Butanol production in a sugarcane biorefinery using ethanol as feedstock. Part I: Integration to a first generation sugarcane distillery

Butanol production from renewable resources has been increasingly investigated over the past decade, mostly for its use as a liquid biofuel for road transportation, since its energy density is higher than that of ethanol and it may be used in gasoline driven engines with practically no changes, but also for use as a feedstock in the chemical industry. Most of the research concerning butanol production focuses on the ABE process (fermentation of sugars into a mixture of acetone, butanol and ethanol), which has several drawbacks regarding microorganism performance and product inhibition. An alternative to ABE fermentation, ethanol catalytic conversion to butanol can produce a higher quality product with less retrofitting than ABE in existing ethanol producing facilities. There are different types of catalysts for the chemical conversion of ethanol to butanol being developed in laboratory scale, but their actual use in a sugarcane processing plant has never before been assessed. Butanol production from ethanol in a sugarcane biorefinery, using data from the literature, was assessed in this study; different technological alternatives (catalytic routes) were evaluated through computer simulation in Aspen Plus (including production of electricity, sugar, ethanol and other products) and economic and environmental impacts were assessed. Results indicate that vapor-phase catalysis presents higher potential for industrial implementation, and commercialization of butanol for use as a chemical feedstock has an economic performance similar to that of current, optimized first generation sugarcane distilleries, but can potentially contribute to cost reduction that will allow commercialization of butanol as a fuel in the future.     

Butanol production in a sugarcane biorefinery using ethanol as feedstock. Part II: Integration to a second generation sugarcane distillery

Production of second generation ethanol and other added value chemicals from sugarcane bagasse and straw integrated to first generation sugarcane biorefineries presents large potential for industrial implementation, since part of the infrastructure where first generation ethanol is produced may be shared between both plants. In this context, butanol from renewable resources has attracted increasing interest, mostly for its use as a drop in liquid biofuel for transportation, since its energy density is greater than that of ethanol, but also for its use as feedstock in the chemical industry. In this paper, vapor-phase catalytic production of butanol from first and second generation ethanol in a sugarcane biorefinery was assessed, using data available from the literature. The objective is to evaluate the potential of butanol either as fuel or feedstock for industry, taking into account economical/environmental issues through computer simulation. The results obtained show that, although promising, butanol sold as chemical has a limited market and as fuel presents economic constraints. In addition, investments on the butanol conversion plant could be an obstacle to its practical implementation. Nevertheless, environmental assessment pointed out advantages of its use as fuel for road transportation, if compared with gasoline in terms of global environmental impacts such as global warming.     

Product diversification to enhance economic viability of second generation ethanol production in Brazil: The case of the sugar and ethanol joint production

Commercial simulator Aspen Plus^® was used to simulate the conventional processes of the autonomous distillery producing ethanol and the joint production of sugar and ethanol. Changes in conventional processes were evaluated to increase electricity and second generation ethanol production using bagasse fine fraction composed by parenchyma cells (P-fraction). The evaluated processes were thermal and water integrated. The results indicated that the integration of the second generation process to the conventional processes was possible after thermal and water integration. The economic analysis showed that the second generation process integrated to the joint production presented lower payback time, 2.3 years, in comparison with this process integrated to the autonomous distillery, 4.7 years. Due to the high enzyme costs, the cases without second generation ethanol production presented higher economic viability. Product diversification, as sugar and ethanol production in the same site, lowered the impact of enzymes cost on the payback time of second generation process, showing that the integration of the second generation ethanol production process to the conventional sugar production process could be a step to cellulosic ethanol production feasibility in sugarcane mills.     

Restructuring the processes for furfural and xylose production from sugarcane bagasse in a biorefinery concept for ethanol production

This study consisted in restructuring the processes for furfural and xylose production from sugarcane bagasse in a biorefinery concept for the residues utilization on ethanol production.The dilute acid hydrolysis conditions for furfural or xylose production were firstly established on laboratory scale and then reproduced on a 10-L bench reactor fed with direct steam. The furfural production was maximum when using a 1.25% (w/w on dry fiber) H₂SO₄ solution at 175 °C during 40 min; whereas the xylose production attained the best results when using a 1% (w/v) H₂SO₄ solution in a solid/liquid ratio of 1/4 (g/mL), and the sugarcane bagasse impregnated with the acid solution during 24 h prior to the hydrolysis reaction. Enzymatic hydrolysis of the residual solid material obtained from furfural or xylose production was performed with yields of 17.4 and 9.3 g glucose/100 g initial raw material, respectively. Subsequently, ethanol was produced from the residual solid materials obtained from furfural and xylose production with yields of 87.4% and 89.3% respectively, based on the maximum theoretical value (0.51 g ethanol per g glucose in hydrolysate). Such results demonstrated the possibility of restructuring the processes for furfural or xylose production to obtain solid residues able to be used as substrate for ethanol production by fermentation.     

Syngas production from chemical looping reforming of ethanol over iron-based oxygen carriers:Theoretical analysis and experimental investigation

Chemical looping reforming (CLR) is a recent trend for syngas production,which has several merits compared to the conventional manner.One of the most important issues for CLR is to find low-cost mate-rial as oxygen carriers,so iron is a promising candidate.This paper contributes to testing the thermody-namic ability of iron-based oxygen carrier for chemical looping reforming of ethanol (CLRE).Iron thermodynamically investigated in temperature 100-1300 ℃ and excess oxygen number (Φ) 0-4.It was found that the temperature and Φ have an apparent effect on the gaseous composition produced from the process.Increases in temperature within the range of 100-1300 ℃ enhanced syngas generated and reduced coke formation and CH4.Whereas,increased Φ,particularly at higher temperatures,had also enhanced syngas production as well as reduced coke formation.However,increasing Φ for values beyond one had decreased syngas and not significantly reduced coke deposition.Moreover,an experimental investigation was carried out in a fixed bed reactor for more in-depth verification of iron ability as an oxy-gen carrier through using magnetite ore (mainly Fe3O4).It found that the effect of temperature on syngas production was consistent with that calculated thermodynamically,as syngas increased with raising the temperature through the CLRE.     

Coal-derived methanol for hydrogen vehicles in China: Energy,environment, and economic analysis for distributed reforming

Hydrogen is considered an ideal energy carrier, but the storage and efficient delivery of hydrogen to vehicles still remain a challenging problem currently. This study analyzes the possibilities of using methanol as a hydrogen carrier in China, based on the distributed methanol reforming technology at forecourt refueling stations. A detailed well-to-tank life cycle analysis was applied to the hydrogen production from coal-derived methanol at refueling stations (onsite methanol pathway) from energy, environmental and economic performance aspects, followed by comparisons between the onsite pathway and conventional ones on the delivery cost of hydrogen, energy efficiency, and CO₂ emissions. The study shows that a coal-derived methanol pathway with distributed reforming utilities is well suited for China's specific energy situation, therefore it could play a key role in the transition process to a hydrogen economy in China.     

Experimental study and simulation of syngas generation from methane in the Pulsed Compression Reactor

The Pulsed Compression Reactor (PCR) promises to be a compact, economical and energy efficient alternative to conventional chemical reactors. In this article, the production of synthesis gas using the Pulsed Compression Reactor is investigated. This is done experimentally as well as with simulations. The experiments are done by means of a single shot reactor, which replicates a representative single reciprocation of the Pulsed Compression Reactor with great control over the reactant composition, reactor temperature and reciprocation path. Simulations are done with an ideally stirred tank reactor model using detailed chemical kinetics. Experiments are done with different mixtures and at various initial temperatures. Simulation results show very good agreement with the experimental data, and give great insight into the reaction processes that occur within the one cycle.     

First and second generation biodiesels spray characterization in a diesel engine

Potential improvement on exhaust emissions, biodegradability and the possibility to reduce dependence on fossil fuel resources has led to an increasing interest on the use of biofuels for transport application. In this work, the analysis of the spray behaviour of first and second generation biodiesel in a Euro 5, common rail transparent diesel engine has been performed. GTL, SME and RME fuels have been used in blends at 100% and 50% in volume; while reference fuel consisted of commercial diesel. Two engine operating conditions of the NEDC have been selected: 1500 rpm at 2 bar of brake mean effective pressure (BMEP) and 2000 rpm at 5 bar BMEP. The injection process has been accurately studied, and the influence of the combustion process on the spray behaviour has been taken into account. Typical jets parameters such as penetration and cone angles have been detected and a comparison with theoretical models of Hiroyasu and Siebers has been performed. A new correlation for the forecasting of the jet penetration has been obtained starting from Hiroyasu equations. An image-based method has been applied for the identification of the phenomena that control the spray behaviour during its evolution in the combustion chamber.First generation biodiesels, pure and blends, show longer penetration with respect to the reference fuel at both the engine speed analysed. Moreover, they penetrate for a longer time in the combustion chamber, because of the longer energizing time set, so impingement phenomena can be observed. On the other hand, the second generation biodiesels penetrate less than reference one, due to its lower density, but also because the combustion of the pilot injection causes an increase of pressure that obstructs the penetration in the combustion chamber. Finally, a good agreement between the breakup times computed by means of the Hiroyasu and Siebers correlations and the ones from the experimental data has been found.     

Relative importance of semiochemicals from first and second trophic levels in host foraging behavior ofAphidius ervi

The responses of femaleAphidius ervi to odors from a host food plant (Vicia faba), host aphids (Acyrthosiphon pisum), nonhost aphids (Aphis fabae), and aphid-plant complexes were investigated in a specially designed wind tunnel and a Y-tube olfactometer. In single-target (no-choice) and two-target (dual-choice) experiments, plant volatiles played a crucial role in the host foraging behavior ofA. ervi. The odor from theA. pisum-plant complex elicited the strongest responses byA. ervi females, followed by the odor from plants previously damaged by the feeding ofA. pisum. There was a significantly weaker response to odor fromA. pisum in the absence of the plant and to undamaged plants. Similarly, mechanically damaged plants and plants infested with the nonhost aphidA. fabae did not elicit strong responses. A plant that had been damaged byA. pisum and subsequently washed with distilled water was as attractive as an unwashed, previously infested plant.Aphidius ervi probably overcomes the reliability-detectability problem by selectively responding to herbivore-induced, volatile, semiochemical cues emitted by the first trophic level and by distinguishing between the volatiles induced by host and nonhost aphids.     

高浓度乙醇连续发酵振荡过程中代谢通量分析及诱发机理

在利用普通酿酒酵母进行高浓度乙醇连续发酵的实验中,发现了一种长周期、高振幅的振荡现象。利用流式细胞仪测定了振荡周期不同时点的细胞周期分布,表明这种特殊的振荡现象和酵母细胞周期的同步化不相关。对一个完整振荡周期中不同时点的代谢通量分析,发现胞内碳通量在代谢网络中的分布也呈现出和胞外残糖、乙醇和生物量浓度类似的振荡过程。分析酵母细胞代谢活性与胞外发酵体系乙醇浓度的时程关系,表明酵母细胞对乙醇抑制的延迟反应是诱发这种振荡行为的主要因素,胞内海藻糖积累与乙醇生成同步,进一步支持了这一观点。     

Relative importance of infochemicals from first and second trophic level in long-range host location by the larval parasitoidCotesia glomerata

Recently parasitoids were hypothesized to encounter a reliability-detectability problem relating to chemical stimuli from the first and second trophic level, when searching for hosts. The relative role of infochemicals originating from the host,Pieris brassicae (second trophic level), and its food plant, cabbage (first trophic level), have been investigated with respect to long-range host location by the larval parasitoidCotesia glomerata. Flight-chamber dual choice tests showed that uninfested cabbage plants are least attractive to female wasps. Host larvae and their feces were more attractive than clean plants but far less attractive than artificially damaged and herbivore-damaged plants. The plant-host complex, with host larvae actively feeding on the plant, was the most attractive odor source for the parasitoids. The data indicate that one of the solutionsC. glomerata uses to solve the reliability-detectability problem is to respond to infochemicals that are emitted from herbivore-damaged plants. Whether these infochemicals are herbivore-induced synomones that are produced by the plant remains to be demonstrated. Infochemicals emitted by the herbivore or its by-products are of little importance in the foraging behavior ofC. glomerata.     

Long-term fate of PVC products and their additives in landfills

The development of sustainable products requires not only the consideration of production processes. Rather, strategies and concepts for the end-of-life management of post-consumer products play an important role for their legal compliance, public acceptance and commercial competitiveness as well. With respect to the waste management options for polyvinyl chloride (PVC) products, the currently prevalent disposal in landfills was among the subjects of debate about environmental issues. A material and substance flow analysis was conducted to estimate the quantitative relevance of PVC products and their constituents in municipal solid waste. Landfill simulation assays demonstrated the long-term behaviour of PVC products and the fate of additives under landfill conditions. The methods of an integrated assessment and possible approaches towards life cycle management are discussed.