Conversion of Methane to C2 Hydrocarbons via Cold Plasma Reaction

Direct conversion of methane to C2 hydrocarbons via cold plasma reaction with catalysts has been studied at room temperature and atmospheric pressure. Methane can be converted into C2 hydrocarbons in different selectivity depending on the form of the reactor, power of plasma, flow rate of methane, ratio of N2/CH4 and nature of the catalysts. The selectivity to C2 hydrocarbons can reach as high as 98.64%, and the conversion of methane as high as 60% and the yield of C2 hydrocarbons as high as 50% are obtained. Coking can be minimized under the conditions of: proper selection of the catalysts, appropriate high flow rate of inlet methane and suitable ratio of N2 to CH4. The catalyst surface provides active sites for radical recombination.     

Conversion of natural gas to C_2 hydrocarbons through dielectric-barrier discharge plasma catalysis

The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons i     

滑动弧电极放电等离子体作用甲烷制C2烃的工艺

采用刀片式不锈钢电极放电反应器,以Ar气为稀释气,研究了等离子体作用下甲烷转化制C2烃的工艺条件。考察了CH4流量、高频电源输入电压和电极间距等参数对甲烷转化率、C2烃选择性、收率和反应表观能耗的影响。结果表明,增加CH4流量,表观能耗随之降低;当输入电压和电极间距较小时,甲烷转化率随输入电压和电极间距的增大而增大,但输入电压和电极间距过大时,C2烃收率明显下降,积碳严重。在CH4流量14 mL/min、Ar气流量60 mL/min、高频电源输入电压22 V、电流0.44 A、电极间距4 mm的优化条件下,甲烷最高转化率为43.1%,C2烃收率、选择性和表观能耗分别为40.1%、93.2%和2.41 MJ/mol。C2烃中不饱和烃的体积分数可达95%以上。     

电场增强催化甲烷合成碳二烃催化剂影响研究

本研究提出了在常温、常压电场增强等离子体条件下甲烷直接转化合成碳二烃的洁净工艺 ,在不同的放电电压、放电功率、甲烷进料流量和不同的催化剂作用下 ,甲烷能够以不同的转化率和选择性转变为碳二烃。对影响甲烷转化率和碳二烃选择性的因素 :放电电压、放电功率、甲烷进料流量和催化剂进行了研究 ,对催化剂性能进行了比较 ,并探讨了反应机理。结果表明 ,适宜的工艺条件 :放电电压 2 0kV～ 4 0kV ;输入功率 :2 0W～ 4 0W ;合适的甲烷进料流量 :30mL/min～ 70mL/min。在该条件下 ,碳二烃的选择性可以达到 95 % ;催化剂对甲烷转化率的影响顺序为MnO2 /Al2 O3 >Ni/Al2 O3 >MoO3 /Al2 O3 >Ni/NaY >Pd/ZSM 5 >Ni/H4Mg2 Si3 O4>Ni/ZSM 5 >Co/ZSM 5 >无催化剂。     

Conversion of natural gas to C2 hydrocarbons via cold plasma technology

The plasma technology served as a tool in unconventional catalysis has been used in natural gas conversion, because the traditional catalytic methane oxidative coupling reaction must be performed at high temperature on account of the stability of methane molecule. The focus of this research is to develop a process of converting methane to C2 hydrocarbons with non-equilibrium plasma technology at room temperature and atmospheric pressure. It was found that methane conversion increased and the selectivity of C2 hydrocarbons decreased with the voltage. The optimum input voltage range was 40-80 V corresponding to high yield of C2 hydrocarbons. Methane conversion decreased and the selectivity of C2 hydrocarbons increased with the inlet flow rate of methane. The proper methane flow rate was 20-40 ml/min (corresponding residence time 10-20 s). The experimental results show that methane conversion was 47% and the selectivity of C2 hydrocarbons was 40% under the proper condition using atmospheric DBD cold plasma technology. It was found that the breakdown voltage of methane VB was determined by the type of electrode and the discharge gap width in this glow discharge reactor. The breakdown voltage of methane VB,min derived from the Paschen law equation was established.     

正压、低温脉冲微波等离子体裂解天然气直接转化 制C2烃的研究

利用脉冲微波强化、扩展丝光等离子体反应装置,在常压和正压条件下,对低温脉冲微波等离子体裂解甲烷和氢气混合气制C2烃的反应进行了研究。考察了压力、微波功率、脉冲通/断时间以及氢气/甲烷比例、流量等参数对反应的影响。结果表明,在脉冲微波的作用下,常规高压放电形成的在空间呈非连续分布的丝状等离子体被强化和扩展成为连续分布的伞状等离子体,等离子体利用率和活性均得以大幅度提高;利用这种低温等离子体可以获得高的甲烷转化率,而且产物纯净,只有乙烯和乙炔;通过改变压力,还可能调节产物中C2H2/C2H4的物质的量比值,当气体总流量为300mL/min、物质的量比n(H2)/n(CH4)=2:1、压力为0.13MPa、微波峰值功率为120W、脉冲通/断比=400/400ms时,甲烷转化率可达59.2%,C2烃单程收率可达52%,其中乙炔单程收率达42.7%。     

用无声放电转化甲烷和二氧化碳同时制备合成气与烃

在低温常压条件下,研究了在无声放电反应器中以A型分子筛为催化剂从甲烷和二氧化碳合成烃和合成气,实现了在无声放电反应器中同时合成烃和合成气。实验在原料气流量200－600ml/min、原料气甲烷和二氧化碳摩尔比1／1－3／1及输入功率100－500W的范围内进行。研究结果表明,低原料气流量有利于甲烷和二氧化碳的转化,而高原料气流量有利于烃的生成;原料气甲烷和二氧化碳摩尔比对制得合成气的H2／CO摩尔比的影响最显著;甲烷和二氧化碳转化率及合成气和烃的产率均随输入功率的增加而提高。而所研究的范围内,当原料气流理为200ml/min、甲烷和二氧化碳摩尔比为1／1、输入功率为500S时,甲烷和二氧化碳转化率达到最高值,分别为64％和39％。以此法制备的合成气的H2／CO摩尔可以在很宽的范围内变化,本研究合成气H2／CO摩尔比的变化范围是0.7-3.1。     

脉冲电晕放电下的甲烷氧化偶联反应(英文)

研究了在常温,常压及惰性气体稀释的条件下,用脉冲电晕放电进行的甲烷氧化偶联（OCM）反应。在各种实验条件下,产物CZ烃由一6o／o乙烯,－70rk乙烷和一87％乙炔组成。甲烷的转化率及CZ烃的生成速率依赖于反应气中甲烷与氧气的比值,它们的流速及直流电源的电压等n通过调节这些实验条件,甲烷转化为C4烃的转化率可得到优化,在45kV高压,30ml。／min的流速下（反应气体组成为95％CHn与50／0O2）,CZ烃的最高选择性可达85O／O。当反应气体组成为80％CH4和20O／oOZ时,甲烷的最高转化率达23％。在间歇式反应器中,甲烷转化率随反应时间增长而提高,反应75分钟时甲烷转化率达7lO／O,而CZ烃的产物分布,尤其是乙炔的含量随反应时间增长而明显降低,这些实验结果支持了文献中提出的ZCH4～CZH6—CZH4～CZHZ～CO／COZ反应历程。     

Oxidative Coupling of Methane over Na-W-Mn/SiO2 Catalysts at Elevated Pressures

Na-Mn-W/SiO2 catalysts were studied for the oxidative coupling of methane (OCM) in a micro fixed bed reactor made of stainless steel reactor at elevated pressures. The effect of operating conditions, such as GHSV, pressure, temperature and CH4/O2 ratio on the catalytic performance of OCM was investigated. The C2+ selectivity of 80.3% was obtained at a CH4 conversion of 16.1% at 750℃,1.5× 105h-1 GHSV, and 0.6 MPa. Also, there is a small output of C3 and C4 hydrocarbons in the tail gas. The results show that unfavorable effects due to elevated pressure can be overcome by increasing GHSV, and the OCM reaction is strongly dependent on the operating conditions at elevated pressures,particularly GHSV and the CH4/O2 ratio.     

Conversion of natural gas to C_2 hydrocarbons via cold plasma technology

The plasma technology served as a tool in unconventional catalysis has been used in natural gas conversion,because the traditional catalytic methane oxidative coupling reaction must be performed at high temperature on account of the stability of methane molecule.The focus of this research is to develop a process of converting methane to C2 hydrocarbons with non-equilibrium plasma technology at room temperature and atmospheric pressure.It was found that methane conversion increased and the selectivity of C2 hydrocarbons decreased with the voltage.The optimum input voltage range was 40-80 V corresponding to high yield of C2 hydrocarbons.Methane conversion decreased and the selectivity of C2 hydrocarbons increased with the inlet flow rate of methane.The proper methane flow rate was 20-40 ml/min (corresponding residence time 10-20 s).The experimental results show that methane conversion was 47% and the selectivity of C2 hydrocarbons was 40% under the proper condition using atmospheric DBD cold plasma technology.It was found that the breakdown voltage of methane VB was determined by the type of electrode and the discharge gap width in this glow discharge reactor.The breakdown voltage of methane VB,min derived from the Paschen law equation was established.     

大气压旋转螺旋状电极辉光放电等离子体催化甲烷偶联

采用新研制的具有旋转螺旋状电极的大气压辉光放电等离子体反应器催化甲烷偶联制碳二烃. 实验采用铜电极和不锈钢电极分别考察了输入电场峰值电压和甲烷、氢气进料流量等参数对甲烷转化率和碳二烃收率、选择性的影响. 在长时间连续反应无明显积碳的情况下, 最佳试验结果是电极材料为金属铜, 进料流量为60 mL•min^-1, V(CH₄ )/V(H₂)=1的条件下, 输入电场峰值电压为2.3 kV时, 甲烷转化率为70.64%, 碳二烃单程收率及其选择性分别为69.85%和 99.14%.     

Oxidative coupling of methane over BaCl2-TiO2-SnO2 catalyst

The performance of BaCl2-TiO2-SnO2 composite catalysts in oxidative coupling of methane reaction has been investigated. A series of BaCl2-TiO2, BaCl2-SnO2, TiO2-SnO2, and BaCl2-TiO2-SnO2 catalysts were prepared, and characterized by BET, XRD, XPS, CO2-TPD and H2-TPR, respectively. The synergistic effect among BaCl2, SnO2 and TiO2 compositions enhances the catalytic performance. The best C2 selectivity and ethylene yield are obtained on the catalyst with the equal molar amount of the three compositions (BaCl2 : TiO2 : SnO2 molar ratio of 1 : 1 : 1). The optimal reaction conditions are as follows: 800°C, 44 mL·min-1 for methane, 22 mL·min-1 for oxygen and a space velocity of 5000 mL·h-1 g-1, and the C2H4 yield over the catalyst is 20.1% with the CH4 conversion of 43.8% and C2 selectivity of 53.3%.     

常压辉光放电等离子体转化CH4制C2烃的研究

采用新型的旋转电极辉光放电反应器, 在常温常压下对辉光等离子体作用下的甲烷转化制C₂烃进行了研究. 在氢气共存条件下, 考察了反应器电极的结构、材料, 输入电场峰值电压和反应物流率等参数对甲烷转化率和C₂烃单程收率及其选择性的影响规律, 同时比较了不同反应器的能量效率. 结果表明: 在本实验条件下, 金属铜材料好于不锈钢, 螺旋形结构优于三排圆盘结构. CH₄转化率和C₂烃选择性和收率均随输入电场峰值电压的升高而增大, 随反应物流量的增加而减小. 从CH₄转化率、C₂烃的收率和选择性的指标来评价这些反应器, 采用旋转螺旋状铜电极反应器时最好, 当反应物流量为60 mL/min时, 甲烷最高转化率为77.31%, 对应的C₂烃收率和选择性分别为75.66%和97.88%; 当能量密度为800 kJ/mol时, 能效最高为13.5%.     

脉冲电晕等离子体作用下甲烷偶联反应的研究 Ⅱ.反应添加气的影响

脱氢偶联;脉冲电晕等离子体作用下甲烷偶联反应的研究 Ⅱ.反应添加气的影响     

Scale up and stability test for oxidative coupling of methane over Na2WO4-Mn/SiO2 catalyst in a 200 ml fixed-bed reactor

The study of scale up for the oxidative coupling of methane （OCM） has been carried out in a 200 ml stainless steel fixed-bed reactor over a 5wt% Na2WO4-1.9wt% Mn/SiO2 （W-Mn/SiO2） catalyst. The effects of reaction conditions were investigated in detail. The results showed that, with increasing reaction temperature, the gas-phase reaction was enhanced and a significant amount of methane was converted into COx; with the CH4/O2 molar ratio of 5, the highest C2 （ethylene and ethane） yield of 25% was achieved; the presence of steam （as diluent） had a positive effect on the C2 selectivity and yield. Under lower methane gaseous hourly space velocity （GHSV）, higher selectivity and yield of C2 were obtained as the result of the decrease of released heat energy. In 100 h reaction time, the C2 selectivity of 66%-61% and C2 yield of 24.2%-25.4% were achieved by a single pass without any significant loss in catalytic performance.     

低温甲烷氧化偶联Li- ZnO/La2O3催化剂

采用浸渍法制备了Li- ZnO/La2O3催化剂并考察了其低温催化甲烷氧化偶联反应性能. 反应条件下, 在考察的w(Li)=2%和w(ZnO)=20%的Li- ZnO/La2O3在680 ℃得到了甲烷转化率为27.3%, C2选择性为65.2%, C2收率为17.8%的结果；在700 ℃, C2收率达到21.8%. Raman和XPS表征结果表明, 催化剂低温催化性能与表面的活性吸附氧物种含量相关；La2O2CO3物种可能是提高催化剂的C2选择性的关键.     

STUDY OF THE CATALYTIC TECHNOLOGY IN THE OXIDATIVE COUPLING OF METHANE

The temperature of the catalyst bed in the oxidative coupling ofmethane would rise and be higher than the wall temperature when the amountof catalyst, the space velocity and the ratio of oxygen to methane wereincreased. Various aspects of the catalytic technology including the thickness ofthe catalyst bed, the mode of catalyst charge, the ratio of CH_4 to O_2 and thespece velocity were studied. An optimum temperature of the catalyst bed forhigher methane conversion and C_2 selectivity was investigated. It was foundthat the burning of methane in the gas phase to form CO occurred at certaintemperatures with some ratios of oxygen to methane. Additionally, the effectof adding water to the reaction feed gas was studied.     

Na-W-Mn/SiO2催化剂表面甲烷脉冲反应Ⅱ. 多组分Na、 W、 Mn/SiO2催化剂

制备了多组分Na,W,Mn/SiO2催化剂，在ITD（Ion Trap Detector)装置上进行了催化剂表面晶格氧脱附前后的甲烷恒温脉冲反应（CH4－CTPR）。研究结果表明，Na-W/SiO2催化剂表面晶格氧，具有较高的CH4转化率和C2烃选择性，并对C2H6的生成起着重要的作用，Na-Mn/SiO2催化剂表面晶格氧，也具有较高的CH4转化率和C2烃选择性，但对C2H6的形成有一定的诱导期；W－Mn/SiO2催化剂表面晶格氧，对CH4的转化和CO2的生成具有很高初活性，但对C2烃的选择性较低；Na-W-Mn/SiO2催化剂表面晶格氧，具有很高的CH4转化率和C2烃定向选择性，这是由于Na,W,Mn各组分协同作用的结果。     

Co-Generation of C2 Hydrocarbons and Synthesis Gases from Methane and Carbon Dioxide： a Thermodynamic Analysis

This paper deals with thermodynamic chemical equilibrium analysis using the method of direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4 feed ratio, reaction temperature, and system pressure on equilibrium composition, conversion, selectivity and yield were studied. In addition, carbon and no carbon formation regions were also considered at various reaction temperatures and CO2/CH4 feed ratios in the reaction system at equilibrium. It was found that the reaction temperature above 1100 K and CO2/CH4 ratio=1 were favourable for synthesis gas production with H2/CO ratio unity, while carbon dioxide oxidative coupling of methane （CO2 OCM） reaction to produce ethane and ethylene is less favourable thermodynamically. Numerical results indicated that the no carbon formation region was at temperatures above 1000 K and CO2/CH4 ratio larger than 1.     

Ni/ZrO2催化剂上甲烷水蒸气重整反应的研究

研究了Ni/ZrO2催化剂对甲烷水蒸气重整制合成气的反应性能。考察了催化剂的还原温度、载体焙烧温度以及反应温度、原料配比和空速等对催化剂性能的影响。利用XRD、TEM、XPS等手段对催化剂的织构形貌进行了表征。研究表明，Ni/ZrO2催化剂用于甲烷水蒸气重整制合成气不仅具有较高的活性，也具有较好的稳定性。水蒸气比增加，CH4转化率增大、CO选择性下降。CH4转化率及CO选择性均随空速增大而下降。使用10%Ni/ZrO2催化剂，在650 ℃、空速1.984×104 h－1、原料气配比H2O∶CH4∶N2=2∶1∶2.67的条件下，获得CH4转化率85%、CO选择性70%的结果。