Conversion Of Butyric Acid Research Articles

Esterification of butyric acid with n‐butanol: Kinetic study using experimental data and modeling

AbstractPresent study involves the investigation of the esterification kinetics between butyric acid and n‐butanol. This reaction was conducted in a batch reactor, utilizing homogeneous methanesulfonic acid (MSA) catalyst. Response surface methodology (RSM) was conducted prior to the kinetic study using “Design Expert; version‐11.0” for finding the causal factors influencing the conversion of butyric acid. Most important factors identified with their limits against conversions (during optimization of the process using RSM) were taken up to critically analyze the effect of them on butyric acid conversion. Concentration and activity‐based model of the process were proposed assuming second order reversible reaction scheme using homogeneous MSA catalyst. During the study of non‐ideal behavior of the system, UNIFAC model was adapted for assessing the activity coefficients of species present in equilibrated liquid phase. Experimental data were used to evaluate kinetic and thermodynamic parameters such as rate constants, activation energy, enthalpy, and entropy of the system. The endothermic nature of esterification was confirmed by positive value of enthalpy obtained. The effect of various levels of causal variables like temperature (60–90°C), catalyst concentration (0.5–1.5 wt.%), and molar ratio of n‐butanol to butyric acid (1–3) on conversion kinetics of butyric acid was investigated during transient and equilibrium phase of the reaction. It has been observed that molar ratio of butanol to butyric acid has the highest influence on the conversion. The rate equation derived offered a kinetic and thermodynamic framework to the generated data. It also exhibits a notable degree of conformity of predicted data to the experimental ones and effectively characterizes the system across different reaction temperatures, reactant molar ratio, and catalyst concentration.

Optimization of methane production from co-digestion of citrus agro-industrial waste in a two-stage system: Investigation of the effects of organic matter concentration and alkalinization

The essential oils in citrus waste poses challenges for the anaerobic digestion application to energy recovery from these wastes due to the potential to inhibit the bioprocess. The two-stage system is a practical alternative to overcome these limitations of anaerobic co-digestion of citrus peel waste and wastewater. This study proposes to overcome drawbacks associated with the use of these substrates in anaerobic digestion by separating the phases, performing parameters optimization of the methanogenic stage. To obtain optimized conditions for the methanogenic stage, the Rotational Central Composite Design (RCCD) and Response Surface Methodology (RSM) were applied, evaluating the effects of diluting the Fermentation Reactor Content (FRC) of the first stage (35.7%–100%) and alkalinization (up to 0.60 g sodium bicarbonate.gCOD−1), in methane production and organic matter removal. Values from 2100.4 to 6320.6 mLCH4.L−1 were obtained in the experimental design assays, with no inhibition identified by the high substrate concentration, nor by the limonene content (1.5–5.0 mg.L−1). Lower dilution of the fermentation reactor content (90%–100%) resulted in higher accumulated methane production, while the variation in the alkalinization did not imply significant effects on this response. The optimized condition for maximum production potential was obtained with 99.3% of fermentation reactor content and 0.58 gNaCHO3.gCOD−1, reaching a production of 6549.7 mLCH4.L−1, with organic matter removal (rCOD) of 87.1%, and 58.6% of reduction in solid waste content. For this condition, acetogenic metabolism predominance was observed, in the conversion of butyric acid and propionic acid into acetic acid. In the analysis of the microbial community of the optimized condition assay, a high relative abundance of hydrolytic and acidogenic bacteria (AUTHM297, Lachnospiraceae, and Hungateiclostridiaceae) was observed, as well as methanogenic archaea related to acetoclastic, hydrogenotrophic, and methylotrophic methanogenesis (Methanoregula, Methanolinea, Methanomassiliicoccus, Candidatus Methanomethylicus, and Methanofolis).

Ultrasound enhanced butyric acid-lauric acid designer lipid synthesis: Based on artificial neural network and changes in enzymatic structure

Ultrasound is a green technology for intensifying enzymatic reactions. In this study, an ultrasonic water bath with equipment parameters of 28 kHz, 1750.1 W/m2, 60% duty cycle was used to assist the synthesis of butyric acid-lauric acid designer lipid (BLDL), which was catalyzed by Lipozyme 435. A convincing three-layer feed-forward artificial neural network (ANN) model was established (R2 = 0.949, RMSE = 4.759, ADD = 7.329) to accurately predict the optimal parameters combination, which was described as 13.72 mL reaction volume, 15.49% enzyme loading, 0.253 substrate molar ratio (tributyrin/lauric acid), 56.58 °C reaction temperature and 120 min reaction time. The ultrasonic assistance increased actual butyric acid conversion rate by 11.38%, and also enhanced the consumption rate of tributyrin and lauric acid during the reaction. Meanwhile, the esterification activity of Lipozyme 435 was enhanced and its effectiveness up to 6 cycles. Structurally, ultrasound assistance significantly disrupted the secondary structure of the Lipozyme 435: reduced the content of α-helices, increased the content of β-sheet and β-turn. In addition, sonication caused an increase in crevice and micro-damage on the surface of the immobilized enzyme. In conclusion, low-intensity ultrasound at 28 kHz improved the synthesis efficiency of BLDL, which was scientifically predicted by ANN model, and the change of enzyme structure may be the vital reason for ultrasound enhanced reaction. However, the effect of ultrasound on immobilized enzymes’ activity needs to be further explored.

Synthesis of perbutyric acid with amberlyst catalyst in a continuous microreactor

Perbutyric acid is an important organic compound, which is effective against bacterial spores, viruses, and other microbes as a disinfectant and used in chemical processing and bleaching. Perbutyric acid is having large applications in oil and chemical industries because of its -goodoxidizing properties. The present article reports about the continuous production of Perbutyric acid in a Teflon spiral capillary microreactor. Butyric acid and hydrogen peroxide are used as reactants in the presence and absence of heterogeneous catalyst amberlyst15 hydrogen. Microreactors provide large surface area and safely handle unstable or dangerous materials. In microreactors, heat and mass transfer rates are higher and rapid mixing occurs because of their unique transport capabilities. So the present investigation focuses on understanding the effect of different parameters like temperature, the concentration of hydrogen peroxide and catalyst on the formation of Perbutyric acid. The results revealed the optimum conditions for 56.2% conversion of butyric acid at 90 °C temperature with 30 w/v% of hydrogen peroxide, 6 wt% of concentration of catalyst and 8 min of residence time. It was observed that the reaction rate increased with increase in hydrogen peroxide concentration. Further it could be concluded that the solid catalyst provides higher activity, which leads to the highest formation of Perbutyric acid in short residence times.

Optimisation of Propane Production from Hydrothermal Decarboxylation of Butyric Acid Using Pt/C Catalyst: Influence of Gaseous Reaction Atmospheres

The displacement and eventual replacement of fossil-derived fuel gases with biomass-derived alternatives can help the energy sector to achieve net zero by 2050. Decarboxylation of butyric acid, which can be obtained from biomass, can produce high yields of propane, a component of liquefied petroleum gases. The use of different gaseous reaction atmospheres of nitrogen, hydrogen, and compressed air during the catalytic hydrothermal conversion of butyric acid to propane have been investigated in a batch reactor within a temperature range of 200–350 °C. The experimental results were statistically evaluated to find the optimum conditions to produce propane via decarboxylation while minimizing other potential side reactions. The results revealed that nitrogen gas was the most appropriate atmosphere to control propane production under the test conditions between 250 °C and 300 °C, during which the highest hydrocarbon selectivity for propane of up to 97% was achieved. Below this temperature range, butyric acid conversion remained low under the three reaction atmospheres. Above 300 °C, competing reactions became more significant. Under compressed air atmosphere, oxidation to CO2 became dominant, and under nitrogen, thermal cracking of propane became significant, producing both ethane and methane as side products. Interestingly, under a hydrogen atmosphere, hydrogenolytic cracking propane became dominant, leading to multiple C–C bond cleavages to produce methane as the main side product at 350 °C.

Light olefins from biomass-derived butyric acid by tandem deoxygenation reactions

The feasibility of using a series of Zn-Zr mixed oxides for the gas-phase production of light olefins from butyric acid, a platform molecule derived from biomass processing, was investigated. These materials with Zn/Zr molar ratios of 0.11–0.66 were prepared by incipient wetness impregnation of Zn on Zr(OH)4 and characterized by BET, XRD and CO2 and NH3 TPD. At full butyric acid conversion conditions, a range of C2-C7 olefins was obtained. The molecular weight of the olefin pool as well as the total olefin yield depend on the catalyst composition and experimental conditions. The catalyst acid-base properties can be tuned for optimal olefin yield by generating a high number of Zn-O-Zr species and oxygen vacancies resulting from incorporation of Zn2+ to the ZrO2 lattice. The best olefin yield coincides with the catalyst showing the highest acid site number and moderate basic properties. Also, the reaction temperature and reactor contact time were varied to improve the olefin yield. A total olefin yield of 60.7% was obtained with a catalyst having 11.1 wt% Zn (Zn/Zr=0.25) at 723 K and 835 h g cat./mol. Ethylene (52%) and isobutene (33%) were the main components of the olefin fraction, the other 15% being pentene, isohexene and heptene. The olefin yield can be further improved to 65.8% by increasing the contact time to 1500 h g cat./mol. Butyric acid transformation proceeds with the intermediate formation of different ketones (heptanone, pentanone and acetone), each of which gives rise to a particular olefin. Isobutene forms through tandem butyric acid ketonization/C-C bond rupture by McLafferty rearrangement/aldol condensation/breaking of the aldol adduct reactions. Ethylene is generated during the McLafferty step. The pathways toward other olefins may involve deoxygenation steps such as reduction of unsaturated bonds by in-situ generated hydrogen species, followed by dehydration. Acetic and propionic acids, formed in minor amounts, participate in further tandem sequences. No catalyst deactivation was observed during standard and extended catalytic tests because water co-feeding and hydrogen generation prevent heavy product formation and active site loss.

On the selectivity of butyric acid photoreforming over Au/TiO2 and Pt/TiO2 by UV and visible radiation: A combined experimental and theoretical study

Commercial TiO2 (P25) and synthesized TiO2 nanorods (TNR) decorated by either Pt or Au nanoparticles, were used in the butyric acid photoreforming (BAPR) and characterized by XRD, TEM/EDS, porosimetry, and DRS. The selectivity toward a wide range of products (H2, CO2, alkanes, alkenes, organic acids) was investigated under three different irradiation sources (UV, vis, UV + vis). Butyric acid conversion (XBA) and the selectivity to H2 (SH2), propane (SC3H8), propene (SC3H6) are suggested to be mainly affected by holes in the TiO2 valence band, electrons over the noble metal, electrons in the TiO2 conduction band, and holes over the metal, respectively. The highest XBA and SH2 were recorded with Pt/P25 under UV, whereas the largest SC3H8 and SC3H6 were observed with Au/TNR under UV + vis. First-principles calculations were performed with the aid of density functional theory, to investigate the energetic properties of metal/oxide structures and further elucidate the photocatalytic mechanism observed in the experiments.

Start-up phase optimization of two-phase anaerobic digestion of food waste: Effects of organic loading rate and hydraulic retention time

The effects of organic loading rate (OLR) and hydraulic retention time (HRT) on the dynamics of acidogenic and methanogenic processes in two-phase anaerobic digestion (TPAD) of food waste (FW) were investigated to determine the start-up operational conditions. Seven arrangements of TPAD systems under mesophilic conditions were evaluated, each containing one acidogenic reactor and one methanogenic reactor. The work analyzed two HRTs (2 and 3 days) and four OLRs (2, 3, 4 and 5 kgVS.m−3.d−1). The 2D5KG system obtained VS and COD removal of 68% and 72%; SMP of 273 Lmethane.kg.VS−1. The 3D4KG system obtained VS and COD removal of 70 and 66%; SMP of 252 Lmethane.kg.VS−1. Valeric acid predominated in the acidogenic reactor in both HRT and OLR evaluated, followed by butyric acid. In the methanogenic reactor, the main methane production route was the butyric acid conversion into acetic acid and finally methane. Higher OLR benefits the methane production. The microbiological profile indicated the pathway of methanogenesis by acetoclastic methanogenesis. The canonical correlation analysis allowed to verify that the groups are independent and, therefore, the variables analyzed in the acidogenic reactor have an influence on the methanogenic reactor.

Behaviour of pancreatic lipase enzyme during recyclization when synthesizing butyl butyrate in non-aqueous media

Aromatic substances are widely applied in the creation of fragrances for cosmetic, detergent and food products, as well as medical preparations for external use. Environmentally friendly enzymes obtained using green chemistry methods are of particular value. Therefore, the enzymatic synthesis of esters of aromatic aliphatic acids and aromatic alcohols is of great practical interest. This approach has significant advantages over chemical methods, since it is carried out at low temperatures without the formation of byproducts, thus requiring no special purification techniques. Although the cost of enzyme preparations is rather high, immobilized enzymes can be used repeatedly and continuously. In the present work, we investigate the possibility of using non-immobilized freeze-dried lipase (Lipase from porcine pancreas, Type 11) for repeated esterification of butyl alcohol with butyric acid. The synthesis was carried out in hexane. The completeness of the process was controlled by titration of the residual acid with aqueous alcoholic alkali in the reaction medium. The resulting enzyme preparation was separated from the reaction mixture and reused with a new portion of the substrate. It is shown that the obtained enzyme can be used for more than 10 cycles. It was found that, starting from the second cycle, the enzyme activity increases depending on its concentration in the medium. In addition, the butyric acid conversion increases by 6–180% reaching the initial level only after the 10th cycle. The unusual effect of increasing the enzymatic activity of lipase in recycles can be explained by both the phenomenon of autocatalysis, i.e. activation of the enzyme by water released as a result of esterification, and structural features of the active site of pancreatic lipase.

Enzymatic Esterification under High-pressure CO2 Conditions for in situ Recovery of Butyric Acid from Anaerobic Fermenters

Butyric acid, a short chain carboxylic acid with diverse usages, is produced by Clostridia fermentation. In the industrial scale production of butyric acid, its separation and recovery from fermentation broth requires energy-intensive processes. To reduce the product recovery costs, it is necessary to convert butyric acid into a chemical with a much higher partition coefficient in the hydrophobic extractants than butyric acid. Butyl butyrate, with an excellent partition coefficient to tetradecane, can be produced by the enzymatic conversion of butyric acid via esterification. Moreover, butyl butyrate can be used as a valuable fuel source and additive in the food, cosmetic, and pharmaceutical industries. Novozyme 435, Candida antarctica lipase B immobilized on acrylic resin, and tetradecane were used as the enzyme and extractant, respectively. A high-pressure CO2-facilitated reactor was used to temporarily drop the pH of the fermentation broth so that the enzymatic reaction could be activated. The in situ removal of butyric acid and simultaneous production of butyl butyrate were processed continuously during fermentation. To optimize the enzymatic reaction, it was necessary to maintain a temperature of 40°C at 50 bar and an optimal molar ratio of substrate. In the extractive fermentation, 11.6 g/L butyl butyrate was produced with a productivity of 0.77 g/L/h from butyrate produced through fermentation. This process is expected to be able to extract carboxylic acids with more diverse carbon lengths in ester form.

Hydrogen and Propane Production From Butyric Acid Photoreforming Over Pt-TiO2.

Photocatalysis is a promising technology from economic, energetic, and ecological points of view because it takes advantage of solar light. Hence, it is one of the investigated green routes to produce hydrogen from renewable energy resources. Butyric acid (BA) is largely present in wastewater and as an intermediate product in anaerobic digestion and therefore it is an inexpensive resource, which can be converted to valuable chemicals. In this work, photoreforming of butyric acid (BAPR) under UV light in aqueous suspensions of platinum-modified titanium dioxide-based catalysts is reported for the first time. Titania nanotubes (TNT) synthesized and calcined at different temperatures (300, 400, 500°C) and commercial TiO2 (P25), decorated with platinum nanoparticles, have been tested and characterized through different techniques including X-ray powder diffraction, UV-vis diffuse reflectance and photoluminescence spectroscopy, transmission electron microscopy, BET and porosimetry analysis. The main identified products of the BAPR were H2, propane, CO2 and several organic acids (e.g., pentanoic and 3-methylhexanoic acid). It has been found that the morphology and crystallinity of the photocatalysts affected dramatically their optical properties and, consequently, the reaction rate and the product distribution. Specifically, the highest conversion of BA (XBA) and selectivity toward H2 (SH2) was recorded with P25-Pt (XBA = 26.9%, SH2 = 47.2% after 8 h of irradiation). TNT-400-Pt showed the highest selectivity toward propane (SC3H8 = 16.1%) with XBA = 23.4% and SH2 = 36.2%. The activity results in conjunction with the characterization of the catalysts highlighted that the main factor affecting the activity in terms of XBA and generation of H2 was the crystallinity, and in particular the presence of rutile phase in TiO2, whereas SC3H8 appears to increase when the electron-holes recombination is lower.

PtII -Catalyzed Hydroxylation of Terminal Aliphatic C(sp3 )-H Bonds with Molecular Oxygen.

The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C-H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2 . We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON<10). In this regard, essential reaction parameters affecting the overall activity were identified, along with specific additives to attain catalyst stability at longer reaction times. Notably, deactivation by reduction to Pt0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C-H bonds with O2 is presented.

The isolation, identification, physiological property of pig-isolate Clostridium butyricum LY33 using lactic acid and its effects on intestinal function of weaned piglets

To research the isolation, identification, physiological property of Clostridium butyricum strain using lactic acid from pig and its effects on intestinal function of weaned piglets, the C. butyricum strain LY33 was isolated with an anaerobic culture method from the intestinal contents of healthy piglets fed with lactic acid bacteria fermented feeds. The strain LY33, which was identified as Clostridium butyricum according to morphological, physiological, biochemical and 16S rRNA sequence analyses, was found to be efficient in lactic acid utilisation and butyric acid conversion. Strain LY33 was non-toxic and resistant to heat, gastric acid and bile salts. It utilised lactic acid efficiently when cultured in LADM liquid medium (Lactic acid decomposition medium) under the initial conditions of pH 5.5 and a lactic acid concentration of 132 mmol. Strain LY33 also had inhibitory effects on Escherichia coli, Salmonella, and other pathogens. Conversely, it promoted the growth of lactic acid bacteria. Compared to the control group fed the basal diet, the indexes of intestinal function of piglets in the experimental group fed the strain LY33 preparation improved markedly, and for most of these indicators, a difference at p < .05 was achieved.HighlightsIn this study, one Clostridium butyricum strain LY33 was isolated from intestinal contents in healthy piglets which were fed lactic acid bacteria fermented feed, and was identified as Clostridium butyricum based on its morphological, physiological, biochemical and 16S rRNA sequence analysis.The strain LY33 had better ability of utilising lactic acid, had a certain inhibitory effect on Escherichia coli, Salmonella and other pathogens, can promote the growth of lactic acid bacteria, and the preparation of Clostridium butyricum had a good effect on improving the intestinal function of weaned piglets.

Feasibility of zeolites in converting butyric acid into propylene for biorefineries

ABSTRACTThe biorefinery has been recognized as a new industry to produce both energy and chemical materials such as olefins and BTX from renewable resources. In this context the conversion of butyric acid over zeolites was investigated for establishing a new production route of propylene. Propylene was mainly generated by decarbonylation and dehydration of butyric acid. Our study proved that H-ZSM-5 (750) and silicalite were the best industrial catalyst among the tested ones. For H-ZSM-5 (750), the selectivity of propylene reached 64.2 C% and the ratio of the yield for propylene to theoretical yield (75 C%) became 85.6%.

Enhancing simultaneous response and amplification of biosensor in microbial fuel cell-based upflow anaerobic sludge bed reactor supplemented with zero-valent iron

The development of a convenient and sensitive sensor such as a microbial fuel cell (MFC) to monitor the operation of upflow anaerobic sludge blanket (UASB) is indispensable. However, the biosensor’s properties were affected due to excessive acidification and suffocation of the electron transport. In this study, zero-valent iron (ZVI) was applied to restrain excessive acidification and improve the sensing performance. According to the results, the response rate of electrical signal accumulated with the addition of ZVI compared to the control reactor. As well as the electrical signal amplified and the subsidence rate maximum reached 0.059V/h with 30mg/L ZVI added that 883% higher than the control one during the stage (COD concentration 500mg/L–1000mg/L). With the electrochemical analysis, the internal resistance of ZVI-UASB-MFC decreased and redox activity promoted effectively with ZVI added. During the overloading phase, the fractional content of butyric acid changed from 53% to 31%, while that of acetic acid rose from 18% to 39% after 30mg/L ZVI addition. These results indicated that adding ZVI to the digestion could retard excessive acidification by promoting butyric acid conversion and accumulating direct interspecies electron transfer simultaneous for enhancing the biosensor’s performance. According to the Fe2+ and Fe3+ of effluent were 2.25mg/L and 0.39mg/L with 50mg/L ZVI addition, moderate amount of ZVI was effective for system and safety to the environment. It might helpfully provide a promising way to enhance biosensing.

Kinetics of Enzymatic Synthesis of Cinnamyl Butyrate by Immobilized Lipase.

This work illustrates the enzymatic synthesis of cinnamyl butyrate by esterification of butyric acid and cinnamyl alcohol. Experiments were performed to study the various operating parameters such as molar ratio, enzyme concentration, temperature, and speed of agitation. Also, the suitable kinetic model for esterification reaction was predicted and the various kinetic parameters were determined. It has been observed that the experimental results agree well with the simulated results obtained by following the ping-pong bi-bi mechanism with dead-end inhibition by both the substrate acid and alcohol. The highest 90% conversion of butyric acid was observed after 12h at the following reaction conditions: substrate molar ratio 1:2 (butyric acid/cinnamyl alcohol), temperature 50°C, enzyme loading 2% (with respect to the weight of the substrates), and agitation speed 250rpm. Diffusional mass transfer limitations between substrate and enzyme surface do not show significant effect on reaction kinetics. Enzyme reusability study reveals that it retains 85% of its catalytic activity after five consecutive cycles.

Process intensification of esterification reaction for the production of propyl butyrate by pervaporation

Pervaporation is a membrane separation process vastly used for purification in chemical and allied industries. Esterification reaction can beintensified and enhanced by coupling with pervaporation reactor (PVR). Polyvinyl alcohol (PVA)/polyethersulfone (PES) composite membranewas used for the pervaporation coupled esterification reaction study. Esterification of butyric acid with n-propanol was taken as a model reactionfor the study and to test the performance of pervaporation reactor. Catalyst p-toluenesulfonic acid was used for the esterification reaction. Theeffects of various reaction parameters on conversion of butyric acid such as reaction temperature, initial molar ratio of n-propanol to butyric acid,catalyst loading and reaction time were studied. Experimental results show that the increase of temperature, initial molar ratio, and catalystconcentration enhance the conversion of butyric acid considerably. The highest conversion of 96.41% was obtained at temperature 353 K, molarratio of 2 and catalyst loading of 2.5%w/w at reaction time of 420 minutes. PVA/PES membrane used in the experiments shows the good activityand hydrophilicity and plays a vital role for enhancing the conversion by selectively removing water. Pervaporation coupled esterification showsthe better choice over the conventional route for the production of esters. This technique is environment friendly and energy intensified approachas it reduces pollution and energy requirement.

Process intensification of esterification reaction for the production of propyl butyrate by pervaporation

Abstract Pervaporation is a membrane separation process vastly used for purification in chemical and allied industries. Esterification reaction can be intensified and enhanced by coupling with pervaporation reactor (PVR). Polyvinyl alcohol (PVA)/polyethersulfone (PES) composite membrane was used for the pervaporation coupled esterification reaction study. Esterification of butyric acid with n-propanol was taken as a model reaction for the study and to test the performance of pervaporation reactor. Catalyst p-toluenesulfonic acid was used for the esterification reaction. The effects of various reaction parameters on conversion of butyric acid such as reaction temperature, initial molar ratio of n-propanol to butyric acid, catalyst loading and reaction time were studied. Experimental results show that the increase of temperature, initial molar ratio, and catalyst concentration enhance the conversion of butyric acid considerably. The highest conversion of 96.41% was obtained at temperature 353 K, molar ratio of 2 and catalyst loading of 2.5%w/w at reaction time of 420 minutes. PVA/PES membrane used in the experiments shows the good activity and hydrophilicity and plays a vital role for enhancing the conversion by selectively removing water. Pervaporation coupled esterification shows the better choice over the conventional route for the production of esters. This technique is environment friendly and energy intensified approach as it reduces pollution and energy requirement.

Heterogeneous Char Based Solid Acid Catalysts from Brown Bin Waste to Create a Green Process for the Production of Butyl Butyrate

Brown bin waste can be used for the production of butanol and butyric acid by employing fermentation techniques. This study focuses on heterogeneous solid acid catalyst obtained from solid residues derived from a fermentation process and applied for the efficient conversion of butyric acid to butyl butyrate. The solid acid catalysts were produced by sulfonation of char obtained from the slow pyrolysis of brown bin waste digestate at various temperatures (400, 500 and 600 °C). The catalysts possessing the highest surface area and acid density were shown to have the highest catalytic activity and thus performed better giving competitive results to Amberlyst 15 and H2SO4 (96 % yield), after 24 h reaction. Increasing the catalyst loading was found to positively affect the yields of butyl butyrate, especially at early reaction time. Realistic kinetic parameters were formulated for the optimum char based solid acid catalyst using two power law models.

Synergism and effect of high initial volatile fatty acid concentrations during food waste and pig manure anaerobic co-digestion

Anaerobic co-digestion of food waste (FW) and pig manure (PM) was undertaken in batch mode at 37°C in order to identify and quantify the synergistic effects of co-digestion on the specific methane yield (SMY) and reaction kinetics. The effects of the high initial volatile fatty acid (VFA) concentrations in PM on synergy observed during co-digestion, and on kinetic modelling were investigated. PM to FW mixing ratios of 1/0, 4/1, 3/2, 2/3, 1/4 and 0/1 (VS basis) were examined. No VFA or ammonia inhibition was observed. The highest SMY of 521±29ml CH4/gVS was achieved at a PM/FW mixing ratio of 1/4. Synergy in terms of both reaction kinetics and SMY occurred at PM/FW mixing ratios of 3/2, 2/3 and 1/4. Initial VFA concentrations did not explain the synergy observed. Throughout the study the conversion of butyric acid was inhibited. Due to the high initial VFA content of PM, conventional first order and Gompertz models were inappropriate for determining reaction kinetics. A dual pooled first order model was found to provide the best fit for the data generated in this study. The optimal mixing ratio in terms of both reaction kinetics and SMY was found at a PM/FW mixing ratio of 1/4.