非热等离子体烟气脱硫湿式反应的动力学机制

由于非热等离子体烟气脱硫干式反应器中的主要过程是气相与固体表面液膜之间的复相反应, 采用湿式反应器应该更为合理.对流光放电湿式烟气脱硫的动力学机制进行了分析,导出了烟气脱硫率、能量效率和摩尔能耗与放电注入能量密度、传质效率因子和吸收液pH值的关系.发现在放电注入能量一定的条件下,设法提高传质效率因子和适当调节pH值,能量效率可以显著提高,摩尔能耗可以大幅度降低.所得结果与过去已有实验结果吻合,并表明有可能把该反应的能耗降到工业接受的水平.     

低温等离子体辅助去除含碳固态混合物

柴油发动机尾气中存在大量颗粒物,它易被人体吸入,对人的身体健康造成极大危害。其主要成分——碳烟及可溶性有机成分（SOF）等,可通过氧化燃烧的方法除去。本文从柴油机尾气颗粒物的治理出发,介绍了传统的颗粒物后处理技术,包括颗粒捕集器结合再生、微粒催化氧化转化（DOC）、静电捕集等技术。主要介绍了近年所发展起来的低温等离子体（NTP）辅助去除含碳固态混合物（PM）技术,包括等离子体反应器中的化学反应,常见的低温等离子体反应器结构及等离子体产生的放电类型。此外,根据等离子体反应器的安装位置不同,还介绍了两种不同的等离子体PM处理方法——直接等离子体方法和间接（远程）等离子体方法,后者可避免高温对等离子体过程的不利影响。总结了等离子体技术的应用特点,提出对等离子体辅助PM去除过程的研究可着眼等离子体技术本身,研究各种对气体放电产生影响的因素,为等离子体反应器的开发和应用提供参考。     

用等离子体处理和聚合法提高帘布-橡胶粘合强度

研究了用等离子体处理进行的几种不同类型的PET帘线的改性。聚酯帘线经过等离子体反应器中产生的脉冲表面正电晕放电或经过大气压下共面介电势垒放电处理，帘线与橡胶基质的粘合强度、机械性能和表面特性均发生明显的变化。表面放电是以帘线由氮脉冲等离子体激活为基础，随后用马来酸（MA）溶液接枝，以提高帘线与橡胶的粘合强度。研究了溶液中的MA浓度、帘线移动速度和接枝时间等3个参数。用氮与丁二烯的混合物对帘线进行等离子体聚合改性，通过脉冲表面正电晕放电可以在正常大气压下产生均匀等离子体层。结果显示，等离子体处理的帘线的静、动态粘合强度值可与用RFL标准化学处理的帘线媲美。等离子体处理对机械性能无任何影响。还研究了等离子体改性聚酯帘线的形态变化。     

储存-放电等离子体矿化吸附态萘

针对工业烟气中低浓度有机物难以去除，提出采用高吸附能力β分子筛为吸附剂，展开吸附储存和低温等离子体放电原位矿化处理含萘模拟气体。双极性脉冲电源用来驱动介质阻挡放电装置产生等离子体，探究气体流量、功率、温度和储存时间对萘矿化程度的影响。结果表明：气体体积流量为0.25 L·min^-1时，放电时间更短；高功率、低温度可增加萘的矿化速率；储存量对碳平衡影响显著，最高可达97.65%。该过程具有反应器体积小、萘矿化率高、臭氧残余量低的优点。     

低温等离子体催化技术推广方面的难点问题

低温等离子体催化技术是近年来兴起的一种治理废气的可行方法,与传统方法和工艺相比,具有投资和运行费用较低、处理效率较高、处理时间较短和易于控制等优点。研究表明,利用等离子体技术处理大气污染的应用前景广阔。但低温等离子体技术反应器的选择、匹配和优化、相关催化剂的选择以及与反应器的结合、反应机理等方面还需要进一步深入研究。低温等离子体效率低、能耗高、目标产物选择性低,但加入催化剂可降低能耗,减少二次污染,提高产物选择性,两者取长补短,优势互补。不断改进反应器并提高反应器的能量效率,提升催化剂的稳定性和契合度以及对反应机理的深入研究是今后的发展方向。     

液下辉光放电等离子体重整低碳醇水溶液制氢

探讨了阴极液下辉光放电等离子体重整低碳醇水溶液制氢反应过程.比较了水溶液和低碳醇水混合溶液中阴极等离子体重整制氢实验,发现以低碳醇水溶液为等离子体重整介质时,低碳醇分子在阴极等离子体层中表现出明显高于水分子的反应活性,阴极气体单位体积能耗可以降至2.690×10³ kJ•m^-3,生成气体中氢气含量达95％,并有一氧化碳和二氧化碳.分析了电压对阴极生成气单位体积能耗和气体组成的影响,发现电压越高等离子体密度越大,阴极生成气单位体积能耗降低,被等离子体分解的溶剂溶质分子也越多.比较了不同浓度低碳醇溶液的产气情况,低碳醇浓度对生成气组成和单位体积能耗有重要影响.     

非热等离子体催化转化C1分子及其催化剂研究进展

非热等离子体催化具有反应条件温和、启动快和反应器结构紧凑等特点,在C₁分子催化转化领域（如CO₂加氢、甲烷活化、水煤气变换反应和甲醇重整制氢）有着广阔的应用前景。具体来说,等离子体特有的高能电子可在气相中快速活化稳定性极强的C₁分子并生成活性物质,接着与催化剂结合发生表面化学反应,从而实现常温常压下C₁分子的高效转化。然而,等离子体与催化剂之间的协同作用机制以及催化机理极为复杂,仍有待进一步研究。本综述简单介绍了非热等离子体催化转化C₁分子的近期研究进展,重点探讨了适用于非热等离子 体的催化剂研究以及催化机理的高级原位表征。最后,提出了非热等离子体催化转化C₁分子的未来发展方向：①设计并构筑适用于非热等离子体催化的高效催化剂,并研究其构效关系;②发展高级原位表征技术,揭示活性物质的作用机理以及催化机理;③设计并构建高效的等离子体催化反应器,并建立反应器的理论模型和数值模拟方法,科学指导等离子体反应器的设计、优化和放大。     

液体碳氢燃料蒸汽重整制氢催化剂研究进展

液体碳氢燃料具有能量密度高、氢含量大及便于储存和运输的特点,以其为原料经重整制氢并应用到移动式的燃料电池/加氢站对民用设备及国防武器等具有现实意义。本文首先对液体碳氢燃料蒸汽重整机理进行概述,明确当前催化剂面临的积炭、硫中毒等主要问题,从而指导高性能催化剂的设计和开发;其次,总结了几种典型液体碳氢燃料（汽油、煤油、柴油、焦油、含硫碳氢燃料等）蒸汽重整催化剂的相关进展,对比了不同催化剂在相应工艺条件下的活性及稳定性;最后,归纳了几类蒸汽重整过程强化技术包括等离子体重整、化学链重整、吸附增强重整及反应与分离耦合重整,说明了各类强化技术的优点及存在的不足,提出通过构建高效催化剂与蒸汽重整强化技术耦合有望实现液体碳氢燃料的高效转化制氢。希望本综述能为进一步研究液体碳氢燃料重整制氢提供相关指导。     

热等离子体裂解煤制乙炔下行反应器的研究进展

从反应器的工艺开发角度探讨了热等离子体裂解煤制乙炔下行反应器的研发进程,分析了热等离子体裂解煤制乙炔的快速连串反应特点,对比了下行及上行两种不同类型反应器对能耗及乙炔收率的影响,评述了下行床传递性能的显著优点,进而从超短接触反应、高乙炔收率与流体动力学角度出发指出了热等离子体下行床的集成工艺是裂解煤制乙炔工艺的合理选择。最后提出了制约该工艺实际连续生产的严重结焦难点与解决的方法。     

大气压等离子体射流气源组分研究进展

大气压等离子体射流(APPJ)作为一个新型的大气压冷等离子体放电技术,其在大气压下产生,射流温度接近室温,化学活性高,在生物医学、材料化学和环境卫生等研究领域的应用成为研究热点。随着对大气压等离子体射流应用研究的不断深入,发现APPJ气源组分对其应用研究产生了很大的影响。APPJ气源组分会影响其放电特性、发射光谱和化学特性,其中APPJ中各种化学活性粒子在其应用研究中起到重要作用,APPJ气源成分主要影响化学活性粒子的种类与浓度,这些因素会影响APPJ技术成本和处理效率。因此,本文综述了在不同气源组分条件下大气压等离子体射流的放电特性、发射光谱和化学特性以及在微生物灭活、表面改性和表面清洁中的应用研究,分析总结了气源组分对APPJ应用方面的影响作用并展望了其研究前景。     

Hydrogen production from methanol through dielectric barrier discharge

The hydrogen fuel cell is a promising option as a future energy resource and the production of hydrogen is mainly depended on fossil fuels now. In this paper, methanol reforming to produce H₂ through dielectric-barrier discharge (DBD) plasma reaction was studied. Effects of the power supply parameters, reactor parameters and process conditions on conversion of methanol and distribution of products were investigated. The best reaction conditions were following: input power (45 W), material of inner electrode (stainless steel), discharge gap (3.40 mm), length of reaction zone (90.00 mm), dielectric thickness (1.25 mm), and methanol content (37.65%). The highest conversion of methanol and the yield of H₂ were 82.38% and 27.43%, respectively.     

化学链重整直接制氢技术进展

化学链重整直接制氢技术使用固态金属氧化物作为氧载体代替传统重整过程中所需的水蒸气或纯氧,将燃料直接转化为高纯度的合成气或者二氧化碳和水,被还原的金属氧化物则可以与水蒸气再生并直接产生氢气,实现了氢气的近零能耗原位分离,是一种绿色高效的新型制氢过程。根据产物和供热方式的不同,可以将化学链重整直接制氢工艺分为双床系统和三床系统两类,并对各系统中氧载体与反应器的设计与选择进行了分析。通过Elingham图对不同氧载体的氧化还原能力进行比较,选取适于直接制氢的金属氧化物,并讨论了氧载体材料研发的最新进展。化学链制氢反应器设计应根据不同原料和产品的特点,选择合适的气-固接触方式,以强化化学链重整直接制氢效率。     

Transient modeling of combined catalytic combustion/CH4 steam reforming

This paper presents an investigation into the complex interactions between catalytic combustion and CH₄ steam reforming in a co-flow heat exchanger where the surface combustion drives the endothermic steam reforming on opposite sides of separating plates in alternating channel flows. To this end, a simplified transient model was established to assess the stability of a system combining H₂ or CH₄ combustion over a supported Pd catalyst and CH₄ steam reforming over a supported Rh catalyst. The model uses previously reported detailed surface chemistry mechanisms, and results compared favorably with experiments using a flat-plate reactor with simultaneous H₂ combustion over a γ-Al₂O₃-supported Pd catalyst and CH₄ steam reforming over a γ-Al₂O₃-supported Rh catalyst. Results indicate that stable reactor operation is achievable at relatively low inlet temperatures (400 °C) with H₂ combustion. Model results for a reactor with CH₄ combustion indicated that stable reactor operation with reforming fuel conversion to H₂ requires higher inlet temperatures. The results indicate that slow transient decay of conversion, on the order of minutes, can arise due to loss of combustion activity from high-temperature reduction of the Pd catalyst near the reactor entrance. However, model results also show that under preferred conditions, the endothermic reforming can be sustained with adequate conversion to maintain combustion catalyst temperatures within the range where activity is high. A parametric study of combustion inlet stoichiometry, temperature, and velocity reveals that higher combustion fuel/air ratios are preferred with lower inlet temperatures (≤500 °C) while lower fuel/air ratios are necessary at higher inlet temperatures (600 °C).     

A Study of Ozone Synthesis in Coaxial Cylinder Pulse Streamer Corona Discharge Reactors

Synthesis of ozone in coaxial cylinder non-thermal plasma reactors with different structures was investigated in this paper. With digital measuring technology, the absorption energy of non-thermal plasma reactors induced by pulse streamer corona was estimated. In the view of energy absorption of non-thermal plasma reactors, pulse input energy depended on reactor structures, as well as pulse parameters, such as pulse amplitude and DC bias. With coaxial cylinder reactors energized by pulse voltage, the influences on ozone generation of pulse voltage polarity, pulse amplitude, and pulse repetition rate were studied. It was found that positive pulse voltage induced higher ozone generation than negative pulse voltage and higher amplitude pulses generated more ozone. Increasing the pulse repetition rate at a low level increased ozone generation to some extent, but then leveled off with further increasing. A critical repetition rate was found at which the ozone synthesis was the most efficient. Lower pulse amplitude was associated with higher critical repetition rate. Superimposing DC bias on pulse voltage was an effective method to enhance ozone generation. Besides, discharge modes and electrode structures of reactors affect ozone generation. A mixed discharge mode of volume and surface discharges was the most effective mode to generate ozone in all of the experimental discharge modes, namely volume, surface, volume and surface mixed discharge modes. Moreover, helix-cylinder reactors were better than wire-to-cylinder reactors in generating ozone.     

ALTERNATIVE GENERATION OF H2, CO AND H2, CO2 MIXTURES FROM STEAM-CARBON DIOXIDE REFORMING OF METHANE AND THE WATER GAS SHIFT WITH PERMEABLE (MEMBRANE) REACTORS

A new process is proposed which converts CO₂ and CH₄ containing gas streams to synthesis gas, a mixture of CO and H₂ via the catalytic reaction scheme of steam-carbon dioxide reforming of methane or the respective one of only carbon dioxide reforming of methane, in permeable (membrane) reactors. The membrane reformer (permreactor) can be made by reactive or inert materials such as metal alloys, microporous ceramics, glasses and composites which all are hydrogen permselective. The rejected CO reacts with steam and converted catalytically to CO₂ and H₂ via the water gas shift in a consecutive permreactor made by similar to the reformer materials and alternatively by high glass transition temperature polymers. Both permreactors can recover H₂ in permeate by using metal membranes, and H₂ rich mixtures by using ceramic, glass and composite type permselective membranes. H₂ and CO₂ can be recovered simultaneously in water gas shift step after steam condensation by using organic polymer membranes. Product yields are increased through permreactor equilibrium shift and reaction separation process integration.

CO and H₂ can be combined in first step to be used for chemical synthesis or as fuel in power generation cycles. Mixtures of CO₂ and H₂ in second step can be used for synthesis as well (e.g., alternative methanol synthesis) and as direct feed in molten carbonate fuel cells. Pure H₂ from the above processes can be used also for synthesis or as fuel in power systems and fuel cells. The overall process can be considered environmentally benign because it offers an in-situ abatement of the greenhouse CO₂ and CH₄ gases and related hydrocarbon-CO₂ feedstocks (e.g., coal, landfill, natural, flue gases), through chemical reactions, to the upgraded calorific value synthesis gas and H₂, H₂ mixture products.     

小型碳基燃料水蒸气重整制氢装置研究

设计并加工了一种小型碳基燃料水蒸气重整制氢装置,该装置为不锈钢材料,采用集成式结构设计,使得加热、气化、重整、分散等多功能部件有机地结合在一起,大大减小了装置的设计尺寸,减小了装置占有空间,降低了装置成本,实现了小型、微型化的目的,便于移动、便携式制氢装置的推广。该反应器装载花状微球Ni/CeO₂催化剂,在重整性能测试中甲烷流量为1250mL/min时,水碳比H₂O/CH₄=2：1,560℃反应温度下,该反应器表现出了良好的重整制氢性能,重整气中氢气的组成达到70%以上,甲烷的含量降至16%以下,用于高温燃料电池发电的功率计算,满足500W功率设计要求,达到550W以上。实验表明这种重整制氢装置可用于高温燃料电池供氢系统。     

Performance of CO preferential oxidation reactor with noble-metal catalyst coated on ceramic monolith for on-board fuel processing applications

On-board fuel processors are being developed to provide hydrogen-rich gas to the polymer electrolyte fuel cell automotive propulsion systems. Whereas the anode catalyst in the fuel cell has low tolerance for carbon monoxide, 10–100 ppm, reforming of gasoline and other hydrocarbon fuels generally produces 1–2% of CO. Of the many methods of removing CO from the reformer gas, preferential oxidation (PrOx) of CO over noble-metal catalysts is practiced most frequently. In this paper, we present experimental data for CO conversion on a Pt-based catalyst that is active at room temperature and was coated on a ceramic monolith. The data is used to develop an empirical correlation for selectivity for CO oxidation as a function of CO concentration and oxygen stoichiometry at 30,000–80,000/h space velocity. The selectivity correlation is used in a model to analyze the performance of multi-stage, adiabatic PrOx reactors with heat exchange between the stages to cool the reformate to 100 °C. An optimization algorithm is used to determine the operating conditions that can reduce CO concentration to 10 ppm while minimizing parasitic loss of H₂ in the reformate stream. It is found that the 10 ppm constraint limits the maximum inlet CO concentration to 1.05% in a single-stage reactor and to 3.1% in a two-stage reactor. The results clearly show the incremental reduction in parasitic H₂ loss by addition of second and third stages.     

Syngas production from methane reforming with CO2/H2O and O2 over NiO–MgO solid solution catalyst in fluidized bed reactors

Catalyst performance of NiO–MgO solid solution catalysts for methane reforming with CO₂ and H₂O in the presence of oxygen using fluidized and fixed bed reactors under atmospheric and pressurized conditions was investigated. Especially, methane and CO₂ conversion in the fluidized bed reactor in methane reforming with CO₂ and O₂ was higher than those in the fixed bed reactor over Ni_0.15Mg_0.85O catalyst under 1.0 MPa. In contrast, conversion levels in the fluidized and fixed bed reactor were almost the same over MgO-supported Ni and Pt catalysts. It is suggested that the promoting effect of catalyst fluidization on the activity is related to the catalyst reducibility. On a catalyst with suitable reducibility, the oxidized and deactivated catalyst can be reduced with the produced syngas and the reforming activity regenerates in the fluidized bed reactor during the catalyst fluidization. In addition, the catalyst fluidization inhibited the carbon deposition.     

Plasmacatalytic processes for environmental problems

The application of non-thermal electrical discharges instead of thermal energy has been shown to be a suitable alternative for the treatment of exhaust gases, especially for low concentrations (<100 ppmv) of contaminants. In the present paper, we describe the synergetic application of plasma and catalytic treatment for the oxidative removal of volatile organic compounds (VOCs) and the low-temperature conversion of NO_x to N₂ in excess oxygen.

The catalytic oxidation of butyl acetate and dichloroethene (DCE) as typical VOC has been studied at 50–200°C in combination with pulse corona or dielectric barrier discharges (DBDs). The best results with a significant synergetic effect were obtained with mixed transition metal oxide catalysts, which are able to decompose the ozone at low (<120°C) temperature. With respect to treatment by the plasma alone, the combination shifts the process towards total oxidation. The amount of reaction by-products such as formyl chloride (in case of chlorocarbons), CO, nitric oxides and ozone is lowered. The synergetic effect has been verified at technical conditions in the plasmacatalytic removal of VOC from stripper air in a groundwater cleaning plant.

The NH₃-SCR of NO_x in excess oxygen using a NH₄-loaded zeolite at 100°C can be significantly accelerated if combined with a plasma discharge. The mechanism of the reaction has been verified by labeling NO with ¹⁵NO and by a double-labeled experiment using ¹⁵NO and ¹⁵NH₄-zeolite. Experiments with a diesel engine have shown that the plasmacatalytic conversion of NO_x to N₂ is also effective at real technical conditions.     

Experimental and numerical study of applicability of porous combustors for HCl synthesis

Porous combustors have been studied intensively concerning the combustion of natural gas. The advantages of combustion in porous inert media, such as low emissions, high power turndown ratio of typically 10:1 and compactness, can also be used for different chemical gas phase reactions, e.g. the HCl synthesis from H₂ and Cl₂. The advantages of porous reactors result from the heat transport properties of the porous medium, i.e. emissivity and conductivity. Heat transport mechanisms and chemical reactions were implemented in a numerical code in order to investigate the H₂/Cl₂ system. Important parameters of the reaction, e.g. the laminar flame speed and the adiabatic flame temperature, are higher for the H₂/Cl₂ reaction compared to the CH₄/air combustion. By studying the influence of H₂O and HCl as inert components it was shown by numerical investigations that the maximum temperature could be decreased to a level, which makes the usage of a porous reactor feasible. A porous reactor for laboratory use was tested with O₂/CH₄/N₂ combustion, which delivers even higher adiabatic temperatures and flame speeds than the H₂/Cl₂ reaction. Finally, experiments with H₂/Cl₂/HCl reaction were carried out and first results are presented.