Addition Of Methanol Research Articles

Extraction of rhodium from supported liquid-phase hydroformylation catalysts with supercritical carbon dioxide

The continuous extraction of the rhodium inventory in supported liquid-phase (SLP) catalytic materials utilized in the hydroformylation (HyFo) of 1-butene was investigated by supercritical carbon dioxide (scCO2). Optimization of extraction efficiency involved varying parameters such as temperature (90 and 120 °C), pressure (10, 20 and 30 MPa), and the addition of methanol as a polar co-feed to the extraction medium (0–20 vol%). The results underscored the critical role of methanol in facilitating extraction, as experiments employing pure scCO2 yielded no rhodium recovery. Furthermore, extraction performance demonstrated sensitivity to temperature and pressure adjustments during the process. Notably, the use of 10 vol% methanol at 120 °C and 30 MPa achieved complete rhodium extraction from the grained SLP materials, which was identified as the optimum extraction condition. This study highlights the potential for scaling up in-situ rhodium extraction processes within HyFo production plants based on SLP catalysts, emphasizing significant implications for industrial applications.

N‐Arylphenothiazines and N,N‐Diarylphenazines as Tailored Organophotoredox Catalysts for the Reductive Activation of Alkenes

AbstractA small library of N‐arylphenothiazines, N‐arylbenzo[b]phenothiazines and N,N‐diarylphenazines has been synthesized as strongly reducing organophotocatalysts without the need for sacrificial reagents or electrochemistry. Their opto‐electronic properties and their suitability as organophotoredox catalysts for the efficient activation of olefins was investigated using the addition of methanol to α‐methylstyrene as a model reaction. The findings were supported by DFT calculations. Three photocatalysts were identified that allowed quantitative yields with 10 mol % catalyst loading and 20 h irradiation by a 365 nm LED. The catalyst loading was gradually reduced to 0.5 mol % and the irradiation time was reduced to only 20 min. These experiments revealed that N,N‐diisobutyl‐4′‐(10H‐phenothiazin‐10‐yl)‐[1,1′‐biphenyl]‐4‐amine is the most efficient photocatalyst among the N‐arylphenothiazines. This chromophore combines high electron density introduced by the diisobutylamino phenyl group with high absorptivity at 365 nm caused by the phenylene bridge to the phenothiazine core. In an attempt to shift the excitation wavelength into the visible light range for selectivity and sustainability purposes (potential use of sunlight as a light source), N‐arylbenzo[b]phenothiazines N,N‐diarylphenazines were designed that exhibit a red‐shifted and broad absorbance shoulder into the visible range, but only N,N‐diarylphenazines allow photocatalysis and the one‐electron activation of alkenes by visible light (450 nm LED).

A detailed chemical kinetic model for methanol and ammonia co-oxidation under hydrothermal flames: Reaction mechanism and flame characteristics

A detailed chemical kinetic model for ammonia and methanol co-oxidation under hydrothermal flames was established with pressure and thermodynamic corrections. Simulation model was validated by comparing with experimental temperature rise, and methanol and ammonia removal efficiencies. Species evolutions, reaction paths, and reaction sensitivities for pure ammonia combustion, and ammonia and methanol co-oxidation under hydrothermal flames were analyzed. Ammonia concentration begins to decrease only when methanol is consumed in a certain amount in the ammonia and methanol co-oxidation under hydrothermal flames, indicating the addition of methanol promotes the degradation of ammonia. Moreover, reaction heat is more conductive to ignition and the conversion of ammonia to nitrogen than active free radicals provided from methanol. The ignition delay time presents a minimum as a function of ammonia/methanol concentration ratio, with the minimum values of ignition delay time present at approximately ωNH3/ωCH3OH = 1 for different methanol concentrations. Higher preheating temperatures favor more NOX but less N2O formation, while higher ammonia concentrations favor both NOX and N2O formations. The presence of ammonia increases the laminar flame speed and permits a lower extinction temperature, indicating the mixture of methanol and ammonia can improve the stability of hydrothermal flames.

Low loading of Pt on MoB Constructed by microwave Quasi-solid approach with solvent Regulation for hydrogen evolution reaction

The interaction between metal nanoclusters and the carrier can enhance the electron transfer rate to optimize the hydrogen evolution reaction (HER) performance, but the common synthesis approaches often lead to metal particle agglomeration, and then blocking active sites. Herein, highly-dispersed Pt nanoclusters supported onto molybdenum boride (MoB) is developed through microwave approach with various solvent to regulate the catalytic performance. The synthesized electrocatalyst with the addition of methanol (Pt/MoB-M) exhibits excellent electrocatalytic performance towards HER with low overpotential (13 mV at 10 mA cm−2), small Tafel slope (24 mV dec−1), and high mass activity (10.06 A/mgPt at 50 mV). This work presents a novel approach to prepare highly-efficient electrocatalysts for renewable energy-related applications of non-carbon supported low loading of precious metals.

Optimization of oil extraction from Melia azedarach fruits using methanol-modified SC-CO2 for highly efficient biodiesel production using a modified LAC catalyst

A highly efficient oil extraction method including modified Supercritical carbon dioxide (SC-CO2) with co-solvents was applied for oil extraction from Melia azedarach fruits and then using a modified LAC (luffa activated carbon) catalyst, the oil was converted to biodiesel for the first time. The effect of pressure (22–30 MPa), temperature (40–80 °C), extraction time (0–240 min) and co-solvent (methanol and n-hexane) were determined on SC-CO2 extraction to obtain the optimum condition. The optimum extraction conditions for Melia azedarach oil corresponded to a pressure of 30 MPa and temperature of 40 °C at 180 min using methanol as of co-solvent. The maximum yield was obtained by addition of methanol as co-solvent in an amount of 10 %, w/w. The methanol- modified SC-CO2 extraction oil yield was 43 % (w/w) and the oil yield by n-hexane-modified SC-CO2 extraction was 38 %, while the oil yield obtained by pure SC-CO2 extraction was 32 %. Then, the effect of catalysts LAC-NH2 and LAC-N(Et)2 as safe, economical, free-metal, and less time-consuming heterogeneous catalysts was investigated on biodiesel production from extracted oil. The results revealed that the optimum yields of 98 % was obtained for biodiesel production using 2 wt% of LAC-NH2 catalyst at the reaction conditions of oil to methanol ratio of 1:6, reaction temperature of 60 °C, and reaction time of 3 h.

Effect of subfractions of Allium mongolicum Regel methanolic extract on the proliferation of HepG2 and MCF-7 cells

The aerial part of Allium mongolicum Regel (AMR) which is abundant in the southeastern regions of Mongolia, is used as a food spice. When the crude extracts of this plant were prepared and used for the experiments different biological activities were observed because the extracts contained many polar to nonpolar compounds. This study aimed to prepare subfractions from the crude methanolic extract of AMR and to compare their antiproliferative effects on human cancer cells (HepG2, and MCF-7 cells). The methanolic extracts of AMR were fractionated into six subfractions (methanol, hexane, dichloromethane, ethyl acetate, butanol, and water residue) by solvent–solvent partitioning. The total phenolic content (TPC) was measured by the Folin-Ciocalteu assay. The antioxidant activity of the sub-fractions was determined via DPPH⋅ and ABTS⋅+ assays. Subfraction antiproliferative activity on human cancer cells, HepG2 and MCF-7 cells, was determined by MTS assay. Subfractions showed completely distinct antioxidant and antiproliferative activities (p < 0.001). The highest TPC was in the ethyl acetate fraction (165.4 ± 0.5 mg GAE/g), and the TPC following the addition of dichloromethane, butanol, and methanol. The lowest two were in the n-hexane and water residue fractions. The ethyl acetate fraction showed the highest free radical scavenging activity in both the DPPH⋅ and ABTS⋅+ assays (660.0 ± 5.24 µM TE/g dw the DPPH⋅ assay; 312.7 ± 5.6 µM TE/g dw the ABTS⋅+ assay). The dichloromethane subfraction affected HepG2 cell proliferation and reduced viable cancer cells. Additionally, the dichloromethane and hexane subfractions affects MCF-7 cell proliferation by reducing the number of viable cancer cells. Subfraction methanolic extract by solvent partitioning is helpful for identifying biologically active compounds that show antiproliferative activity.

Effect of Methanol and Polymer Additives on Large-Volume Dual Preconcentration by Isotachophoresis and Stacking (LDIS) in Straight-Microchannels

Effect of Methanol and Polymer Additives on Large-Volume Dual Preconcentration by Isotachophoresis and Stacking (LDIS) in Straight-Microchannels

Enhancement on the lipase activity of M. circinelloides by ARTP mutagenesis for biodiesel production from woody plant oil

The objective is to enhance lipase activity of Mucor circinelloides via atmospheric and room temperature plasma (ARTP). ARTP was employed to treat spores of M. circinelloides for the selection of high lipase producers. With an irradiation time of 100 s at a lethal rate of 95 %, 18 mutants with higher lipase activity were initially selected. Measurements of the lipase activity revealed that a mutant strain LA-26 was characterized by a steady hereditary stability with lipase activity increase to 376.7 U/g. Moreover, the mutant LA-26 was immobilized as whole-cell biocatalyst used in solvent-free system to produce biodiesel. Response surface methodology (RSM) was used to optimize the reaction parameters. With the addition of 8 % biocatalyst, 10 % water content (w/w) and the stepwise addition of methanol (methanol to oil ratio of 4:1), the highest biodiesel (FAME) yield up to 98 % was achieved within 48 h. Immobilized LA-26 can be used for repeated batches, maintaining 70 % FAME yield after 6 cycles. The identified mutant strain LA-26 exhibits great potential for biodiesel production.

Influence of ethanol–gasoline–hydrogen and methanol–gasoline–hydrogen blends on the performance and hydrogen knock limit of a lean-burn spark ignition engine

This study investigates the effects of ethanol–gasoline and methanol–gasoline blends on the performance of a lean-burn spark ignition engine and the hydrogen knock limit of the engine with hydrogen-enriched fuel. The experimental setup includes liquid in-cylinder fuel injection and hydrogen port induction. Ethanol and methanol are blended with pure gasoline up to 50% by volume (20%, 35% and 50%) and all fuels are drip-fed with hydrogen until combustion knock is detected in step size of 2LPM. The hydrogen knock limit extension is achieved with ethanol–gasoline and methanol–gasoline blends and is further extended by spark-timing retardation. Retarded spark timing and ethanol–methanol blended fuels reduce the brake thermal efficiency, brake mean effective pressure, and peak in-cylinder pressure. The cyclic variation increases with ethanol and methanol addition and decreases with spark-timing retardation and hydrogen enrichment. Unlike hydrogen enrichment, ethanol and methanol addition reduce the CO2 and NOx emissions but increase the CO emission.

EFFECT OF SNO2 POROUS STRUCTURE ON ITS OPTICAL AND PHOTOELECTROCHEMICAL PROPERTIES IN WATER AND WATER-METHANOL SOLUTIONS

Tin(IV) oxide is a wide-gap semiconductor material that is widely used in photooxidation reactions of organic compounds. However, the relationship between energetic and photoelectrocatalytic properties in the oxidation of small organic molecules has not yet been sufficiently explored. In this work, a series of tin oxides were synthesized using hydrothermal, sol-gel, and template methods. Polystyrene spheres with a size of 250 nm, as well as cetyltrimethylammonium bromide, were used as templates. X-Ray diffraction, low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy and diffuse reflectance spectroscopy methods were used to study the structure, surface composition, optical and energy characteristics. Using photoelectrochemical methods, the potentials of the conduction band and valence band were determined, and photocurrents in aqueous and aqueous-methanol solutions were studied depending on electrode polarization. It is shown that the preparation method (sol-gel or hydrothermal) does not affect the position of energy bands, while the use of a template during synthesis leads to an increase in the average pore diameter in the samples and an increase in photocurrent values in the presence of methanol. It has been established that for template-synthesized samples, the magnitude of photocurrents in a water-methanol mixture increases with an increase in the valence-band potential. The sample prepared by the hydrothermal method using a template showed the highest photocurrent values both in the background electrolyte (17.3 μA/cm2) and in the presence of methanol (26 μA/cm2), compared to the sample prepared without using a template in the electrolyte with the addition of methanol (7.6 μA/cm2) and without it (7.8 μA/cm2).

Generation of citric acid-hyperproducers independent of methanol effect by high-level expression of cexA encoding citrate exporter in Aspergillus tubingensis.

Methanol reportedly stimulates citric acid (CA) production by Aspergillus niger and A. tubingensis; however, the underlying mechanisms remain unclear. Here, we elucidated the molecular functions of the citrate exporter gene cexA in relation to CA production by Aspergillus tubingensis WU-2223L. Methanol addition to the medium containing glucose as a carbon source markedly increased CA production by strain WU-2223L by 3.38-fold, resulting in a maximum yield of 65.5 g/L, with enhanced cexA expression. Conversely, the cexA-complementing strain with the constitutive expression promoter Ptef1 (strain LhC-1) produced 68.3 or 66.7 g/L of CA when cultivated without or with methanol, respectively. Additionally, strain LhC-2 harboring two copies of the cexA expression cassette produced 80.7 g/L of CA without methanol addition. Overall, we showed that cexA is a target gene for methanol in CA hyperproduction by A. tubingensis WU-2223L. Based on these findings, methanol-independent CA-hyperproducing strains, LhC-1 and LhC-2, were successfully generated.

New approaches for solubilization of phosphate rocks through solid-state fermentation by optimization of oxalic acid production

This study explores the enhancement of phosphate rock (PR) solubilization through solid-state fermentation (SSF) by optimizing oxalic acid production using Aspergillus niger. Key process parameters, including the use of agro-industrial by-products (sugarcane bagasse (SCB), wheat bran (WB), soybean bran (SB)), pH levels, sucrose supplementation, and methanol addition, were systematically evaluated through sequential experimental designs. The results identified SCB and SB in a 1:1 ratio as the most effective substrate. Remarkably, the inclusion of methanol (7 %) and sucrose (0.5 %) resulted in a 3-fold increase in oxalic acid production. Under these optimized conditions, significant phosphorus solubilization of Bayóvar, Itafós, and Registro PRs was achieved, with Bayóvar rock releasing up to 12.1 g/kgds of soluble P (63.8 % efficiency). Additionally, the SSF process effectively released organic phosphorus from the agro-industrial substrates. These findings hold promise for advancing the bio-based economy and developing future industrial biofertilizers.

Optimization of biological nitrogen removal in full-scale municipal WWTPs using activated sludge model simulation

The study evaluated the most efficient biological nitrogen removal (BNR) process in four full-scale municipal wastewater treatment plants (WWTPs) by using BioWin, a simulation software based on the activated sludge model (ASM). A series of experiments were conducted to determine the kinetic and stoichiometric parameters for the ASM. Results indicated that autotrophic maximum specific growth rates in the studied WWTPs were generally higher compared to previous findings, likely due to their low COD/N ratios, emphasizing the importance of local parameterization. Continuous water quality monitoring in each plant was employed to validate the model. Dynamic simulation results indicated that the error remained within an acceptable range, with a mean relative error of less than 20%, confirming the reliability of ASM parameters derived from batch experiments. Subsequently, various operational scenarios were analyzed to determine the optimal BNR process for each plant, considering influent flow rate, internal recycling, and methanol addition. Simulation outcomes suggested that O/A (oxic/anoxic) operation is preferable for plants with low organic content (COD = 60–110 mg/L), considering both operational costs and total nitrogen removal rate. Conversely, A/O (anoxic/oxic) operation might be advantageous for plants with higher influent organic matter (COD = 200 mg/L).

Influence of Polyethylene Glycol and Methanol Additions on the Mechanical Alloying Behavior of Cu-4B4C Composite Powder

This study investigated the effect of different process control agent (PCA) usage on mechanical alloying behavior of boron carbide (B4C) reinforced copper (Cu) based composite powder. For this purpose, elemental Cu and B4C powders were weighed and powder specimens were prepared with respect to appropriate mass ratios (96% Cu and 4% B4C). Two different PCA additives, namely polyethylene glycol (PEG) and methanol, were also used to prepare powder samples. The amount of PCA was kept constant at 5wt.% for both specimen. These prepared powder samples were then milled using a planetary type ball-mill. After specified milling periods, milling runs were interrupted and powder samples were extracted from the milling vials for further powder characterization including powder morphology using scanning electron microscopy (SEM) and average particle size (APS) via laser diffraction analysis (Mastersizer). Accordingly, after the completion of milling runs, namely 15 hours of ball-milling, methanol addition was found much more effective at reducing particle sizes than PEG. Final APS values for powder specimens having PEG and methanol as PCAs were determined to be 8.237 and 4.101 microns, respectively.

Oxygen evolution reaction activity of carbon aerogel supported Pd–Ni–Al catalysts synthesized by microwave irradiation method

The oxygen evolution reaction (OER) is a critical step for oxygen production during the electrochemical splitting of water. Effective OER catalysts support the development of clean energy technologies by increasing the energy efficiency of these processes. In this study, carbon aerogel (CA) was first synthesized as a catalyst support material using sol-gel, supercritical drying, and pyrolysis process. Then, mono-metallic (Pd/CA, Al/CA), bi-metallic (Pd–Al/CA, Pd–Ni/CA), and tri-metallic (Pd–Ni–Al/CA) catalysts were synthesized by microwave irradiation method. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy have been made to examine the structural properties of the synthesized catalysts. Electrochemical analysis was carried out through cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) in alkaline media (1 M KOH: Methanol) to examine the effect of metal loading of CA support material towards OER performance. All the compositions showed excellent activity toward OER, among all Pd–Ni/CA catalysts showed the highest activity. The OER peak current increased remarkably up to 48 mA cm−2 with methanol addition, which signifies the substantial application of carbon aerogel supported-Pd-Ni-Al catalysts in direct methanol fuel cells (DMFCs). Pd–Ni/CA display high OER performance with maximum diffusion coefficient, Do (6.6 × 10−8 cm2 s−1) and heterogeneous rate constant, ko (4.706 × 10−4 cm s−1), and smaller value of Tafel slope (128 mV dec−1). Electrochemical studies predicted that all the prepared carbon aerogel supported-Pd-Ni-Al catalysts can be used as efficient catalysts for OER and other related electrocatalysis applications.

Enhanced dehydroaromatization of methane with methanol on Mo-ZSM-5/ZSM-11 intergrown zeolite materials

Methane dehydroaromatization (MDA) represents an appealing route for the direct utilization of abundant methane resources. Currently, the major challenge of MDA reaction lies in the rapid catalyst deactivation via coke formation, hindering large-scale industrialization of the process. Herein we report an enhanced conversion route of MDA in the presence of methanol on Mo-based zeolite materials. Compared to regular ZSM-5, ZSM-11, and their mechanically mixed counterparts, Mo embedded in ZSM-5/ZSM-11 intergrown matrix exhibits higher methane conversion (16.0%) and aromatics selectivity (62.5%) while limiting coke production to 12.1% under the co-feeding of methane and methanol (nCH4/nCH3OH = 30). If no methanol addition, coke selectivity is up to 45.1% in MDA reaction. Additionally, hydrogen enriched syngas (nH2/nCO = 6) was obtained as a co-product of the methane and methanol co-aromatization. NH3-adsorbed 1H MAS NMR, Co2+ titrated UV-vis and Raman spectroscopy characterizations reveal that a proper amount of Brönsted acid sites and the binuclear Mo anchored on the Al pairs at the intersection cavity may account for the superior reaction performance of the intergrown zeolites. A catalytic mechanism was also proposed via 13CH3OH isotopic labeling tracer and in-situ13C solid-state NMR studies. Methanol is first decomposed into CO/H2, while CO is hydrogenated to CH4 and converted into CO2 via the water-gas shift reaction. Alternatively, methanol is converted into CO/CO2 through formate intermediates. Subsequently, CO2 reduces coke deposition via the reverse Boudart reaction, which improves the catalytic performance.

Effect of short-term sample storage and preparatory conditions on losses of 18 per- and polyfluoroalkyl substances (PFAS) to container materials

There is a lack of agreement on a suitable container material for per- and polyfluoroalkyl substances (PFAS) analysis, particularly at trace levels. In this study, the losses of 18 short- and long-chain (C4–C10) PFAS to commonly used labware materials (high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polypropylene co-polymer (PPCO), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and glass were investigated. The influence of sample storage and preparation conditions, i.e., storage time, solvent composition, storage temperatures (4 °C and 20 °C), and sample agitation techniques (shaking and centrifugation) on PFAS losses to the container materials were investigated. The results showed higher losses for most of the considered PFAS (up to 50.9%) in 100% aqueous solutions after storage for 7 days regardless of the storage temperature compared to those after 3 days. Overall, the order of losses to different materials varied for individual PFAS, with the highest losses of long-chain PFAS observed to PP and HDPE after 7-day storage at room temperature. The addition of methanol to aqueous PFAS solutions reduced the losses of long-chain PFAS to all tested materials. The use of sample centrifugation and shaking did not influence the extent of losses for most of the PFAS in 80:20 water:methanol (%, v/v) to container materials except for 8:2 fluorotelomer sulfonic acid (8:2 FTS), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS), perfluorodecanoic acid (PFDA) and 4:2 fluorotelomer sulfonic acid (4:2 FTS). This study demonstrates lower losses of both long- and short-chain PFAS to glass and PET. It also highlights the need for caution when deciding on sample preparatory steps and storage during the analysis of PFAS.

Effect of 2-hexanol and methanol on the &lt;i&gt;one-pot&lt;/i&gt; process of dehydration and alkoxycarbonylation for the synthesis of esters

Objectives. To study the possibility of one-pot synthesis (combination of two processes in one reactor) for the following pairs of processes: (1) dehydration of 2-hexanol and isomerizing alkoxycarbonylation of the resulting 2-hexene, in order to obtain 2-hexyl heptanoate, and (2) dehydration of 2-hexanol and isomerizing methoxycarbonylation of the resulting 2-hexene, in order to obtain methyl esters of C7 carboxylic acids. To investigate the effect of the concentrations of 2-hexanol and methanol on the rate of the one-pot synthesis.Methods. One-pot synthesis was studied in a toluene medium in a steel batch reactor designed to operate at elevated pressure and equipped with a glass insert, a magnetic stirrer, a sampler, and gas input and discharge devices. Samples of the reaction mass were taken during the combined process and were analyzed by means of gas–liquid chromatography with a flame ionization detector.Results. The possibility of one-pot combination was demonstrated for 2-hexanol dehydration catalyzed by methanesulfonic acid, as well as for the isomerizing alkoxycarbonylation of the resulting 2-hexene with 2-hexanol and CO, catalyzed by the Pd(PPh3)2Cl2–XANTPHOS–methanesulfonic acid system. The dependencies of the rates of the dehydration of 2-hexanol and the formation of esters of C7 carboxylic acids on the concentration of 2-hexanol were shown to pass through a maximum. The possibility of the one-pot process was proved for the synthesis of esters from 2-hexanol, methanol, and CO with the predominant formation of heptanoic acid esters in the presence of the above catalytic system. The rates of dehydration of 2-hexanol and the formation of 2-hexyl esters of C7 carboxylic acids were found to decrease with increasing the concentration of methanol in the reaction mass. Under mild conditions (temperature 115°C, CO pressure 3 MPa) with the addition of methanol, the total fraction of 2-hexyl and methyl heptanoic acid esters among C7 carboxylic acid esters was determined to be 85.5%.Conclusions. The reactions of intramolecular acid–catalytic dehydration of 2-hexanol and isomerizing alkoxycarbonylation of the resulting 2-hexene, catalyzed by the Pd(PPh3)2Cl2–XANTPHOS–methanesulfonic acid system, can be performed as a one-pot process. Methanesulfonic acid simultaneously functions as a catalyst for the dehydration of 2-hexanol and a cocatalyst for the palladium–phosphine system for the alkoxycarbonylation of hexenes. In the presence of the Pd(PPh3) 2Cl2–XANTPHOS–methanesulfonic acid catalytic system, processes for the synthesis of heptanoic acid esters from 2-hexanol, methanol, and CO can be combined within one reactor. An increase in the methanol concentration negatively affects the rate of the dehydration of 2-hexanol and the formation of 2-hexyl esters of C7 carboxylic acids. A small amount of methanol in the reaction mass leads to an increase in the fraction of heptanoic acid esters among C7 carboxylic acid esters.

Evaluating Lean Combustion Cycle Stability and Emissions in Spark Ignition Engines with Gasoline, Ethanol, and Methanol Blends

Abstract Fuels for vehicles account for a large portion of the world’s total energy demand, which in turn leads to increased carbon emissions. Ethanol and methanol are a fuel with a simple carbon chain and OH- bonds. It has similar properties to gasoline, and ethanol can be made from the fermentation of plant carbohydrates, called bioethanol. The advantage of using bioethanol is that it contributes to carbon neutrality. This paper will investigate the use of three manually blended gasoline ethanol and methanol (GEM) fuels in a spark ignition engine to address cycle-to-cycle variation (CCV), knock potential, and emissions with lean blend conditions. In the experiments conducted, the air-fuel ratio was conditioned lean by utilizing an electronic control unit to adjust the injector spray duration. This experiment provides results that there is a potential for mild knocking on the use of alcohol fuel with lean fuel mixture conditions at engine speed 4000 RPM, while at engine speed 6000 RPM and 8000 RPM the use of GEM tends to be stable, but in the CCV results the increase in COV (coefficient of variation) value using GEM fuel tends to be more sloping, especially with the addition of more methanol. Emission results from the use of GEM produce top emission CO2 value obtained by the E5M15 mixture at λ=1.2 and an engine speed of 8000 RPM, with a value of 13.75% and then peak CO2 emissions at a value of λ = 1.2 whereas in the use of pure gasoline peak CO2 is at a value of λ = 1.1.

Stabilization of Eversa® Transform 2.0 lipase with sorbitol to enhance the efficiency of ultrasound-assisted biodiesel production

Ultrasound technology has emerged as a promising tool for enhancing enzymatic biodiesel production, yet the cavitation effect induced can compromise enzyme stability. This study explored the efficiency of polyols in enhancing lipase stability under ultrasound conditions to further improve biodiesel yield. The incorporation of sorbitol resulted in the highest fatty acid methyl ester (FAME) content in the ultrasound-assisted biodiesel production catalyzed by Eversa® Transform 2.0 among the investigated polyols. Furthermore, sorbitol enhanced the stability of the lipase, allowing it to tolerate up to 100 % ultrasound amplitude, compared to 60 % amplitude in its absence. Enzyme activity assays revealed that sorbitol preserved 99 % of the lipase activity, in contrast to 84 % retention observed without sorbitol under an 80 % ultrasound amplitude. Circular dichroism (CD) and fluorescence spectroscopy analyses confirmed that sorbitol enhanced lipase rigidity and preserved its conformational structure under ultrasound exposure. Furthermore, employing a stepwise methanol addition strategy in ultrasound-assisted reactions with sorbitol achieved an 81.2 wt% FAME content in 8 h with only 0.2 wt% enzyme concentration. This promising result highlights the potential of sorbitol as a stabilizing agent in ultrasound-assisted enzymatic biodiesel production, offering a viable approach for enhancing biodiesel yield and enzyme stability in industrial applications.