基于Cu2O光阴极的光电催化CO2还原研究

光电催化CO₂还原制备碳氢燃料是缓解当前能源和环境危机的潜在策略。现阶段，光电极的构建依然是光电催化CO₂技术的关键点。由于Cu基催化剂具有低成本、高C2+选择性、高稳定性等适宜CO₂还原应用的特性，构建新型Cu基光电极仍是CO₂还原研究领域中研究热点。本文从P型Cu₂O光阴极入手，系统研究了电沉积工况与光电催化CO₂还原反应之间构效关系。研究结果表明，在恒温环境中，施加0.5 mA/cm²恒电流密度可获得结晶度良好的Cu₂O光阴极，并实现C2产物的合成。其中，乙醇的选择性可达5.3%。本文研究结果可为设计和制造具有高活性的光电催化CO₂还原光电阴极提供可行策略。     

钯碳催化木质素模型化合物制备烷烃的试验研究

针对木质素的转化,以木质素模型化合物愈创木酚催化加氢脱氧制备烷烃为模型反应,研究酸溶液中,活性炭负载Pd、Pt、Ru、Rh金属催化剂的催化性能。研究发现:在测试的催化剂中,Pd/C催化剂显示出较高催化加氢脱氧性能,烃类产物收率达到80%。随后,考查反应条件对催化性能的影响,发现在适中反应温度(200~250℃)、酸浓度(0.5wt%~1.0wt%)和较高氢气压力(5MPa)下,反应有利于烃类产物的生成。最后,探讨愈创木酚加氢脱氧的反应历程。     

新型人工光合作用系统的能量和质量平衡研究

该文提出一种新型人工光合作用（AP）系统,通过PV/T装置将太阳能光热综合利用,转化为热能和电能,分别供给吸附式碳捕获和碳还原的反应过程。建立并耦合PV/T模型、吸附碳捕获与碳还原反应模型,随后基于CO₂还原反应所需的CO₂质量进行能量-质量匹配性分析。结果表明,金属有机骨架74（MOF-74）的CO₂捕获量比活性炭大了6倍,具有较大的CO₂捕获潜力,但当MOF-74吸附剂的质量高于50 kg时,CO₂捕获的热效率降低到20%以下。采用聚光度为10的1 m²的PV/T时,15 kg的MOF-74可在一天内捕获0.45 kg的纯CO₂,并制备0.152 kg甲烷。     

臭氧耦合双金属催化剂共同氧化NO和VOC的研究

通过等体积浸渍法合成一系列M-MnO_x/γ-Al₂O₃催化剂(M=Ce、Co、Cr、Fe),用于低温催化臭氧共同氧化NO和邻二甲苯(o-C₈H₁₀)的研究,试验发现,Fe/Mn催化剂表现出最高的催化氧化活性,最佳的温度区间为60～100℃;在NO与邻二甲苯共同存在时,臭氧优先将NO氧化为NO₂,之后NO₂深度氧化与邻二甲苯初步氧化同时进行,最后多余的臭氧将邻二甲苯初步氧化生成的小分子有机物氧化为CO与CO₂;催化剂对不同初始污染物浓度适应性良好,研究结果可为臭氧一体化脱除烟气污染物的工业化推广应用提供依据。     

碳基固体酸预处理结合酶解糖化玉米芯的研究

以自合成的木质素磺酸钠基固体酸（Sl-C-S-H₂O₂）为催化剂,并耦合纤维素酶实现玉米芯的两步水解建立糖平台。考察预处理条件对木糖收率的影响,最高木糖收率可达83.4％;在国产纤维素酶的作用下,48 h葡萄糖收率即可达92.6%,两步反应的总还原糖收率达88.1%。     

增溶易分离离子液体均相催化剂合成及催化制备生物柴油工艺研究

以离子液体和磷钨酸为原料,制得3种功能化磷钨酸盐离子液体,采用红外光谱、热重分析等进行表征验证,并用其催化棕榈油酯交换制备生物柴油,考察醇油物质的量之比、反应温度、反应时间和离子液体用量对反应的影响及离子液体的稳定性。结果表明:所制备的磷钨酸盐离子液体具有较好的温控相转移和酸催化性能,能实现高温反应和低温分离效果,与纯H₂PW₁₂O₄₀、固定化H₂PW₁₂O₄₀、[MIMPS]H_SO₄传统催化剂相比,表现出更好的溶解、催化和回收性能,在n(甲醇)∶n(棕榈油)=10∶1,反应温度120℃,反应时间8 h,1-丙基磺酸-3-甲基咪唑磷钨酸盐离子液体([MIMPS]H₂PW₁₂O₄₀)质量为棕榈油7%的条件下,生物柴油收率可达95.6%,且该离子液体稳定性良好,循环使用5次催化性能无明显降低。     

Ni-xFe/Mayenite促进CO2-CH4重整的稳定性调控实验研究

采用湿法混合-浸渍法制备了一系列 Ni-xFe/mayenite(Ca₁₂Al₁₄O₃₃)催化剂,并在 700 ℃、常压、CH₄/CO₂为 1 的条件下进行了干重整实验研究．系统考察了金属负载量、金属组分等对干重整活性和稳定性的影响．其中7.5% Ni-0.1Fe/mayenite 能够得到接近热力学平衡值的 CO₂和 CH₄转化率(分别为 90.1%、86.0%),氢碳比为0.94.Ni-x Fe/mayenite 的活性随着 Ni 负载量从 5%增加到 10%显著提高;进一步增加到 30%时,活性提升有限．Ni 负载量较高的 Ni/mayenite 更容易发生碳沉积,导致反应器堵塞,而 Ni-x Fe/mayenite 在干重整过程中稳定性显著提高．Fe 掺杂提高催化剂表面氧浓度,形成 Ni-Fe 合金有利于 Ni 位点分散,抑制 CH₄过快裂解;钙铝石作为载体,促进了 CO₂与金属之...     

电催化二氧化碳还原制乙烯铜基催化剂研究进展

由太阳能、风能驱动CO₂电化学还原为高附加值的燃料和化学品是缓解温室效应和实现碳减排的方法。铜基催化剂作为CO₂还原为碳氢化合物的催化剂受到广泛的关注,但反应过电位高、目标产物选择性低和催化剂稳定性差等仍是开发铜基催化剂需解决的问题和面临的挑战。简述了电催化还原CO₂为乙烯的反应机理,总结了最近铜基催化剂形貌和晶面调控、缺陷构造、杂原子掺杂以及双金属合金化对其性能影响的研究进展,为电催化CO₂还原制乙烯高效催化剂的研发提供参考。     

Cu源对Cu-SSZ-13催化剂脱除NOx性能的影响

通过离子交换法制备了不同Cu源（硝酸铜、硫酸铜和乙酸铜）的Cu-SSZ-13催化剂,并利用X射线衍射（XRD）、比表面积（BET）、X射线光电子能谱（XPS）、H₂程序升温还原（H₂-TPR）和NH₃程序升温脱附（NH₃-TPD）等表征手段结合固定床反应器研究了Cu源对催化剂选择性催化还原（SCR）活性的影响．结果表明：采用离子交换法制备的Cu-SSZ-13催化剂具有良好的SCR催化活性和N₂选择性,其中利用有机铜源（乙酸铜）制备的CuSSZ-13催化剂具有较好的低温催化活性和NH₃吸附稳定性．水热老化后,催化剂的NO_x转化率达到90%及以上的温度窗口(T₉₀)为175～575℃,其CHA结构的特征衍射峰强度有所降低,但结构并未发生明显变化,表明经过水热老化处理后的催化剂能够保持较高的活性．温度为300℃时,在反应进料中添加体积分数为500×10^-6的丙烯（C₃H     

联合CO2捕集的生物质化学链气化制备合成气系统分析

本文提出以Fe₂O₃为载氧体、以CaO捕集CO₂的生物质化学链气化系统,利用Aspen Plus软件对该系统进行了模拟,以合成气组成（干基）、合成气氢碳比、含碳产物的碳摩尔分布、冷气效率及收率等为系统性能评价指标,重点分析了燃料反应器温度（T_FR）、载氧体Fe₂O₃与生物质碳摩尔比（Fe₂O₃/C）、水蒸气与生物质碳摩尔比（Steam/C）、CaO与生物质碳摩尔比（CaO/C）等系统参数对固体生物质化学链气化系统的影响。结果表明,在T_FR = 825℃、Fe₂O₃/C = 0.5、Steam/C = 0.71和CaO/C = 0.26条件下,合成气制备系统性能较优,合成气中H₂和CO₂含量分别为55.2%和15.4%,氢碳比为1.93,冷气效率为78.2%,被CaCO₃捕集的生物质碳为18.2%,收率（湿气基）为1.95 Nm³/kg_biomass,其中合成气中H₂和CO收率为1.24 Nm³/kg_biomass。     

Ni-Co双金属催化剂上沼气重整制氢宏观动力学

用传统湿式浸渍法制备La2O3掺杂的商业γ-Al2O3负载的沼气重整催化剂Ni-Co/La2O3-γ-Al2O3,通过对NiCo双金属催化剂上沼气重整制氢在常压下的宏观动力学分析,得出该催化剂上CH4与CO2消耗、H2与CO生成时的表观反应速率方程.通过改变进料中CH4与CO2的分压,求出各物质的反应分级数,确定总反应...     

Kinetic study on fermentation from CO2 and H2 using the acclimated-methanogen in batch culture

Methane was produced from H₂ and CO₂ using the acclimated-mixed methanogens in a 3.71 fermentor in batch culture at pH 7.2 and 37°C. The Fermentation kinetics parameter for the growth of methanogens, overall mass transfer coefficient of the reactor, and the conversion rate of H₂ and CO₂ to CH₄ by the acclimated-mixed culture were determined using the technique of Vega et al. The maximum specific growth rate (μ_max) and H₂ specific consumption rate (q_max) were found to be 0.064(h⁻¹) and 104.8 (mmol h⁻¹ g⁻¹) respectively. Monod saturation constants for growth (Kp) and for inhibition (K′p) were found to be 3.54 (kPa) and 0.57 (kPa), respectively. These findings indicate that without very low dissolved H₂ levels, the fermentations are carried out under μ_max, and the specific uptake rate (q) was almost not affected at any dissolved H₂ level in the range studied. The yield of CH₄ (Yp/s) was calculated to be 0.245 (mol CH₄ mol⁻¹ H₂), which is near the stoichiometric value of 0.25. DH₂ was also measured using the Teflon tubing method and was in good agreement with those estimated by kinetic calculations.     

Hydrogen production by biomass gasification in supercritical or subcritical water with Raney-Ni and other catalysts

Gasification of peanut shell, sawdust and straw in supercritical or subcritical water has been studied in a batch reactor with the presence of a series of Raney-Ni and its mixture with ZnCl₂ or Ca(OH)₂. The main gas products were hydrogen, methane, carbon dioxide, and a small amount of carbon monoxide. Different types of Raney-Ni, containing different metal components such as Fe, Mo or Cr, have different influences on the gasification yield and hydrogen selectivity. The catalysis effect can be improved obviously by adding ZnCl₂ or Ca(OH)₂. Increasing the reaction temperature or adding ZnCl₂ and Ca(OH)₂ could improve the mass of H₂ in gas products and reduce the mass of CH₄ and CO₂ at the same time. The possible mechanism is that ZnCl₂ can decompose the biomass particle by accelerating cellulose hydrolyzation in high-temperature water, increasing more specific surface to admit catalysts, while Ca(OH)₂ can absorb CO₂ to produce CaCO₃ deposit, which can drop out from the reactant system, and which will drive the reaction to get more hydrogen. With respect to the biomass conversion to gas product and selectivity of H₂ at low temperature, the series of Raney-Ni has shown many advantages over other catalysts; thus, this kind of catalyst has great potential to be utilized in the hydrogen industry for the gasification of biomass.     

Characterisation of oils from the fluidised bed pyrolysis of biomass with zeolite catalyst upgrading

Biomass in the form of pine wood was pyrolysed in an externally heated 7.5 cm diameter, 100 cm high fluidised bed pyrolysis reactor with nitrogen as the fluidising gas. A section of the freeboard of the reactor was packed with zeolite ZSM-5 catalyst. The pyrolysis oils before and after catalysis were collected in a series of condensers and cold traps. In addition, gases were analysed off-line by packed column gas chromatography. The compositions of the oils and gases were determined in relation to the primary fluidised bed and after catalysis at increasing catalyst bed temperatures from 400° to 550°C. The oils were analysed by a number of techniques to determine composition, including liquid chromatography, gas chromatography/mass spectrometry. Fourier transform infrared spectroscopy and size exclusion chromatography. The results showed that the oils before catalysis were highly oxygenated; after catalysis the oils were markedly reduced in oxygenated species with an increase in aromatic and polycyclic aromatic species.

The gases evolved from the fluidised bed pyrolysis of biomass were CO₂, CO, H₂, CH₄, C₂H₄, C₃H₆ and minor concentrations of other hydrocarbon gases. After catalysis the concentrations of CO₂ and CO were increased. The conversion of oxygenated compounds was mainly to H₂O at lower catalyst temperatures and CO₂ and CO at high catalyst temperatures. Detailed analysis of the oils showed that there were high concentrations of biologically active polycyclic aromatic species in the catalysed oil which increased with increasing catalyst temperature. The oxygenated compounds in the uncatalysed oil were mainly phenols and carboxylic acids. After catalysis these decreased in concentration with increasing catalyst temperature     

Fermentative biohydrogen production by a new chemoheterotrophic bacterium Citrobacter sp. Y19

A newly isolated Citrobacter sp. Y19 for CO-dependent H₂ production was studied for its capability of fermentative H₂ production in batch cultivation. When glucose was used as carbon source, the pH of the culture medium significantly decreased as fermentation proceeded and H₂ production was seriously inhibited. The use of fortified phosphate at 60–180 mM alleviated this inhibition. By increasing culture temperatures (25–36°C), faster cell growth and higher initial H₂ production rates were observed but final H₂ production and yield were almost constant irrespective of temperature. Optimal specific H₂ production activity was observed at 36°C and pH 6–7. The increase of glucose concentration (1–20 g/l) in the culture medium resulted in higher H₂ production, but the yield of H₂ production (mol H₂/mol glucose) gradually decreased with increasing glucose concentration. Carbon mass balance showed that, in addition to cell mass, ethanol, acetate and CO₂ were the major fermentation products and comprised more than 70% of the carbon consumed. The maximal H₂ yield and H₂ production rate were estimated to be 2.49 molH₂/mol glucose and 32.3 mmolH₂/gcellh, respectively. The overall performance of Y19 in fermentative H₂ production is quite similar to that of most H₂-producing bacteria previously studied, especially to that of Rhodopseudomonas palustris P4, and this indicates that the attempt to find an outstanding bacterial strain for fermentative H₂ production might be very difficult if not impossible.     

Reduction of hydrogen peroxide production at anode of proton exchange membrane fuel cell under open-circuit conditions using ruthenium–carbon catalyst

This study examines the effect of hydrogen peroxide (H₂O₂) on the open-circuit voltage (OCV) of a proton exchange membrane fuel cell (PEMFC) and the reduction of H₂O₂ in the membrane using a ruthenium/carbon catalyst (Ru/C) at the anode. Each cathode and anode potential of the PEMFC in the presence of H₂O₂ is examined by constructing a half-cell using 1.0 M H₂SO₄ solution as an electrolyte and Ag/AgCl as the reference electrode. H₂O₂ is added to the H₂SO₄ solution and the half-cell potential is measured at each H₂O₂ concentration. The cathode potential is affected by the H₂O₂ concentration while the anode potential remains stable. A Ru catalyst is used to reduce the level of H₂O₂ formation through O₂ cross-over at the interface of a membrane and the anode. The Ru catalyst is known to produce less H₂O₂ through oxygen reduction at the anode of PEMFC than a Pt catalyst. A Ru/C layer is placed between the Nafion^® 112 membrane and anode catalyst layer and the cell voltage under open-circuit condition is measured. A single cell is constructed to compare the OCV of the Pt/C only anode with that of the Ru/C-layered anode. The level of hydrogen cross-over and the OCV are determined after operation at a current density of 1 A cm⁻² for 10 h and stabilization at open-circuit for 1 h to obtain an equilibrium state in the cell. Although there is an increase in the OCV of the cell with the Ru/C layer at the anode, excessive addition of Ru/C has an adverse effect on cell performance.     

Effects of ZrO2-promoter on catalytic performance of CuZnAlO catalysts for production of hydrogen by steam reforming of methanol

When ZrO₂-promoter was added to CuZnAlO catalyst, its methanol conversion H₂ yield and H₂ selectivity improved greatly during production of hydrogen by methanol steam reforming. Using COPZr-2 catalyst that expressed best catalytic performance as an example, the optimized reaction conditions were first confirmed. Then the 150 h stability test of COPZr-2 catalyst showed that the catalyst had good stability: methanol conversion and H₂ yield were kept at 88% and 83%, respectively; and outlet H₂ and CO content were >63% and 0.20–0.31%, respectively. A series of techniques, such as SEM, XRD, XPS, were used to characterize the catalysts with or without ZrO₂-promoter. SEM and XRD results show that ZrO₂-promoter can improve the dispersion of CuO and Cu crystallites. XPS results show that ZrO₂-promoter can lower Al content on the surface of catalyst in effect, and weaken the interaction between CuO and Al₂O₃ so as to avoid the generation of CuAl₂O₄ spinel-type compound.     

Fast pyrolysis of cellulose in a single pulse shock tube

A shock tube technique was employed to study the thermal decomposition of cellulose in an inert argon gas under the conditions of high temperature, high heating rate, and short reaction times. The influence of temperature and reaction times on product yields and their distribution were investigated. A clean, tar and char free gas consisting mainly of CO, CO₂, C₂H₂, C₂H₄ and CH₄ were produced throughout the course of this investigation. A mass conversion of cellulose to gas exceeding 90 wt% has been realized between the temperatures 700 and 2200°C for the reaction times examined. Carbon monoxide is the major product and attains a yield in excess of 65 wt% for temperatures above 1300°C. Global kinetic parameters for the decomposition of cellulose and its principal gas products were obtained by fitting the experimental data to a single, first order kinetic model. The energy of activation for the decomposition of cellulose was found to be 130.5 kJ/mol. The material balances made for the total mass, carbon and oxygen are good.     

Thermodynamic possibilities and constraints for pure hydrogen production by iron based chemical looping process at lower temperatures

Iron offers the possibility of transformation of a syngas or gaseous hydrocarbons into hydrogen by a cycling process of iron oxide reduction (e.g. by hydrocarbons) and release of hydrogen by steam oxidation. From the thermodynamic and chemical equilibrium point of view, the reduction of magnetite by hydrogen, CO, CH₄ and a model syngas (mixtures CO + H₂ or H₂ + CO + CO₂) and oxidation of iron by steam has been studied. Attention was concentrated not only on convenient conditions for reduction of Fe₃O₄ to iron at temperatures 400–800 K but also on the possible formation of undesired soot, Fe₃C and iron carbonate as precursors for carbon monoxide and carbon dioxide formation in the steam oxidation step. Reduction of magnetite at low temperatures requires a relatively high H₂/H₂O ratio, increasing with decreasing temperature. Reduction of iron oxide by CO is complicated by soot and Fe₃C formation. At lower temperatures and higher CO₂ concentrations in the reducing gas, the possibility of FeCO₃ formation must be taken into account. The purity of the hydrogen produced depends on the amount of soot, Fe₃C and FeCO₃ in the iron after the reduction step. Magnetite reduction is the more difficult stage in the looping process. Pressurized conditions during the reduction step will enhance formation of soot and carbon containing iron compounds.     

水蒸气气氛下生物质与聚丙烯共气化产气特性数值分析

搭建生物质与废塑料共气化动力学模型,并用实验数据对其进行验证。选用6种生物质和聚丙烯作为共气化反应物,以水蒸气为气化剂,计算气化温度在300～1000℃之间、气化压强在0.1～0.8 MPa之间、聚丙烯和松木锯末质量比例在0.5～2.5之间,以及不同生物质类型等对生物质和聚丙烯共气化产气特性的影响。结果表明：松木锯末气化中添加聚丙烯后,最高产气量和最大产气速率增加,最高产气总流量提高21.46%,最高产气速率提高4.64%,H₂和CO最高产量分别提高54.27%和79.51%;压强增加不利于提高共气化产气的H₂和CO含量,有利于提高CH₄含量;6种常见生物质和聚丙烯共气化产氢量大小顺序为：果皮>棉花秆≈玉米秸秆>杨树木屑>稻秆>条浒苔;聚丙烯掺混比率增加有利于提高H₂、CO和CH₄等组分产量。