On the Production of Hydrogen from Bio-Oil: A Representative Study Using Propylene Glycol

In a bio-refinery focused on fast pyrolysis, hydrogen (H₂) producible from reforming of the aqueous fraction of bio-oil with steam can be utilized for upgrading pyrolytic lignin into fuels by hydrotreatment. In this work, propylene glycol (PG) was chosen as a typical compound symbolizing higher polyols in the bio-oil aqueous fraction. Catalytic processing of PG into H₂ at low temperature (T = 500°C) was investigated using several commercial catalysts such as Ni/Al₂O₃, Ru/Al₂O₃, Ru/C, Pt/C, and Pd/C in a laboratory-scale fixed-bed reactor. The efficiencies of the catalysts were presented as selectivity to CO, CO₂, CH₄ and H₂, and PG conversion into gaseous phase. Wide ranges of temperature (300–500°C), W/F_O (18.6–92.9 g h/mol), and S/C ratio (5.6–12.7 mol/mol) were examined using Ni/Al₂O₃. At T = 500°C, H₂ selectivity (73.7%) and PG conversion (66.2%) were maximized using ratios of catalyst mass to molar flow rate of PG (W/F_O) = 18.6 g h/mol and steam to carbon (S/C) = 12.7 (10 wt% PG solution). It was found that Ni/Al₂O₃ demonstrates stable operation for at least 6 h of time-on-stream. Finally, a plausible reaction pathway for PG reforming was proposed.     

乙二醇气相催化氧化合成乙二醛

在一定颗粒大小的银催化剂存在下,在一定的反应温度、停留时间和惰性气体浓度下,通过催化氧化乙二醇制备乙二醛。通过试验,确定了较佳的工艺条件：反应温度450～520℃,氧醇比1．25-1．50,惰醇比40-50,乙二醛的产率≥75％。     

Hydrogen Production by Steam Reforming of Ethanol on Potassium-Doped 12CaO · 7Al2O3 Catalyst

The performance of hydrogen production from steam reforming of ethanol were investigated by using the K-doped 12CaO · 7Al₂ O₃ catalyst (defined as C12A7–O⁻/x%K). The conversion of ethanol and hydrogen yield over C12A7–O⁻/x%K catalyst mainly depended on the temperature, K-doping amount, steam-to-carbon ratios (S/C) and contact time (W/F). In order to identify the catalyst’s characteristic and active species on the catalyst’s surface, Brunauer-Emmett-Teller (BET) surface area, CO₂ temperature programmed desorption (CO₂TPD), X-ray diffraction (XRD), Fourier transform infrared (FT–IR) and X-ray photoelectron spectroscopy (XPS) were carried out. Based on the characterization, it was found that active oxygen species and doped potassium play important roles in steam reforming of ethanol over C12A7–O⁻/27.3%K catalyst.     

乙二醇焚烧炉工艺流程优化

随着工业生产的迅速发展,环境污染阻碍了工业生产的进一步发展。在现有的乙二醇焚烧炉控制工艺的基础上,经过分析提出用流量计控制阀门开度对焚烧炉控制工艺进行优化改造,使乙二醇废气在焚烧炉中充分燃烧,减少废气的排放。     

Methane Steam Reforming Kinetics on a Ni/Mg/K/Al2O3 Catalyst

The kinetics of methane steam reforming were studied on a Ni/Mg/K/Al₂O₃ catalyst that was developed for conditioning of biomass-derived syngas. Reactions were conducted in a packed-bed reactor while the concentrations of reactants (methane and steam) and products (hydrogen, carbon monoxide, and carbon dioxide) were varied at atmospheric pressure, with the effects of temperature (525–700 °C) and residence time also being investigated. A power law rate model was developed using nonlinear regression to provide a predictive capability for the rate of methane conversion over this catalyst, to be used for reactor design and technoeconomic analysis of process designs. In order to provide some mechanistic insight, and to compare this catalyst to other non-promoted Ni/Al₂O₃ catalysts reported in the literature, a reaction mechanism consisting of five elementary steps, using a Langmuir–Hinshelwood type approach, was also considered. These five steps included: (i) CH₄ adsorption, (ii) H₂O adsorption, (iii) surface reaction of adsorbed CH₄ and H₂O to form CO and H₂, (iv) CO desorption, and (v) H₂ desorption. Nonlinear regression was then used to fit each of the rate laws to the experimental data. From these results, the model that assumed CH₄ adsorption to be the rate determining step provided the best fit of the experimental data. This finding is consistent with literature studies on non-promoted Ni/Al₂O₃ catalysts, in which methane adsorption has been proposed to be the rate determining step during catalytic methane steam reforming. Both the power rate laws and the rate law assuming CH₄ adsorption to be the rate determining step can be used as predictive tools for determining methane conversion for a given set of process conditions. Additionally, a rate expression that assumed the rate was only a function of methane partial pressure was considered, namely, $rate = k*P_{{CH_{4} }}$ rate = k ? P CH 4 , where $k = k_{0} *e^{{^{{ - {\text{Ea}}/{\text{RT}}}} }}$ k = k 0 ? e ? Ea / RT , with P_CH4 in units of Torr. This first-order-methane rate expression fit the data well, yielding an apparent activation energy over this catalyst of E_a = 93 kJ/mol and the pre-exponential rate constant of k₀ = 7.67 × 10⁵ mol/(g-cat s Torr CH₄).     

乙二醇为原料制备乙二醇乙醚用催化剂及其失活

以硫酸铵浸渍改性的HZSM-5为催化剂催化乙二醇和乙醇合成乙二醇乙醚和乙二醇二乙醚时催化剂效率很高,乙二醇转化率能达到69.1%,乙二醇乙醚选择性达到72.9%,乙二醇二乙醚的选择性为25.3%。但催化剂在重复使用时催化活性降低较快,因此分别采用X射线衍射仪（XRD）,NH3-TPD,扫描电子显微镜（SEM）,电子能谱（EDS）,比表面积及孔径测定仪和热重/差热分析仪（TG）对催化剂改性及使用前后晶型结构,表面酸强和酸量,表面吸附物,催化剂形貌,表面元素变化,比表面积,孔径大小等对催化剂失活原因及再生条件进行研究。结果表明,在使用后未对催化剂处理情况下,催化剂失活主要是由于表面积碳导致催化剂孔道堵塞造成的。经多次使用后催化剂缓慢失活主要是由于催化剂表面负载的S流失造成的,在整个过程中催化剂晶型结构未发生变化。     

Investigation of Promoted Cu/ZnO/Al2O3 Methanol Steam Reforming Nanocatalysts by Full Factorial Design

A Cu/ZnO/Al₂O₃ nanocatalyst was applied for hydrogen production via steam reforming of methanol in a fixed‐bed reactor. Modified forms of the catalyst were prepared by adding small amounts of Ba, Zr, and Ce oxides. The catalysts were characterized by means of N₂ adsorption‐desorption, X‐ray diffraction, and scanning electron microscope techniques. Full factorial design was used to optimize the required number of experiments and evaluate the catalytic activity in a fixed‐bed reactor. The oxide additives reduced the production of carbon monoxide and increased the selectivity of carbon dioxide as well as the yield of hydrogen production. Among the studied catalysts, the Cu/ZnO/Al₂O₃/CeO₂/ZrO₂ catalyst presented the best performance.     

乙二醇合成技术研究

介绍了合成乙二醇的工艺进展情况,包括催化水合法、碳酸乙烯酯法和合成气法,并对各种方法的工艺技术特点进行了评述。     

乙二醇合成工艺进展及前景分析

乙二醇是一种重要的化工原料。介绍了石油路线和煤路线生产乙二醇的工艺进展,并对国内生产乙二醇进行了分析。在我国石油路线仍是主要方法,但易受到国际油价的限制,而煤路线将是国内未来发展的重点。但应加强乙二醇的新型催化剂和技术的研发,并拓展煤化工的多元化发展。     

Steam reforming of the aqueous fraction of bio-oil over structured Ru/MgO/Al2O3 catalysts

A catalyst consisting of Ru (5%) dispersed on 15% MgO/Al₂O₃ carrier exhibits high activity and selectivity, as well as satisfactory stability with time on stream, under conditions of steam reforming of acetic acid, a model compound for pyrolysis oil. The presence of MgO in the catalyst formulation is shown to be related to oxygen and/or hydroxyl radical spillover from the carrier to the metal particles. A series of Ru/MgO/Al₂O₃ catalysts supported on cordierite monoliths, ceramic foams and γ-Al₂O₃ pellets were prepared and tested for the production of hydrogen by catalytic steam reforming of the aqueous fraction of bio-oil. All different structural forms of the catalyst exhibited satisfactory activity, converting completely the bio-oil, good selectivity toward hydrogen and satisfactory stability with time on stream. However, the catalyst supported on pellets exhibited the best catalytic performance, among all catalysts investigated. Reforming reactions, and thus hydrogen production, are favoured at high temperatures and low space velocities. Coking is one of the most significant problems encountered in these processes. It was found that only a small part of the incoming carbon is deposited on the catalyst surface, which is mainly present as CH_x. However, coke deposition is more intense on the reactor wall above the catalytic bed, due to homogeneous polymerization of unstable ingredients of bio-oil.     

Sustainable hydrogen production via reforming of ethylene glycol using a novel spouted bed reactor

Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil fuels and as a means for clean power generation via fuel cells. The aqueous fraction of bio-oil can be effectively reformed to hydrogen rich streams in the presence of active catalytic materials. In this paper we present the experimental work carried out in a novel spouted bed reactor for the reforming of bio-oil. The use of a specially designed injection nozzle in combination with the particular hydrodynamic characteristics of the spouted bed resulted in efficient processing of the organic feed. The known problem of coking was notably avoided regardless of the loading material of the reactor. The effect of reaction temperature and steam to carbon ratio in the feed was investigated in the presence of various catalytic and non-catalytic particles. Runs were conducted with ethylene glycol as a representative model compound of the aqueous phase of bio-oil. Olivine, when associated with nickel, proved to be a very suitable catalytic material for the process combining high activity in reforming, anti-coking characteristics combined with exceptional mechanical strength.     

Kinetic Study of CO2 Reforming of Propane over Ru/Al2O3

The rate of reaction of propane over a Ru/Al₂O₃ catalyst was determined as a function of the partial pressures of the reactants, C₃H₈ and CO₂ at 600 and 650°C. The order of the reaction was found to be fractional with respect to carbon dioxide, indicating its involvement in the rate-determining step of the reaction. The order of the reaction was zero in propane indicating the fast reaction of propane over the catalyst. The apparent activation energies for propane and the formation of hydrogen and carbon monoxide were investigated. Values for the formation of hydrogen and carbon monoxide indicated a decrease in the CO:H₂ ratio with an increase in temperature. Modelling of the kinetic data was inconclusive in the selection of a possible mechanism as good fits were observed for a Langmuir–Hinshelwood and a Mars–van Krevelen mechanism.     

草酸二甲酯气相法加氢制乙二醇催化剂研究进展

草酸二甲酯的气相加氢具有高水平的活性,采用共沉淀法制备需要不同特性规格的沉淀剂,催化剂的组合和反应条件都对乙二醇的合成性质具有明显的性能影响。通过采用独特的吸附方法表征制备的催化剂,以及通过试验获得的值表明草酸二甲酯的独特氢化反应与铜离子的独特活性状态密切相关。此外,通过气相催化得到的乙二醇,草酸二甲酯的比转化率可超过97%;乙二醇的选择性特征高达85%;制备的催化剂突出了最佳的稳定性能。     

乙二醇的合成方法

阐述了乙二醇的几个主要合成方法,着重介绍了合成乙二醇的新技术方法：碳酸亚乙酯法。     

重整重芳烃选择加氢Ni-M/Al_2O_3催化剂性能

为提高镍基催化剂对萘系化合物的加氢活性和单环芳烃的收率,本研究以Al_2O_3为载体采用浸渍法制备了不同金属助剂修饰的系列Ni-M/Al_2O_3加氢催化剂,对催化剂的物性结构和形貌进行了表征,并考察了其在重整重芳烃中萘系化合物的加氢反应性能。结果表明,含Cu助剂的催化剂具有较佳的织构性能,金属活性组分高度分散,在C_(10)~+重芳烃加氢中具有良好的反应选择性和活性。在反应温度为140℃,压力为1.5 MPa,氢油体积比为300,新鲜油体积空速为1.0 h~(-1)的条件下,萘的转化率和四氢萘的选择性分别达到98%和99%,反应1 000 h稳定性良好。     

Testing of a Ni‐Al2O3 Catalyst for Methane Steam Reforming Using Different Reaction Systems

Ni‐Al₂O₃ catalyst activity was tested for methane steam reforming using two different reaction systems: a catalyst particle bed (0.42–0.5 mm catalyst particles diluted in SiC) with a surface area‐to‐volume ratio SA/V of 910 m^–1 and a porosity ? of 52 % and a catalyst‐coated metal monolith with an SA/V of 3300 m^–1 and an ? of 86 %. Under a steam‐to‐carbon ratio of 2.5 and at a temperature of 700 °C, the highest specific reaction rates were found for the catalyst‐coated monolith. The high SA/V and ?, together with the high rate of heat transfer of the metal monolith were found to be responsible of this optimum behavior. However, in both systems, the Ni‐Al₂O₃ catalyst suffered a catalyst deactivation during operation.     

Compact Reforming Process Using High-Performance and Long-Lived CO Preferential Oxidation over an Activated Ru/Al2O3 Catalyst for PEFC

Compact natural gas reforming process using high-performance and long-lived CO preferential oxidation (PROX) over an activated Ru/Al₂O₃ catalyst has been developed for residential polymer electrolyte fuel cell (PEFC) systems. The long-term durability of the catalyst was demonstrated for more than 40,000 h. After 40,000 h operation, CO was removed from a reformed gas to below 1 ppm on the activated Ru/Al₂O₃ catalyst at [O₂]/[CO] = 1.5. The high activity and selectivity of the catalyst were maintained for more than 40,000 h. Moreover, the start–stop durability for more than 3,000 cycles of the activated Ru/Al₂O₃ catalyst was also demonstrated without N₂ purge.     

ZnO/Al_2O_3催化剂乙醇水蒸气重整反应失活研究

采用浸渍法制备了一系列ZnO/Al2O3催化剂,考察了该催化剂在水醇摩尔比为3、常压、450℃工作条件下乙醇水蒸气重整(SRE)制氢反应活性及稳定性。结果表明,ZnO负载量达到10wt%时,C2H5OH转化率最高,但催化剂在160 min内出现明显失活。利用BET等表征手段考察了反应前后催化剂的物理化学性质,并通过失活模型模拟,提出了ZnO/Al2O3催化剂上SRE制氢反应的失活原因。     

国产Ru/Al2O3甲烷化催化剂的工业应用与探讨

对国产Ru/Al2O3催化剂研制开发、侧线试验及工业化试用情况进行了探讨,为国产Ru/Al2O3催化剂的推广应用提供了依据.     

陶瓷膜过滤技术在煤制乙二醇工艺中的应用

介绍了陶瓷膜过滤技术在煤制乙二醇工艺中应用,通过试验和分析,采用微孔陶瓷膜过滤器较好的解决了煤制乙二醇过程中微细颗粒精密过滤技术难题,提升煤制乙二醇成品的品质。