电沉积Ni-P/Ti电极电催化氧化甲醇性能研究

研究了钛电极上负载Ni-P和Ni在碱性介质中的甲醇氧化催化性能。结果表明,在Ni电极中掺杂P原子能够显著提高Ni电极电催化氧化甲醇的性能,主要表现在提高甲醇氧化反应电流和降低甲醇氧化反应的起始电位。氢与Ni-P之间的结合能较弱,使得吸附在Ni-P电极表面的氢原子能够快速容易的去除,提供更多的清洁表面来吸附甲醇分子以及形成甲醇氧化中间物CO的主要氧化剂H2Oa。研究还发现,Ni-P电极上甲醇氧化的起始电位与Ni(OH)2/NiOOH的氧化电位一致,而在Ni电极上甲醇氧化的起始电位比Ni(OH)2/NiOOH的电位更高,其主要是由于H原子与Ni之间的结合能比Ni-P更强。另外,P的存在能够显著降低Ni-P的晶粒尺寸、增加比表面积,从而有利于提高甲醇氧化反应电流。     

铜基非贵金属催化剂在甲醇氧化中的研究进展

综述了近几年来铜基非贵金属催化剂在甲醇氧化中的研究进展,主要阐述了直接甲醇燃料电池(DMFCs)电化学理论和甲醇氧化的原理,铜的化合物、铜的硫化物和铜的其他材料等基于铜的纳米材料催化剂在甲醇氧化方面的最新研究,给出在甲醇氧化中的最佳性能数据,开发低铂、非铂催化剂对解决铂的成本非常有意义,最后对非贵金属催化剂的未来发展方向做了一些展望。     

铜基非贵金属催化剂在甲醇氧化中的研究进展

综述了近几年来铜基非贵金属催化剂在甲醇氧化中的研究进展,主要阐述了直接甲醇燃料电池(DMFCs)电化学理论和甲醇氧化的原理,铜的化合物、铜的硫化物和铜的其他材料等基于铜的纳米材料催化剂在甲醇氧化方面的最新研究,给出在甲醇氧化中的最佳性能数据,开发低铂、非铂催化剂对解决铂的成本非常有意义,最后对非贵金属催化剂的未来发展方向做了一些展望。     

甲烷直接氧化制甲醇研究新进展

文章主要介绍了国内外在甲烷直接氧化制甲醇研究方面取得的最新进展。其中包括传统催化氧化,酶催化氧化,光催化氧化,非热式等离子体在合成甲醇中的应用和膜技术的应用。     

Pt-金属磷化物复合材料在催化甲醇电氧化上的研究进展

直接甲醇燃料电池具有能量密度高,绿色环保,燃料运输、储存方便等特点,是最具有潜力的未来小型化学电源与可移动电源之一。甲醇电催化氧化是直接甲醇燃料电池的核心反应,因此研发高效、低成本、长寿命的甲醇电氧化催化剂,是当前该领域的研究重点。由于在酸性条件下进行甲醇电催化氧化过程中Pt的不可替代性,开发能够促进甲醇转化为二氧化碳和水的助催化剂是当前主要的研究方向。过渡金属磷化物由于其导电性好,种类丰富,优异地促进水分解产生-OH的能力,非常适合于作为Pt的助催化剂与载体材料。因此,总结了近年来用于催化甲醇电氧化的几类Pt-金属磷化物复合催化剂的研究进展,着重阐述了甲醇电氧化的反应机理,复合催化剂各组分在甲醇电氧化各阶段的作用,复合催化剂的形貌特征、催化活性,以及复合催化剂中不同组分之间协同作用等。最后对目前应用于甲醇电氧化的Pt-金属磷化物复合催化剂的缺点以及未来的发展方向进行了展望。     

碱性溶液中醇在Pd电极上失去电子数研究

用循环伏安法研究了碱性条件下甲醇、乙醇和异丙醇在Pd电极上氧化失去电子能力.甲醇和乙醇氧化是失去6个和4个电子.异丙醇容易失去2个电子氧化为丙酮,丙酮会进一步氧化,但氧化程度很低.乙醇和异丙醇在低于-0.4V范围内失去电子数比不上甲醇,但在-0.9到-0.4V的积分电量是甲醇的19.1和41.2倍.说明了乙醇和异丙醇在...     

甲醇直接氧化制备二甲氧基甲烷催化剂研究进展

作为一种新型的高性能柴油添加剂,二甲氧基甲烷的研究与生产受到越来越多的关注。论述了气相法甲醇部分氧化直接制备二甲氧基甲烷的机理,通过对甲醇部分氧化直接制备二甲氧基甲烷反应所用的Re、Ru、Mo、V等不同系列的催化剂的研究进展的综述,比较了各催化体系的特点;介绍了液相法甲醇直接氧化制二甲氧基甲烷的研究进展。最后对甲醇直接氧化制备二甲氧基甲烷提出了建议。     

国内外化工简讯

液相甲醇氧化羰化合成碳酸二甲酯催化剂中国科学院成都有机化学有限公司承担的中科院西部行动高新技术项目“100 t/a液相甲醇氧化羰化合成碳酸二甲酯催化剂(CuMP)工业生产技术开发”于11月11日通过了中科院高技术研究与发展局组织的项目验收。该项研究解决了甲醇液相氧化羰化合     

PtNi纳米合金催化剂制备及电催化性能

甲醇氧化是直接甲醇燃料电池(DMFC)的阳极反应,开发高效、稳定的甲醇氧化催化剂对提高DMFC的性能至关重要.本研究采用非均相微乳液法,室温下一步还原合成了PtNi催化剂.结果表明,Ni原子随机进入Pt原子晶格中,形成PtNi纳米合金纳米粒子,粒子分散均匀大小均一.PtNi纳米合金催化剂显著提高了Pt催化剂的甲醇氧化活...     

甲醇氧化电催化剂的理论研究

铂是目前已知对甲醇吸附解离催化活性最好的金属元素,也是在燃料电池环境中稳定性最好的电极材料。文章通过对甲醇在铂二元、三元、四元合金体系中的氧化及非铂体系中的研究,进一步了解甲醇电化学的氧化过程。     

Kinetics of Methanol Oxidation on Supported and Unsupported Pt/Ru Catalysts Bonded to PEM

The kinetics and mechanism of methanol adsorption and oxidation on real Pt/Ru (1:1) electrodes were investigated. In model electrode systems, the addition of supporting proton-conducting electrolyte is necessary. Therefore, the influence of sulphuric acid on the kinetics of methanol adsorption and oxidation was also investigated. It turns out that the steady state adsorption is not significantly affected by the addition of sulphuric acid. However, if sulphuric acid is used as an additional electrolyte, the rate of methanol adsorption and steady state oxidation decreases, whereas the active surface of the catalyst increases. The mechanism of methanol oxidation is not affected by the addition of sulphuric acid. At low potentials, the adsorption of methanol is found to be much faster than its oxidation. Hence, the oxidation of the methanol intermediate species is believed to be the rate-determining step under these conditions. This result is confirmed by apparent orders of reaction of about 0.5. At potentials in the range of 0.3–0.5 V, a mixed activation-adsorption control is supposed, whereas at potentials more positive than 0.5 V, the adsorption of methanol is probably the rds. This is supported by the apparent reaction orders and apparent activation energies of methanol oxidation.     

Characterisation of platinised Ti mesh electrodes using electrochemical methods: methanol oxidation in sodium hydroxide solutions

Characterisation of a platinised Ti mesh electrode, prepared by electrodeposition of Pt, by methanol oxidation has been studied over a range of NaOH and methanol concentrations using cyclic voltammetry (CV), quasi-steady-state polarisation, and electrochemical impedance spectroscopy (EIS). The activity of methanol oxidation in aqueous alkaline systems increased with pH or OH species coverage on the electrode surface. A reaction order of close to 0.5 was obtained for both NaOH and methanol in NaOH solutions indicating that adsorption of methanol and OH⁻ on the platinised electrode follows Termkin isotherm. In the high potential region, a poisoning effect was observed at methanol/[OH⁻] concentration ratio greater than 1, which could have arisen from an excess of methanol at the electrode surface and/or depletion of OH⁻ at the electrode surface. The methanol oxidation behaviour conforms with that on Pt electrodes suggesting a promising new method of preparing electrodes for fuel cells.     

Two-step pyrolysis process to synthesize highly dispersed Pt-Ru/carbon nanotube catalysts for methanol electrooxidation

Highly dispersed Pt-Ru particles with different atomic ratios supported on carbon nanotubes were synthesized using an easy two-step synthesis method including adsorption and pyrolysis. In this method, the functionalized carbon nanotubes act as adsorption sites for metallic ions and subsequently act as nucleation center for catalyst deposition in the pyrolysis process. The deposited Pt-Ru nanoparticles disperse on the carbon nanotubes surface uniformly, and the bulk composition of the Pt-Ru particles can be adjusted simply by changing atomic ratios of the metallic solution for adsorption. Finally, the electrocatalytic activity of the as-prepared catalysts supported on carbon nanotubes toward oxidation of methanol was studied. Results showed that their electrocatalytic activity, having long-term stability, strongly depends on the atomic ratio of Pt to Ru. The higher the concentration of Pt in the binary system is, the greater the electrocatalytic activity will be.     

甲醇在新型纤维上的吸附性能研究

研究了新型纤维对甲醇蒸汽的吸附行为,并测定了不同温度下的吸附等温线,探讨了吸附热力学,结果表明,纤维对甲醇蒸汽具有很强的吸附能力,随着吸附温度的升高,甲醇的平衡吸附量逐渐减少,吸附过程是放热过程,该吸附过程可以用BET方程来拟合,并估算出了吸附过程的焓变。     

In situ surface Raman spectroscopy studies of oxygen adsorbed on electrolytic silver

In situ Raman spectroscopy has been employed to investigate oxygen adsorption on electrolytic silver catalyst under industrial conditions for methanol oxidation to formaldehyde. Both adsorbed atomic and molecular oxygen species are shown to exist on the silver surface in O₂ flow above 870 K. The peroxide species is determined to be a precursor to atomic adsorbed oxygen. In consideration of the industrial process, the molecular mechanism of the partial oxidation of methanol and the adsorption mechanism of oxygen on electrolytic silver surface are discussed.     

低温等离子体协同填料床吸附净化甲醇废水

采用低温等离子体协同填料床吸附强化氧化降解高浓度甲醇废水。研究表明单独采用4A分子筛、陶粒、陶瓷Rasching环和γ-Al₂O₃不同填料均可吸附废水中甲醇,但较易达到吸附饱和,其中4A分子筛的吸附速率和平衡吸附量优于其他3种填料。单独采用多针板式介质阻挡放电低温等离子体技术,化学需氧量（COD）降解率随放电时间和放电电压增加而增大。采用低温等离子体协同填料降解甲醇废水优于单一净化过程,协同初始阶段以吸附为主,随放电时间延长以等离子体降解反应为主,液相和填料吸附的甲醇同时被等离子体活性基团逐渐氧化降解,最大降解率达90%以上。单独填料吸附过程符合准二级吸附动力学方程。低温等离子体对COD降解反应级数随污染物浓度降低和反应时间延长逐渐增大。低温等离子体协同填料吸附对降解过程相互影响,等离子体活性基团对液相和固相吸附的污染物都有一定的活化作用。填料的吸附作用和等离子体氧化作用会不断改变液相中的污染物浓度与·OH浓度比值,降解过程宏观反应动力学级数随着液相中甲醇浓度降低而逐渐增大。     

Adsorption and anodic oxidation of methanol on iridium and rhodium electrodes

Adsorption and electro-oxidation of methanol on smooth iridium and rhodium electrodes have been studied. The regularities obtained were compared with the results of previous measurements on smooth platinum. The adsorption of methanol on iridium has been established as characterized by regularities peculiar to a surface with an exponentially distributed inhomogenity of adsorption sites (Freundlich isotherm, linear change of the activation energy of adsorption with logarithm of surface coverage). The adsorption regularities for rhodium are more complex. The character of the isotherms on iridium and rhodium, as well as on platinum, does not depend on the nature of adsorbed neutral particles (methanol, hydrogen etc) and is apparently determined by the electrode surface properties. As follows from kinetic regularities (influence of potential, concentration and pH of solution, surface coverage) the rate-determining step of steady-state methanol electro-oxidation on iridium and rhodium is the oxidation of carbonaceous chemisorbed particles by adsorbed OH radicals.     

用大孔树脂精制甲醇相中茶皂素影响因素的研究

考察了静态吸附过程中树脂型号、甲醇相溶液pH值、茶皂素质量浓度、吸附温度及时间等因素对大孔树脂吸附性能的影响规律,同时在静态脱附过程中分别改变脱附液浓度、脱附液体积、脱附温度及时间,考察其对脱附率的影响。确定了最佳的吸脱附工艺条件,得出了较优化的操作条件下,树脂吸附量可达145.45 mg/g,脱附率达到90%。     

Mechanisms of Carbon Monoxide and Methanol Oxidation at Single-crystal Electrodes

The electrochemical oxidation of carbon monoxide and methanol on single-crystal noble metal electrodes has been studied using cyclic voltammetry, chronoamperometry, in situ FTIR spectroscopy, online electrochemical mass spectrometry, and theoretical methods. The oxidation of CO was found to be enhanced by steps and defects. Furthermore, the surface diffusion rate was found to have a significant influence on the kinetics of the oxidation process: for high diffusion rates, such as the oxidation of CO on platinum, the kinetics can be described by a mean field model, while for low diffusion rates, such as CO oxidation on rhodium in sulfuric acid, a nucleation-and-growth model was found to be more suitable. Voltammetric and mass spectrometric measurements on the oxidation of methanol on platinum indicate that steps enhance the overall reaction rate. In general, the selectivity towards the direct oxidation pathway through soluble intermediates was found to be higher in the absence of strongly adsorbing anions. In both perchloric and sulfuric acid, this selectivity was also found to increase with increasing step density. In sulfuric acid, Pt(111) shows the highest relative contribution for the direct pathway of all surfaces studied in that electrolyte. Based on these results, a detailed reaction scheme for the electrochemical oxidation of methanol is presented.     

生物柴油副产粗甘油的精制工艺研究

对生物柴油副产物粗甘油的分离精制工艺进行了研究。采用减压蒸馏结合活性炭吸附脱色的方法对粗甘油进行了精制提纯,并对操作条件进行了优化,同时,利用过程模拟软件AspenPlus进行了模拟计算,实验结果和计算结果吻合。实验所得的甘油产品的纯度为99.5%,甘油收率为91.8%,原料中的甲醇回收率为96.0%,纯度为99.5%。