Experimental and kinetic modeling study of PAH formation in methane coflow diffusion flames doped with n-butanol

In order to understand the interactions between butanol and hydrocarbon fuels in the PAH formation, experimental and kinetic modeling investigations were combined to study methane laminar coflow diffusion flames doped with two inlet mole fractions of n-butanol (1.95% and 3.90%) in this work. Mole fractions of flame species along the flame centerline were measured using synchrotron VUV photoionization mass spectrometry. A detailed kinetic model of n-butanol combustion, extended from a recent published n-butanol model, was provided in this work to reproduce the fuel decomposition and the formation of benzene and PAHs in the investigated flames. Numerical simulations were performed with laminarSMOKE code, a CFD code specifically conceived to handle large kinetic mechanisms. The simulation results were able to follow the observed effects of n-butanol addition from the experimental results. In particular, unsaturated hydrocarbons, especially C6–C16 aromatics, were predicted satisfactorily. The reaction flux analysis revealed that benzene precursors, especially C3 radicals, increase significantly with increasing inlet mole fraction of n-butanol. This enhances the formation of phenyl and benzyl radicals, which are important PAH precursors. Reactions of benzyl, phenyl radicals and benzene with C2–C3 species are the major formation pathways for indene and naphthalene. And PAHs with more carbon atoms are dominantly formed from naphthyl and indenyl radicals.     

Modulation of crude glycerol fermentation by Clostridium pasteurianum DSM 525 towards the production of butanol

High production yields and productivities are requisites for the development of an industrial butanol production process based on biodiesel-derived crude glycerol. However, impurities present in this substrate and/or the concentration of glycerol itself can affect the microbial metabolism. In this work, the effect of crude glycerol concentration on the production of butanol and 1,3-propanediol (1,3-PDO) by Clostridium pasteurianum DSM 525 is studied. Also, the effect of acetate and butyrate supplementation to the culture medium and the culture medium composition are evaluated. The results showed a marked effect of crude glycerol concentration on the product yield. The competitive nature of butanol and 1,3-PDO pathways has been evident, and a shift to the butanol pathway once using higher substrate concentrations (up to 35 g l⁻¹) was clearly observed. Butyrate supplementation to the culture medium resulted in a 45% higher butanol titre, a lower production of 1,3-PDO and it decreased the fermentation time. Acetate supplementation also increased the butanol titre but the fermentation was longer. Even though glycerol consumption could not be increased over 32 g l⁻¹, when the concentrations of NH₄Cl and FeCl₂ were simultaneously increased, the results obtained were similar to those observed when butyrate was supplemented to the culture medium; a 35% higher butanol yield at the expense of 1,3-PDO and a shorter fermentation. The results herein gathered suggest that there are other factors besides butanol inhibition and nutrient limitation that affect the glycerol consumption.     

Investigation of Ionic Liquids for the Separation of Butanol and Water

Abstract

With the continual rise in the cost of fossil fuel based energy, research into economic and sustainable alternatives is of increasing importance. One significant source of increased cost and demand is the consumption of fossil fuels for automotive fuels. While ethanol has received the most attention as a fuel additive; butanol could be a better direct fuel alternative owing to its physical properties and energy value when compared to ethanol. Commercial butanol is nearly exclusively produced from petroleum feedstocks currently; however, some recent interest has begun to refocus on its generation via fermentation. Unfortunately, this production is limited due to the nature of the process and the use of energy-intensive separation techniques. Ionic liquids are novel green solvents that have the potential to be employed as an extraction agent to remove butanol from the aqueous fermentation media. A hurdle to this potential is the limited availability of solubility data for ionic liquids. This research investigates the phase behavior of two ionic liquids, butanol, and water. Additionally, issues related to the implementation of the investigated ionic liquids are discussed.     

Conversion of jet fuel and butanol to syngas by filtration combustion

Replacing batteries with fuel cells is a promising approach for powering portable devices; however, hydrogen fuel generation and storage are challenges to the acceptance of this technology. A potential solution to this problem is on-site fuel reforming, in which a rich fuel/air mixture is converted to a hydrogen-rich syngas. In this paper, we present experimental results of the conversion of jet fuel (Jet-A) and butanol to syngas by non-catalytic filtration combustion in a porous media reactor operating over a wide range of equivalence ratios and inlet velocities. Since the focus of this study is the production of syngas, our primary results are the hydrogen yield, the carbon monoxide yield, and the energy conversion efficiency. In addition, the production of soot that occurred during testing is discussed for both fuels. Finally, an analysis of the potential for these fuels and others to be converted to syngas based on the present experiments and data available in the literature is presented. This study is intended to increase the understanding of filtration combustion for syngas production and to illuminate the potential of these fuels for conversion to syngas by non-catalytic methods.     

Hydrogen-rich gas production for solid oxide fuel cell (SOFC) via partial oxidation of butanol: Thermodynamic analysis

Butanol partial oxidation for hydrogen-rich gas production has been studied by Gibbs free energy minimization method. The optimum conditions for hydrogen-rich gas production are identified: reaction temperatures between 1115 and 1200 K and oxygen-to-butanol molar ratios between 1.6 and 1.7 at 1 atm. Under the optimal conditions, complete conversion of butanol, 93.07%–96.56% yield of hydrogen and 94.02%–97.55% yield of carbon monoxide could be achieved in the absence of coke formation. The butanol partial oxidation with O₂ is suitable for providing hydrogen-rich fuels for Solid Oxide Fuel Cell (SOFC). Higher pressures have a negative effect, but inert gases have a positive effect, on the hydrogen yield. Coke tends to form at lower temperatures and lower oxygen-to-butanol molar ratios.     

Optical resolution of n-butyl d- and l-lactates using immobilized lipase catalyst

n-Butyl d- and l-lactates (BuDLa and BuLLa) were incubated with immobilized lipase. ¹H-NMR showed that BuDLa reacted to oligomers, while BuLLa did not react. A mixture containing 90.4% of BuLLa and 9.6% of BuDLa was incubated with the enzyme for 72 h, then distilled. The purity of BuLLa increased to 98.6%.     

An experimental and mechanistic study on the laminar flame speed,Markstein length and flame chemistry of the butanol isomers

Laminar flame speeds and Markstein lengths for n-butanol, s-butanol, i-butanol and t-butanol at pressures from 1 to 5 atm were experimentally measured in a heated, dual-chamber vessel. Results at all pressures show that n-butanol has the highest flame speeds, followed by s-butanol and i-butanol, and then t-butanol. Results further show that the reduced Markstein length measured for n-butanol as compared to other isomers is a flame thickness effect, and that all four isomers have similar Markstein numbers, which is the appropriate nondimensional parameter to quantify flame stretch. Computation and flame chemistry analysis were performed using two recently published kinetic models on butanol isomers by Sarathy et al. and Ranzi et al., respectively. Comparison shows the former model satisfactorily agrees with the present results while agreement of the latter is less satisfactory. Based on reaction path analysis the major differences of the two models on fuel cracking pathway were identified. It is concluded that the primary reason for the lowered flame speed of s-butanol, i-butanol and t-butanol is that they crack into more branched intermediate species which are relatively stable, such as iso-butene, iso-propenol and acetone. This indicates that the general rule that fuel branching reduces flame speed for hydrocarbons can also be applied to alcohols, and that the fundamental reason for this generality is that in alcohols CO has similar bond energy to the CC bond while OH has similar bond energy to the CH bond.     

水溶液中丁醇在树脂上的吸附

水溶液中丁醇在树脂上的吸附杨立荣姚善泾朱自强（浙江大学化工系，杭州３１００２７）焦朝晖（浙江临海制药厂，临海３１７０００）关键词丁醇吸附吸附热力学１前言发酵产物在发酵液中浓度一般在２０～１００（ｇ／Ｌ）之间［１］，如丙酮／丁醇发酵液中总溶剂浓度为１８...     

微波辐射条件下HY沸石催化对甲酚与叔丁醇的烷基化反应

以对甲酚为原料,以不同硅铝物质的量比的HY为催化剂,在微波辐射条件下与叔丁醇进行烷基化反应合成2⁃叔丁基对甲酚（2⁃TBC）。以二甲苯为溶剂,考察微波辐射时间和功率、反应温度、原料物质的量比、溶剂种类等工艺参数对反应的影响。结果表明,以硅铝物质的量比为5.4的HY沸石为催化剂,n（叔丁醇）/n（对甲酚）=1.3,微波辐射功率为700 W,在140 ℃下微波反应40 min,微波辐射加热时间只需油浴加热反应时间的1/8,而对甲酚转化率提高3倍左右,对甲酚转化率最高可达72.91%;目标产品2⁃TBC产率可达68.08%,选择性达到93.32%;副产物为醚化产物对甲基苯叔丁基醚（TBPE）和二烷基化产物2,6⁃二叔丁基对甲酚（2,6⁃DTBC）     

Bioconversion of barley straw and corn stover to butanol (a biofuel) in integrated fermentation and simultaneous product recovery bioreactors

In these studies concentrated sugar solutions of barley straw and corn stover hydrolysates were fermented using Clostridium beijerinckii P260 with simultaneous product recovery and compared with the performance of a control glucose batch fermentation process. The control glucose batch fermentation resulted in the production of 23.25 g L⁻¹ ABE from 55.7 g L⁻¹ glucose solution resulting in an ABE productivity and yield of 0.33 g L⁻¹ h⁻¹ and 0.42, respectively. The control reactor (I) was started with 62.5 g L⁻¹ initial glucose and the culture left 6.8 g L⁻¹ unused sugar due to butanol toxicity resulting in incomplete sugar utilization. Barley straw (BS) hydrolysate sugars (90.3 g L⁻¹) resulted in the production of 47.20 g L⁻¹ ABE with a productivity of 0.60 g L⁻¹ h⁻¹ and a yield of 0.42. Fermentation of corn stover (CS) hydrolysate sugars (93.1 g L⁻¹) produced 50.14 g L⁻¹ ABE with a yield of 0.43 and a productivity of 0.70 g L⁻¹ h⁻¹. These productivities are 182–212% higher than the control run. The culture was able to use 99.4–100% sugars (CS & BS respectively) present in these hydrolysates and improve productivities which were possible due to simultaneous product removal. Use of >100 g L⁻¹ hydrolysate sugars was not considered as it would have been toxic to the culture in the integrated (simultaneous fermentation and recovery) process.