Influence of Contaminants in Steel Mill Exhaust Gases on Cu/ZnO/Al2O3 Catalysts Applied in Methanol Synthesis

The influence of impurities in steel mill exhaust gases on ternary Cu/ZnO/Al₂O₃ catalysts was studied for conventional methanol synthesis, which is one of the central reactions within the cross-industrial approach of Carbon2Chem®. A series of hydrocarbons was identified as inert spectators for methanol synthesis. Several catalyst poisons like N-containing compounds or O₂ show reversible characteristics at low pressure. However, by increasing the partial pressure of O₂, poisoning becomes irreversible, indicating different poisoning mechanisms concerning the reversibility of deactivation.     

美罗培南合成用钯炭催化剂的失活及再生研究

采用物理吸附、X射线衍射、扫描电镜、X射线能谱及等离子体发射光谱法对在美罗培南合成过程中失活的Pd/C催化剂比表面积、孔容、孔径、钯粒径形貌、表面元素及钯含量的变化进行分析,对催化剂的失活原因及再生方法进行研究。结果表明,催化剂在反应过程中吸附体系物质对钯活性中心的覆盖包裹及金属钯的少量流失是催化剂失活的主要原因。以30%四氢呋喃水溶液在超声条件下洗涤可以部分去除催化剂表面沉积的有机物,同时补加质量分数30%催化剂时,再次使用时效果较好。     

The process for catalytic incineration of waste gas on IC-12-S102 platinum glass fiber catalyst

The process for catalytic afterburning of volatile organic compounds (VOCs) in waste industrial gases was developed on the basis of a new platinum glass fiber catalyst (GFC) IC-12-S102 with low platinum content (∼0.02 wt %). The catalyst was shown to be more effective than the known industrial afterburning catalysts. The way of glass fiber catalyst loading to a reactor in the form of vertical spiral cartridges, structured with wire mesh of bulk weaving is described. The successful application of the IC-12-S102 catalyst was confirmed by its operation at OAO Nizhnekamskneftekhim in the process of waste gases afterburning in an industrial reactor with cleaned gases capacity up to 15000 m³/h. During the reactor operation in harsh conditions (low oxygen content, high content of water vapor), the degree of gas cleaning was 99.5–99.9% and the residual VOC content in the purified gases was no higher than 10–15 mg/m³. For more than 15 months of catalyst operation, the degree of gas purification was not reduced; thus, overall lifetime of the IC-12-S102 catalyst may be substantially longer than the life of well-known industrial afterburning catalysts.     

Short Vapour Residence Time Catalytic Pyrolysis of Spruce Sawdust in a Bubbling Fluidized-Bed Reactor with HZSM-5 Catalysts

Catalytic pyrolysis of spruce sawdust was carried out in a bubbling fluidized-bed reactor using HZSM-5 catalysts. The effects of space velocity, catalyst deactivation, catalyst acidity and catalyst regeneration were studied. The use of catalysts decreased the yield of organic liquids compared to non-catalytic yields while the yields of pyrolytic water and gases increased. Decreasing the space velocity enhanced these effects. The rate of catalyst deactivation depended on the acidity of the catalyst, with more acidic catalysts deactivating more rapidly. Using a catalyst with a Si/Al ratio of 140 resulted in the largest changes in bio-oil properties. Periodic regeneration of the catalyst in the fluidized-bed reactor was also demonstrated using varying regeneration times and temperatures. It was shown that compared to BFB reactors, CFB reactor types would offer better operating characteristics for commercial scale catalytic pyrolysis processes in regard to vapour residence times, and catalyst activity and regeneration.     

羰基镍导致碳化铁F-T合成催化剂失活过程分析

羰基铁催化的F-T合成反应中出现反常的失活现象,催化剂在短时间内活性显著下降,同时伴随产物中甲烷含量升高。对反应后催化剂进行ICP表征,检测到Ni元素。对反应原料气进行红外分析,检测到微量羰基镍的存在,推测羰基镍有可能是催化剂中毒的物质。经过更换原料气和增设冷阱净化反应气后,催化剂快速失活现象仍然明显,发现毒性物质在热电偶内衬管上附着,进行抛光处理后成功解决催化剂失活问题。     

超临界条件下甲基萘与甲醇烷基化反应

引　言2 ,6 二甲基萘 (2 ,6 DMN)是生产新型高性能聚酯材料聚萘二甲酸乙二醇酯 (PEN)的重要原料 .目前已工业化的邻二甲苯与丁二烯烷基化生产2 ,6 DMN路线生产步骤多 ,工艺过程复杂 ,生产成本高 ,制约了PEN的发展[1,2 ] .HZSM 5沸石是一种具有强酸性、高硅铝比和独特孔道结构的分子筛 ,对许多正碳离子反应有良好的择形催化性能[3] .HZSM 5催化甲基萘 (DMN)与甲醇烷基化合成 2 ,6 DMN路线工艺过程简单 ,产品选择性高 ,是一条具有发展前景的技术路线[4 ] .然而 ,在常压下进行烷基化反应时 ,反应活性低 ,催化剂容易因结焦而失去原有的活性[5～ 7] .超临界流体具有良好的溶解和扩散性能 .在超临界条件下进行的化学反应不仅可以提高催化剂的反应活性 ,而且还可以原位维持非均相催化剂的活性 ,延长催化剂的寿命[8,9] .本文正是基于超临界流体独特的性质 ,探索在超临界条件下甲基萘与甲醇烷基化反应中提高反应活性和延长催化剂寿命的可能性 .1　实验部分1 1　催化剂的制备NaZSM 5沸石 (硅铝比为 38)由南开大学催化剂厂提供 .在 80℃下用 1mol...     

Multinuclear NMR and catalytic investigations of deactivation of zeolite H-ZSM-5

Coke formation and catalyst deactivation by the reaction of methanol over a zeolitic catalyst based on H-ZSM-5 for various stream gases (N₂, H₂ or C₄H₁₀) were studied by¹³C CP MAS NMR,²⁹Si MAS NMR,¹²⁹Xe NMR and catalytic test reactions with different stream gases (N₂, H₂, C₄ H₁₀). The rate of deactivation varies in the order N₂ < H₂ < C₄H₁₀, which can be explained by cracking of paraffinic, olefinic and alkylaromatic coke deposits under the influence of the hydrogenating properties of the stream gas.     

H2S为毒物对乙炔氢氯化反应中AuCl3/AC催化剂催化活性的影响

采用等体积浸渍法制备了1% AuCl₃/AC催化剂,探究了硫化氢(H₂S)为毒物对乙炔氢氯化反应中催化剂催化活性的影响及失活机理。催化活性测试结果表明,以H₂S为毒物可导致乙炔氢氯化反应中的AuCl₃/AC催化剂的失活,且是一个不可逆过程;程序升温还原(TPR)和X射线光电子能谱(XPS)分析结果表明,H₂S的加入可有效地加快Au³⁺还原为Au⁰;透射电镜能谱(TEM-EDX)观测分析形成的Au-S化合物也可导致催化剂失活,即随着H₂S量的增大,更多的Au³⁺被还原为Au⁰,且形成的Au-S化合物覆盖在活性位点,使有效的活性组分降低进而导致AuCl₃/AC催化剂失活。     

Pd-based catalysts for catalytic wet oxidation of combined Kraft pulp mill effluents in a trickle bed reactor

Catalytic wet oxidation of combined pulp mill effluents was studied in a trickle bed reactor. Two types of supported Pd-based catalysts, eggshell and uniform catalysts, and a supported Pd–Pt uniform catalyst were employed. Supported Pd catalysts showed high activity for total organic carbon (TOC) and color removal at temperatures of 353–448 K and 1.84 MPa. Compared to uniform catalysts, the eggshell catalysts with a 0.2 wt.% Pd loading show promise for treatment of combined pulp mill effluents. High activity for TOC and color removal can be attributed to the high density of active Pd sites in the shell area and to the decrease of diffusion path for reactants and intermediates. No apparent deactivation of eggshell catalysts was observed after 40 h on stream. Potential application of the supported Pd catalysts for treatment of combined pulp mill effluents is discussed.     

钴钼系变换催化剂反硫化动力学的研究

在微型石英管反应器中研究了温度、汽气比和硫化钼浓度对钴钼变换催化剂反硫化动力学的影响.在消除了外扩散和反应率不太高的情况下,建立了催化剂的失活动力学模型.实验证明,催化剂的失活与温度、汽气比和硫化钼浓度有很大关系,并结合工业生产实际状况对钴钼催化剂反硫化动力学模型进行了讨论.     

Enantioselective hydrogenation of ethyl pyruvate in supercritical fluids

The enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate has been studied using gases under supercritical conditions as solvents. The catalyst was a 5 wt% Pt/alumina modified with cinchonidine. In supercritical ethane the reaction time could be reduced by a factor of 3.5 compared to toluene under similar conditions, without any loss in enantioselectivity. A further advantage of ethane is that the enantioselectivity remains high even at high catalyst/reactant ratio, which is interesting in view of a possible application of a continuous fixed-bed reactor for this reaction. A strong catalyst deactivation was observed in supercritical CO₂, which is due to the reduction of CO₂ on Pt as indicated by FTIR.     

Purification of waste gases in the desulfurization of coke-oven gas

The operation of equipment for the hydrolysis of waste gases from the desulfurization of coke-oven gas is analyzed on the basis of chromatographic data. Specifically, the data relate to the operation of such equipment in shop 2 for trapping coking byproducts at OAO Magnitogorskii Metallurgicheskii Kombinat, over a period of four years (2004–2008). The reduced efficiency of the system in the third year of operation is due to sharp deactivation of the CR-31 aluminum-oxide catalyst (La Roche Chemicals) in the R-6301 reactor on account of sulfate formation on opening the reactor. In normal operation, the life of the catalyst in the R-6301 reactor is at least 2–3 years. To restore the efficiency of hydrolysis, the catalyst in the R-6301 reactor must be completely replaced, preferably with a specialized catalyst for hydrolysis and hydrogenation.     

A novel continuous reactor for catalytic reduction of NOx—fixed bed simulations

A novel dual‐zone fluidized bed reactor was proposed for the continuous adsorption and reduction of NO_x from combustion flue gases. The adsorption and reaction behaviour of such a reactor has been simulated in a fixed bed reactor using Fe/ZSM‐5 catalyst and propylene reductant with model flue gases. Fe/ZSM‐5 exhibited acceptable activity at T = 350°C and GHSV = 5000 h^?1 when O₂ concentration was controlled at levels lower than 1% with a HC to NO molar ratio of about 2:1. XPS and BET surface area measurement revealed the nature of the deactivation of the catalyst. Those performance data demonstrated the feasibility of a continuous dual‐zone fluidized bed reactor for catalytic reduction of NO_x under lean operating conditions.     

Life Cycle Assessment of Steel Mill Gas-Based Methanol Production within the Carbon2Chem® Project

Within the Carbon2Chem® project, new processes have been developed to valorize steel mill gases by producing methanol. This article compares the global warming impact of integrated steel and methanol production to the stand-alone production of steel and methanol. In order to generate mass and energy balances of the cross-industrial network, several simulation approaches were conducted, and two power sources investigated. In the case of a power mix in 2030, the conventional production of steel and methanol is favorable, and in the case of wind power, the integrated production of steel and methanol shows greater benefit. If an electricity mix with a carbon intensity of less than 0.23 kg_CO2-eq.kWh⁻¹ electricity is used, the integrated production of steel and methanol has a lower global warming impact than stand-alone steel and methanol production.     

Catalytic Treatment of Vacuum Carburizing Off Gas

The aim of this investigation was to find a suitable procedure for the treatment of higher polycyclic aromatic hydrocarbons, produced during vacuum carburizing of steel. In a lab scale apparatus the carburizing gas acetylene was pyrolyzed and the generated gases converted in a downstream catalytic bed reactor. The results show that it is possible to remove the higher pyrolysis products from the off gas. A complete conversion of the off gases into carbon and hydrogen was achieved with a Ni/SiO₂/SiC‐catalyst at temperatures ? 520 °C. Coke, formed during the conversion of the hydrocarbons on the catalyst, is removed from the catalyst by burning it off. The functionality of the catalyst is investigated for both the reduced and the non‐reduced state, whereby the non‐reduced catalyst deactivates faster.     

Catalytic reforming of tar during gasification. Part I. Steam reforming of biomass tar using ilmenite as a catalyst

Ilmenite, a natural iron-containing mineral, has been investigated as an inexpensive catalyst for the steam reforming of volatiles (tar) from the pyrolysis of mallee woody biomass. The results indicate that ilmenite has good activity for the steam reforming of tar into gases due to its highly dispersed iron-containing species. The supply of external steam, in addition to the H₂O and CO₂ produced during the pyrolysis of biomass, plays an important role in minimising the formation of coke on the catalyst surface and thus the catalyst activity. The catalyst deactivation due to coke formation has more adverse effects on the reforming of larger aromatic ring system with steam than that of smaller ones. In addition, the supply of additional oxygen at low concentration changed the outcomes of tar reforming mainly because oxygen activated the smaller aromatic ring systems and polymerised them into larger aromatic ring systems in the gas phase.     

Selective kinetic deactivation model for methanol synthesis from simultaneous reaction of CO2 and CO with H2 on a commercial copper/zinc oxide catalyst

A kinetic model for the deactivation of copper/zinc oxide catalyst during the methanol synthesis has been developed. This model is of the Langmuir-Hinshelwood-Hougen-Watson type and considers two types of active sites for the deactivation of catalyst. One of the site types on copper is allocated for the deactivation of the catalyst due to carbon dioxide while another type is assigned for the deactivation of the catalyst due to carbon monoxide. The parameters of the deactivation rate equations based on the above concept have been determined using the experimental data of Hoffmann (1993). The validity of the deactivation model has been checked by comparing the results predicted by the model with experimental data different than of those used to evaluate the parameters of the model. The good agreement that noticed in this comparison confirmed the idea that CO and CO₂ are responsible at different extent for the deactivation of Cu/ZnO catalyst during methanol synthesis.     

Deactivation of a Ni-Based Reforming Catalyst During the Upgrading of the Producer Gas, from Simulated to Real Conditions

The deactivation of a nickel reforming catalyst during the upgrading of the producer gas obtained by gasification of lignocellulosic biomass was studied. The research involved several steps: the selective deactivation of the catalyst in a laboratory scale; the streaming of the catalyst with the producer gas of a downdraft and an oxygen/steam circulating fluidized bed (CFB) gasifier; and tests in a reformer placed in a slipstream of the CFB gasifier. The information obtained allowed to elucidate the catalyst deactivation mechanisms taking place during the reforming of the producer gas: physical deactivation by deposition of fine ashes, aerosol particulate or carbon; poisoning by H₂S and HCl present in the gas phase and thermal sintering because of the high operation temperatures required to avoid the chemical deactivation. These physical and chemical effects depended on the composition of the biomass fuel.     

Combination of Refractometry and Densimetry – A Promising Option for Fast Raw Methanol Analysis

Besides water, raw methanol produced from steel mill gases within the Carbon2Chem® project contains dissolved carbon dioxide. Refractometry and densimetry were investigated as analysis methods to analyze raw methanol samples quickly and reliably. To verify existing calibration curves, a set of standard solutions from pure chemicals was produced. Experimental results differed significantly from published refractive index data, especially in the range of high methanol weight fractions, which are of particular interest for the Carbon2Chem® project.