化剂上的加氢反应进行了研究。通过对复合催化剂的配比、反应温度以及气体空速的考察,确定了由ＣＯ_２加氢合成异丁烷的最佳反应条件。在对反应机理研究后发现,ＣＯ_２在复合催化剂上的加氢反应是一个混合了甲醇合成和甲醇制汽油（ＭＴＧ）的反应过程,而不是传统的ＦＴ反应过程。实验结果指出,反应中生成的烯烃是产生异丁烷的重要中间产物。在所有的催化剂上,异丁烷的组成在烃类中是最高的。在Ｈ２／ＣＯ２＝３,５ Ｍｐａ, ３０００ｈ~（－１）及３６０℃的反应条件下, ＣＯ_２在Ｆｅ－Ｚｎ－Ｚｒ／ＨＹ复合催化剂上进行加氢反应时,异丁烷在烃类中的选择性高达３８％,异丁烷的时空产率可达３．０ Ｃ－ｍｏｌ％,这是迄今为止我们所知由ＣＯ_２加氢合成异丁烷所得的最好结果。     

Titanium aminophosphates as efficient,economical, and recyclable catalysts for the synthesis of xanthenediones

Titanium aminophospates have been used as catalysts in the synthesis of xanthenediones at room temperature. Among the three catalysts tested, titanium n-propyl aminophosphate (TNPAP) was found to be more efficient catalyst for the synthesis of xanthenediones. The solvent-screening studies for this catalytic reaction reveals that MeOH: H₂O was the most suitable solvent system, yielding higher amounts (89%) of products. The TNPAP catalyst was found to be reusable for five successive cycles. The optimized reaction conditions are 1.0?mmol of benzaldehyde, 2.0?mmol of dimedone, methanol/water (5.0?mL) as solvent, rt, and 100?mg of TNPAP. A plausible mechanism for the catalytic reactions has been proposed.     

Study on the deactivation and regeneration of the ZSM-5 catalyst used in methanol to olefins

ZSM-5 zeolite catalyst modified by a trace of metal cations shows high activity and high selectivity for the reaction of methanol to olefins (MTO), but it inclines to deactivate during the reaction. In this paper, the mechanism of the catalyst deactivation and the regeneration method were studied by X-ray diffraction (XRD), N2 adsorption-desorption, infrared spectra (IR), and infrared spectra coupled with NH3 molecular probes (IR-NH3). These characterizations indicated that coke formation was the main reason for the catalyst deactivation. To regenerate the deactivated catalyst, two methods, i.e., calcination and methanol leaching, were used. N2 adsorption-desorption, IR and IR-NH3 characteriza-tions showed that both methods can eliminate coke deposited on the catalyst and make the catalyst reactivated. XRD showed that the structure of the catalyst did not change after regeneration. Interestingly, the regenerated catalyst even showed better catalytic performance of the MTO reaction than the fresh one. Besides, the calcination regeneration can eliminate coke more completely, however, the methanol leaching method can be more easily carried out in situ in the reactor.     

New process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis

A new process of low-temperature methanol synthesis from CO/CO₂/H₂ based on dual-catalysis has been developed. Some alcohols, especially 2-alcohol, were found to have high catalytic promoting effect on the synthesis of methanol from CO hydrogenation. At 443 K and 5 MPa, the synthesis of methanol could process high effectively, resulting from the synergic catalysis of Cu/ZnO solid catalyst and 2-alcohol solvent catalyst. The primary results showed that when 2-butanol was used as reaction solvent, the one-pass average yield and the selectivity of methanol, in 40 h continuous reaction at temperature as low as 443 K and 5 MPa, were high up to 46.51% and 98.94% respectively. The catalytic activity was stable and the reaction temperature was 80 K or so lower than that in current industry synthesis process. This new process hopefully will become a practical method for methanol synthesis at low temperature.     

New process of low-temperature methanol synthesis from CO/CO_2/H_2 based on dual-catalysis

A new process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis has been developed. Some alcohols, especially 2-alcohol, were found to have high catalytic promoting effect on the synthesis of methanol from CO hydrogenation. At 443 K and 5 MPa, the synthesis of methanol could process high effectively, resulting from the synergic catalysis of Cu/ZnO solid catalyst and 2-alcohol solvent catalyst. The primary results showed that when 2-butanol was used as reaction solvent, the one-pass average yield and the selectivity of methanol, in 40 h continuous reaction at temperature as low as 443 K and 5 MPa, were high up to 46.51% and 98.94% respectively. The catalytic activity was stable and the reaction temperature was 80 K or so lower than that in current industry synthesis process. This new process hopefully will become a practical method for methanol synthesis at low temperature.     

浆态床中合成气制二甲醚宏观动力学的研究(英文)

以液体石蜡为介质,在合成甲醇催化剂与甲醇脱水催化剂比例为5、催化剂浓度为10 g/300 mL液体石蜡,温度为250℃~280℃,压力为3 MPa~5 MPa,气体空速为4 000 mL/(g(h)~7 000 mL/(g(h)的条件下,建立了浆态床合成气制二甲醚宏观动力学模型。甲醇合成反应和甲醇脱水反应的活化能分别为14.06 kJ/mol和23.53 kJ/mol。甲醇当量生成速率和二甲醚生成速率的计算值与实验值的相对误差在10%和20%以内。     

铜基催化剂催化合成气一步合成甲醇和甲酸甲酯IV.空速、反应时间、杂质和Cu-Cr摩尔比的影响(英文)

在低温低压和浆态反应条件下,考察了空速、反应时间、杂质及Ｃｕ－Ｃｒ摩尔比对铜基催化剂催化合成气一步合成甲醇和甲酸甲酯反应的影响。实验结果表明,空速对催化剂活性有较显著的影响;ＣＯ转化率与反应时间无关,但Ｈ２的转化率与反应时间有关。在１５小时之内Ｈ２的转化率随反应时间增加而缓慢增加,此后与反应时间无关。此外,高浓度的杂质使催化剂的活性和寿命下降,而且Ｃｕ／Ｃｒ摩尔比和热处理气氛对催化剂的物相和活性也有显著的影响。