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141.
The ordered mesoporous aluminosilicate molecular sieve (MASMS-1) stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O (φ=20%) in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups. 相似文献
142.
Ethanol production in immobilized-cell bioreactors from mixed sugar syrups and enzymatic hydrolysates of steam-exploded biomass 总被引:4,自引:0,他引:4
Isabella De Bari Daniela Cuna Francesco Nanna Giacobbe Braccio 《Applied biochemistry and biotechnology》2004,114(1-3):539-557
We investigated ethanol production from mixed sugar syrups. Hydrolysates were prepared from enzymatic saccharification of
steam-pretreated aspen chips. Syrups containing 45 g/L of glucose and 12 g/L of xylose were detoxified through two ion-exchange
resins and then fermented with Pichia stipitis and Saccharomyces cerevisiae immobilized in Ca-alginate gel beads. Combinations of different gel fractions in the fermentation volume, amount of yeast
cells, and ratios of P. stipitis vs S. cerevisiae within each bead were compared. In the best conditions, by using a total beads volume corresponding to 25% of the working
volume, we obtained a yield of 0.39 gethanol/ginitial sugars. This amount of gel entrapped an initial cell concentration of 6×1012cells/L with ratio of S. cerevisiae/P. stipitis of 0.25 g/g. Modified stirredtank reactors were obtained either by adding marbles or by inserting a perforated metal cylinder,
which reduced considerably the rupture of beads while visibly improving oxygenation of the medium. 相似文献
143.
高效甲醇水蒸气重整制氢的SBA-15改性的Cu/ZnO/Al2O3催化剂 总被引:1,自引:0,他引:1
以介孔SBA-15为结构助剂, 制备出用于甲醇水蒸气重整制氢的新型高效氧化硅掺杂的Cu/ZnO/Al2O3催化剂, 并与传统Cu/ZnO/Al2O3催化剂在相同条件下的催化性能进行了比较. 结果表明, 添加适量介孔SBA-15可显著提高催化剂的催化活性和选择性, 在大幅度提高甲醇转化率的同时有效降低了重整产气中CO的含量. 原位XRD分析证实适量介孔SBA-15的添加对传统Cu/ZnO/Al2O3催化剂的微结构性质可产生重要的调控作用, 从而大大改善其催化活性和制氢选择性. 相似文献
144.
采用反应蒙特卡罗方法研究了狭缝孔内甲烷蒸汽重整反应的化学平衡. 模拟中将CH4, CO和H2均描述成球形LJ分子, H2O和CO2分子的势能分别采用TIP4P和EMP2模型计算. 狭缝孔壁与LJ点位之间的相互作用采用Steele的10-4-3模型计算. 由于没有狭缝孔内该反应的实验数据, 因此比较了用经典热力学预测与RCMC方法得到的主体相平衡组成. 两种方法得到的结果比较吻合, 表明采用RCMC方法预测孔内的化学平衡是可靠的. 讨论了其它工艺条件对孔内化学平衡的影响. 相似文献
145.
Stenberg Kerstin Tengborg Charlotte Galbe Mats Zacchi Guido Palmqvist Eva Hahn-Hägerdal Bärbel 《Applied biochemistry and biotechnology》1998,(1):697-708
In ethanol production from lignocellulose by enzymatic hydrolysis and fermentation, it is desirable to minimize addition of
fresh-water and waste-water streams, which leads to an accumulation of substances in the process. This study shows that the
amount of fresh water used and the amount of waste water thereby produced in the production of fuel ethanol from softwood,
can be reduced to a large extent by recycling of either the stillage stream or part of the liquid stream from the fermenter.
A reduction in fresh-water demand of more than 50%, from 3 kg/kg dry raw material to 1.5 kg/kg dry raw material was obtained
without any negative effects on either hydrolysis or fermentation. A further decrease in the amount of fresh water, to one-fourth
of what was used without recycling of process streams, resulted in a considerable decrease in the ethanol productivity and
a slight decrease in the ethanol yield 相似文献
146.
Renata Bura Rodney J. Bothast Shawn D. Mansfield John N. Saddler 《Applied biochemistry and biotechnology》2003,106(1-3):319-335
A batch reactor was employed to steam explode corn fiber at various degrees of severity to evaluate the potential of using
this feedstock as part of an enzymatically mediated cellulose-to-ethanol process. Severity was controlled by altering temperature
(150–230°C), residence time (1–9 min), and SO2 concentration (0–6% [w/w] dry matter). The effects of varying the different parameters were assessed by response surface
modeling. The results indicated that maximum sugar yields (hemicellulose-derived water soluble, and cellulose-derived following
enzymatic hydrolysis) were recovered from corn fiber pretreated at 190°C for 5 minutes after exposure to 3% SO2. Sequential SO2-catalyzed steam explosion and enzymatic hydrolysis resulted in a conversion efficiency of 81% of the combined original hemicellulose
and cellulose in the corn fiber to monomeric sugars. An additional posthydrolysis step performed on water soluble hemicellulose
stream increased the concentration of sugars available for fermentation by 10%, resulting in the high conversion efficiency
of 91%. Saccharomyces cerevisiae was able to ferment the resultant corn fiber hydrolysates, perhydrolysate, and liquid fraction from the posthydrolysis steps
to 89, 94, and 85% of theoretical ethanol conversion, respectively. It was apparent that all of the parameters investigated
during the steam explosion pretreatment had a significant effect on sugar recovery, inhibitory formation, enzymatic conversion
efficiency, and fermentation capacity of the yeast. 相似文献
147.
An on-line solvent (eluent) evaporator is used for reconcentrating a fraction from a first LC column before introduction into a second LC separation step, possibly involving another mobile phase. For pentane and pentane containing 10 % of dichloromethane, evaporation rates of 1 ml/min were achieved. On evaporating a volume of 6 ml, 2-ethylnaphthalene was retained to more than 75%. Separation of aliphatic and polyaromatic hydrocarbons in a linseed oil is shown as an application. 相似文献
148.
在运用连续流动反应(CFR)技术(尾气技术)的基础上提出了1种可筛选催化剂并能进行非均相催化动力学研究的实验原理和方法--程序升温连续流动反应器(TPCFR)技术。在用此法筛选过的Cu-Ni催化剂上对甲醇分解反应和甲醇水蒸汽重整反应进行了系统研究,证明这种方法合理、可信。利用1条TPCFR曲线可求出各个动力学参数。 相似文献
149.
王民昌 《浙江大学学报(理学版)》1997,24(4):312-316
本文分析了高温饱和水在满管流动的爬高过程中,其密度发生明显变化的动态机理,利用此动态特性,就实现低压高温凝结水无泵回收的可能性进行分析讨论. 相似文献
150.
J. M. Nazzal 《Journal of Thermal Analysis and Calorimetry》2001,65(3):847-857
Jordan oil shale from El-Lajjun deposit was pyrolysed in a fixed-bed pyrolysis reactor and the influence of the pyrolysis
temperature between 400 to 620°C and the influence of the pyrolysis atmosphere using nitrogen and nitrogen/steam on the product
yield and gas composition were investigated. The gases analysed were H2, CO, CO2 and hydrocarbons from C1 to C4. The results showed for both nitrogen and nitrogen/steam that increase the pyrolysis bed temperature from 400 to 520°C resulted
in a significant increase in the oil yield, after which temperature the oil yield decreased. The alkene/alkane ratio including
ethene/ethane, propene/propane, and butene/butane ratios, can be used as an indication of pyrolysis temperature and the magnitude
of cracking reactions. Increasing alkene/alkane ratio occurring with increasing pyrolysis temperature. The alkene/alkane ratio
for nitrogen/steam pyrolysis atmosphere was lower than the one found under nitrogen atmosphere.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献