In situ time-resolved FTIR investigation on the reaction mechanism of partial oxidation of methane to syngas over supported Rh and Ru catalysts

In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane (POM) to synthesis gas and the reaction of CH4/O2/He (2/1/45, molar ratio) gas mixture with adsorbed CO species over Rh/SiO2, Ru/γ-Al2O3 and Ru/SiO2 catalysts at 500-600℃. It was found that CO is the primary product of POM reaction over reduced and working state Rh/SiO2 catalysts. Direct oxidation of CH4 is the main pathway of synthesis gas formation over Rh/SiO2 catalyst. CO2 is the primary product of POM over Ru/γ-Al2O3 and Ru/SiO2 catalysts. The dominant reaction pathway for synthesis gas formation over Ru/γ-Al2O3 catalyst is via the reforming reactions of CH4 with CO2 and H2O. For the POM reaction over Rh/SiO2 and Ru/γ-Al2O3 catalysts, consecutive oxidation of surface CO species is an important pathway of CO2 formation.     

甲烷氧化偶联催化剂和部分氧化反应机理的原位及非原位谱学表征

采用原痊红外和原位显微Raman光谱技术及XPS、吡啶（Py)吸附的漫反射UV谱、Py-TPD、CO2-TPD等方法对含氟稀土基催化剂上甲烷氧化偶联（OCM）反应活性氧物种、催化剂表面酸碱性进行了考察。在O2预处理和/或工作条件下的SrF2/La2O3,SrF2/Nd2O3,LaOF,BaF2/LaOF和BaF2/CeO2等催化剂上原位观测到超氧物种（O2^-),并在其中前4种催化剂上检测到O2^-物种与CH4反应生成的气相C2H4,CO2和表面碳酸盐等OCM反应主、副产物。这些结果为O2^-是相应催化剂上OCM反应的活性氧物种首次提供了直接的光谱证据。研究结果表明,催化剂的OCM反应性能与其表面酸碱性的强弱并无简单的对应关系。采用原拉时间分辨红外光谱和原位显微Raman光谱技术对SiO2和γ-Al2O3负载的Rh、Ru催化剂上甲烷部分氧化（POM）制合成气反应的研究表明,由CH4直接氧化生成CO和H2是Rh/SiO2上POM反应的主要途径,而燃烧-重整机理是Ru/γ-Al2O3和Ru/SiO2上CO和H2生成的主要途径,反应条件下催化剂表面氧（O^2-)物种浓度的差异很可能是导致这两种催化剂体系上POM反应机理不同的主要原因,其本质可能源于Rh和Ru对氧的亲合力的不同。     

CuO/CeO2催化剂在温度变动过程中的CO-PROX催化性能

采用浸渍方法制备不同Cu/Ce原子比的CuO/CeO₂催化剂,用于富氢气体中CO优先氧化反应(CO-PROX),考察其在温度变动情况下的催化性能. 利用X射线衍射(XRD)、程序升温还原(TPR)方法对反应前后催化剂样品进行了表征. XRD测试表明,催化反应后的催化剂中有金属Cu0生成. 这与文献结果一致. 与不含CO₂的情况比较,当模拟富氢气体中含有CO₂时,低温段催化活性明显下降. Cu/Ce原子比为10%的催化剂在温度变动过程中具有较稳定的催化性能.      

Selective catalytic reduction of NO x by hydrogen over modified Pd/TiO2-Al2O3 catalyst under lean-burn conditions

A series of Ni, Sn and Ca modified Pd/TiO2-Al2O3 catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOx by H2 was evaluated. The results showed that the NOx conversion and N2 selectivity were improved over Pd-Sn/TiO2-Al2O3 and Pd-Ni/TiO2- Al2O3 catalysts above 200 ℃. More importantly, the N2 selectivity and high-temperature activity of Pd-Sn/TiO2- Al2O3 catalyst was far superior to the single Pd/TiO2-Al2O3 catalyst. The optimal Sn loading was 2 wt.%. X-ray diffrac- tion （XRD） results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3. Temper- ature-programmed reduction （Ha-TPR） results demonstrated that the addition of Sn contributes to the formation of PdO and improving the redox property of Pd/TiOz-Al2O3. The addi- tives of Ni and Sn also facilitated the absorption of NOx and the oxidation of NO to NOa, which play important roles in the selective catalytic reduction of NOx by hydrogen.     

Synthesis and structure determination of ruthenium and osmium complexes with 2,6-bis-(diphenylphosphinomethyl) pyridine

2,6-Bis (diphenylphosphinomethyl) pyridine (PNP) reaction with Na₂OsCl₆ · 6H₂O to give the five coordinated, sixteen-electron complex Os (PNP)Cl₂. In the presence of formaldehyde, the reaction between Na₂OsCl₆· 6H₂O and PNP proceeds rapidly in boiling ethanol to give the coordinately saturated Os(PNP)Cl₂(CO). The IR spectrum of Os(PNP)Cl₂(CO) shows a strong absorption band at 1 970 cm⁻¹ assignable tov _∞ stretch. PNP reacts with RuCl₂(PPh₃)₃ and RuCl₂(DMSO)₄ (DMSO=dimethyl sulfoxide) to give Ru(PNP)Cl₂ (PPh₃) and Ru(PNP)Cl₂ (DMSO) respectively. The average Ru−Cl, Ru−P and Ru−N bond distance in Ru(PNP)Cl₂(PPh₃) determineby X-ray crystallography are 0.242, 0.236 and 0.216 nm, respectively. Li Zhaoying: born in July 1949, associate professor     

Synthesis of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/SiO<Subscript>2</Subscript>/Au magnetic composites for immobilization of bovine serum albumin

A method for the two-step synthesis of magnetic composites with a γ-Fe₂O₃ core, silica inner layer and numerous gold nanoparticles supported on the surface of the silica (γ-Fe₂O₃/SiO₂/Au) is described. First, thiol-functionalized γ-Fe₂O₃/SiO₂ composites and gold colloids are prepared by modifying γ-Fe₂O₃/SiO₂ composites with mercaptosilane and reduction of Au³⁺ to Au⁰ with citrate, respectively. Gold nanoparticles are then assembled on the surface of the thiol-functionalized γ-Fe₂O₃/SiO₂ composites to form γFe₂O₃/SiO₂/Au composites. The structure of the composite particles is confirmed by transmission electronic microscopy and powder X-ray diffraction. Immobilization studies with bovine serum albumin (BSA) demonstrate that the γ-Fe₂O₃/SiO₂/Au composites can be used to immobilize BSA, making them useful for biomedical and biological applications.     

Au/CexZr1-xO2催化剂在高浓度CO室温催化氧化中的活性

 以柠檬酸溶胶凝胶法制备的铈锆氧化物为载体,采用沉积-沉淀法制备了Au/Ce_xZr_1-xO₂催化剂.探讨了载体组成、焙烧温度、金担载量对该催化剂催化氧化一氧化碳性能的影响,并对催化剂进行XRD表征,优化了制备条件.结果表明:当载体为Ce_0.75Zr_0.25O₂,焙烧温度为550℃,金担载量为4.7%的催化剂在室温下催化氧化CO的效果最好.该催化剂的优点是具有较强的耐水性;在用量少,一氧化碳浓度高的条件下仍能氧化CO₃0%~40%左右.     

Synthesis of biodiesel from rapeseed oil using K2O/ γ -Al2O3 as nano-solid-base catalyst

Nano-solid-base catalyst K₂O/γ-Al₂O₃ was prepared and adopted for the synthesis of biodiesel by transesterification of rapeseed oil with methanol. The particle diameter of the catalyst was about 50 nm, which was measured by transmission electron microscopy (TEM). The variables affecting the yield of biodiesel during transesterification, such as mass ratio of KNO₃ to γ-Al₂O₃, calcination temperature, calcination time, and catalyst content, molar ratio of methanol to oil, reaction temperature and reaction time were investigated. The catalyst obtained by calcining a mixture of KNO₃ and γ-Al₂O₃ at 600 °C for 3 h, was found to be the optimum one, which gave the highest catalytic activity in reaction. With 3% (m _catalyst/m _oil) catalyst, when the transesterification carried out at a molar ratio of methanol to oil 12:1, a reaction temperature of 70 °C, and a reaction time of 3 h, yield of 94% was achieved. Foundation item: Supported by the National High-Technology Research and Development Program of China (863 Program) (2007AA100703)     

气固相催化合成吡咯的催化剂的研究

以ZSM-5、SiO₂-Al₂O₃和Al₂O₃为催化剂,在连续流动固定床反应器中,氨与呋喃催化合成吡咯。用程序升温氨脱附法（NH₃-TPD）测定了催化剂表面相对酸强度及酸量分布,筛选出了催化活性好和选择性高的SiO₂-Al₂O₃-d硅酸铝催化剂,并对金属氧化物进行了改性。在反应温度为425～435℃、n (AM)：n (FN)为10：1以及催化剂负荷（以呋喃计）为16.6 mmol /(h•g)的条件下,吡咯的收率可达90％以上。     

Preferential Oxidation of CO in a Hydrogen-Rich Gas Through Au/NaY Catalytic Membranes

This paper describes novel Au/NaY catalytic membranes for preferential oxidation of CO (CO-PROX) in an H2-rich gas. NaY zeolite membranes with a high CO2/N2 separation factor were loaded with nanosized Au particles using an ion-exchanged method. X-ray diffraction analyses showed that the structure of the NaY zeolite was not damaged by the ion exchange process. CO-PROX experiments showed that the catalytic membranes had excellent catalytic performance for selective oxidation of CO. The CO/H2 molar ratio on the permeate side decreased with increasing operating temperature in the range of 80-200℃. At 200℃, almost no CO was detected from the permeate stream of a catalytic membrane with the feed con-taining 0.67% CO, 1.33% O2, 32.67% H2, and He in balance. Thus, these Au/NaY catalytic membranes show a promise for CO removal from hydrogen fuels.     

PdCl_2-CuCl_2/γ-Al_2O_3催化剂室温催化氧化CO的研究

采用等体积浸渍法制备了一系列PdCl2-CuCl2/γ-Al2O3催化剂,以CO催化氧化作为目标反应,分别考察了活性组分负载量、反应气浓度及湿度、反应温度对催化剂性能的影响。结果表明:水气的存在是该催化反应能够发生的前提;反应温度的变化对催化效能影响较小,而反应气浓度变化对催化性能影响显著;实验条件下负载2%Pd-2%Cu的催化剂效果最好。室温下,该催化剂在相对湿度为50%～60%、体积空速为30000h-1,对2.23×10-4mol/L的CO转化率可达90%以上。     

N-doped porous graphene for carbon dioxide separation: a molecular dynamics study

Using molecular dynamics simulations, it is shown that N-doped porous graphene membrane can efficiently separate CO₂ from the CO₂/CH₄ mixture. The effects of pore rim modifications, N-doping sites, initial gas pressure, and feed gas compositions on CO₂ separation performance of N-doped porous graphene membrane are also examined. It is found that gas permeability increases with increasing initial gas pressure or the feed gas percentages. Pore rim modifications with nitrogen atoms (pyridinic N) can significantly improve the selectivity of CO₂ over CH₄ owing to the enhanced electrostatic interactions compared to the unmodified one, and the all-N-modified pore-16 shows the highest CO₂ selectivity over CH₄ (~29). Doping N atoms on the graphene sheets (quaternary N) has little effect on the CO₂ selectivity. Our study demonstrates that the N-doped porous graphene is an excellent candidate for CO₂ separation, which may be beneficial for the realization of a low carbon society.     

LF精炼过程中SAE8620钢所含MgO复合夹杂物分析

采用非水溶液电解的方法,萃取分离出SAE8620齿轮钢中含MgO复合夹杂物,利用扫描电镜、能谱分析仪对夹杂物的组成、类型和形貌特征进行分析。结果表明,SAE8620齿轮钢在LF精炼过程中,含MgO复合夹杂物中MgO、CaO含量逐渐增加,SiO2含量逐渐减少,Al2O3含量呈先上升后下降的趋势;夹杂物的形貌多不规则,呈块状且棱角分明;夹杂物类型主要为SiO2-Al2O3-MgO、SiO2-MgO、SiO2-Al2O3-CaO-MgO等,此类夹杂物的尺寸较大、熔点较高,直接影响钢材的质量和使用性能。     

Density functional study on mechanism of CO oxidation with activated water on O/Au （1 1 1 ） surface

With density functional theory, the mechanism of water-enhanced CO oxidation on oxygen pre-covered Au （111） surface is theoretically studied. First, water is activated by the pre-covered oxygen atom and dissociates to OHads group. Then, OHads reacts with COads to form chemisorbed HOCOads, Finally, with the aid of water, HOCOads dissociates to CO2. The whole process can be described as 1/2H2Oads ＋ H2Oads ＋ 1/2Oads＋ COads→H3Osds ＋ CO2, gas. One CO2 is formed with only 1/2 pre-covered oxygen atom. That is why more CO2 is observed when water is present on oxygen pre-covered Au （111） surface. Activation energy of each elementary step is low enough to allow the reaction to proceed at low temperature.     

不同类型分子筛对甲缩醛的催化性能

在间歇反应方式下, 研究了以甲醛和甲醇为原料合成甲缩醛反应所需的催化剂. 在30 ℃, 醛醇摩尔比为1∶2, 加入5%（质量分数）的催化剂条件下, 考察了HY, HM , Hβ, γ-Al₂O₃和 HZSM-5等催化剂对该合成反应的催化效果, 从中优选出HZSM-5. 进一步对不同硅铝比和 不同交换度的HZSM-5进行评价. 实验结果表明, 硅铝比为38, 交换4次的HZSM-5分 子筛对该 合成反应具有良好的催化作用, 甲醛的转化率为45%, 甲缩醛的选择性达99%. 该催化剂经 20次重复使用, 甲醛的转化率、 甲缩醛的选择性无明显变化, 表现出良好的催化稳定性 .     

纳米蛋壳型Ca-Pd/SiO2催化剂的催化性能

在高压微反催化剂考评装置上,研究了自制的纳米蛋壳型Ca-Pd/SiO₂催化剂用于CO加氢合成甲醇的工艺条件,考察了催化剂的还原温度、反应温度和反应压力等因素对催化性能的影响。实验结果表明,该催化剂应用于CO加氢合成甲醇反应最适宜的还原和反应条件为：还原温度400℃,反应压力5MPa,反应温度300℃。在此工艺条件下,该催化剂呈现良好的活性和选择性,其活性为48.14mmol/(mol·s),选择性为92.93%。     

Ni/α-Al2O3催化剂上甲烷水蒸气重整本征动力学

在消除扩散影响的条件下，在装填工业Ni/α-Al₂O₃催化剂的微分反应器内进行了甲烷水蒸气重整的本征动力学研究。实验证明在低产物浓度时H_2, CO和CO₂为主要产物，且两者的生成速率均与CH₄分压成正比，同时CO的生成速率与CO₂分压成正比关系，而CO₂的生成速率与H₂O分压成正比关系。考虑了5种可能的模型推导了本征动力学方程，通过参数估计和模型比较确定了比较满意的甲烷水蒸气重整本征动力学方程。     

Kinetic study on the reaction between CO2-CO and wustite using the isotope exchange method

To investigate the reaction between CO₂-CO and wustite using the isotope exchange method at 1073, 1173, 1273, and 1373 K, the experiment apparatus was designed to simulate the fluidized bed. The chemical rate constant was estimated by considering the effect of gas phase mass transfer on the reaction. It is found that the chemical rate constant is inversely decreased with the increase in the ratio of CO₂/CO by volume. The activation energy of reaction is in a linear relationship with the ratio of CO₂/CO by volume, and the average activation energy is 155.37 kJ/mol.     

Zr-pillared montmoril lonite supported cobalt nanoparticles for Fischer – Tropsch synthesis

In this article Fischer–Tropsch(FT) synthesis was studied over cobalt nanoparticles supported on modifed Montmorillonite(Zr-PILC).Co-loaded/Zr-PILC catalysts were synthesized by hydrothermal methods and were characterized by XRD,XRF,BET,H2-TPR,TGA and SEM techniques.FT reactions were carried out in fxed bed microreactor(T 225 1C,260 1C and 275 1C,P 1,5 and 10 bars).The FT-products obtained over Co-loaded/Zr-PILC catalysts showed increased selectivity of C2–C12hydrocarbons and decreased selectivity towards CH4and higher molecular weight hydrocarbons(C21) at a TOS of 2–30 h as compared to the Co-loaded/NaMMT catalysts.With increase in reaction temperature from225 1C to 275 1C,CO-conversion and CH4selectivity increases while that of C5+hydrocarbons decreases.Decrease in CH4selectivity while increase in C5+hydrocarbons and CO-conversion were observed on increasing the pressure of reaction.     

可商业化催化剂Cu/γ-Al2O3的制备和活性研究

用浸渍法制备出低成本的可商业化的Cu/γ-Al₂O₃催化剂，催化剂在NH₃做还原剂下对NO有良好的活性。研究了Cu负载量和煅烧温度对催化剂结构和催化活性的影响，借助XRD和N₂吸附法对催化剂的晶体结构、比表面积和平均孔径进行了表征；以NH₃为还原剂，NO转化率为活性评价指标，对所制备催化剂进行了选择催化还原反应研究。结果表明：Cu负载量对催化活性有影响，而煅烧温度的影响不大。煅烧温度为723K，Cu负载量为质量分数10%时，催化剂的活性最高。