A facile co-solvent strategy for preparation of graphene nanoplatelet powder: An industrially viable innovative approach

We report an industrially viable promising approach to produce micrometer-sized multilayer graphene nanoplatelet powder (MGNP) in a scalable quantity via microwave-assisted exfoliation of graphite (MEG) and fragmented into MGNP through liquid-phase exfoliation in the co-solvent mixture by kitchen mixer (KM). KM allows rapid delaminating MEG into MGNP by shear force dominated exfoliation. Majority of MGNPs are with a diameter of few micrometers and thickness is in nanometers. MGNP are crystalline with very limited defects was confirmed by Raman measurements and transmission electron microscopy. This process transforms, more than 86% of graphite flakes into MGNP. This advanced approach opens a new pathway to produce MGNP in bulk quantity as it is feasible, rapid, and cost-effective.     

酒精中甲醇,水在NaA沸石上吸附性能的研究

本文测定了酒精中甲醇、水单组分及二元组分的吸附等温线,并用Langmuir方程进行了拟合。在固定床动态吸附研究申测定了酒精中甲醇、水单组分及双组分吸附穿透曲线;着重考察了流速、温度、不同甲醇和水含量对双组分吸附性能的影响。对二个组分的传质机理及置换关系进行了分析探讨。     

负载型金属催化剂上甲醇液相重整制氢研究

研究了Pt,Ru,Ni为活性金属的负载型催化剂上甲醇质量分数为5%的水溶液的液相重整反应。在合适的温度、体积空速下，Pt基催化剂表现出较好的反应性能，甲醇转化率可达99%，H2选择性达98%以上，产物中CO体积分数小于0.01%。Ni/Al2O3催化剂可使甲醇转化率最高达到98%以上，H2选择性随转化率升高而下降，但不低于80%。Ru/Al2O3催化剂上甲醇的转化率最高，可达到98%以上，但其H2选择性随着转化率的升高，从68%快速下降至20%，明显与Pt、Ni基催化剂上的反应机理不同。根据反应条件和产物组成变化，进一步探讨甲醇反应路径，当产物中H2与CH4选择性比值高于2/3时，反应路径以重整制氢为主；当比值低于2/3时，反应路径以甲烷化为主。     

Single-phase gold/palladium catalyst: The nature of synergistic effect

The liquid phase oxidation of glycerol with oxygen has been studied using mono and bimetallic catalysts based on Au and Pd metals supported on activated carbon, in order to study the effect of the metal on the distribution of the products and on activity of catalysts. It was found that by using bimetallic catalysts (Au–Pd) a strong synergistic effect was shown. By using a preformed nucleating centre we were able to obtain a single alloyed phase, which allowed us to address the synergistic effect to the presence of alloyed Au/Pd. The advantage of using this latter catalyst lies not only in the high activity but also in a prolonged catalyst life. Although a partial leaching of palladium and assembling of the particles have been revealed by ICP and HRTEM respectively, activity after 10 re-cycles decreased less than expected (about 10%).     

液相水解法合成金红石型TiO2

提出的钛液反应水解法，改变了传统的外加晶种存在下具有工业意义的水解过程。该法无须外加晶种，选择了以酒石酸，聚丙烯酰胺为沉淀剂，絮凝剂，在常压下使钛液直接长温水解，液相共沉淀制备金红石型ＴｉＯ２。还研究了反应条件，分析了产品的特性。     

Use of renewables for the production of chemicals: Glycerol oxidation over carbon supported gold catalysts

As a renewable feedstock and due to its high functionality glycerol is an attractive reactant for the production of a large number of valuable compounds. We report on an environmentally friendly alternative to produce chemicals from the glycerol oxidation, which are currently produced either by stoichiometric oxidation processes or by enzymatic routes. We investigate the heterogeneously catalyzed liquid-phase oxidation of glycerol with carbon supported gold catalysts. The prepared nanosized gold catalysts are highly active, so that the reaction could be performed under atmospheric pressure. The influence of the preparation method of the catalysts has been investigated. Moreover, the support effect on the catalytic process has been studied and discussed in terms of pore structure of the investigated carbon materials. The promotor effect of platinum on Au/C catalysts was examined and it could be shown that the presence of Pt increases not only the catalyst activity but also the selectivity. By promoting the gold catalysts with platinum the selectivity to dihydroxyacetone could be increased from 26% (Au/C) to 36% (Au–Pt/C).     

邻硝基苯甲醚液相加氢制邻氨基苯甲醚的研究

对邻硝基苯甲醚液相加氢还原制邻氨基苯甲醚的工艺进行了研究。试验结果表明,加氢还原工艺在产品质量、收率及经济效益方面都优于传统还原工艺。     

Role of WC additive on reaction,solid-solution and densification in HfB2–SiC ceramics

A comparative study of phase components and compositions was performed for the pressureless sintered HfB₂–SiC–WC composites by various analytical methods. The relative decrease of HfB₂ phase leads to a new reaction of HfO₂ removal by WC to create B₂O₃. By using SiC instead of Si₃N₄ as milling medium, the WB phase was suppressed to the trace level while the W solid-solution in HfB₂ phase was favored. The W solution in both the primary HfB₂ and resultant HfC phases indicates that the WC additive was involved throughout the sintering process by dissolving into sintering liquid, which remains at the intergranular regions to form amorphous oxides as well as trace W-rich phases. This is effectively a reactive liquid-phase sintering to realize the reaction, solid-solution and densification collectively to achieve a designable HfB₂–SiC–HfC composite by pressureless sintering, which may also be extended to other sintering methods.     

预硫化加氢催化剂钝化技术研究进展

钝化是预硫化加氢催化剂的关键处理过程。预硫化催化剂经过钝化处理后,有效抑制了自热性质和硫的脱离,便于催化剂的存储和运输,并保持催化剂的活性,有利于器外预硫化催化剂的大规模生产。介绍了气相、液相和固相3种钝化方式、钝化机理及其应用和研究进展。     

Liquid-phase flash sintering 8YSZ with alkali halide sintering aids

The properties of ZrO₂: 8 mol% Y₂O₃ (8YSZ) ceramics with LiF and KCl sintering aids for liquid phase formation during electric field-assisted sintering were studied. Sintering experiments were carried out at 650 °C under 200 V cm⁻¹ AC electric field by varying current density, current application time, as well as LiF and KCl contents. Pellets sintered with KCl addition had cavities, cracks and fractures. Pellets sintered with 15 wt.% LiF, on the other hand, were homogeneous after thermal removal of LiF upon Joule heating. Low electric current densities coupled with longer application times produced homogeneous specimens. Three different stages were identified during sintering experiments: (i) LiF melting with the electric field applied at furnace temperatures lower than its melting point, (ii) shrinkage due to liquid phase formation and LiF removal, (iii) final densification due to grain growth and pore elimination. The electrical behavior and an estimate of the porosity were carried out by electrochemical impedance spectroscopy measurements.