摘要 :This paper presents a multiobjective optimization to obtain the optimal planning of butanol production, considering the optimal selection of feedstock and the correct ratio of fermentable sugars. This multiobjective methodology wa...
展开This paper presents a multiobjective optimization to obtain the optimal planning of butanol production, considering the optimal selection of feedstock and the correct ratio of fermentable sugars. This multiobjective methodology was applied during both the fermentation and purification process of butanol. The multiobjective optimization problem considers minimizing the total annual cost and environmental impact as objective function. The economic objective function takes into account the availability of bioresources, the cost of feedstocks, the fermentation conditions, and the separation units. On the other hand, the environmental assessment includes the overall impact measured through the eco-indicator 99 which is based on a life cycle analysis methodology. Both objective functions were applied to a case study for the optimal planning to produce biobutanol in Mexico. After the optimization process, we generated a set of solutions represented by a Pareto curve that identifies a group of optimal solutions for both objectives. Considering the best compromise of both targets, the best solution involves initially a raw material with a moderate content of sugars followed by a separation unit designed as a hybrid separation process. This hybrid process considers the inclusion of a liquid–liquid extraction column followed by three thermally coupled distillation columns.
收起
摘要 :
The isomers of butanol have slightly different properties, which can be exploited to improve combustion characteristics. To investigate the potential of this concept, normal-butanol (nB) and iso-butanol (isoB) were blended togethe...
展开
The isomers of butanol have slightly different properties, which can be exploited to improve combustion characteristics. To investigate the potential of this concept, normal-butanol (nB) and iso-butanol (isoB) were blended together in four different ratios (5% of each, 10% of each, and 7% plus 13% of each in both variations, by volume) with conventional diesel. The experimental data were analyzed via analysis of variance to evaluate significant differences between engine parameters. Brake power for the 5% isoB-5% normal-butanol-90% diesel blend was slightly improved while specific fuel consumption was increased with the increase in all dual blends. The high blend ratios of isoB (10% and 13% isoB) produced higher peak in-cylinder pressures and heat release rates as well as a substantial reduction in carbon monoxide emissions. The higher blend ratios of nB (10% and 13% nB) produced much lower unburnt hydrocarbon emissions because the energy required to crack the C-H bonds of nB is less than that required for isoB. Therefore, the hydrocarbons are more easily oxygenated. A slight reduction was found in NOx emissions when increasing either nB or isoB, with nB being slightly more effective. Therefore, a blend of n- and isoB could be a promising alternative to a single isomer additive (iso/nB) to optimize engine performance.
收起
摘要 :
Due to the complex mechanisms involved in butanol-induced stress response, butanol tolerance phenotype is difficult to engineer even in microorganisms with welldefined genetic backgrounds.We therefore aimed to isolate butanol-tole...
展开
Due to the complex mechanisms involved in butanol-induced stress response, butanol tolerance phenotype is difficult to engineer even in microorganisms with welldefined genetic backgrounds.We therefore aimed to isolate butanol-tolerant microorganisms from environmental samples as potential alternative hosts for butanol production. Soil samples collected were subjected to butanol stress. A microbial strain capable of 2.5-3 % (w/v) butanol tolerance was isolated and identified as Enterococcus faecium by 16S rDNA analysis. The isolate grew readily under both aerobic and anaerobic conditions and was capable of producing butanol anaerobically. In comparison with the obligate anaerobe Clostridium acetobutylicum, the growth under both aerobic and anaerobic conditions of the isolated strain, together with no detection of butyrate and lack of two-phase fermentation suggests different metabolic networks from the obligate anaerobe C. acetobutylicum. Under anaerobic condition, butanol reached up to 0.4 gl-1 in a batch culture without heterologous introduction of butanol biosynthetic pathway. Besides butanol tolerance, the isolated E. faecium IB1 showed high tolerance to 10 % (w/v) ethanol and 3 % (w/v) isobutanol. With distinct features including high butanol tolerance and natural butanol production, the isolated E. faecium IB1 with minimum metabolic engineering can be explored as a potential host for butanol production.
收起
摘要 :
A unique Clostridium species strain G117 was obtained in this study to be capable of producing dominant butanol from glucose. Butanol of 13.50. g/L was produced when culture G117 was fed with 60. g/L glucose, which is ~20% higher ...
展开
A unique Clostridium species strain G117 was obtained in this study to be capable of producing dominant butanol from glucose. Butanol of 13.50. g/L was produced when culture G117 was fed with 60. g/L glucose, which is ~20% higher than previously reported butanol production by wild-type Clostridium acetobutylicum ATCC 824 under similar conditions. Strain G117 also distinguishes itself by generating negligible amount of ethanol, but producing butanol and acetone as biosolvent end-products. A butanol dehydrogenase gene (bdh gene) was identified in strain G117, which demonstrated a ~200-fold increase in transcription level measured by quantitative real-time PCR after 10. h of culture growth. The high transcription suggests that this bdh gene could be a putative gene involved in butanol production. In all, Clostridium sp. strain G117 serves as a potential candidate for industrial biobutanol production while the absence of ethanol ensures an economic-efficient separation and purification of butanol.
收起
摘要 :
Pentanol isomers such as 2-methyl-1-butanol and 3-methyl-1-butanol are a useful class of chemicals with a potential application as biofuels. They are found as natural by-products of microbial fermentations from amino acid substrat...
展开
Pentanol isomers such as 2-methyl-1-butanol and 3-methyl-1-butanol are a useful class of chemicals with a potential application as biofuels. They are found as natural by-products of microbial fermentations from amino acid substrates. However, the production titer and yield of the natural processes are too low to be considered for practical applications. Through metabolic engineering, microbial strains for the production of these isomers have been developed, as well as that for 1-pentanol and pentenol. Although the current production levels are still too low for immediate industrial applications, the approach holds significant promise for major breakthroughs in production efficiency. Keywords Pentanol - 2-Methyl-1-butanol - 3-Methyl-1-butanol - Biofuels
收起
摘要 :
Butanol production from sugarcane juice by Clostridium acetobutylicum ATCC 824 was studied inbatch fermentation at 35 °C and pH 5.0. In a comparative study of fermentation performance between usingglucose medium and sugarcane jui...
展开
Butanol production from sugarcane juice by Clostridium acetobutylicum ATCC 824 was studied inbatch fermentation at 35 °C and pH 5.0. In a comparative study of fermentation performance between usingglucose medium and sugarcane juice medium at the initial reducing sugar concentration of 45 g/L, the totalsolvent concentrations of 16.62 and 7.89 g/L were obtained from the system using glucose medium andsugarcane juice medium, respectively. The inhibition of butanol fermentation at initial glucose concentrationsabove 60 g/L was reported. On the other hand, since sugarcane juice is composed predominantly of sucrose,enhancement of butanol formation and total solvent production were achieved by the utilization of sugarcanejuice medium with the initial sugar concentration of 80-90 g/L. By utilization of sugarcane juice medium at theoptimal sugar concentration (80 g/L), the total solvents of 24.73 g/L (composed of 15.35 g/L butanol, 4.58 g/Lacetone and 4.80 g/L ethanol) with the conversion yield (Yp/s) of 32.67% and 0.26 g/(L·h) production rate wasobtained.
收起
摘要 :
Henry's law constants and infinite dilution activity coefficients of propane, propene, butane, 2-methylpropane, 1-butene, 2-methylpropene, trans-2-butene, cis-2-butene, 1,3-butadiene, dimethyl ether, chloroethane, and 1,1-difluoro...
展开
Henry's law constants and infinite dilution activity coefficients of propane, propene, butane, 2-methylpropane, 1-butene, 2-methylpropene, trans-2-butene, cis-2-butene, 1,3-butadiene, dimethyl ether, chloroethane, and 1,1-difluoroethane in benzene, toluene, o-xylene, m-xylene, p-xylene, and styrene in the temperature range of (250 to 330) K were measured by a gas stripping method, and partial molar excess enthalpies and entropies were evaluated from the activity coefficients. A rigorous formula for evaluating the Henry's law constants from the gas stripping measurements was used for the data reduction of these highly volatile mixtures. The estimated uncertainties are about 2 % for the Henry's law constants and 3 % for the infinite dilution activity coefficients. The Henry's law constants followed the order of increasing Henry's law constant with decreases in the normal boiling point temperature of the liquefied gas except polar gases. In general, the partial molar excess enthalpies and entropies of gases in the aromatics increase with decreases of the polarities of the gases and increasing molecular size of the gases.
收起
摘要 :
Butanol has a great potential as a biofuel and to date a lot of research has been done both in terms of more efficient butanol production as well as in developing product recovery methods. Many of them deal with separation techniq...
展开
Butanol has a great potential as a biofuel and to date a lot of research has been done both in terms of more efficient butanol production as well as in developing product recovery methods. Many of them deal with separation techniques which can be used for selective recovery of acetone, n-butanol and ethanol from model solutions and fermentation broths. This work is a review of techniques used for ABE recovery, such as distillation, adsorption, gas stripping, liquid-liquid extraction, pertraction, membrane distillation, sweeping gas pervaporation, thermopervaporation and vacuum pervaporation. Advantages and disadvantages of using particular methods, examples of applications and integrated processes are also described. (C) 2015 Elsevier Ltd. All rights reserved.
收起
摘要 :
N-butanol, a valued solvent and potential fuel extender, could possibly be produced by fermentation using either native producers, i.e. solventogenic Clostridia, or engineered platform organisms such as Escherichia coli or Pseudom...
展开
N-butanol, a valued solvent and potential fuel extender, could possibly be produced by fermentation using either native producers, i.e. solventogenic Clostridia, or engineered platform organisms such as Escherichia coli or Pseudomonas species, if the main process obstacle, a low final butanol concentration, could be overcome. A low final concentration of butanol is the result of its high toxicity to production cells. Nevertheless, bacteria have developed several mechanisms to cope with this toxicity and one of them is active butanol efflux. This review presents information about a few well characterized butanol efflux pumps from Gram-negative bacteria (P. putida and E. coli) and summarizes knowledge about putative butanol efflux systems in Gram-positive bacteria.
收起
摘要 :
While the continuous depletion of fossil fuel reserves, and rises in fuel demands and prices, have prompted the development of plant-based alternative fuels all over the world, the production of these fuels, especially ethanol, ha...
展开
While the continuous depletion of fossil fuel reserves, and rises in fuel demands and prices, have prompted the development of plant-based alternative fuels all over the world, the production of these fuels, especially ethanol, has become a controversial issue. Merits and demerits of these fuels have been discussed in editorials, conferences and even internet forums. In many discussions, the production of plant-based fuels is criticized, considering the use of agricultural lands. Sometimes, issues such as the high price of biofuels are also raised. In a recent editorial article 'The nonsense of biofuels', the use of plants for energy was heavily criticized; criticism was based on the limited photosynthetic efficiency of plants. The article deplores the way lands are used to harvest plants for energy production. Moreover, the article also disapproves the CO_2 neutrality of these fuels, as most biofuel production operations use fossil fuels to some extent.
收起
This paper presents a multiobjective optimization to obtain the optimal planning of butanol production, considering the optimal selection of feedstock and the correct ratio of fermentable sugars. This multiobjective methodology wa...
展开
原文获取