Highest Yield Of Acetic Acid Research Articles

Regulation on C2-C8 carboxylic acid biosynthesis from anaerobic CO2 fermentation.

Bioconversion of CO2 into liquid fuels or chemicals, preferred medium chain carboxylic acids (caproic and caprylic acid), is an attractive CO2 utilization technology. The present study aims to investigate the effects of different ratios of H2/CO2 on regulating the distribution of C2-C8 carboxylic acid products, while the headspace pressure of 1.5bar was set to amplify the effect of different ratios. The H2/CO2 ratio of 4:1 was more suitable for preparing acetic acid, where the highest acetic acid yield was 17.5g/L. And the H2/CO2 ratio of 2:1 showed excellent chain elongation ability with the highest n-caprylic yield of 2.4g/L. Additionally, the actual H2/CO2 ratios of 4:1 reactors were higher than that in 2:1 may be course chain elongation often accompanied by H2 production. The 16S rRNA genes analysis shows that the genus Terrisporobacter and Coriobacteriales may be related to acetic acid production enriched in H2/CO2 ratio 4:1 reactors, and the genus Clostridium and Paenibacillaceae may associate with the chain elongation pathway were enriched in H2/CO2 ratio 2:1 reactors.

Impact of NaOH on the Hydrothermal Oxidation of Guaiacol for the Production of Value-Added Products

In this study, the impact of NaOH on the hydrothermal oxidation of guaiacol was investigated. It was found that NaOH significantly accelerated the production of formic acid and acetic acid with H2O2 or CuO as the oxidant. With the strong oxidant, H2O2, the highest acetic acid yield (15.73%) and formic acid (5.64%) were obtained at 300 °C for 90 s with NaOH 1.0 mol·L−1 and a 100% H2O2 oxygen supply. In comparison, with CuO as the oxidant, the highest values of acetic acid (13.42%) and formic acid (4.21%) were acquired at 250 °C for 6 h with NaOH 1.0 mol·L−1. Formic acid and acetic acid were generated through the oxidation of intermediates, such as levulinic acid, fumaric acid, maleic acid, etc. These results demonstrated that NaOH catalytic hydrothermal oxidation has potential for the production of value-added chemicals from biomass materials. When CuO is used as the oxidant, this process could also be used as a green method for copper smelting along with the utilization of lignin biomass.

Enhancing the proportion of gluconic acid with a microbial community reconstruction method to improve the taste quality of Kombucha

In this study, a synthetic microbial community (SMC) was used to enhance the proportion of gluconic acid in order to improve the taste quality of Kombucha. The sensory properties of gluconic acid were analyzed for the first time. The proportions of gluconic acid (r = 0.986, p < 0.05) and acetic acid (r = −0.986, p < 0.05) were significantly correlated with the taste score of Kombucha, which was confirmed by the analysis of the sensory properties of organic acid monomers. Starmerella davenportii with the highest yield of ethanol and Gluconacetobacter intermedius with the highest yield of acetic acid were screened and used for microbial community reconstruction to obtain Kombucha with the highest proportion of gluconic acid (74%). In addition, the sensory quality and concentrations of the main functional metabolites in Kombucha fermented by SMC were significantly increased compared with the traditional Kombucha. The microbial community reconstruction method effectively improved the taste quality of Kombucha.

Direct Low-Temperature Oxidative Conversion of Methane to Acetic Acid on Rhodium-Modified Zeolites

Oxidative conversion of methane to acetic acid at 150°С and a pressure of 6.5 MPa with the assistance of carbon monoxide on rhodium-modified ZSM-5 zeolites with different SiO2/Al2O3 molar ratios was studied. A decrease in SiO2/Al2O3 from 300 to 30 leads to a 2.7-fold increase in the acetic acid yield. Such behavior of the catalytic system correlates with an increase in the acidity, primarily with an increase in the density of Bronsted acid sites on the zeolite surface. Introduction of 0.1–0.5 wt % rhodium into the zeolite increases the acetic acid yield by a factor of more than 3. The highest acetic acid yield (0.53 mmol/gcat) is attained on the zeolite with SiO2/Al2O3 = 33 modified with 0.5 wt % Rh. The methane transformation to acetic acid occurs while involving both the acid sites of the zeolite and the sites formed by reactive rhodium particles.

Synergy effects of Al2O3 promoter on a highly ordered mesoporous heterogeneous Rh-g-C3N4 for a liquid-phase carbonylation of methanol

The effects of Lewis acid Al2O3 on Rh-incorporated mesoporous g-C3N4 (AlRh-CN) were investigated to verify an enhanced activity and stability in a liquid-phase carbonylation of methanol. The novel AlRh-CN with 2.0 wt%Al (Al(2)Rh-CN) revealed a higher yield of acetic acid (AA) and methyl acetate (MA) with a small Rh leaching. The enhanced activity on the optimal Al(2)Rh-CN was attributed to the highly dispersed and partially reduced Rh nanoparticles by preserving initial oxidation states as well as by maintaining its stronger interaction on the Al-modified g-C3N4 surfaces. Its superior activity was originated from the highly dispersed Lewis acid Al3+ sites assigned to Al2O3 phases due to an increased reverse esterification reaction rate. The higher activity on the Al(2)Rh-CN was originated from synergy effects such as a larger Lewis acid Al2O3 sites acting as a pillaring material to increase specific surface area of Al(2)Rh-CN and to increase a reverse esterification reaction.

Comparison between the catalytic and photocatalytic activities of Cu/Al2O3 and TiO2 in the liquid–phase oxidation of methanol–ethanol mixtures: Development of a kinetic model for the preparation of catalyst

This work presents the preparation and characterization of copper supported on gamma alumina (γ–Al2O3) as a catalyst and compared with the photocatalytic activity of titania (TiO2) in the oxidation of methanol and ethanol mixtures; the ratio of both alcohols in the mixture was according to the commercial alcoholic beverages. In order to understand the thermal transformations of Cu/Al2O3 catalyst, a kinetic model of its synthesis has been developed and analyzed in terms of the oxidation of the precursor CuCl2∙2H2O impregnated onto Al2O3 to form CuO/Al2O3, and also its reduction to form the metallic copper supported on alumina (Cu/Al2O3) catalyst. The sequence of reactions was considered according to the X–ray diffraction (XRD) at different temperatures and thermal characterizations. The kinetic parameters revealed how the alumina support intervened in some steps to form the catalyst through chemical metal–support interactions. It was also verified that during the chemical changes that the active phase undergoes, its good dispersion is maintained on the support and the activation energy values of the model can predict that these metal–support chemical interactions were also preserved from the salt added to the formation of elementary copper. These kinetic model’s predictions were accurately demonstrated by High–resolution transmission electron microscopy (HRTEM) micrographs and X–ray photoelectron spectra (XPS) techniques, where the appearance of the copper aluminate phase (CuAl2O4) is an evidence of the metal–support interaction, which could have contributed to the elementary copper nanoparticles formation and the catalytic activity as an active phase in the oxidation of alcohols. Cu/Al2O3 catalyst showed a higher yield of acetic acid from ethanol than formic acid from methanol. In comparison, the TiO2 in the photocatalytic oxidation presented a higher yield of formic acid from methanol than acetic acid from ethanol. A similar behavior was observed in the oxidation tests of each alcohol separately, since, the photocatalytic oxidation of methanol, using TiO2, showed nearly the 100% of selectivity in the formation of formic acid from methanol, and the Cu/Al2O3 catalyst exhibited similar results but, in this case, the selectivity towards to acetic acid from ethanol. Stable acetate intermediates detected by FTIR in ethanol oxidation to acetic acid on Cu/Al2O3 showed that this oxidation proceeds via acetaldehyde intermediates.

Fermentation of lignocellulosic sugars to acetic acid by Moorella thermoacetica.

A systematic study of bioconversion of lignocellulosic sugars to acetic acid by Moorella thermoacetica (strain ATCC 39073) was conducted. Four different water-soluble fractions (hydrolysates) obtained after steam pretreatment of lignocellulosic biomass were selected and fermented to acetic acid in batch fermentations. M. thermoacetica can effectively ferment xylose and glucose in hydrolysates from wheat straw, forest residues, switchgrass, and sugarcane straw to acetic acid. Xylose and glucose were completely utilized, with xylose being consumed first. M. thermoacetica consumed up to 62% of arabinose, 49% galactose and 66% of mannose within 72h of fermentation in the mixture of lignocellulosic sugars. The highest acetic acid yield was obtained from sugarcane straw hydrolysate, with 71% of theoretical yield based on total sugars (17g/L acetic acid from 24g/L total sugars). The lowest acetic acid yield was observed in forest residues hydrolysate, with 39% of theoretical yield based on total sugars (18g/L acetic acid from 49g/L total sugars). Process derived compounds from steam explosion pretreatment, including 5-hydroxymethylfurfural (0.4g/L), furfural (0.1g/L) and total phenolics (3g/L), did not inhibit microbial growth and acetic acid production yield. This research identified two major factors that adversely affected acetic acid yield in all hydrolysates, especially in forest residues: (i) glucose to xylose ratio and (ii) incomplete consumption of arabinose, galactose and mannose. For efficient bioconversion of lignocellulosic sugars to acetic acid, it is imperative to have an appropriate balance of sugars in a hydrolysate. Hence, the choice of lignocellulosic biomass and steam pretreatment design are fundamental steps for the industrial application of this process.

Acetic acid production from the hydrothermal transformation of organics in waste liquid crystal display panels

The widespread usage of liquid crystal display (LCD) has led to a large quantity of waste LCD panels, causing serious harm to environment and human health due to toxic substances they contain. Existing literature on this topic mainly deals with recovery of indium and glass from waste LCD panels while the recycling of organics is often neglected. Organics in waste LCD panels are generally treated by incineration and pyrolysis while both can bring about secondary pollution. In this study, the hydrothermal method, an efficient and environment-friendly way, was adopted to treat waste LCD panels with aim of recycling waste organics. Quality and quantity of liquid product (acetic acid) were determined by gas chromatography mass spectrometry and high performance liquid chromatography. Investigated factors included reaction time, temperature, pH value and oxidant supply. The highest yield of acetic acid was 44.91% under the following conditions: a temperature of 300 °C, a reaction time of 5 min, 3 mL of water, and a pH of 10. Additionally, the mechanism of acetic acid production was analyzed.

The effect of the Au loading on the liquid-phase aerobic oxidation of ethanol over Au/TiO2 catalysts prepared by pulsed laser ablation

Gold nanoparticles (NPs) synthesized by pulsed laser ablation of a gold target in water were efficiently deposited on TiO2 (P25) without any post-treatment yielding catalysts with Au loadings up to 10wt%. Regardless of the loading, the Au NPs had a mean diameter of 8nm before and after deposition. The ligand-free Au NPs strongly bind to TiO2 surface oxygen vacancies and maintain a homogeneous distribution with loadings up to 4wt%, while a further increase in Au content up to 10wt% results in additional weakly adsorbed Au NPs. The catalytic tests of the Au/TiO2 samples in the selective oxidation of ethanol in the liquid phase identified an optimal loading of 4wt% resulting in the highest yield of acetic acid, which is ascribed to the homogeneous Au distribution and the adequate occupation of surface oxygen vacancies by strongly bound Au NPs without significant Au sintering during reaction.

Preparation of Acetic Acid by Hydrothermal Catalytic Oxidation Degradation of Cellulose Simulants

A hydrothermal catalytic oxidation degradation process was investigated to improve acetic acid production from cellulose simulants. Filter paper, being a cellulose simulant as the test material, was oxidized in a batch reactor with catalysts. An L16 (45) orthogonal array design (OAD) with five factors at four levels was employed. Of the five, reaction temperature was the most influential for the yield of acetic acid. Afterwards, a series of process optimization experiments were conducted. And a higher yield of acetic acid (28.53%) was obtained under the following conditions: temperature was 320°C; reaction time was 26 min; water consumption was 8 ml; oxidant and catalyst supplied were 0.8% and 0.2% of the raw material respectively.

Hydrothermal Oxidation of Industrial Alkali Lignin for Producing Small Molecular Organic Acids

To control the serious pollution caused by alkaline pulping in paper industry and utilize alkali lignin – the main organic ingredient residing in black liquor, an experimental research on hydrothermal oxidation of industrial alkali lignin for producing small molecule organic acids (mostly formic and acetic acids) was conducted using batch reactors. The results showed that the yields of acetic acid almost entirely increased and then decreased with oxygen supplies, reaction times and reaction temperatures, while the yields of formic acid fell in a narrow range of ~ 4% irrespective of all the hydrothermal conditions. A highest total yield of formic and acetic acids of 23.0% was achieved at the conditions of 300 °C, a 100% oxygen supply and a 60 s reaction time, and at the same time a highest yield of acetic acid of 20.3% was obtained. Based on the products recognized, the main pathways for producing small molecular organic acids, particularly formic and acetic acids were discussed.

Study on fermentation conditions of palm juice vinegar by response surface methodology and development of a kinetic model

Abstract - Natural vinegar is one of the fermented products which has some potentiality with respect to a nutraceutical standpoint. The present study is an optimization of the fermentation conditions for palm juice vinegar production from palm juice ( Borassus flabellifer) wine, this biochemical process being aided by Acetobacter aceti (NCIM 2251) . The physical parameters of the fermentation conditions such as temperature, pH, and time were investigated by Response Surface Methodology (RSM) with 2 3 factorial central composite designs (CCD). The optimum pH, temperature and time were 5.5, 30 °C and 72 hrs for the highest yield of acetic acid (68.12 g / L). The quadratic model equation had a R 2 value of 0.992. RSM played an important role in elucidating the basic mechanisms in a complex situation, thus providing better process control by maximizing acetic acid production with the respective physical parameters. At the optimized conditions of temperature, pH and time and with the help of mathematical kinetic equations, the Monod specific growth rate (

Improving acetic acid production of Acetobacter pasteurianus AC2005 in hawthorn vinegar fermentation by using beer for seed culture

SummaryFruit vinegar can be obtained biologically from the fermentation of fruit wine using species of the genera Acetobacter. However, the productivity of vinegar is generally low because of the inhibition by substrate ethanol and product acetic acid. In this research, the yield of acetic acid, as well as the cell growth, in hawthorn vinegar fermentation was enhanced using beer for seed preparation. The higher yield of acetic acid of AC2005 was because of the higher alcohol dehydrogenase and aldehyde dehydrogenase activities caused by using beer for seed preparation. Furthermore, Acetobacter pasteurianus AC2005 showed acid stability during the fed‐batch fermentation of hawthorn vinegar.

Production of acetic acid by hydrothermal two-step process of vegetable wastes for use as a road deicer

This study aimed to produce acetic acid from vegetable wastes by a new hydrothermal two-step process. A continuous flow reaction system with a maximum treatment capacity of 2 kg/h of dry biomass developed by us was used. Five kinds of vegetables of carrots, white radish, chinese cabbage, cabbage and potato were selected as the representation of vegetable wastes. First, batch experiments with the selected vegetables were performed under the condition of 300°C, 1 min for the first step, and 300°C, 1 min and 70% oxygen supply for the second step, which is the optimum condition for producing acetic acid in the case of using starch as test material. The highest yields of acetic acid from five vegetables were almost the same as those obtained from starch. Subsequently, similar the highest yield of acetic acid and experimental conditions from vegetables were also obtained successfully using the continuous flow reaction system. These results should be useful for developing an industrial scale process.

High performance direct ethanol fuel cell with double-layered anode catalyst layer

Double-layered anode catalyst layers with two reverse configurations, which consist of 45 wt.% Pt 3Sn/C and PtRu black catalyst layers, were fabricated to improve the performance of a direct ethanol fuel cell (DEFC). The in-house 45 wt.% Pt 3Sn/C catalyst was characterized by XRD and TEM. The cross-sectional double-layered anode catalyst layer was observed by SEM. In DEFC performance test and anode linear sweep voltammetry measurement, the anode with double-layered catalyst layer exhibited better catalytic activity for ethanol electro-oxidation than those with single-layered 45 wt.% Pt 3Sn/C and PtRu black catalyst layers. In terms of anode product distribution, the DEFC with double-layered anode catalyst layer showed a higher yield of acetic acid than that with single-layered PtRu black catalyst layer and a higher yield of CO 2 than that with single-layered 45 wt.% Pt 3Sn/C catalyst layer, respectively. These results suggest that the double-layered anode catalyst layer possessed the advantages of both Pt 3Sn/C and PtRu black catalysts for ethanol electro-oxidation, and thus showed a higher ethanol electro-oxidation efficiency and DEFC performance in the practical polarization potential region.

Wet oxidation pretreatment of lignocellulosic residues of sugarcane, rice, cassava and peanuts for ethanol production

AbstractWet oxidation (WO) pretreatment of sugarcane bagasse, rice hulls, cassava stalks and peanut shells was investigated. WO was performed at 195 °C for 10 min, with 2 g kg−1 of Na2CO3 and under either 3 or 12 bar of oxygen. Oxygen pressure and the type of raw material used had a major effect on the fractionation of the materials, formation of sugars and by‐products, and cellulose enzymatic convertibility. Cellulose content in the solid fraction increased after pretreatment of all materials, except rice hulls. The greatest increase, from 361 g kg−1 to almost 600 g kg−1, occurred for bagasse. The solubilisation of individual components was different for each material. Bagasse xylan was solubilised to a large extent, and 45.2% of it was recovered as xylose and xylo‐oligosaccharides in the liquid fraction. In the prehydrolysates of rice hulls around 40% of the original glucan was recovered as gluco‐oligosaccharides, due to hydrolysis of starch contained in grain remains. The formation of by‐products was modest for all the materials, but increased with increasing oxygen pressure. The highest yield of acetic acid (34–36 g kg−1 of raw material) and furfural (0.7–1.8 g kg−1) occurred for bagasse. The pretreatment enhanced the enzymatic convertibility of cellulose giving the best result (670.2 g kg−1) for bagasse pretreated at the highest oxygen pressure. However, for the other materials the pretreatment conditions were not effective in achieving cellulose conversions above 450 g kg−1. Some enzymatic conversion of xylan was observed. Copyright © 2007 Society of Chemical Industry

A New Hydrothermal Process for Producing Acetic Acid from Biomass Waste

Calcium/magnesium acetate (CMA) is known as a low corrosive and environmentally friendly deicer, but is too expensive in comparison to conventional salt deicers. CMA's high cost is mostly attributed to the acetic acid required to produce CMA. This study aimed to develop a hydrothermal reaction system to produce acetic acid from biomass waste. Based on the results obtained using a batch reactor, a continuous flow reaction system with a maximum treatment capacity of 2 kg h −1 of dry biomass was constructed. Results showed that the highest yield of acetic acid and the conditions for obtaining the highest yield of acetic acid in this continuous flow reaction system were almost the same as those obtained in batch experiments not only for usual wet oxidation but also for the new two-step reaction. Results obtained so far indicate that the continuous flow reaction system developed in this study has the expected fundamental performance to produce acetic acid for both usual wet oxidation and the two-step reaction.

Wet oxidation of lignin model compounds and acetic acid production

To investigate the wet oxidation (WO) pathways of acetic acid production from lignin, 2-methoxyphenol, 2,6-dimethoxyphenol, and phenol, as lignin model compounds were oxidized in a batch reactor at a temperature of 300°C, residence times of 10–60 seconds and oxygen supplies of 50–100%. Oxidation experiments using major intermediate products in WO of lignin model compounds, as reactants were also performed.Based on the intermediate products identified by GC/MS and HPLC, WO pathways of lignin model compounds are discussed. Acetic acid production by WO of lignin model compounds is also discussed. It was found that the yield of acetic acid for lignin model compounds was lower, at about 9%. The reason that lignin model compounds cannot produce a large amount of acetic acid may be contributed to the fact that the oxidation of phenols easily forms unsaturated dicarboxylic acids with 4 carbon atoms, which cannot produce a large amount of acetic acid. However, saturated dicarboxylic acids and glutaconic acid can produce a higher yield of acetic acid. Therefore, it is possible to increase the yield of acetic acid from lignin by controlling reaction pathways to increase the formation of saturated dicarboxylic acids and glutaconic acid.

Methane oxidation to acetic acid catalyzed by Pd 2+ cations in the presence of oxygen

Synthesis of acetic acid from methane catalyzed by Pd 2+ cations dissolved in sulfuric acid was investigated to determine the effects of reaction conditions and the mechanism. Acetic acid yield was found to be a strong function of CH 4 and O 2 partial pressures. High O 2/CH 4 ratio and high total pressure delivered the highest yield of acetic acid (14.2 turnovers of Pd 2+) and the highest retention of Pd 2+ in solution (96%). Byproducts were sulfur containing compounds (most notably methyl bisulfate) and CO x , but the acetic acid selectivity was maximized (82%) by lowering the reaction temperature. Methane is activated by Pd(OSO 3H) 2, forming (CH 3)Pd(OSO 3H). CO, generated from the oxidation of methyl bisulfate, inserts into the CH 3 Pd bond creating a (CH 3CO)Pd(OSO 3H) species. Reaction of this complex with H 2SO 4 produces acetic acid. Pd 2+ is reduced to Pd 0 during the oxidation of methyl bisulfate or CO, and Pd 0 is reoxidized to Pd 2+ by H 2SO 4 and O 2.

Production of acetic acid and glycerol from salted and dried whey in a membrane cell recycle bioreactor

The use of salted whey (liquid by-product from the dairy industry containing 7.5% NaCl) as a substrate for either acetic acid or glycerol production was investigated using two yeast strains. One was Kluyveromyces fragilis. The other organism (strain L) can utilize whey lactose that was isolated from waste whey (disposal stream). 8% NaCl, 3% Na 2SO 3 and pH 8.5 at 32°C were the optimum operating conditions for maximum acetic acid production (25.84 g l −1) from salted whey using immobilized cells of yeast strain L. Also, strain L gave a higher yield of acetic acid (0.497 g acetic acid per gram lactose) as compared with K. fragilis (0.322 g acetic acid per gram lactose). 1% Na 2SO 3 at pH 7 and whey supplemented with peptone and malt extract were the optimal conditions for maximum batch glycerol production (13.2 g l −1) from salted whey using immobilized cells of K. fragilis. The extreme values, 18.7 g l −1 for glycerol concentration and 39.78 for the percent yield of glycerol (based on sugar concentration) in a membrane cell recycle bioreactor were higher than those obtained for the immobilized cell batch reactors (13.2 g l −1 and 28, respectively).