A Preliminary Study of the Plasma Pyrolysis of Waste Tyres

Thermal plasma pyrolysis of waste tyres for recovering energy was performed in a nitrogen plasma reactor. The main gaseous products were identified by chromatography as H2, CO, CH4, C2H2 and so on. From a series of experiments, the effects of the process parameters of thermal plasma pyrolysis were investigated. Under our experimental conditions with steam injection, the total contents of H2 and CO reached up to 38.3% in the gas product, C2H2 up to 4%, and the maximum calorific value of the pyrolysis gas was 8.96 MJ/m3. The results indicate that plasma-assisted thermal decomposition of waste tyre particles may be a useful way for recovering energy and useful chemicals.     

Performance characteristics of fluidized bed syngas methanation over Ni-Mg/Al2O3 catalyst

The performance characteristics of isothermal fluidized bed syngas methanation for substitute natural gas are investigated over a self-made Ni–Mg/Al2O3 catalyst. Via atmospheric methanation in a laboratory fluidized bed reactor it was clarified that the CO conversion varied in 5% when changing the space velocity in 40–120 L·g?1·h?1 but the conversion increased obviously by raising the superficial gas velocity from 4 to 12.4 cm·s?1. The temperature at 823 K is suitable for syngas methanation while obvious deposition of uneasy-oxidizing Cγoccurs on the catalyst at temperatures around 873 K. From a kinetic aspect, the lowest reaction temperature is suggested to be 750 K when the space velocity is 60 L·g?1·h?1. Raising the H2/CO ratio of the syngas increased proportionally the CO conversion and CH4 selectivity, showing that at enough high H2/CO ratios the active sites on the catalyst are sufficient for CO adsorption and in turn the reaction with H2 for forming CH4. Introducing CO2 into the syngas feed suppresses the water gas shift and Boudouard reactions and thus increased H2 consumption. The ratio of CO2/CO in syngas should be better below 0.52 because varying the ratio from 0.52 to 0.92 resulted in negligible increases in the H2 conversion and CH4 selectivity but decreased the CH4 yield. Introducing steam into the feed gas affected little the CO conversion but decreased the selectivity to CH4. The tested Ni–Mg/Al2O3 catalyst manifested good stability in structure and activity even in syngas containing water vapor.     

Chemical Effects of CO2 Concentration on Soot Formation in Jet-stirred/Plug-flow Reactor

Soot formation was investigated numerically with CO2 addition in a jet-stirred/plug-flow reactor （JSR/PFR） C2H4/OJN2 reactor （C/O ratio of 2.2） at atmospheric pressure. An updated Kazakov mechanism empha- sizes the effect of the O2/CO2 atmosphere instead of an O2/N2 one in the premixed flame. The soot formation was taken into account in the JSR/PFR for C2H4/O2/N2. The effects of CO2 addition on soot formation in different C2H4/O2/CO2/N2 atmospheres were studied, with special emphasis on the chemical effect. The simulation shows that the endothermic reaction CO2 ＋ H - CO ＋ OH is responsible of the reduction of hydrocarbon intermediates in the CO2 added combustion through the supplementary formation of hydroxyl radicals. The competition of CO2 for H radical through the above forward reaction with the single most important chain branching reaction H ＋ O2, ＇ O ＋ OH reduces significantly the fuel burning rate. The chemical effects of CO2 cause a significant increase in residence time and mole fractions of CO and OH, significant decreases in some intermediates （H, C2H2）, polycyclic aromatic hydrocarbons （PAHs, C6H6 and CI6H10, etc.） and soot volume fraction. The CO2 addition will leads to a decrease by only about 5% to 20% of the maximum mole fractions of some C3 to Clo hydrocarbon intermediates. The sensitivity analysis and reaction-path analysis results show that C2H4 reaction path and products are altered due to the CO2 addition.     

气体添加剂对热脱硝过程影响的实验和建模研究

An experimental study of thermal DeNOx process with different additives was performed in an electricity- heated tubular flow reactor, showing that CO is less effective to lower the optimum temperature than H2 and CH4. The maximum NO reduction is lowered with H2 added, while it is hardly affected by CO or CH4. The temperature window is widened appreciably with CH4 added, while it is narrowed slightly by H2 or CO. The disadvantage of CH4 is that it causes CO emission due to its incomplete oxidation, and the maximum conversion of CH4 to CO is more than 50%. In general, the calculation using a detailed chemical kinetic model predicts most of the process features reasonably well. The analysis on reaction mechanism shows that the effects of these additives on NO reduction are achieved principally by promoting the production of &;#8226;OH radical.     

DMFCs用SPEEK/SiOx-S复合质子交换膜

A sulfonated poly(ether ether ketone) (SPEEK) membrane with a fairly high degree of sulfonation (DS) can swell excessively and even dissolve at high temperature. To solve these problems, insolvable functionalized silica powder with sulfonic acid groups (SiOx-S) was added into the SPEEK matrix (DS 55.1%) to prepare SPEEK/ SiOx-S composite membranes. The decrease in both the swelling degree and the methanol permeability of the membranes was a dose-dependent result of addition of the SiOx-S powder. Pure SPEEK membrane swelled 52.6% at 80°C, whereas the SPEEK/SiOx-S (15%, by mass) membrane swelled only 27.3% at the same temperature. From room temperature to 80℃, all SPEEK/SPEEK/SiOx-S composite membranes had methanol permeability of about one order of magnitude lower than that of Nafion115. Compared with pure SPEEK membranes, the addition of the SiOx-S powder not only leads to higher proton conductivity, but also increases the dimensional stability at higher temperatures, and greater proton conductivity can be achieved at higher temperature. The SPEEK/SiOx-S (20%, by mass) membrane could withstand temperature up to 145°C, at which in 100% relative humidity (RH) its proton conductivity exceeded slightly that of Nafion115 membrane and reached 0.17 S•cm－1, while pure SPEEK mem-brane dissolved at 90°C. The SPEEK/SiOx-S composite membranes are promising for use in direct methanol fuel cells because of their good dimensional stability, high proton conductivity, and low methanol permeability.     

ADSORPTION EQUILIBRIA OF GASES ON H-MORDENITE UNDER HIGH PRESSURE

The adsorption equilibria of N_2,Ar,CH_4,CO_2,and N_2O on H-Mordenite were studied with a constant volume appa-ratus under pressure from 3.04×10~3 to 1.43×10~7 Pa at—196°,0°,25°,50°and 75℃.The amount of adsorption ofN_2,Ar and CH_4 increases with pressure until approaching saturation at about 6.08×10~6 Pa.A maximum exists on theadsorption isotherm of CO_2 and N_2O,and their isotherms at different temperatures cross each other.All the data obtainedin this work can be correlated by the extended adsorption potential theory quite well.All experimental points can be repre-sented by the generalized characteristic curve.     

Integration of coal pyrolysis process with iron ore reduction:Reduction behaviors of iron ore with benzene-containing coal pyrolysis gas as a reducing agent☆

An integrated coal pyrolysis process with iron ore reduction is proposed in this article. As the first step, iron oxide reduction is studied in a fixed bed reactor using simulated coal pyrolysis gas with benzene as a model tar compound. Variables such as reduction temperature, reduction time and benzene concentration are studied. The carbon deposition of benzene results in the retarded iron reduction at low temperatures. At high temperatures over800 °C, the presence of benzene in the gas can promote iron reduction. The metallization can reach up to 99% in20 min at 900 °C in the presence of benzene. Significant increases of hydrogen and CO/CO2 ratio are observed in the gas. It is indicated that iron reduction is accompanied by the reforming and decomposition of benzene. The degree of metallization and reduction increases with the increasing benzene concentration. Iron oxide can nearly completely be converted into cementite with benzene present in the gas under the experimental conditions. No sintering is found in the reduced sample with benzene in the gas.     

The influence mechanism of solvent on the hydrogenation of dimethyl oxalate

The hydrogenation of dimethyl oxalate(DMO) for the producing of C2-C4 alcohols with methanol as solvent was researched at the temperature of 270 °C to 310 °C. Ethylene glycol(EG) was the main product at low temperature and the selectivity of which was 61.9% at 230 °C. However, EG selectivity decreased sharply with the increase of temperature while ethanol became the main liquid products with the selectivity of 43.5% at 270 °C. It can be ascribed to a thorough hydrogenation of DMO at a high temperature. In addition, the promotion of Guerbet reaction led to the production of propanol and butanol. Simultaneously, the amount of gas products including CO, CO_2 and dimethyl ether(DME) also increased, which became a competition factor in the conversion of DMO to liquid products including C2-C4 alcohols. The blank test was carried out with pure methanol as feedstock with and without Cu/SiO_2 catalyst, which revealed that methanol was involved in the formation of gas products and higher alcohols on Cu-based catalyst, and the main gas product was CO.     

Evolvement behavior of microstructure and H2O adsorption of lignite pyrolysis☆

The effect of pyrolysis on the microstructure and moisture adsorption of lignite was investigated with low field nuclear magnetic resonance spectroscopy. Changes in oxygen-containing groups were analyzed by Fourier transform infrared spectroscopy(FTIR), and H2 O adsorption mechanism on the surface of lignite pyrolysis was inferred. Two major changes in the pore structure of lignite char were observed as temperature increased in 105–200 °C and500–700 °C. Pyrolysis temperature is a significant factor in removing carboxyl and phenolic hydroxyl from lignite.Variation of ether bond content can be divided into three stages; the content initially increased, then decreased,and finally increased. The equilibrium adsorption ratio, content of oxygen-containing groups, and variation of pore volume below 700° were closely correlated with each other. The amount of adsorbed water on char pyrolyzed at700 °C increased. Moreover, the adsorption capacity of the lignite decreased, and the adsorption state changed.     

CO2稀释对甲烷高温低氧条件下自燃着火特性影响的数值模拟（英文）

Homogeneous mixtures of CH4/air under moderate or intense low-oxygen dilution(MILD) combustion conditions were numerically studied to clarify the fundamental effects of exhaust gas recirculation(EGR),espe-cially CO2 in EGR gases,on ignition characteristics.Specifically,effects of CO2 addition on autoignition delay time were emphasized at temperature between 1200 K and 1600 K for a wide range of the lean-to-rich equivalence ratio(0.2~2).The results showed that the ignition delay time increased with equivalence ratio or CO2 dilution ratio.Fur-thermore,ignition delay time was seen to be exponentially related with the reciprocal of initial temperature.Special concern was given to the chemical effects of CO2 on the ignition delay time.The enhancement of ignition delay time with CO2 addition can be mainly ascribed to the decrease of H,O and OH radicals.The predictions of tem-perature profiles and mole fractions of CO and CO2 were strongly related to the chemical effects of CO2.A single ignition time correlation was obtained in form of Arrhenius-type for the entire range of conditions as a function of temperature,CH4 mole fraction and O2 mole fraction.This correlation could successfully capture the complex be-haviors of ignition of CH4/air/CO2 mixture.The results can be applied to MILD combustion as "reference time",for example,to predict ignition delay time in turbulent reacting flow.     

工艺条件对Ni/Al2O3和Ni/CeO2-Al2O3催化剂在甲烷自热重整制氢反应中催化性能的影响

采用共沉淀法制备γ-Al₂O₃载体和不同Ce添加量的CeO₂-Al₂O₃载体,然后用浸渍法制备Ni负载质量分数10%的Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂。在固定床微反装置中考察了反应温度、原料气配比和CH₄空速等工艺条件对Ni/γ-Al₂O₃和Ni/Ce₃₀Al₇₀O_δ催化剂在甲烷自热重整制氢反应中催化性能的影响。结果表明,添加Ce的催化剂催化性能有较大提高,在Ni/Ce₃₀Al₇₀O_δ催化剂上,反应温度750 ℃时, CH₄转化率94.3％,与Ni/Al₂O₃催化剂相比,提高20％。Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂的CH₄转化率均随反应温度的升高而增大。原料气中n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的增加均能提高各催化剂的CH₄转化率。但n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的变化对各催化剂的催化性能的影响不同。随着n(O₂)∶n(CH₄)的增大,产物中n（H₂）∶n（CO）降低,n（CO₂）∶n(CO＋CO₂)升高;而n(H₂O)∶n(CH₄)增大时,产物中n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均升高。随着CH₄空速的增加,Ni/Al₂O₃催化剂上CH₄转化率、n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均较大程度下降;而在Ni/Ce₃₀Al₇₀O_δ催化剂上,随着CH₄空速的增加,CH₄转化率、n（H₂）∶n（CO）和n(CO₂）∶n(CO＋CO₂)变化不大。     

Cu1Zr1Ce9Oδ催化剂选择性氧化CO性能的研究

用共沉淀法制备了Cu₁Zr₁Ce₉O_δ催化剂,考察了反应温度和反应气体中各组分对Cu₁Zr₁Ce₉O_δ催化剂上选择性氧化CO反应的影响。结果表明,降温的过程中Cu₁Zr₁Ce₉O_δ催化剂的活性滞后。H₂的存在有利于CO的脱附,促进了低温下选择性氧化CO的反应;而温度较高时,H₂氧化副反应的发生降低了CO的转化率,反应气中H₂O和CO₂降低了催化剂的活性和选择性,最佳反应温度为（160~200） ℃,O₂的进入量取3为宜。     

铁含量对Fe-Mn-K催化剂上CO2加氢反应性能的影响

在370 ℃、2.0 MPa和600 h^－1条件下，考察了Fe-Mn-K复合催化剂上的CO₂选择性加氢合成低碳烯烃性能。XRD表征表明，复合催化剂中负载的金属组分主要以Fe₂O₃和MnO₂形式存在。通过H₂-TPR和CO₂-TPD研究了Fe-Mn-K催化剂对H₂的还原性能和CO₂吸附性能的影响，当催化剂中Fe负载质量分数为12%时，H₂-TPD温度较低，CO₂转化率大于30%，C⁼₂～C⁼₄低碳烯烃选择性也较高。CO₂-TPD结果表明，随Fe含量的增加，初始脱附温度提高，脱附量增加，催化剂对CO₂的吸附强度逐渐增大。     

CO和H2在Cu-Fe催化剂上TPD研究

用XRD、TG-DTG、CO-TPD和H₂-TPD等技术, 对三种Cu-Fe催化剂的物相、还原和程序升温脱附行为进行研究, 发现不同制备方法得到的CuO-Fe₂O₃复合体系间存在着不同的相互作用。高温焙烧后形成化合物CuFe₂O₄, 浸渍型样品使得CO在表面的吸附中心均匀化。不同的相互作用导致CO和H₂的吸附中心种类、相对数量发生变化求得了各类脱附中心的反应级数n和活化能Ed。     

CH4-CO2重整催化剂用纳米MgO载体的制备

CO₂重整甲烷反应中，采用纳米MgO作为催化剂载体使其具有高的活性和稳定性。纳米MgO的制备以六水氯化镁和氨水为原料，考察了氯化镁的浓度、反应pH、反应温度、中间产物焙烧温度和焙烧介质以及表面活性剂聚乙二醇（PEG）对纳米MgO的影响，并用X射线衍射仪（XRD）、透射电子显微镜（TEM）及物理吸附仪（ASAP-2020）对产物进行了表征。通过适宜工艺条件的控制，制备了粒径约为20 nm、且基本上无团聚的纳米MgO。     

无机方法制TS-1催化剂上的环己酮氨氧化反应

用无机方法合成了钛硅分子筛催化剂TS-1,并优化了TS-1催化环己酮氨氧化反应的条件。结果表明,无机催化剂可以取代有机催化剂。同时,物料比、溶剂以及温度都对氨氧化反应有很大影响。适当调整反应条件,可得到较好的结果。其最优的反应条件为：n(氨)∶n(酮)＝2,n(H₂O₂)∶n(酮)＝1.5,溶剂用蒸馏水,n(水)∶n(酮)＝7.5,反应温度为74 ℃。     

Co-ZSM-5催化剂上烃类选择性催化还原NOx机理研究进展

烃类选择性催化还原氮氧化物可能是富氧条件下脱除汽车尾气中氮氧化物污染的有效途径。以Co-ZSM-5催化剂为例,综述了国内外有关Co-ZSM-5催化剂及其在富氧条件下烃类选择还原氮氧化物的机理研究,并将烃类选择还原氮氧化物的过程概括为以下三个步骤：(1) (NO)ad + (O₂)ad (NOy)ad ( y ≥2 );(2) (NOy)ad + (CxHy)ad …… (NCaObHc )ad;(3) (NCaObHc )ad + NO + O₂ …… N₂ + CO₂ + CO + H₂O。     

二氧化碳加氢合成二甲醚CuO-ZnO-Al2O3/HZSM-5型催化剂的研究

以乙醇为溶剂，草酸作沉淀剂，采用共沉淀浸渍法制备了性能优良的二氧化碳加氢合成二甲醚催化剂(CuO-ZnO-Al₂O₃/HZSM-5)，在245℃、2.0MPa、2400h-1、H₂/CO₂=2.79的条件下，CO2转化率达22.61%，二甲醚选择性为45.90%，甲醇选择性为14.81%，含氧化合物收率为13.73%。对CuO-ZnO-Al₂O₃/HZSM-5催化剂进行了反应条件及活性稳定性的初步考察。     

白杨木粉碱性过氧化氢漂白条件的优化

研究了碱性条件下过氧化氢对杨木木粉的漂白工艺,探讨漂白温度、漂白时间、H₂O₂用量、pH值及偏硅酸钠用量对白度的影响。结果表明,过氧化氢对杨木木粉漂白的最佳工艺条件为:H₂O₂用量为40%,Na₂SiO₃·9H₂O用量为8%,pH值为10~11,漂液温度在60~70℃,漂白时间40 min。该工艺对杨木粉进行漂白,最高白度可达到85%~90%(ISO),高于文献上报道的H₂O₂漂白白度。     

Hydrogenation of α-alkyl benzoic alcohol into corresponding alkyl benzene catalyzed by Pd/C

研究了在H₂-HAc-HClO₄体系中,Pd/C催化氢化α-烷基取代苯甲醇到相应的支链烷基苯的反应.讨论了反应温度、氢气压力、Pd/C催化剂用量对反应的影响,以及高氯酸作为助催化剂在此反应中起的重要作用.高氯酸作为助催化剂时,最佳的反应条件是：质量分数为5%～10%的Pd/C催化剂,室温15～30 ℃,氢气压力400～800 kPa.XPS能谱分析表明,在高氯酸存在下Pd的表面生成了PdO_xCl_y原子簇化合物,形成高活性的活性中心,对催化氢化起到了促进作用.