通过共沉淀法制备多组添加TiO2助剂改性的Cu-ZnO-Al2O3(CZA)基甲醇合成催化剂(TiO2掺杂CZA,即TiO2/CZA,TiO2/CZA=0/10,0.5/10,1.0/10,2.0/10和3.0/10),采用氮气吸脱附BET、H2-TPR、NH3-TPD和SEM等技术对其进行表征,并考察不同助剂添加量对合成气制甲醇催化性能的影响.结果表明,TiO2助剂可以调变催化剂活性组分铜物种的分散度、比表面积、晶粒大小和形貌结构等.其中TiO2/CZA比低于0.5/10时,催化剂具有粒度小、颗粒分布均匀的特点,能够促进Cu物种分散,使催化剂表面酸性降低,有利于催化剂表面对CO和H2的吸附和活化,促进CO转化和甲醇的生成.当TiO2/CZA比为0.5/10时,催化剂比表面积为102.20 m2·g-1,CO转化率为64.2％,催化剂活性最好;而当TiO2/CZA比高于0.5/10时,过量助剂可能占据催化剂孔道和覆盖表面活性位,降低活性组分分散性,造成CuO与H2有效接触减少,催化活性下降.因此,添加适量TiO2助剂可促进CO加氢反应合成甲醇,增强CZA催化剂的耐热稳定性.

A small amount of CO2 in syngas (CO/H2) is beneficial to methanol synthesis over Cu-based catalysts. To obtain more information on the CO2 effect, a series of binary Cu-based catalysts including Cu/ZnO and Cu/MgO were prepared and evaluated under feed gas (CO/H2/Ar) with or without CO2. Evaluation results show that when CO2 was added, the CO conversion of Cu0.6ZnO0.3 catalyst jumped from -4% to -68%, while the activity of Cu/MgO catalyst decreased from -15% to -0% (230 degrees C, 4 MPa, 8000 h-1 with 78.5% H2, 12.75% CO, 1.75% CO2 and 7% Ar). In situ X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were employed to examine the states of catalysts under different treatment conditions. The migration and transformation of metal species on the catalysts surface should be a reason that caused the opposite change of catalysts activity with and without CO2.

Methanol, a versatile chemical, fuel additive and potential H2 carrier, has attracted great attention. Despite of the wide industrialization, improvement of Cu-based methanol-synthesis catalysts is highly anticipated. Accordingly, a series of Cu/ZnO/Al2O3 with designed precursor structures were prepared, and its structure–function relationship was investigated to make progress on this area. Results showed the catalyst derived from highly zinc-substituted malachite demonstrated the best catalytic performance in this work. It was found that the well-behaved catalyst possessed relatively high Cu specific surface area and exposed Cu concentration, and the well Cu/ZnO synergy. CuZn alloy was found by In-situ XRD tests, and its effect on the catalyst's thermostability was discussed. Fractional precipitation, which facilitated the Cu2+ substitution by Zn2+ in malachite lattice, could be an efficient preparation method of the Cu/ZnO/Al2O3 catalyst.

Improvement on strength and ductility synergy has always been the unremitting pursuit for structural materials. In this study, the strengthen and ductility of CoCrFeMnNi HEA were improved simultaneously via a designed continuous driven friction process. The results show that a hierarchical structure, which consists of 3 zones: the homogenously distributed ultrafine grains in fusion zone, severely distorted grains in thermal mechanical effect zone and coarsening equiaxed grains with high dislocation density in base zone, was formed in CoCrFeMnNi HEA, leads to the tensile strength enhanced from 598 to 629 MPa with the ductility increased from 27% to 38%. The findings provide new insight into solution to strength and ductility trade-off for structural materials.

针对合成气一步法制烯烃反应过程中催化剂床层上部产生的"积炭环"现象,结合积炭层沉积物EDS元素分析与XRD分析、空管条件下CO转化率与产物选择性分析探究了"积炭环"形成原因.积炭层沉积物元素分析表明,实验条件下,沉积物主要含Fe、C;XRD分析显示,该"积炭环"区域的Fe元素主要以Fe3O4和Fe5C2形式存在,其基本形成过程为:久置钢瓶存储合成气中CO与钢瓶壁的铁反应生成羰基铁,反应过程中羰基铁随着合成气进入反应管,在593～603 K区域分解形成氧化铁,其部分碳化形成碳化铁,这些含铁物质催化合成气发生积炭和歧化反应形成积炭.空白反应结果显示,上述铁物种催化合成气反应生成CO2、CH4、C2～C4等轻质烃类.对比ZnCr2O4反应前/后XRF表征结果显示,Fe浓度并未增加,表明羰基铁在到达催化剂床层之前已彻底分解.通过增加活性炭吸附罐可脱除钢瓶合成气中的羰基铁等杂质,避免了"积炭环"的生成.

相比于合成气(CO/H2)经甲醇制芳烃的路线,合成气一步法制芳烃(STA)具有路线短、设备投资低等优势,是一条具有广阔应用前景的技术路线.本文首先简单陈述了合成气一步法制芳烃的基本过程,详细总结了合成气一步法制芳烃催化剂开发的进展.重点讨论了金属氧化物组成、双金属配比、晶型晶粒尺寸、氧化物与分子筛的配比以及分子筛的酸性、扩散性等物化性质对反应性能的影响规律.然后归纳了反应温度、反应压力、反应空速等反应工艺条件对反应性能的影响规律.接着总结了双功能催化剂上含氧中间体的形态及其形成机理,同时阐述了催化剂的失活研究以及抑制CO2选择性的方法.最后分析了合成气一步法制芳烃存在的问题和面临的挑战,指出高性能催化剂的开发是今后的主要研究方向.

Strong interactions between Fe–Cu–K and SAPO-34 in admixed catalysts composed of Fe–Cu–K and SAPO-34 result in the changes of structures, reducible properties and mass transfer between Fe-Cu-K and SAPO-34, which contribute to good activities.

利用X射线衍射(XRD)分析了合成气制甲醇CuZnAl催化剂的物相,结果表明:主要为单斜相的CuO,未见ZnO和Al2O3的衍射峰.单斜相CuO的衍射峰可以分峰为较窄的衍射峰和弥散衍射峰.利用Bruker的XRD数据分析软件EVA、TOPAS计算这两部分对应的晶粒尺寸和含量,分别为5～9nm、含量20％～30％的大晶粒和1～2nm、含量70％～80％的微细晶粒.把样品中的活性组分区分为微细晶粒和大晶粒,而不是把微细晶粒作为非晶相,这更能准确反映催化剂的组成特点.催化剂性能评价的结果表明:合成气制备甲醇时,微细晶粒含量越高、大晶粒尺寸相对较小的样品,其催化性能更好.

对自主研制的甲醇合成催化剂进行工艺参数优化,同时根据实验结果对合成气条件下甲醇合成的反应机理进行探讨.实验采用16通道反应器,考察反应温度和接触时间对合成甲醇反应速率的影响,确定适宜的催化剂工艺条件.结果表明,在较长接触时间下,随着温度的升高,CO转化率、H2转化率和甲醇相对含量先升高后降低,CO2转化率降低.在较低温度下,CO2转化率随接触时间延长基本不变,表明甲醇中碳元素主要来自于CO,而CO2浓度处于水汽变换反应与加氢形成甲醇反应之间的平衡状态.

通过浸渍法制备不同K2 CO3含量的K-CuCoAl催化剂,考察K含量对催化剂织构及低碳醇合成性能的影响.结果表明,K加入能中和催化剂表面的酸性;同时使催化剂对CO的线式吸附能力呈先升后降的趋势,相对应的产物中醇选择性也呈先升后降的趋势;K的负载会降低催化剂对CO的加氢反应活性.K含量对总醇收率影响呈火山型变化规律,最佳负载质量分数为0.9％.

Aluminum is an essential ingredient in the ternary Cu/ZnO/Al2O3 catalyst for methanol synthesis from syngas. This work investigated the effect of Al-containing precursors on Cu/ZnO/Al2O3 catalysts during catalyst preparation. A series of Cu0.6Zn0.3Al0.1 catalysts with various Al-containing precursors, including Cu-Zn-Al hydrotalcite, aluminum hydroxide and Zn-Al hydrotalcite, were prepared by co-precipitation and fractional-precipitation, respectively. The catalysts were characterized with XRD, TG, XRF, N2 physisorption, N2O chemisorption, SEM, TEM/EDS and TPR. Results show that the Al-containing precursor has an important effect on the Cu substitution by Zn in malachite lattice, leading to various performances of the obtained catalysts. The catalyst with Al existing as aluminum hydroxide performed high Cu substitution in the co-precipitated zinc malachite, and exhibits better catalyst performance compared to its counterparts. Aluminum hydroxide can be a suitable Al-containing precursor for preparing the Cu/Zn/Al methanol-synthesis catalyst.

Candidates of precious metal catalysts, prepared in a facile and environmental way and showing high catalytic performances at low temperatures, are always highly desired by industry. In this work, large-scale Cu-Fe-Al-O nanosheets were synthesized by facile dealloying of Al-Cu-Fe alloys in NaOH solution. The composition, microscopic morphology, and crystal structure were respectively investigated using wavelength-dispersive x-ray spectroscopy with an electron probe microanalyzer, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. Furthermore, we found that the 2D Cu-Fe-Al-Onanosheets gave excellent catalytic performances in hydrogen production by methanol steam reforming at relatively low temperatures, e.g. 513 K.

Aluminum is an important ingredient in the ternary Cu/ZnO/Al2O3 catalyst for methanol synthesis from syngas. The objective of this work is to investigate the effect of Al addition methods on the property of Cu/ZnO/Al2O3 catalyst. A series of Cu0.6Zn0.3Al0.1 catalysts with various Al-containing precursors were prepared by co-precipitation and fractional-precipitation methods. The catalyst samples were characterized by XRD, TG-MS, XRF, N2 physisorption and TPR. Results show that the Al addition methods have strong effect on the substitution of Cu by Zn in the subcarbonate lattice, leading to various performances of the obtained catalysts. Al addition with fractional precipitation performed higher substitution of Cu than that with the traditional co-precipitation method. And thus, it can be a promising method for preparing the Cu/ZnO/Al2O3 methanol synthesis catalyst.

Mg-containing Cu/Zn/Al industrial catalysts for methanol synthesis have been widely used in coal industry. The objective of this work is to investigate the influence of precipitation methods and Mg addition on the performance of Cu/Zn/Al/Mg methanol synthesis catalyst. A series of Cu0.6Zn0.3Al0.1 Mg-x catalysts (x: 0-0.04) were prepared by co-precipitation and fractional-precipitation methods, respectively. The catalyst samples were characterized with various methods including XRD, TG-MS, XPS, SEM, TEM/EDS, N-2 physisorption and N2O chemisorption. Results show that Mg improved the BET surface area and Cu dispersion of the catalysts prepared by co-precipitation, while the corresponding catalytic activity decreased with the addition of Mg. Fractional precipitation could facilitate the Cu substitution by Zn in the subcarbonate precursor, and eliminate the negative effect caused by Mg addition. Though the formation of Mg-Al hydrotalcite was unfavorable, the catalysts obtained with fractional precipitation demonstrated better catalytic performances than those prepared by co-precipitation method. It is suggested that fractional precipitation method is more suitable than co-precipitation for preparing the Cu/Zn/Al/Mg methanol synthesis catalyst. Published by Elsevier B.V.

The weak power distribution grid with high-density distributed generation is different from traditional distribution grid in voltage stability, which is easy to cause inaccurate estimation of stability margin in extreme running-mode verification. The local absorption of optical record will cause excess energy storage capacity thus impacts the operating economy. In this paper, an analysis method of stability margin with input variable based on power distribution grid was proposed. In addition, through the adaptive genetic algorithm of quantum code, the voltage deviation of all nodes were qualified with the power-type battery optimization of each node in the weak power grid under the fracture surface of the input variable. Then effectiveness of the method was verified with the IEEE36 node example.