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1.
Pretreatment was the essential step for industrial application of lignocellulosic biomass. Combination of steam explosion and fungal treatment was conducted, and synergistic mechanism of the combined pretreatment was evaluated in terms of pore size distribution, crystallinity index, chemical compositions and enzymatic hydrolysis. The results showed that steam explosion destroyed the rigid structure of corn stalk, increased pore size and porosity, and exposed crystalline component of cellulose. Steam explosion broke the lignin-carbohydrate-complex structure of lignocellulosic biomass and facilitated the fungal treatment. Phellinus baumii could selectively degrade 34.7% and 36.58% of lignin for 1.4 MPa and 1.7 MPa steam-exploded corn stalk, respectively. As a result, the highest glucose yield of corn stalk pretreated by the condition of 1.7 MPa steam explosion associated with 21 d P. baumii reached 313.31 g kg−1, which was 2.88 and 1.32 times higher than that of the untreated corn stalk and the 1.7 MPa steam-exploded corn stalk, respectively. The combined pretreatment enhanced the enzymatic hydrolysis, which was a promising technology that might be explored as alternative to the existing pretreatment. 相似文献
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Peng Fu Weiming Yi Zhihe Li Xueyuan Bai Andong Zhang Yanmei Li Zou Li 《International Journal of Hydrogen Energy》2014
Hydrogen production via catalytic steam reforming of maize stalk fast pyrolysis bio-oil over the nickel/alumina supported catalysts promoted with cerium was studied using a laboratory scale fixed bed coupled with Fourier transform infrared spectroscopy/thermal conductivity detection analysis (FTIR/TCD). The effects of nickel loading, reaction temperature, water to carbon molar ratio (WCMR) and bio-oil weight hourly space velocity (WbHSV) on hydrogen production were investigated. The highest hydrogen yield of 71.4% was obtained over the 14.9%Ni-2.0%Ce/A12O3 catalyst under the reforming conditions of temperature = 900 °C, WCMR = 6 and WbHSV = 12 h−1. Increasing reaction temperature from 600 to 900 °C resulted in the significant increase of hydrogen yield. The hydrogen yield was significantly enhanced by increasing the WCMR from 1 to 3, whereas it increased slightly by further increasing WCMR. The hydrogen yield decreased with the increase of WbHSV. Meanwhile, the coke deposition percentage changed little with increasing WbHSV up to 12 h−1 and then it increased by 4.5% with the further increase of WbHSV from 12 to 24 h−1. 相似文献
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The second generation biomass to bio-ethanol production is of growing interest. Energy crop were becoming important for second generation biomass to bio-ethanol production for their growth advantages. Hybrid Pennisetum as a new hybrid energy crop was selected as a model to compare with corn stalk. As pre-treatment methods, steam explosion and its combined action with dilute sulfuric acid, bisulfite, and mixed dilute acid and bisulfite were selected. The enzymatic hydrolysis demonstrated that the cellulose conversion is a strong function of the pre-treatment method applied, with corn stalk providing slightly better results. With dilute acid steam explosion (DA-SE), conversions were 67.6% and 54.5% for corn stalk and pennisetum, respectively. This can be attributed to the higher Cr. I of pennisetum (65.03%) than of corn stalk (54.05%). The cell lumen of pretreated pennisetum was smaller than for corn stalk as shown in SEM photos, meaning there was a substantially higher enzyme accessible surface and porosity in pennisetum, thus responsible for the higher cellulase adsorption of pretreated pennisetum. DA-SE was the most effective pre-treatment method, but the inhibitors' concentration was higher than in other methods. Combined dilute acid and bisulfite can moderately remove hemicelluloses and lignin. Cr. I values, lignin content, accessible surface and porosity were supplied the energy crop evaluation standards for bio-ethanol production. 相似文献
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《International Journal of Hydrogen Energy》2020,45(53):28350-28360
A straightforward thermodynamic analysis of bio-oil steam reforming was carried out in the context of hydrogen and syngas production, employing Gibbs energy minimization method to determine equilibrium composition and global reaction heat. The bio-oil model compound was a mixture of acetic acid, phenol, and acetone. The effects of process variables, such as temperature and inlet S/C molar ratio, were investigated over a wide range of conditions. Thermodynamic analysis was performed using the software Aspen Plus v.11. It was identified the best operational conditions that could maximize syngas and further hydrogen production considering energy efficiency. The optimum production of hydrogen is 2.28 mol per carbon mole at S/C = 10 and 850 K, and syngas is 2.37 mol per carbon mole at S/C = 10 and 900 K. It has been demonstrated that the equilibrium calculations can be used to simulate these steam reforming reactions, given the catalyst's behavior. 相似文献
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S.-T. Jiang 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(2):295-299
This article focused on the saccharification of wheat bran with steam explosion pretreatment and enzymatic hydrolysis. Wheat bran was pretreated with steam explosion to improve saccharification with enzymatic hydrolysis, and a maximum reducing sugar yield reached 194.6 mg/g (dry), which was about 63% higher than that of the wheat bran without pretreatment. Electronic microscope scanning and infrared spectroscopy showed that steam explosion with low pressure destroyed the structure and promoted the enzymatic hydrolysis of wheat bran effectively. Further, higher pressure produced harmful substances to hinder the saccharification and subsequent fermentation rather than increase saccharification ability of blasting bran. 相似文献
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Svein J. Horn Quang D. NguyenBjørge Westereng Pål J. NilsenVincent G.H. Eijsink 《Biomass & bioenergy》2011,35(12):4879-4886
The conversion of wheat straw to fermentable sugar for bioethanol production typically involves a thermal pretreatment step, followed by enzymatic hydrolysis. In this study we have investigated the effect of steam explosion parameters on wheat straw digestibility using a newly designed steam explosion unit and a process without acid impregnation. The wheat straw was steam pretreated using 18 different conditions in the temperature range of 170-220 °C and the resulting material was used directly (i.e. without washing) for enzymatic hydrolysis and fermentation in either a separate hydrolysis and fermentation (SHF)-type or a simultaneous saccharification and fermentation (SSF)-type set-up. Maximum glucose yields upon enzymatic hydrolysis were obtained after pretreatment at 210 °C for 10 min and yields were similar at harsher conditions. Xylose yields increased with temperature and residence time up to 190 °C, but decreased at harsher pretreatment conditions since these led to xylan degradation and concomitant production of furfural. In an SHF-type set-up ethanol formation did not follow enzymatic glucose release and was inversely correlated with furfural levels. An SFF-type set-up displayed a straightforward correlation between the expected amount of released glucose and the ethanol yields. The highest saccharification yields corresponded to about 90% of the cellulose in the substrate. Overall, this study shows that steam explosion without an acid catalyst is a good pretreatment method for saccharification of wheat straw. Optimal steam explosion conditions need to be a compromise between sugar accessibility and sugar degradation. 相似文献
7.
A novel hybrid plant for a mixture of methane and hydrogen (enriched methane) production from a steam reforming reactor whose heat duty is supplied by a molten salt stream heated up by a concentrating solar power (CSP) plant developed by ENEA is here presented. By this way, a hydrogen stream, mixed with natural gas, is produced from solar energy by a consolidated production method as the steam reforming process and by a pre-commercial technology as molten salts parabolic mirrors solar plant. After the hydrogen production plant, the residual heat stored in molten salt stream is used to produce electricity and the plant is co-generative (hydrogen + electricity).The heat-exchanger-shaped reactor is dimensioned by a design tool developed in MatLab environment. A reactor 3.5 m long and with a diameter of 2″ is the most efficient in terms of methane conversion (14.8%) and catalyst efficiency (4.7 Nm3/h of hydrogen produced per kgcat). 相似文献
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This research is devoted to the use of ethanol (i.e. bio-ethanol) in the combined production and purification of hydrogen by redox processes. The process has been studied in a single lab scale fixed bed reactor. Iron oxides, apart from their remarked redox behavior, exert an important catalytic role allowing the complete decomposition of ethanol at temperatures in the range from 625 to 750 °C. The resulting gas stream (mainly H2 and CO) reduces the solid to metallic iron. During a subsequent oxidation with steam, the solid can be regenerated to magnetite producing high purity hydrogen (suitable to be used in PEM fuel cells). Even though small amounts of coke are deposited during the reduction step, this is barely gasified by steam during the oxidation step (detection of COx in concentrations lower than 1 ppm). Influence of parameters like temperature, ethanol partial pressure and alternate cycles' effect has been studied in order to maximize the production of pure hydrogen. 相似文献
10.
Agricultural residues represent an abundant, readily available, and inexpensive source of renewable lignocellulosic biomass. However, biomass has complex structural formation that binds cellulose and hemicellulose. This necessitates the initial breakdown of the lignocellulosic matrix. Steam explosion pretreatment was performed on barley straw grind to assist in the deconstruction and disaggregation of the matrix, so as to have access to the cellulose and hemicellulose. The following process and material variables were used: temperature (140–180 °C), corresponding saturated pressure (500–1100 kPa), retention time (5–10 min), and mass fraction of water 8–50%. The effect of the pretreatment was assessed through chemical composition analysis. The severity factor Ro, which combines the temperature and time of the hydrolytic process into a single reaction ordinate was determined. To further provide detailed chemical composition of the steam exploded and non-treated biomass, ultimate analysis was performed to quantify the elemental components. Data show that steam explosion resulted in the breakdown of biomass matrix with increase in acid soluble lignin. However, there was a considerable thermal degradation of cellulose and hemicellulose with increase in acid insoluble lignin content. The high degradation of the hemicellulose can be accounted for by its amorphous nature which is easily disrupted by external influences unlike the well-arranged crystalline cellulose. The carbon content of the solid steam exploded product increased at higher temperature and longer residence time, while the hydrogen and oxygen content decreased, and the higher heating value (HHV) increased. 相似文献
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Biogas production often competes with food and feed production for the raw materials and cropland required for cultivation. Common reed offers an alternative source of biomass for biogas production, alleviating this conflict. Effective microbiological conversion of this type of lignocellulosic biomass requires a pretreatment process. This study aims to determine the specific methane yields of steam-exploded reed as well as to identify how pretreatment conditions influence its physico-chemical characteristics. For this purpose, reed was pretreated with steam explosion at severity factors ranging from 2.47 to 4.83. The effects on methane yields were analyzed in batch experiments. Scanning electron microscopy (SEM) images were captured and detailed chemical analyses of the substrates carried out. Results show that the digestibility of reed biomass improved remarkably after pretreatment. Compared to the untreated sample, steam explosion increased the specific methane yield up to 89% after pretreatment at 200 °C for 15 min. However, methane yield decreased under harsher conditions, which may be due to the formation of degradation compounds during the pretreatment. 相似文献
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碱和双氧水预处理玉米秸秆的试验研究 总被引:2,自引:0,他引:2
研究了在5%NaOH中加入不同质量分数的双氧水时,对玉米秸秆的预处理效果;在预处理后的玉米秸秆中加入纤维素酶,考察此时酶解还原糖得率随预处理程度的变化;对浸泡时间、双氧水浓度、固液比3个因素进行单因素试验。试验结果表明,质量分数为2.5%的浓度下,糖得率最大;在2.5%H2O2浸泡24 h,固液比对酶解糖化几乎没有影响;当浸泡时间为24,72,96 h时,糖得率相差甚微。设计正交试验对预处理的条件进行优化,分析预处理玉米秸秆的各因素,以木质素去除率为基准参数,得到水解木质纤维素的适宜预处理条件:5%NaOH下加入质量分数为2.5%的双氧水,浸泡时间为72 h,固液比为1∶20。预处理后木质素的去除率为61.52%;加入纤维素酶酶解,还原糖得率为39.30%。 相似文献
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分析了甘蔗渣的水蒸气气化过程,基于气化过程的物料平衡和化学平衡关系,建立了一种生物质气化过程的数学模型。用该模型模拟计算甘蔗渣在水蒸气氛围下气化后的气体成分,计算结果与试验数据基本相符,尤其在温度950℃之后,计算值和测量值更接近。以甘蔗渣和木薯渣为例,研究该气化模型的特性。甘蔗渣和木薯渣水蒸气气化的最佳水蒸气/燃料值(S/B)分别为0.3和0.2。气化气组分和气化效果随温度和S/B变化的结果表明:提高温度有利于气化反应的进行,提高S/B,可以增加气体产率,气体热值有所降低。 相似文献
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使用star ccm+软件,以完全断裂的高能管道为研究对象,针对3~15MPa的饱和蒸汽喷射过程进行了数值模拟研究。主要研究了管道断裂后喷射过程中喷射锥的影响范围、喷射锥内压力和速度分布规律,并针对不同的压力、喷管长径比研究了喷嘴后不同位置处所受的喷射冲击力。研究表明在喷嘴出口处压力快速下降,蒸汽速度迅速增大,之后会有一定波动;压力升高对喷嘴出口蒸汽最高速度的影响不大,但会影响喷射冲击力的大小;除此之外,距喷嘴出口处的距离、喷管长径比等也会影响喷射冲击力的大小。 相似文献
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Zhao-Xia Song Zhi-Yuan WangLi-Yang Wu Yao-Ting FanHong-Wei Hou 《International Journal of Hydrogen Energy》2012
The bio-hydrogen production potential from corn stalk was significantly affected by microwave irradiation pretreatment of cow dung compost in batch tests. The maximum hydrogen yield of 144.3 ml/g-corn stalk and hydrogen production rate of 3.6 ml/g-corn stalk h−1 were observed using the pretreated compost by microwave radiation of 1.5 min at fixed Na2CO3 dosage of 800 mg/l, Fe dosage of 400 mg/l, substrate concentration of 20 g/l, which increased about 99.6% and 85.2% compared with that of the control. The effects of microwave irradiation on microbial characteristics were further discussed by Atomic Force Microscope (AFM), determination of protein content and PCR-DGGE. The four dominant hydrogen-producing strains had been isolated and confirmed to be Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus subtilis and Enterococcus faecium, respectively. The diversity and symbiosis relations of the mixed bacteria were also observed in fermentation hydrogen production process. 相似文献
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Aingeru Remiro Beatriz ValleLide Oar-Arteta Andrés T. AguayoJavier Bilbao Ana G. Gayubo 《International Journal of Hydrogen Energy》2014
The feasibility of the steam reforming of bio-oil aqueous fraction and bio-ethanol mixtures has been studied in a continuous process with two in-line steps: thermal step at 300 °C (for the controlled deposition of pyrolytic lignin during the heating of the bio-oil/bio-ethanol feed) followed by steam reforming in a fluidized bed reactor on a Ni/α-Al2O3 catalyst. The effect of bio-ethanol content in the feed has been analyzed in both the thermal and reforming steps, and the suitable range of operating conditions (temperature and space-time) has been determined for obtaining a high and steady hydrogen yield. Higher ethanol content in the mixture feed improves the reaction indices and reduces coke deposition. Operating conditions of 700 °C and space-times higher than 0.23 gcatalyst h (gbio-oil+EtOH)−1 are suitable for attaining almost fully conversion of oxygenates (bio-oil and ethanol) and hydrogen yields above 93%, with low catalyst deactivation. 相似文献
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《International Journal of Hydrogen Energy》2022,47(52):22261-22272
To study the effect of initial temperature of 30, 60, 90, and 120 °C on the explosion limits and the explosion process of the syngas-air mixtures, the explosion limits were tested by the explosive limit instrument, and the flame propagation process in the spherical pressure vessel was recorded by the high-speed camera. The ANSYS Fluent 3D software was used to simulate the explosion behavior of syngas-air mixtures. The results showed that with the increase of the initial temperature, the lower explosion limit of syngas decreased and the upper explosion limit increased, and the effect of initial temperature on the upper explosion limit of syngas was greater than that on the lower explosion limit. The flame development process in the simulation was consistent with that in the experiment, propagating outward spherically until it filled the entire container. Both experimental and numerical results presented the same trend of accelerating the flame propagation speed with the increase of initial temperature. In addition, the simulation also obtained multi-dimensional transient explosion parameters that were difficult to obtain in the experiment. The explosion process of syngas was analyzed by the explosion parameters such as temperature and pressure field in the explosion area. An increase in temperature decreased the maximum explosion pressure and shortened the time to reach the maximum explosion pressure. 相似文献