乙醇水蒸气重整制氢热力学分析

采用吉布斯自由能最小原理对乙醇水蒸气重整制氢的反应体系进行了热力学分析,考察了温度、压力、水醇比(H_2O/Et OH)和甲醇/乙醇比(MeOH/EtOH)对该体系平衡组成的影响。在压力为1×10~5~80×10~5 Pa,温度为700~1 300 K,水醇比为1∶1~11∶1,甲醇/乙醇比为0∶1~0.9∶1条件下,研究了H_2,CH_4以及C的平衡摩尔数。在选取的条件下,乙醇转化率达到100%。通过分析H_2,CH_4以及C的平衡摩尔数,得出最佳压力为1×105Pa,最佳温度为900 K,最佳水醇比为11∶1,最佳甲醇/乙醇比为0.9∶1。在所研究的条件范围内,通过调整反应条件可以避免积碳的生成。     

太阳能吸附制冷用复合吸附剂制备及其吸附机理探讨

以乙醇为吸附质，选取13X分子筛、凹凸楱土和氯化锶等为主要吸附材料．通过混合法制备了一系列有着优良吸附能的复合吸附剂。测定了乙醇在主要吸附材料和自制复合吸附剂上的吸附量，用TG-DTA法对主要吸附材料的热稳定性和自制吸附剂DTA脱附乙醇峰端温度进仃了分析.对吸附剂原料复合比例和扩孔剂种类等制备条件进行了实验研究。结果表明：自制复合吸附剂比单一吸附材料对乙醇确着更大的吸附能力；DTA分析的脱乙醇峰端温度明显低于单一吸附材料；加入扩孔剂E1或E2，可增加自制复合吸附剂孔容和孔径，改善其吸附性能；自制复合吸附剂对乙醇的吸附量显著高于活性炭。其中，M4-0003和M1-0001复合吸附剂对乙醇的平衡吸附量约为活性炭的2．5～4倍；M1-0001—乙醇工质对的吸附制冷量是活性炭—乙醇的2～6倍。对吸附剂复合的机理初步探讨表明：增加复合吸附剂弱吸附中心数，可降低其脱附温度。     

Fe-Ag/La_2O_3-ZrO_2催化乙醇水蒸气重整制氢

用草酸盐沉淀法制备La2O3-ZrO2复合氧化物载体,用浸渍法制备Fe-Ag/La2O3-ZrO2催化剂;用X射线衍射技术表征催化剂;考察了催化剂在乙醇水蒸气重整反应中的催化活性。结果表明,La含量较低的La2O3-ZrO2复合载体具有明显的四方晶相结构;Fe-Ag/La2O3-ZrO2催化剂在乙醇水蒸气重整反应中表现出良好的催化性能,气相产物中H2物质的量分数很高,CO和CH4物质的量分数很低;La,Ag,Fe含量影响催化剂的活性及选择性。在以(1Ag20Fe)20(2La8Zr)为催化剂,反应温度为823 K、乙醇与水物质的量比为1∶6,乙醇水溶液流速为0.1 mL/min的反应条件下,乙醇转化率达到95.7%,气相产物中H2物质的量分数为78.7%、CO的物质的量分数小于1.2%。     

MWCNTs-水合盐复合相变材料的蓄热性能研究

研究CH₃COONa·3H₂O(SAT)/Na₂HPO₄·12H₂O(DSP)共晶盐的相变过程，分析亲水碳纳米管(HCNTs)对共晶盐热性能的优化效果。结果表明：SAT/DSP质量比为9∶1时共晶盐循环稳定性最好，且过冷度仅为2.5℃；随着HCNTs掺量提高，复合材料的热导率呈线性增长趋势，最高达到1.29 W/(m·K)，较未加HCNTs时提升了182.89%，蓄热密度呈线性下降趋势，最多降低了5.59%。最后对各组HCNTs/SAT/DSP复合相变材料(CPCM)进行200次固-液循环，结果表明各组材料的循环稳定性良好，具备实际应用价值。     

钻井液用两性离子P(AM-AMPS-DAC)共聚物反相乳液的制备与性能评价

作为钻井液处理剂,反相乳液聚合物与粉状聚合物相比,能够减少聚合物在烘干、粉碎过程中由于降解、交联等反应造成的不利影响,产品可以直接加入钻井液并快速分散,在达到同样效果的前提下,可减少用量,降低钻井液处理费用,且更容易实现绿色环保生产。以丙烯酰胺、2-丙烯酰胺-2-甲基丙磺酸、丙烯酰氧乙基三甲基氯化铵为原料,采用氧化还原引发剂体系,通过反相乳液聚合,制备了两性离子P(AM-AMPS-DAC)反相乳液聚合物。研究了复合乳化剂的HLB、乳化剂用量、引发剂用量、油水体积比、AMPS和DAC用量对共聚物的水溶液表观黏度及所处理钻井液的流变性和滤失量的影响,测定了聚合物的红外光谱和TG曲线。结果表明,当油水体积比为1.0,单体质量分数为30%,复合乳化剂质量分数为5%~6%,复合乳化剂HLB值为7.1,引发剂用量为0.2%,n(AM)∶n(AMPS)∶n(DAC)=0.59∶0.35∶0.06时,能够制得热稳定性好的反相乳液聚合物,且在淡水、盐水、饱和盐水和复合盐水基浆中具有较好的增黏、降滤失能力,抗温、抗盐能力强,同时具有较强的润滑和防塌能力。     

Mo2C/Al2O3的制备及其催化二甲醚水蒸气重整性能研究

通过浸渍沉淀法结合程序升温碳化法制备了Mo₂C/Al₂O₃复合催化剂,并应用于二甲醚水蒸气重整催化体系的研究。考察了二甲醚水解催化载体、水解功能组分Al₂O₃与重整功能组分Mo₂C的比例、反应物浓度对复合催化剂活性的影响。结果表明,β-Mo₂C与γ-Al₂O₃载体以Mo/Al = 1/1耦合后能够高效催化二甲醚重整制氢,其最佳进料水醚比为5,最适反应温度为400℃。     

松子壳基活性炭光催化剂的制备及其催化性能研究

为了提高TiO_2光催化剂对水体有机污染物的降解能力,将松子壳基活性炭作为载体负载TiO_2,研究载体比表面积、载体与TiO_2的复合比例以及煅烧温度对复合光催化剂降解水体有机污染物亚甲基蓝的影响。通过BET,XRD,FTIR和SEM分析方法对复合光催化剂的比表面积、晶体结构、有机官能团和表面形貌进行了表征。研究结果表明:适当的增加载体的比表面积,有利于Ti O2的负载和复合光催化剂催化活性的提高;当活化水量为1.5 mL/min时,在充分的水蒸气活化反应下,松子壳炭可制备成比表面积为634.65 m~2/g的活性炭,使其负载TiO_2后具有较好的亚甲基蓝吸附作用和光降解作用;当TiO_2与活性炭的质量比为0.8∶1时,复合光催化剂的催化效果较好;当煅烧温度为450℃时,复合光催化剂具有较优的催化效果,降解率可达77.10%。     

酵母菌复合培养物对木质纤维素稀酸水解液原位脱毒乙醇发酵

为了解决木质纤维素稀酸水解产物中发酵抑制剂对微生物的抑制作用以及木糖的乙醇发酵问题,该研究用本实验室开发的能高效代谢葡萄糖产乙醇并代谢糠醛和5-羟甲基糠醛的2株酵母菌种Saccharomyces cerevisiae Y5和Ismtchenkia/orientalis Y4分别与Pichia.stipitis CBS6054组成2个复合菌种,用复合菌种对木质纤维素稀酸水解产物进行原位脱毒乙醇发酵.结果证明,复合菌种S.cerevisiae Y5,P.stipitis CBS6054显示出了很好的代谢稀酸水解液中的葡萄糖和木糖产乙醇并快速代谢糠醛和5-羟甲基糠醛的能力,乙醇产率为0.43g/g(达到理论值的85.1%).该复合培养物可作为木质纤维索稀酸水解产物不需任何脱毒处理直接进行乙醇发酵的复合菌种.     

膨胀石墨/多壁碳纳米管基共晶盐复合相变材料的制备及热特性北大核心CSCD

单一水合盐作为相变蓄热材料使用时常常由于过冷、相分离、易泄漏以及其相变温度而受到限制,因此迫切需要制备出一种储热密度高、相变温度适宜、热导率大的复合相变材料。本工作采用熔融共混法在NH_(4)Al(SO_(4))_(2)·12H_(2)O(AASD)中掺入不同质量分数的MgSO_(4)·7H_(2)O(MSH),成功制备了AASD-MSH共晶盐相变材料,其质量比为55∶45,相变温度为76.4℃,相变潜热为189.4 J/g。共晶盐的X射线衍射图谱和傅里叶红外光谱表明其为物理混合。引入质量分数1%成核剂CaCl_(2)·2H_(2)O及1%增稠剂可溶性淀粉降低共晶盐过冷度,过冷度从34.9℃降低至28.0℃。引入改性膨胀石墨(MEG)与多壁碳纳米管(MWCNTs)制备复合相变材料,改善共晶盐易泄漏及热导率低等问题,当MWCNTs质量分数为0.5%时,复合相变材料的热导率高达8.185 W/(m·K),为共晶盐的19.98倍,其中共晶盐占比为75.6%,相变温度为74.3℃,相变焓值为133.5 J/g,过冷度进一步降低至22.2℃。热重实验表明与MEG-MWCNTs的复合增加了共晶盐的热稳定性,且经过100次冷热循环后复合相变材料的相变焓值基本不变,具有良好的循环稳定性。本工作制备得到的AASD-MSH/MEG-MWCNTs复合相变材料是一种相变温度适合、相变焓值较高、热导率较大的相变材料,且具有良好的热循环稳定性,应用潜力极大。     

反应精馏催化改性生物质热解油

以生物热解油和乙醇为原料,在固体酸催化作用下,首次采用氧化预处理和反应精馏的方法对生物质热解油进行了催化改性.对SO2-4/MzOy系列的固体酸的催化性能进行了考察,其中SO2-4/ZrO2具有较高的活性.改性所得两种改性油与原料油相比在各方面性能上有较大的提升,经过GC和FT-IR分析,轻油主要成分是原料油中的轻组分所转化的酯类化合物,重油主要是原料油中不溶于水且沸点较高的成分.两种改性油都具有较高的储存稳定性,在平均温度20℃以上的环境下不避光储存3个月各项性能没有发生较大变化.     

Comparative study of fuel gas production for SOFC from steam and supercritical-water reforming of bioethanol

Theoretical study of fuel gas (H₂ + CO) production for SOFC from bioethanol was carried out to compare performances between two reforming technologies, including steam reforming (SR) and supercritical-water reforming (SCWR). It demonstrates that the fuel gas productions are comparable among the two reforming systems; however, SCWR requires the operation at much higher temperature and pressure than SR. The maximum hydrogen yield can be obtained at 850 K, atmospheric pressure, ethanol to water molar feed ratio of 1:20 for SR system and at 1300 K, 22.1 MPa, and ethanol to water feed ratio of 1:20 for SCWR. The use of a distillation column to purify the bioethanol feed was proven to improve the fuel conversion efficiency of both systems. The analysis reveals that SCWR is a promising system for fuel production for SOFC when a gas turbine is incorporated to the system for energy recovery. Further, it is not necessary to distil bioethanol to obtain too high ethanol recovery (i.e. >90%) as higher energy consumption at the distillation column could lead to lower overall thermal efficiency.     

High yield simultaneous hydrogen and ethanol production under extreme-thermophilic (70 °C) mixed culture environment

The effect of pH and medium composition on extreme-thermophilic (70 °C) dark fermentative simultaneous hydrogen and ethanol production (process performance and microbial ecology) was investigated. Hydrogen and ethanol yields were optimized with respect to glucose, peptone, FeSO₄, NaHCO₃, yeast extract, trace mineral salts, vitamins, and phosphate buffer concentrations as well as initial pH as independent variables. A combination of low levels of both glucose (≤2 g/L) and vitamin solutions (≤1 mL/L) and high levels of initial pH (≥7), mineral salts solution (≥5 mL/L) and FeSO₄ (≥100 mg/L) stimulated the hydrogen production, while high level of glucose (≥5 g/L) and low levels of both initial pH (≤5.5) and mineral salts solution (≤1 mL/L) enhanced the ethanol production. High yield of simultaneous hydrogen and ethanol production (1.58 mol H₂/mol glucose combined with an ethanol yield of 0.90 mol ethanol/mol glucose) was achieved under extreme-thermophilic mixed culture environment. Results obtained showed that the shift of the metabolic pathways favouring either hydrogen or ethanol production was affected by the change in cultivation conditions (pH and medium composition). The mixed culture in this study demonstrated flexible ability for simultaneous hydrogen and ethanol production, depending on pH and nutrients formulation. The microorganisms involved could be regarded as simultaneous hydrogen/ethanol producers, as hydrogen and ethanol fermentation under all conditions was carried out by a group of extreme-thermophilic bacterial species related to Thermoanaerobacter, Thermoanaerobacterium and Caldanaerobacter.     

Hydrogen production from an ethanol reformer with energy saving approaches over various catalysts

The reforming of ethanol for hydrogen production was carried out in this study. The effects of ethanol supply rate, catalysts, O₂/EtOH and different energy-saving approaches on the reforming temperature, H₂ + CO (syngas) concentration and thermal efficiency were investigated. The results showed that the best H₂ + CO concentration of 43.41% could be achieved by using rhodium (Rh), while the next best concentration of about 42.08% could be obtained using ruthenium (Ru). The results also showed that the conversion efficiency of ethanol, concentrations of H₂ and CO, and the energy loss ratio could be improved by heat insulation and heat recycling; and the improvement in the reforming performance was greater by the Ru catalyst rather than by the Rh catalyst with the energy-saving approaches. The greatest improvement in hydrogen production was achieved when using the Ru catalyst with the addition of steam and heat recycling system under an O₂/EtOH ratio of 0.625 and S/C ratio of 1.0.     

Techno-economic comparison of energy usage between azeotropic distillation and hybrid system for water–ethanol separation

Conventional azeotropic distillation, consuming very high energy, is mostly used to produce high purity ethanol for renewable energy usage. In this study, the techno-economic comparison between azeotropic distillation (distillation followed by practical azeotropic distillation) and hybrid system (distillation followed by pervaporation system) for producing high purity of ethanol is demonstrated using the Pro II by Provision version 8.0. In the hybrid system, NaA zeolite membrane is used to separate the water from ethanol–water mixture. It is found that the hybrid system is the most effective technique for producing more than 99.4%wt of ethanol with an energy consumption of 52.4% less than the azeotropic distillation.     

The recycle of sulfuric acid and xylose in the prehydrolysis of corn stover

Ethanol may be produced from agricultural residues by using a two-stage acid hydrolysis followed by acid recovery, fermentation, and distillation. With sulfuric acid as a catalyst, xylose-rich and glucose-rich streams can be obtained from corn stover in the prehydrolysis and hydrolysis steps, respectively. After acid separation, the sugar solutions are fermented to ethanol and concentrated by distillation.The acid recovery and distillation steps are the most expensive portions of the process; therefore, any reduction in the requirements for these steps will significantly improve the economics of the overall process. One means by which this may be accomplished is the addition of a recycle stream in the prehydrolysis step. The result will be an increased xylose concentration in the the prehydrolyzate fluid, which will reduce the acid recovery and distillation costs for each unit of ethanol produced. Thus, both capital and operating costs can be lowered while the net energy production is increased.In this investigation, the prehydrolysis step was carried out in a batch reactor at a temperature of 100 °C and a reaction time of 80 min. A 2-1. reaction vessel was used for the first two batches, each of which resulted in approx. 600 milliliters (ml) of prehydrolyzate fluid. This fluid, consisting primarily of xylose dissolved in the dilute sulfuric acid solution, was then mixed in varying ratios with fresh acid and used as the acid catalyst in later experiments to determine the effects of recycle on sulfuric acid activity and xylose concentration. In one set of recycle experiments, the activity of the recycled acid was as much as 90% of the activity of fresh acid on a volume per volume basis. Because the recycled fluid contained approx. 3% xylose, the xylose concentrations obtained in these experiments depended on the ratio of recycled acid to fresh acid. Concentrations averaged 27.5 grams per liter (g/l) for an acid residence time of 80min and 51.4 g/l for an acid residence time of 160 min.The effect of the increased concentration of xylose on the economics of a 4.5 × 10⁶ gallon per year ethanol plant were estimated to be a 16% reduction in capital costs and a 17% reduction in operating costs. For corn stalks at $25 per ton and ethanol at $1.185 per gallon (ga), the estimated rate of return on investment would increase from 3.4% without recycle to 18.0% with recycle.     

Refining bioethanol from stalk juice of sweet sorghum by immobilized yeast fermentation

The relationship between total soluble sugar content and Brix in stalk juice of sweet sorghum was determined through one-dimensional linear regression. Meanwhile, bioethanol fermentation experiments were conducted in shaking flasks and 10 l fluidized bed bioreactor with stalk juice of Yuantian No. 1 sweet sorghum cultivar when immobilized yeast was applied. The experimental results in the shaking flasks showed that the order of influence on improving ethanol yield was (NH₄)₂SO₄>MgSO₄>K₂HPO₄, and the optimum inorganic salts supplement dose was determined as follows: K₂HPO₄ 0%, (NH₄)₂SO₄ 0.2%, MgSO₄ 0.05%. When the optimum inorganic salts supplement dose was used in fermentation in 10 l fluidized bed reactor, the fermentation time and ethanol content were 5 h and 6.2% (v/v), respectively, and ethanol yield was 91.61%, which was increased by 9.73% than blank. In addition, the results showed that the fermentation time was about 6–8 times shorter in fluidized bed bioreactor with immobilized yeast than that of conventional fermentation technology. As a result, it can be concluded that the determined optimum inorganic salts supplement dose could be used as a guide for commercial ethanol production. The fluidized bed bioreactor with immobilized yeast technology has a great potential for ethanol fermentation of stalk juice of sweet sorghum.     

Thermodynamic model of pressure swing distillation for a high pressure process of hydrochloric/water separation and hydrogen production

Recycling of concentrated HCl within the CuCl cycle for hydrogen production is necessary to achieve lower operating costs and higher efficiency. HCl and water molecules have an attraction that leads to a maximum boiling azeotrope. Thus, HCl cannot be separated from water by using a conventional distillation column. In this paper, a novel thermodynamic model and simulations in Aspen Plus are presented for a pressure swing distillation high-pressure process to separate the HCl-water azeotropic binary mixture into a concentrated HCl stream. Furthermore, a heat transfer analysis is presented to predict the packing column height. All of the stream properties and compositions in the binary azeotropic mixture, thermodynamic analysis and steady-state simulation of a high pressure distillation column are examined with Aspen Plus. The present results indicate that the high-pressure distillation system enhances the mole fraction of HCl (aq) from 0.11 up to 0.21 and the increase of reflux ratio and feed temperature assist it to be higher. The increment of 76% and 42% for the condensation and re-boiler heat duties with the growth of reflux ratio indicate the significant impact of this parameter on the high pressure distillation column. Furthermore, at the specific system operating condition, the results from the heat transfer model suggest that the distillation column with a height of 2 m would be suitable for practical operation.     

Novel sorbents of ethanol “salt confined to porous matrix” for adsorptive cooling

In this paper a new family of sorbents, specifically designed for ethanol sorption, is presented. The composites were synthesized by a dry impregnation of matrices with an aqueous solution of various salts. The ethanol sorption capacity of the composites, under conditions typical for adsorptive air conditioning cycle, has been measured by using an express method based on the Polanyi principle of temperature invariance. Results obtained show that the best novel composites have the ethanol sorption ability which is higher than that of known ethanol sorbents. The composite LiBr(30 wt.%)/SiO₂ appears to show the highest sorption capacity and an uptake variation Δw = 0.56 and 0.40 g/g for air conditioning and ice making cycles, respectively. They are much larger than those obtained for conventional adsorbents. The correspondent cooling coefficient of performance (COP) was estimated to be 0.66 and 0.61, which is comparable with the COP of the best water sorbents.     

Thermodynamic assessment of solid oxide fuel cell system integrated with bioethanol purification unit

A solid oxide fuel cell system integrated with a distillation column (SOFC–DIS) has been proposed in this article. The integrated SOFC system consists of a distillation column, an EtOH/H₂O heater, an air heater, an anode preheater, a reformer, an SOFC stack and an afterburner. Bioethanol with 5 mol% ethanol was purified in a distillation column to obtain a desired concentration necessary for SOFC operation. The SOFC stack was operated under isothermal conditions. The heat generated from the stack and the afterburner was supplied to the reformer and three heaters. The net remaining heat from the SOFC system (Q_SOFC,Net) was then provided to the reboiler of the distillation column. The effects of fuel utilization and operating voltage on the net energy (Q_Net), which equals Q_SOFC,Net minus the distillation energy (Q_D), were examined. It was found that the system could become more energy sufficient when operating at lower fuel utilization or lower voltage but at the expense of less electricity produced. Moreover, it was found that there were some operating conditions, which yielded Q_Net of zero. At this point, the integrated system provides the maximum electrical power without requiring an additional heat source. The effects of ethanol concentration and ethanol recovery on the electrical performance at zero Q_Net for different fuel utilizations were investigated. With the appropriate operating conditions (e.g. C_EtOH = 41%, U_f = 80% and EtOH recovery = 80%), the overall electrical efficiency and power density are 33.3% (LHV) and 0.32 W cm⁻², respectively.     

Heat pump assisted distillation. VIII: Design of a system for separating ethanol and water

A heat pump assisted distillation system has been designed for the separation of ethanol from 7 per cent aqueous mixtures to produce 93 per cent ethanol by weight. The distillation column has been designed on the basis of conventional design procedures. Valve trays were chosen to provide operational flexibility. R114 was chosen as the working fluid for the mechanical vapour compression heat pump. The heat pump system has been designed to match the heat loads determined for the column. Auxiliary heat exchangers have been provided to aid flexibility and control of column operation.