非担载铁—钼催化剂在氢还原过程中的物相研究

本文利用原位穆斯堡尔谱和XRD研究了10%Fe/MoO_3催化剂在氢还原过程中铁和钼的物相及其变化.结果表明.在铁和钼还原的同时,它们之间的相互作用增强,使得在350℃—500℃的温度范围内.升高还原温度,催化剂的还原度反而下降.在350℃铁可部分地还原为零价,这时钼仅还原为MoO_2在500℃,钼开始还原到零价.这时还原生成的Fe~0形成Fe-Mo合金,在550℃铁和钼全部还原为零价,铁以Fe-Mo合金存在,其穆斯堡尔谱显示精细结构.     

Maximum Hydrogen Production by Autothermal Steam Reforming of Bio-oil With NiCuZnAl Catalyst

Autothermal steam reforming (ATR) of bio-oil, which couples the endothermic steam reform-ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600 oC, the ratio of steam to carbon fed (S/C) of 3 and the oxygen to carbon ratio (O/C) of 0.34. The reaction con-ditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.     

Low-Temperature Oxidation of Heavy Oil Asphaltene with and without Catalyst

In this study, the asphaltene extracted from Luntai heavy oil was oxidized by a mixture of propionic anhydride and hydrogen peroxide without and with a catalyst. Elemental analysis and infrared spectroscopy results indicated the occurrence of oxygen addition, condensation, and side chain cleavage reactions in the oxidation process. Oxidation products were divided into methanol solubles and methanol insolubles. The H/C and O/C atomic ratios of the MeOHS in the oxidation products without a catalyst were higher than those of the Luntai asphaltene. MeOHS had fewer aromatic rings than Luntai asphaltene. Compared with the oxidative reaction without a catalyst, the total mass of oxidation products and the proportion of MeOHS in oxidation products both increased after catalytic oxidation. This low-temperature oxidation technology can be used to upgrade asphaltenes, and thus can promote the exploitation and processing of heavy oil.     

复合催化剂及稀土助催的甲醇水蒸汽重整制氢的研究

采用并流共沉淀法制备了不同配比的CuZnAl复合氧化物催化剂,通过X-衍射(XRD)和程序升温还原(TPR)等表征技术考察了焙烧温度对催化剂催化活性的影响,且考察了La助剂对催化剂催化活性的影响。结果表明,La的含量为15%时的的催化剂具有最高的催化活性。当反应温度为250℃,水醇摩尔比为1:1,焙烧温度为550℃时,甲醇转化率可高达95%左右。     

在Ni/HZSM-5催化剂上低温水蒸汽重整生物油制氢

We investigated high catalytic activity of Ni/HZSM-5 catalysts synthesized by the impregna-tion method, which was successfully applied for low-temperature steam reforming of bio-oil. The influences of the catalyst composition, reforming temperature and the molar ratio of steam to carbon fed on the stream reforming process of bio-oil over the Ni/HZSM-5 catalysts were investigated in the reforming reactor. The promoting effects of current passing through the catalyst on the bio-oil reforming were also studied using the electrochemical catalytic re-forming approach. By comparing Ni/HZSM-5 with commonly used Ni/Al₂O₃ catalysts, the Ni₂₀/ZSM catalyst with Ni-loading content of about 20% on the HZSM-5 support showed the highest catalytic activity. Even at 450 oC, the hydrogen yield of about 90% with a near complete conversion of bio-oil was obtained using the Ni₂₀/ZSM catalyst. It was found that the performance of the bio-oil reforming was remarkably enhanced by the HZSM-5 supporter and the current through the catalyst. The features of the Ni/HZSM-5 catalysts were also investigated via X-ray diffraction, inductively coupled plasma and atomic emission spectroscopy, hydrogen temperature-programmed reduction, and Brunauer-Emmett-Teller methods.     

石墨炉原子吸收光谱绝对分析法测定催化剂及重油中的钒

本文以硝酸钙为钒的基体改进剂，用石墨炉原子吸收光谱测定了钒的特征质量，并将实验值与L’vov提出的特征质量计算方法算出的理论值进行了比较，两者基本吻合。在此基础上用绝对分析法测定了催化剂及重油中的钒的含量，分析结果与化学法测出的结果无显著差异。     

Hydrogen Selectivity in the Steam Reforming of Alcohols

Theoretical and Experimental Chemistry - The previously proposed approach to the calculation of hydrogen selectivity in ethanol steam reforming is extended to the reforming of other alcohols. It is...     

Ni/MgO-CeO2催化低温乙醇水蒸气重整制氢

采用固相燃烧法制备了MgO,CeO2载体和不同摩尔比的Mgo-CeO2复合载体,采用浸渍法制备了Ni/MgO,Ni/CeO2,Ni/Mgo-CeO2系列催化剂,考察了各催化剂催化乙醇水蒸气重整反应的性能.用BET技术测定了载体的比表面,并用X射线衍射(XRD)、程序升温还原(TPR)和热重(TG)技术对催化剂进行表征.结果表明,在Ni/CeO2和Ni/Mgo-CeO2上,Ni以高分散的NiO、体相NiO和与载体发生相互作用的NiO的形式存在,显示了良好的低温乙醇水蒸气重整性能;其中Mg,Ce摩尔比为1:1时,Ni/MgO-CeO2催化剂显示了良好的活性和选择性,并且具有很好的稳定性和抗积炭能力.     

重质油胶体聚集结构的耗散粒子动力学模拟

重质油是以沥青质为胶核分散于饱和油分中形成的极其复杂的胶体体系.本文采用耗散粒子动力学(DPD)方法研究重质油的胶体结构及其影响因素.根据重质油各组分的分子结构特征,构建了描述重质油组分的粗粒化模型化合物.模拟结果表明,本文构建的粗粒化模型能很好地反映重质油的胶体聚集结构.沥青质分子结构对胶体聚集结构有序性有显著影响,较高稠合程度的芳香环结构将使胶束结构有较高的有序性,烷基侧链则表现出分散作用.重质油中的胶质具有胶溶作用,胶质与沥青质的浓度比存在一个极限,当小于这个极限时,重质油将出现聚沉.     

改性HY型分子筛对废塑料油轻质化的影响

以HY分子筛和硝酸盐[M(NO3)2,M=Ni,Zr,Ca和Ce]为原料,通过浸渍法制得改性HY型分子筛(M/HY)催化剂,其结构和性能经XRD,比表面积,IR和SEM表征。考察了M/HY催化重质油轻质化的效果,结果表明,稀土金属的添加使重质油转化率得到了提高,平均转化率均在40%以上。从总选择性以及类汽油选择性来看,其中Ni/HY活性较好,类汽油选择性平均值为53.98%,最高达72.56%,选择性均优于HY分子筛(21.32%)。     

Properties of Aqueous Suspensions of Highly Dispersed Silica in the Presence of Polyvinylpyrrolidone

The effect of polyvinylpyrrolidone (PVP) on stability, rheological, electrokinetic and electrophysical properties of aqueous dispersions of A-300 pyrogenic silica was studied. The suspensions were shown to be most stable at PVP concentrations in the range from 0.12 to 0.24 wt % that was provided by structure-related mechanical factors. In the presence of PVP, the value of -potential decreases, the ac conductivity increases, and rheological properties vary similarly to variations of oxide dispersity.     

Ultrafiltration of Aqueous Solutions of Bromocresol Purple in the Presence of Dispersed Carbon

Ultrafiltration of solutions of Bromocresol Purple on a UFM-50M membrane in the presence of dispersed carbon was studied. The variation of the flow rate through unit surface area of the membrane and of the dye retention factor with time was traced. The influence exerted on the ultrafiltration by dye adsorption on dispersed carbon and by formation of a dynamic membrane was determined. For the initial stage of filtration, the dependence of the retention factor on the dye concentration in solution was found and accounted for.     

不同载体对钌基催化剂催化乙醇水蒸气重整制氢性能的影响

采用La2(CO3)3空气焙烧法制备了La2O2CO3载体, 采用浸渍法制备了不同比例的ZnO-La2O2CO3复合载体及Ru/ZnO, Ru/La2O2CO3, Ru/ZnO-La2O2CO3催化剂, 考察了各催化剂催化乙醇水蒸气重整反应的性能, 并用XRD, TPR技术对催化剂进行表征. 结果表明, 在复合载体负载的催化剂中有钌镧复合氧化物生成, 其中Zn:La摩尔比为1:1时, 催化剂显示了最好的乙醇水蒸气重整性能, 450 ℃时乙醇的转化率为100%, 氢气的选择性达到90%, 而CO的选择性低于1%.     

Oxidative Cracking of Propane in the Presence of Hydrogen

Russian Journal of Applied Chemistry - An effect of hydrogen additions to the initial mixture on the parameters of the oxidative cracking of propane at atmospheric pressure, temperatures of...     

硫酸氢钠催化下甲苯的硝化

研究了硫酸氢钠催化下甲苯用硝酸的硝化.结果表明,在醋酐存在条件下,以CCl4为溶剂,以质量分数为95%的硝酸为硝化剂,反应温度控制在45℃,反应进行60 min,选用硫酸氢钠催化剂.对甲苯表现出了强的区域选择性,甲苯硝化产物邻对位比达1.09,较硝酸硫酸混酸的1.67显著降低.硝化产物收率达到99.9%.催化剂可循环使用5次,催化活性基本不变,是一种极具工业化开发价值的硝化反应催化剂.     

Assay of Peracid in the Presence of Excess Hydrogen Peroxide

ABSTRACT

A simple and rapid colorimetric method for the determination of peracids in the presence of excess hydrogen peroxide is described. The method is based on the selective destruction of hydrogen peroxide by the enzyme catalase, a procedure which leaves the peracid unaffected. The residual solution, then containing only peracid, can be assayed using the stoichiometric oxidation of 2, 2′-azino-bis-(3-ethyl-benzthiazoline-6-sulfonate) diammonium salt (ABTS) in the presence of peroxidase, a reaction that can be quantified photometrically at 405 run. The double-enzyme method was extended to microtiter plate-based systems, thus providing an easy way of analyzing multiple samples for their peracid content.     

Palladium-Catalyzed Hydroesterification of Alkenes in the Presence of Molecular Hydrogen

The effects of molecular hydrogen on the palladium-catalyzed alkene-alcohol-carbon monoxide and alkene-formate reactions have been studied. Yields of esters were generally increased, especially in the alkene-formate reaction, in which an improvement up to 46% yield has been observed. A possible explanation is proposed in which the molecular hydrogen promotes the oxidative addition of formate to palladium. Decarbonylation of formate ester is unlikely to be the initial step.     

Dispersed Phase Size During the Blending of Relatively-Inelastic Polymer Melts

The influence of simultaneous drop breakup and drop coalescence on polymer-morphology was studied during the blending of polymer melts in a commercial counter-rotating twin-screw extruder. The polymers employed were PET and nylon 66, and these were chosen to minimize fluid elasticity and drop coalescence effects. Each material was dispersed in the other, and the dispersed phase size was determined using scanning electron microscopy. Variables examined included dispersed phase concentration, shear rate, residence time in the extruder and the addition of a compatibilizer. As has been the experience of others, it was found that coalescence was significant at all concentrations examined, and it increased with increasing dispersed phase concentration. However, coalescence could be drastically reduced with the help of a compatibilizer. It appeared that there were no elastic effects, and the measured drop size seemed to approach the Taylor limit as the dispersed phase concentration was lowered. An unexpected finding was that an increase in shear rate resulted in an increase in droplet size, especially at high concentrations.     

Tailoring MWD of Bimodal Polyethylene in the Presence of Ziegler-Natta Catalyst

Summary: Linear poly (ethylene-co-1-butene) was produced through two-step polymerization in one reactor using a Ziegler-Natta catalyst, where in the first step, low molecular weight homopolymer of ethylene in the presence of hydrogen and in the next step, high molecular weight copolymer of ethylene with 1-butene in the absence of hydrogen were produced. Molecular weight distribution of bimodal polyethylene was tailored through adjustment of polymerization time of each stage and hydrogen concentration of the first stage. Increasing hydrogen concentration shifted the molecular weight distribution curve to the lower molecular weights and broadened molecular weight distribution while interestingly increased high molecular weight incorporation of copolymer produced in the second stage due to increasing of reaction rate in the second step. To achieve bimodal molecular weight distribution, the polymerization times of the first and the second steps, which are highly dependent on the amount of hydrogen, were adjusted properly. The effects of the mentioned parameters on the processability as well as rheological properties of some samples were investigated. The rheological results showed shear thinning behavior of all specimens and confirmed the changes in molecular weight and molecular weight distribution. It was also demonstrated that the melt miscibility between low molecular weight and high molecular weight fractions improved with increasing of chains having very low molecular weight.