Direct catalytic conversion of methane

Processes are being developed for the direct catalytic oxidative conversion of methane to higher hydrocarbons and oxygenates. The role of the catalyst in generating methyl radicals is established, and subsequent gas-phase reactions are well understood. However, the role of several catalyst surface species remains a subject of interest. Application of present process technology using the most promising catalysts shows that direct methane conversion is not yet competitive with conventional processes. Increased yields of desirable products using new process configurations are required to obtain an economically viable process.     

Sensitivity analysis of a light gas oil deep hydrodesulfurization process via catalytic distillation

In this work, a sensitivity analysis of a light gas oil deep hydrodesulfurization catalytic distillation column is presented. The aim is to evaluate the effects of various parameters and operating conditions on the organic sulfur compound elimination by using a realistic light gas oil fraction. The hydrocarbons are modeled using pseudocompounds, while the organic sulfur compounds are modeled using model compounds, i.e., dibenzothiophene (DBT) and 4,6-dimethyl dibenzothiophene (4,6-DMDBT). These are among the most refractive sulfur compounds present in the oil fractions. A sensitivity analysis is discussed for the reflux ratio, bottom flow rate, condenser temperature, hydrogen and gas oil feed stages, catalyst loading, the reactive, stripping, and rectifying stages, feed disturbances, and multiple feeds. The results give insight into the qualitative effect of some of the operating variables and disturbances on organic sulfur elimination. In addition, they show that special attention must be given to the bottom flow rate and LGO feed rate control.     

Thermal and catalytic conversion of waste polyolefines

Waste samples of polyethylene and polystyrene were cracked thermally or in the presence of catalyst and hydrogen in closed autoclaves. The obtained products were submitted to analysis, unsaturated hydrocarbons in gasoline and diesel fuel range boiling were hydrogenated over platinum catalyst. It was stated that the optimum thermal cracking temperature of waste polyolefines is 410–430°C, in the case of catalytic process lower temperature, ca. 390°C, can be used, with reaction time ca. 1.5 an hour. More than 90% yield of gas and liquid fractions with b.p.<360°C was attained. The dependencies between process parameters, feed composition and product yield as well as composition of the obtained fuel fractions were found. On the basis of the obtained results hypothetical continuous process of waste plastics processing for engine fuel production was presented.     

乙醇催化转化到丁醇研究进展

乙醇的规模化生产和其在汽油中有限的添加量推动了乙醇的高值化利用。由于丁醇具有独特的物化性能,将乙醇一步催化转化为丁醇受到人们的普遍关注。本文主要综述了乙醇催化转化到丁醇的最新研究进展,阐述了不同均相催化剂、羟基磷灰石、氧化物和金属促进氧化物催化剂对乙醇转化率和丁醇选择性的影响,探讨了典型催化剂上乙醇催化转化到丁醇中的双分子机理和Guerbet机理,总结了乙醇催化转化到丁醇中存在的问题、机遇和挑战。提出未来乙醇催化转化的研究重点应该放在高乙醇转化率下丁醇的选择性控制上,即利用均相催化剂研究策略,借助近原位条件下反应机理研究的结果,设计合成新型催化剂体系,实现乙醇到丁醇的高效转化。     

汽油催化改质反应过程数值模拟

在汽油催化反应动力学模型和气固两相流动模型的基础上,建立了汽油改质反应过程流动-反应耦合模型。针对不同的转化反应器构型（提升管、提升管-床层反应器）,对汽油改质过程进行了数值模拟。模拟结果表明,对提升管反应器而言,汽油经过低温改质反应后,烯烃含量可以从35.1%降低到18%左右,烯烃降低幅度可达48%,汽油中烯烃主要转化为异构烷烃。另外,随着反应温度的升高,汽油转化反应中的裂化反应增强,导致汽油收率下降。对于提升管-床层反应器而言,汽油中的烯烃含量可以降得更低,在床层空速4时,烯烃含量可以降低到5%左右,汽油收率为80%左右。     

Heterogeneous catalytic oxidative conversion of ethane to ethylene

Multicomponent and multiphase oxide catalysts with a uniform composition Mo₁V_0.3Te_0.23Nb₁₂ but different phase contents were studied in the oxidative conversion of ethane to ethylene and characterized by X-ray diffraction analysis. The phase composition of the samples was varied by modifying such conditions of catalyst preparation as the pH of raw precursor, the drying of the wet precursor, and the conditions of solid precursor calcination. The content of the detected phase is determined via Rietveld refinement. The catalytic activity of MoVTeNb oxide catalysts studied in the oxidative conversion of ethane was found to be determined by the content of the orthorhombic M1 phase (the layered four-component compound (TeO)_0.23(Mo,V,Nb)₅O₁₄).     

Kinetic modelling of the catalytic conversion of synthesis gas

A kinetic study for the one-step conversion of synthesis gas to gasoline on a ZnO–Cr₂O₃–ZSM-5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr₂O₃ component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well-mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO₂ was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.     

One-stage catalytic conversion of natural gas into liquid products

Galloaluminosilicates with silica ratios from 30 to 80 containing different gallium oxide proportions ([Ga₂O₃] = 1.2 and 2.2 wt %) have been prepared by hydrothermal synthesis. The activity and selectivity of the catalysis in the conversion of natural gas to aromatic hydrocarbons have been studied.     

热驱动CO2多相催化合成化学品研究进展

由于CO₂分子较高的化学惰性,导致其选择性活化及可控转化极具挑战。相比于电和光驱动CO₂催化转化,热驱动CO₂多相催化转化反应是操作简便、目标产物可调且产品收率较高的方法。通过该类反应实现CO₂还原或非还原制备多种化学品既可促进CO₂的资源化利用,又可有效缓解温室效应,在环保、能源和材料等领域具有重要意义。本综述基于作者在CO₂捕集和转化方面的研究工作,结合近年来国内外的相关文献,对目前热驱动多相催化CO₂转化为CO、CH₄、甲酸、甲醇、碳氢化合物和其它精细化学品的研究现状进行综合评述。重点讨论反应机理、所用催化剂及反应体系的研究进展,并对其未来的研究方向进行了前景展望和探讨。     

Cu基催化材料在CO_2转化中的应用

综述了近年来Cu基催化材料用于CO_2资源化利用的研究进展,介绍了其在热催化加氢、电催化和光催化等技术中的最新研究,指出了目前研究中存在的问题和不足,并对其未来的研究方向进行了前景展望。     

Hydrothermal catalytic conversion of biomass for lactic acid production

The production of lactic acid has increased owing to growing polymer markets, increased demand in the chemical sector and many applications in the food industry. Biomass hydrothermal decomposition is potentially a method for lactic acid production. To obtain a higher yield of lactic acid, the influence of metal ions (Zn(II), Ni(II),Co(II) and Cr(III)) on biomass decomposition in sub‐critical water (T = 300 °C) was investigated and the catalyst function in the complex reaction network of biomass degradation was discussed. In comparison with a non‐catalytic process, the addition of 400 ppm Ni(II) catalyst increased the yield of lactic acid from 3.25% to 6.62% at 300 °C and 120 s for microcrystalline cellulose. The lactic acid yield for glucose was 9.51% for 400 ppm Co(II) catalyst at 300 °C and 120 s. In the case of Cr(III) and Ni(II), the conversion of maize straw, sawdust and rice husk first increased, and then decreased from 0 to 800 ppm. For catalyst Cr(III), Zn(II) and Ni(II), the conversion of wheat bran indicated a decreasing trend. Transition metal ions have a great influence on raw materials conversion to lactic acid. In the conversion of pyruvaldehyde to lactic acid, the ionic catalyzed Cannizzaro‐type reaction would take place. Copyright © 2007 Society of Chemical Industry     

乙烷和二氧化碳催化转化的研究进展

CO₂与乙烷反应是实现碳减排目标、利用非常规能源的重要手段,符合国家重大需求和国际学术前沿。其中,二氧化碳通过“活性氧”机理、“晶格氧”机理以及“反应耦合”机理促进乙烷的活化。通过催化剂设计选择性地断裂C—H/C—C键,可以实现反应定向地按照两条路径进行——乙烷干重整反应（DRE）和乙烷氧化脱氢（ODH）。综述了DRE和ODH两类反应的热力学、反应物活化机制和催化剂研究进展,分析了催化剂均存在产物选择性低、易烧结、积炭问题的主要影响因素以及催化剂设计和改进策略,并对该研究未来的发展方向进行展望。     

乙烷和二氧化碳催化转化的研究进展

CO₂与乙烷反应是实现碳减排目标、利用非常规能源的重要手段,符合国家重大需求和国际学术前沿。其中,二氧化碳通过“活性氧”机理、“晶格氧”机理以及“反应耦合”机理促进乙烷的活化。通过催化剂设计选择性地断裂C—H/C—C键,可以实现反应定向地按照两条路径进行——乙烷干重整反应（DRE）和乙烷氧化脱氢（ODH）。综述了DRE和ODH两类反应的热力学、反应物活化机制和催化剂研究进展,分析了催化剂均存在产物选择性低、易烧结、积炭问题的主要影响因素以及催化剂设计和改进策略,并对该研究未来的发展方向进行展望。     

MFI结构分子筛用于甲醇制低碳烯烃技术的研究进展

综述了MFI结构分子筛的改性方法及其在MTO工艺中的作用,主要介绍了高温水热处理、磷改性和金属改性的方法及德国Lurgi公司使用该催化剂的甲醇制取丙烯工艺开发情况。     

One-step catalytic conversion of ethanol into 1,3-butadiene using zinc-containing talc

Compared with previously reported catalysts, zinc-containing talc exhibited the highest formation rate of 1,3-butadiene in one-step conversion of ethanol at 673 K. Our results showed that talc containing just 1.4 wt.% of ZnO produced 1,3-butadiene at a rate of 1.9 × 10^− 2 mol g^− 1 h^− 1.     

Effect of momentum transport on conversion in adiabatic catalytic tubular reactors

Neglecting the effect of velocity change on conversion in a gaseous plug flow solid catalysed reactor can lead to an overestimation of conversion by a factor of 3 or underestimation of reactor size for a given conversion by factors of 2 or more in highly exothermic adiabatic cases. Diffusion control, reaction control, and combined domination of rate situations are considered. For many practical situations in monoliths at subsonic velocity the effects of friction and momentum convection on velocity change can be neglected. The direct relationship between velocity and gas temperature in these situations can be accurately derived by assuming isobaric flow. In packed bed reactors reducing particle size below critical limits can appreciably reduce conversion (with increased pressure drop) compared with values estimated by neglecting the effect of friction. An adaptive variable order finite difference method has operated successfully in all cases studied for values of solids Peclet number, Pe_s <200.     

煤氮催化转化研究中的主要影响因素分析

作为煤的重要组成部分,矿物质对煤热解、气化过程中含氮物的迁移变化具有较强的作用,针对影响各类矿物质在煤氮催化转化过程中的因素进行了分析,主要介绍了煤中矿物质的脱除,所选矿物质的加入方法、操作条件,矿物质的前驱体以及煤的自身特性等对煤氮催化转化研究的影响,添加剂在煤中的存在形态和分散程度是其作用能力大小的决定因素,在实验结果和文献资料的基础上归纳出改善矿物质催化作用的操作条件.     

生物质液体燃料2,5-二甲基呋喃的催化合成进展

2,5-二甲基呋喃（DMF）是一种可替代化石能源的新型液体生物质燃料,对于缓解当今能源危机具有重要意义。鉴于其优良的性质和广阔的应用前景,以生物质资源为原料通过绿色、经济的方法制备DMF逐渐成为科学研究的热点。本文归纳和总结了近年来国内外由生物质糖类化合物出发制备DMF的一些催化技术研究新进展,着重从活性中心和载体的构效关系出发对比了不同金属催化剂的催化效果,讨论了影响多相反应体系的关键因素,分析了不同反应路线和制备方法。对进一步研究和开发从生物质糖类化合物“一锅法”转化成DMF的催化新技术提出了一些建议和展望,为探索高效、经济、绿色、可持续的DMF合成途径提供科学依据和创新思路,促进生物质制DMF的工业技术发展。     

人工神经元网络在甲烷催化转化反应中的研究进展

人工神经元网络(ANN)是一种通过模拟大脑处理信息的方式发展起来的数据处理技术,在石油和天然气领域中被广泛用于产量预测、甲烷物性计算、甲烷吸附与分离以及甲烷催化转化等领域。针对甲烷催化转化领域,综述了近年来ANN技术在甲烷干重整、蒸汽重整、联合重整和氧化偶联反应中的应用进展,结果表明：ANN在预测甲烷转化率、产物收率等方面具有准确性好、泛化能力强、鲁棒性好的优点,在催化工艺优化、催化剂组成优化等方面也有很好的应用,对该领域存在的问题以及未来的研究方向进行了总结和展望。