铜渣耦合木屑制备可燃气的热力学分析

从生物质的热解原理出发,以木屑为原料,使用热重分析方法研究了木屑的热解特性,并基于能量平衡对热态铜渣耦合生物质余热利用系统进行热力学分析。根据实验结果,木屑在热解终温分别为400、500、600、700、800℃时热解需热量分别为335、373、430、513、643 k J/kg。随着热解温度的升高,铜渣余热利用率逐渐增加,在800℃的热解温度下,铜渣余热利用率达86.78%。1 250℃的铜渣冷却至常温余热量达1 574.26 k J/kg,在热态铜渣耦合木屑反应体系中,气化1 kg的木屑只需1.92 kg的铜渣,系统的热损失为37.07%,能量转化率达69.46%,可产生热值为13 319 k J的可燃气。针对铜渣富含碱金属并含有大量余热的特点,铜渣耦合生物质制备可燃气具有很大的工业应用前景。     

反应吸附强化模拟沼气蒸汽重整制氢的计算和实验研究

文章对反应吸附强化模拟沼气-水蒸气重整制氢技术(Re SER-Biogas)进行了热力学计算和实验研究。首先,建立甲烷蒸汽重整反应耦合氧化钙与二氧化碳反应的制氢反应模型,对CO2和CH4体积比(α)分别为0.25,0.43和0.67的模拟沼气进行改变CO2移除率(ζ)、反应温度(T)、水碳摩尔比(β)对甲烷转化率和氢气浓度影响规律的模拟计算。计算结果表明,提高ζ,T和β值能有效强化重整反应,当P=0.1 MPa,ζ=0.95,T=600℃,β=4时,甲烷转化率可达94%,产物中氢气的浓度可达96%。其次,采用镍系催化剂与纳米Ca O基CO2吸附剂,在固定床反应器中进行模拟沼气Re SER-Biogas制氢实验,改变T,β以及α值得到不同反应条件下的甲烷转化率与产品氢气浓度,从实验层面上验证模拟计算结果和反应条件影响规律的可靠性。实验结果表明,在P=0.1 MPa,ζ=0.95,T=600℃,β=4和α=0.43的实验条件下,产物中氢气的浓度高达93%,CO的浓度低至0.32%。和传统无吸附强化的沼气蒸汽重整制氢工艺相比,Re SER-Biogas技术能够在更低的温度条件下直接制取低CO浓度的高纯氢气产品,对开发高效,节能的沼气制氢新技术具有重要的实际意义。     

低浓度甲烷稀土催化燃烧实验研究

制备了碳化硅蜂窝陶瓷载体稀土催化剂,对甲烷进行稀土催化燃烧实验研究。实验测量了催化燃烧温度和尾气组分,并对催化燃烧反应的甲烷转化率进行计算和分析。实验结果表明：在200～400℃甲烷转化率在92％左右,在500～800℃甲烷转化率达到99％以上,而且尾气中的CO,NOx和HC含量非常低。     

甲烷三重整制合成气热力学分析

甲烷三重整反应(TRM,Tri-reforming of methane)具有过程能效高、合成气H2/CO适宜和较低催化剂积炭的优点。采用平衡常数法对TRM反应制合成气进行了热力学分析,研究了反应温度、压力及反应原料进气组分对重整特性的影响。结果表明:温度在1073K以上时TRM反应表现出很好的效果,温度升高有利于转化率的提高;但是压力的升高不利于反应正向进行。氧气含量增加,将使甲烷和二氧化碳转化率分别升至95%以上和降至10%以下,但是H2/CO值维持在1.5附近;水蒸气和二氧化碳含量增加,甲烷转化率升高,二氧化碳转化率降低,而且H2/CO值在1.4～2.1之间变化,前者使之升高,后者使之降低。     

甲烷快速部分氧化重整试验研究

采用常规浸渍法制备了Rh/α-Al2O3催化剂,建立了甲烷快速部分氧化重整试验体系。通过控制变量法,考察了甲烷快速部分氧化重整反应中反应条件参数(CH4/O2、反应气体预混合温度、空速)变化对反应物的转化率、反应产物及分布的影响。试验结果表明,在试验条件下,CH4的转化率始终大于85%,O2转化率接近100%,CO的选择性为85%左右,H2的选择性为40%～60%。反应过程大致为催化剂入口处的部分氧化反应和下游的水蒸气重整,大部分的CO由部分氧化产生,而H2的产生受水蒸气重整反应的影响较大;随着反应温度的上升,CH4的转化率上升,CO,H2的选择性也上升;随着空速的增大,H2的选择性减小,表明甲烷催化部分氧化反应是一个受传质控制的反应。     

介质阻挡放电辅助甲烷蒸汽重整的实验研究

利用介质阻挡放电辅助甲烷蒸汽重整试验平台进行了大量试验,基于试验数据系统地分析了350-500℃温度下蒸汽甲烷摩尔比(S/C)、反应物驻留时间、壁面温度及输入功率等对甲烷转化率、有效碳回收率及产物选择性等指标的影响规律,并考察了不同影响因素之间的相互作用关系。研究发现:驻留时间对各指标的影响最为明显,在不同壁面温度下,随着驻留时间的增加,产物选择性出现转折性变化,由60%左右下降到20%左右;与驻留时间的影响不同,随着输入功率或S/C的增加,重整特性的各评价指标均呈现缓慢增长趋势;而温度对等离子体辅助甲烷蒸汽重整结果是否有影响与驻留时间、输入功率等参数有关,只有当驻留时间大于0.59 s时,温度对重整反应的影响变得较小,且当输入功率也大于80 W时,温度对重整反应不再有影响。     

CO_2/CH_4重整镍基碳纤维催化剂的制备与性能研究

为研制高性能的甲烷二氧化碳重整催化剂,采用静电纺丝法制备了镍基原纤维经预氧化、炭化后的原位镍基碳纤维催化剂和浸渍法制备的浸渍镍基碳纤维催化剂.通过SEM、H_2-TPR、重整反应分析了两种制备方法下催化剂结构及性能的变化,结果表明,原位镍基碳纤维催化剂较浸渍法所得催化剂保持了更好的纤维结构及金属分散性.并且,原位碳纤维的镍含量只有浸渍碳纤维的5%,,当温度大于900,℃以后,其转化率明显高于浸渍镍基碳纤维.在850,℃进行两种催化剂的寿命评价得出的结果显示,浸渍法所得镍基碳纤维催化剂在50,min内表现出失活,而原位法所得镍基碳纤维催化剂在200,min时仍然保持活性.     

滑动弧等离子体协助甲烷蒸汽重整制氢

采用甲烷为主要原料,在常温和常压条件下,利用滑动弧等离子体放电技术,进行了甲烷与空气、水蒸气重整反应的试验。试验研究了过量空气系数、反应气流量和水蒸气含量等参数对甲烷与空气、水蒸气重整反应的影响,并对重整副产物进行了分析。试验表明,当过量空气系数为0.8时,氢气选择性最高可达到45.9%;反应气流量达到14L/min时,单位氢气生产成本最低;在反应气中加入一定量的水蒸气,有利于重整反应的进行。     

基于甲烷催化部分氧化的SOFC性能研究

基于固体氧化物燃料电池的热电联供系统可以实现能源的梯级利用,实现较高的效率,降低污染排放,具有很好的发展前景.针对该系统中传统重整器存在的高能耗等问题,对新型重整方式催化部分氧化进行了研究.本文首先研究了催化剂为0.5%Rh/Al2O3,以甲烷为燃料时CPOX的性能变化规律.通过调节控制温度、体积空速和入口气C/O比,研究了不同工况下CH4转化率、H2选择性、CO选择性和甲烷重整效率的变化规律,对工况进行优化.在优化工况下,即温度800℃、体积空速200 min-1、C/O摩尔比为1.0时,实现了催化部分氧化与微管式固体氧化燃料电池四管电堆的直接耦合,并对电池性能进行测试,结果表明,最大功率可达到纯氢燃料的87.8%.     

煤制天然气过程催化甲烷化的数值模拟

两步法煤制天然气的第一步反应主要生产粗煤气CO和 H2,调整CO与 H2的比值后进行甲烷化反应。在计算软件HSC中分别控制反应温度、压力和CO与H2比例,计算了甲烷化产物变化规律,得到第二步甲烷化反应最适条件是1．8 M Pa、700℃;通过在计算软件FL U EN T 中进行一步对催化甲烷化反应的模拟,0．1 M Pa、720℃时的催化甲烷化即可达到无催化高压条件的甲烷摩尔产率,甲烷化产率最高时对应的n（H2）∶ n（C O ）比值为1．8。     

Energy absorption characteristics and kinetics of carbonaceous solid waste gasification with copper slag as heat carrier

High energy consumption is the bottleneck for gasification technology of carbonaceous waste. Exactly, copper slag has such cheap and huge energy that can be used. Copper slag waste heat can provide energy and metallic oxide in copper slag has catalytic effect on carbonaceous solid waste gasification reaction. The gasification energy absorption characteristics and kinetics of typical solid waste, sludge, enteromorpha and lignite with air as oxidation agent has been studied using copper slag as heat carrier. Gasification reaction of waste is scored as multi-stage reactions. For sludge and enteromorpha gasification reactions, there are two and three reaction stages respectively. Gasification reaction rate becomes unstable when copper slag added. The addition of copper slag has little effect on the peak value and peak temperature. Pyrolysis reaction rate of heat absorption is controlled by material diffusion. At medium and high temperature, the limitation of gasification endothermic reaction of sludge and enteromorpha is chemical reaction rate. When copper slag added, the total energy absorption of lignite, sludge and enteromorpha are 11285.8 mw/mg, 8994.2 mw/mg and 9461.7 mw/mg respectively. Copper slag has catalytic decomposition effect on the gasification reaction at high and medium temperature, and improves the heat exchange rate.     

储运油泥热解机理研究

利用管式炉,通入氯气和二氧化碳两种不同气氛,研究储运油泥的热解特性.分析油泥的气、液、渣的不同特性,探讨两种气氛下的不同热解特点.二氧化碳气氛下油泥热解的最佳温度为450℃,而氮气气氛下为500℃2.二氧化碳气氛下的渣是致密性渣,氮气气氛下是薄壁型渣.冷凝液中的低烷烃类、单环芳烃,二氧化碳气氛下比氮气气氛下高.而气体成分中甲烷和氢气含量氮气气氛比二氧化碳下高.得出同温度下,氮气的热解程度大于二氧化碳,而且二氧化碳参与了热解反应.     

Hydrogen production from biogas using hot slag

Possibility of hydrogen production from biogas using hot slag has been studied, in which decomposition rate of _CO2${\mathrm{CO}}_2$–_CH4${\mathrm{CH}}_4$ in a packed bed of granulated slag was measured at constant flow-rate and pressure. The molten slag, discharged at high temperature over 1700 K from smelting industries such as steelmaking or municipal waste incineration. It has enough potential for replacing energy required for hydrogen production due to the catalytic steam reforming or carbon decomposition of hydrocarbon. However, heat recovery of hot slag has never been established. Therefore, the objective of this work is to generate hydrogen from methane using heated slag particles as catalyst, in which the effect of temperature on the hydrogen generation was mainly investigated at range from 973 to 1273 K. In the experiments a mixed gas of _CH4${\mathrm{CH}}_4$ and _CO2${\mathrm{CO}}_2$ was continuously introduced into the packed bed of hot slag at constant flow-rate and atmospheric pressure and then the outlet gas was monitored by gas chromatography. The results indicate that slag acted as not only thermal media but also good catalyst, for promoting decomposition. The product gases were mainly hydrogen and carbon monoxide with/without solid carbon deposition on the surface of slag, depending on the reaction temperature. Increasing temperature led to large hydrogen generation with decreasing un-reacted methane in the outlet gas, at when the largest methane conversion was about 96%. The results suggested a new energy-saving process of hydrogen production, in which the waste heat from molten slag can replace the energy required for hydrogen production, reducing carbon dioxide emission.     

镍、钌均相催化裂解生物油低聚物的试验研究

以油酸镍和三(三苯基膦)二氯化钌为催化剂对均相催化裂解生物油中的低聚物进行试验研究。结果表明:油酸镍的催化效果优于三(三苯基膦)二氯化钌。当以油酸镍为催化剂时,较佳的反应条件为:反应温度150℃、反应时间24h、催化剂与生物油低聚物质量比R催化剂/低聚物=0.034,在此条件下二氧化碳生成量为4.43mmol,粘度从4.16mm2/s下降到3.49mm2/s;催化精制后,气相质谱联用仪可检测到的酚类物质含量基本都较之前有所增加。     

Coke-resistance over Rh–Ni bimetallic catalyst for low temperature dry reforming of methane

Methane and carbon dioxide can be converted into syngas using the prospective dry reforming of methane technology. Carbon deposition is a major cause of catalyst deactivation in this reaction, especially at low temperature. The superior stability of bimetallic catalysts has made their development more and more appealing. Herein, a series of bimetallic RhNi supported on MgAl₂O₄ catalysts were synthesized and used for low temperature biogas dry reforming. The results demonstrate that the bimetallic RhNi catalyst can convert CH₄ and CO₂ by up to 43% and 52% over at low reaction temperature (600 °C). Moreover, the reaction rate of CH₄ and CO₂ of RhNi–MgAl₂O₄ remains stable during the 20 h long time stability test, most importantly, there was no obviously carbon deposition observed over the spent catalyst. The enhanced coking resistance should be attributed to the addition of a little amount of noble metal Rh can efficiently suppress dissociation of CH_X1 species into carbon, and the high surface areas of MgAl₂O₄ support can also promote the adsorption and activation of carbon dioxide to generate more O1 species. Balancing the rate of methane dissociation and carbon dioxide activation to inhibit the development of carbon deposition is a good strategy, which provides a guidance for design other high performance dry reforming of methane catalysts.     

One step methane production based on catalytic pressurized calcium looping gasification with in-situ CO2 capture and self-sustained heat supply

Catalytic steam hydrogasification of coal is a direct method for methane production. Calcium looping concept is usually used in coal gasification process for in-situ carbon dioxide removal and heat supply. In this paper, a new process combining catalytic steam hydrogasification and calcium looping was proposed and investigated using a self designed instantaneously feeding reactor under high-temperature and pressurized conditions. The effects of operation conditions (including hydrogen concentration with a range of 0–50 vol%, gasification pressure with a range of 0.1–3.5 MPa, gasification temperature with a range of 700–800 °C, and gasification-calcination cycle number up to six) on the performance of the new process have been studied. The results show that: (i) increasing H₂ concentration is beneficial to methane products; (ii) high temperature and low pressure are not conducive to methane production and carbon dioxide capture as well as the self-sustained heat supply in gasifier; (iii) the methane content and carbon conversion can be maintained at 30–40 vol% and 75–80% for the durability tests. According to the performance of gas products, 750 °C 3.5 MPa and Ca/C = 0.5 are suggested for the new process. In addition, the gasification reactivity can be affected by the Ca–K-Char interaction as indicated by the XRD, FT-IR and SEM-EDX analysis.     

Theoretical modeling of a directly heated solar-driven chemical reactor

A theoretical formulation for calculating the performances of a solar-driven catalytic chemical reactor was developed. It accounts for the spatial distribution of the deposition of primary energy within the receiver, the heat transfer into the catalytic bed and the thermochemical endothermic reaction, chemical composition and flow distribution within the reactor. The theory set forth was applied to analyze results obtained in a solar furnace with a directly heated U-shaped tubular reactor, wherein catalytic carbon dioxide reforming of methane occurred. We find that the receiver/reactor assembly acts as a self-regulating system. Beyond a fractional catalytic bed length of 0.14, solar energy can be converted primarily into chemical enthalpy. The fluid temperature gradient monitors the heat balance by adjusting the overall rate of conversion to the rate at which energy is being transferred through the reactor walls. Under certain circumstances, the process may be heat-transfer limited or controlled by chemical thermodynamics. A good fit between theory and experiment and accountability of all the intricate details in the various calculated performances of the receiver/reactor system support the theoretical model set forth in this study. We offer it as a tool for simulating future experimental results and for designing solar-driven reactors.     

Enhanced porosity of Ni@Hollow meso-SiO2 catalyst for CO2 reforming of methane

The dry reforming of methane is a potential reaction that converts methane and carbon dioxide to syngas while mitigating the two greenhouse gases. Challenges for this reaction include sintering and severe carbon deposition. This paper reports a post-treatment strategy to develop Ni@hollow meso-SiO₂ (Ni@HMS) catalyst from the existing Ni@SiO₂ core-shell structure by utilizing the mechanism of etching and re-deposition of silica in mild alkaline solution with CTAB as a stabilizer. The varied post-treatment temperature changed the properties of Ni@HMS and demonstrated high catalytic performance compared to Ni@SiO₂. The results from TEM and XPS showed the Ni particles were confined inside the mesoporous SiO₂ shell and inhibit Ni particle mobility. The catalysts exhibited high conversion of methane (>80%) and carbon dioxide (>90%) for 50 h at 800 °C and WHSV of 54 000 mL g_cat^?1h^?1 with high TOF_CH4 of 7.08 s^?1.     

焦炭体系下添加剂对CO2重整CH4特性的影响

利用固定床试验装置,以SiO2、MgO和CaO为添加剂,在焦炭体系下进行了CO2重整CH4活性的试验研究,并分析了反应温度和CaO含量对重整反应的影响.利用热重分析仪和扫描电镜分别对重整过程中焦炭失重和反应后焦炭微观形貌进行研究,探讨了反应机理.结果表明:加入SiO2后,制得的焦炭催化活性降低,加入CaO和MgO后,制得的焦炭催化活性提高,且CaO优于MgO;温度对重整反应影响显著,随着温度升高,反应气转化率增加;CaO添加剂含量控制在15%~20%之间对反应速率的提高较合适,且CaO的添加使焦炭失重速率也有所提高.