Pure Methanol Research Articles

Biological potentials of Landolphia owariensis leaf methanolic extract against pathogenic fungi isolates from different Dioscorea species

Abstract Regarding economic significance, the Dioscoreaceae family, which includes the well-known Dioscorea (yam) species, is the fourth most important tuber crop globally. A basic meal found all across the world, yams encourage and ensure the food security of households. Although they are challenging to preserve and store however a post-harvest deterioration control must be developed. Over the years, Nigerian farmers have employed medicinal herbs to manage post-harvest pest invasion; nevertheless, the scientific basis for this fungal management has not yet been well documented. As a result, Landolphia owarensis leaf extract was used as a biological control, and fungi were isolated from Dioscorea cayenensis, Dioscorea alata, and Discorea rotundata. Samples of yam tubers – both rotten and healthy – were procured in the markets and brought to the lab for fungus isolation and identification. Leaves of Landolphia oweriensis were collected, air-dried, milled, and macerated in pure methanol for 72 h, extracted and concentrated with a rotary evaporator. The agar-well diffusion method was used for the biological control assay against the fungal isolates. The biological control results were presented as mean ± SD (standard deviation) while analysis of variance (Anova) was used to deduce least significant difference (LSD). A total number of 605 fungi isolates were observed in which D. cayenensis had the highest, 50.58 %, D. alata and Discorea rotundata 24.71 % respectively. Aspergillus niger and Aspergillus fumigatus were found in the three species while Aspergillus flavus, Rhizopus stolonifer, Collentotricum spp. and Penicillium spp. in either of the species. L. owarensis methanolic leaves extracts possesses biological potentials against Colletotrium spp., A. fumigatus, A. niger and A. flavus only. The problem of postharvest fungal invasion of Dioscorea species can be solved with the inhibition observed with L. owarensis methanolic leaves extracts as a biological control measure thereby sustaining food security in the world.

Chiral Hydroxy Metabolite of Mebendazole: Analytical and Semi-Preparative High-Performance Liquid Chromatography Resolution and Chiroptical Properties.

Mebendazole (MBZ) is a benzimidazole carbamate anthelmintic used worldwide for the treatment and prevention of parasitic disorders in animals and humans. A large number of in vivo and in vitro studies have demonstrated that MBZ also has anticancer activity in multiple types of cancers. After oral administration, the phenylketone moiety of MBZ is rapidly reduced to the hydroxyl group to form the chiral hydroxy metabolite (MBZ-OH). To the best of our knowledge, there is no information in the literature on the stereochemical course of transformation and the anthelmintic and antitumor activity of individual enantiomers of MBZ-OH. In the present study, we describe in detail the direct HPLC resolution of MBZ-OH on a 100 mm × 4.6 mm Chirapak IG-3 column packed with 3 μm silica particles containing amylose (3-chloro-5-methylphenylcarbamate) as a selector. At 25 °C and using pure methanol as the mobile phase, the enantioseparation and resolution factors were 2.38 and 6.13, respectively. These conditions were scaled up at a semi-preparative scale using a 250 mm × 10 mm Chiralpak IG column to isolate multi-milligram amounts of both enantiomeric forms of the chiral metabolite. The chiroptical properties of the collected enantiomers were determined and, through a theoretical study, were related to the more stable conformations of MBZ-OH. The first and second eluted enantiomers were dextrorotatory and levorotatory, respectively, in dimethylformamide solution. Finally, by recording the retention factors of the enantiomers as the water content in the water-acetonitrile mobile phases was progressively varied, U-shaped retention maps were generated, indicating a dual and competitive hydrophilic interaction liquid chromatography and reversed-phase liquid chromatography retention mechanism on the Chirapak IG-3 chiral stationary phase.

Kraft lignin-based Vanillin production – Process modification, techno-economic evaluation, and energy analysis

This correspondence outline specific modifications implemented in the vanillin production process derived from kraft lignin, with the primary objective of minimizing the release of chemical substances into the environment and optimizing facility utilization. The processes were meticulously designed using Aspen Plus V12.1 software, followed by a sensitivity analysis conducted on the specifications of the main distillation column for each process. Subsequently, the obtained results underwent techno-economic evaluation and energy analysis, employing Aspen Process Economic Analyzer V12 and Aspen Energy Analyzer V12.1. The calculations reveal that increasing the purity of methanol and water from 95 to 99 wt % during methanol recycling effectively reduces chemical releases into the environment but significantly raises utility costs, thereby diminishing the Net Present Value. Furthermore, the energy analysis demonstrates that the implemented modifications markedly reduce energy consumption, exerting a direct impact on economic parameters. In the process design phase, while Aspen Plus software showed no errors in the results, Aspen Energy Analyzer detected errors in the modified scenario in two heat exchangers because of high temperature at the shell outlet based on its respective criteria, necessitating increasing the cooling flowrates to cover this issue.

New Levan-Based Chiral Stationary Phases: Synthesis and Comparative HPLC Enantioseparation of (±)-trans-β-Lactam Ureas in the Polar Organic Mode.

In this paper, the preparation of three new polysaccharide-type chiral stationary phases (CSPs) based on levan carbamates (3,5-dimethylphenyl, 4-methylphenyl, and 1-naphthyl) is described. The enantioseparation of (±)-trans-β-lactam ureas 1a-h was investigated by high-performance liquid chromatography (HPLC) on six different chiral columns (Chiralpak AD-3, Chiralcel OD-3, Chirallica PST-7, Chirallica PST-8, Chirallica PST-9, and Chirallica PST-10) in the polar organic mode, using pure methanol (MeOH), ethanol (EtOH), and acetonitrile (ACN). Apart from the Chirallica PST-9 column (based on levan tris(1-naphthylcarbamate), the columns exhibited a satisfactory chiral recognition ability for the tested trans-β-lactam ureas 1a-h.

Pillared graphene oxide frameworks for the adsorption and separation of polar protic and aprotic liquid solvents: The cases of pure water, methanol, dimethyl sulfoxide, and dimethyl sulfoxide-water mixtures.

Potential applications of previously synthesized pillared graphene oxide frameworks with phenyldiboronic acid linkers in the field of the adsorption and separation of polar protic and aprotic liquid solvents have been systematically explored using grand canonical Monte Carlo simulations. Particular attention was initially paid to the adsorption of pure liquid water, methanol, and dimethyl sulfoxide. The results obtained a significant increase in the isosteric heat of adsorption at low uptake in the case of dimethyl sulfoxide, which is about 17.9 and 26.8kJ/mol higher than the values corresponding to methanol and water adsorption. These findings indicated that from a thermodynamic point of view, these pillared graphene oxide frameworks could be used in the separation of dimethyl sulfoxide-water liquid mixtures. Systematic grand canonical Monte Carlo simulations were then subsequently performed for dimethyl sulfoxide-water mixtures, with a low dimethyl sulfoxide concentration. The calculated values of the separation selectivity indicate that these materials could have potential applications in the separation of these mixed liquid solvents. Molecular dynamics simulations performed for a representative adsorbed mixture have revealed a substantial slowing down of the dynamics under confinement, particularly in the case of the hydrogen bonds formed between water and dimethyl sulfoxide.

Sub-chronic Toxicity Study of Heracleumlasiopetalum Extract Towards Healthy Sprague Dawley Rats

Background: Heracleum species are commonly used as spices, flavorings, and food additives. Members of the genus Heracleum offer many medicinal benefits but may also pose adverse effects on human health. Objectives: To prepare a crude leaf extract of Heracleumlasiopetalum and assess its toxicity profile towards healthy rats. Methods: The H. lasiopetalum leaf extract was prepared using pure methanol and ethyl acetate (1:10) at room temperature over a period of 72 hours. After filtration, the crude extract was obtained using a rotary evaporator at 40 - 45°C. Subsequently, various doses of the H. lasiopetalum extract were administered orally to healthy Sprague Dawley rats at three doses (300, 600, and 900 mg/kg body weight) for four weeks to test for toxicity. Blood samples were examined for hematologic and biochemical changes, while the liver, kidneys, and heart were examined for histopathological changes. Results: The toxicity study revealed no mortality at low and medium doses, as well as no clinical toxicity indicators. Additionally, there were no significant alterations observed in the haematological, biochemical, and histopathological profiles of the treated animals throughout the 28-day experiment. However, at high doses, the mortality rate was significantly elevated, accompanied by notable histopathological changes. Conclusions: Continuous administration of high doses of H. lasiopetaum may induce potential toxic effects in the treated animals.

Purity Detection of Some Liquids by Using Reflection Values Based on Metamaterial

The aim of this work is to design and fabricate a type of sensor based on Metamaterials. This structure determines the purity of Methanol and Ethanol mixture in the water by using the Octagonal form of a resonator and sample holder. The proposed structure has been employed in the 8-12 GHZ frequency band. The important thing in the work is the changes of the waveform at the resonance frequency. The output waveform of materials (reflection coefficient S11 or transmission coefficient S12) must be changed in the liner figure by considering the dielectric coefficient. We use copper for the metal layer and resonator and Isola IS680 (3.2DK) (lossy) for substrate layer. We simulate one unit cell of this Meta-material sensor by CST microwave software and then achieve the results and evaluate them. Both the numerical and experimental tests, give the same outcomes and results and they will be in good agreement with each other. The proposed structure can be used in many applications where purity and determining of some materials might be necessary.

Effects of operating parameters on start performance of compression ignition engine by using high-pressure direct-injection pure methanol fuel

Methanol was one of the research hotspots in internal combustion engines over recent years. The application of methanol is a promising approach to transport decarbonization due to low carbon content. However, the utilization of methanol in compression ignition (CI) engines faces some challenges as a result of low reactivity and high latent heat of vaporization, such as cold start and operation stability. Furthermore, the impact mechanisms of operating parameters on cold start and operation stability in CI engine have not been understood deeply. In this work, the effects of operating parameters on average cycle of start and coefficient of speed variation (CoVspeed) of idle were studied on a CI engine fueled by pure methanol fuel. Results show that the injection strategy of the minimum average starting cycle number is the pre-main injection, which includes lower injection pressure, −4 °CA ATDC (degree crank angle after top dead center) main timing, smaller pre mass, and larger pre-main interval. The injection strategy of the minimum CoVspeed of idle is the pilot-pre-main injection, which includes lower injection pressure, −4 °CA ATDC main timing, smaller pre mass, larger pre-main interval, smaller pilot mass, and shorter pilot-main interval. Under the same operating conditions, the average cycle of start is 12 and 5 for methanol and diesel respectively. The CoVspeed of idle is 6.72% and 0.53% for methanol and diesel respectively. When coolant temperature is 30 °C, the minimum intake temperature is 120 °C. Upon adjusting the coolant temperature to 80 °C, the minimum intake temperature decreases to 80 °C.

Effect of methanol purity on biodiesel production from lauric acid using esterification reaction

Indonesia is a leading country in agriculture, thus opening up great opportunities for the development of biodiesel. However, the main challenge is ensuring the sustainable acquisition of feedstock, including using methanol as a reactant to manufacture biodiesel. Making biodiesel using lower-purity methanol is possible. This study aims to compare the effect of methanol purity on biodiesel manufacturing. This research uses esterification reactions to manufacture biodiesel from lauric acid and methanol. The catalyst used is an amberlyst catalyst. A design was applied using catalyst amounts of 5% to 20% and variations in the purity of methanol from 95% to 99%. The best esterification reaction conditions are obtained at 99% methanol purity and 20% catalyst amount, which is 98.9%. In contrast, there is no significant difference in results for the flash point obtained, and the results obtained have met the standards of the American Society for Testing and Materials (ASTM).

Investigating the Sole Olefin-Based Cycle in Small-Cage MCM-35-Catalyzed Methanol-to-Olefins Reactions.

Small-pore zeolites catalyze the methanol-to-olefins (MTO) reaction via a dual-cycle mechanism, encompassing both olefin- and aromatic-based cycles. Zeolite topology is crucial in determining both the catalytic pathway and the product selectivity of the MTO reaction. Herein, we investigate the mechanistic influence of MCM-35 zeolite on the MTO process. The structural properties of the as-synthesized MCM-35 catalyst, including its confined cages (6.19 Å), were characterized, confirming them as the catalytic centers. Then, the MTO reactions were systematically performed and investigated over a MCM-35 catalyst. Feeding pure methanol to the reactor yielded minimal MTO activity despite the formation of some aromatic species within the zeolite. The results suggest that the aromatic-based cycle is entirely suppressed in MCM-35, preventing the simultaneous occurrence of the olefin-based cycle. However, cofeeding a small amount of propene in methanol can obviously enhance the methanol conversion under the same studied reaction conditions. Thus, the exclusive operation of the olefin-based cycle in the MTO reaction, independent of the aromatic-based cycle, was demonstrated in MCM-35 zeolite.

Study on ammonia/methanol blends with ammonia cracking for low-carbon combustion and NO reduction

This work aims to study the ammonia/methanol blended fuel with ammonia cracking in lean-burn condition. Ammonia on-line cracking to produce hydrogen production has the potential to realize the high-efficiency combustion. A new ammonia/methanol/hydrogen mechanism was updated and simplified using several reduction methods to optimize the computation time in 3D simulation. Visualization measurements in constant volume combustion chamber (CVCC) for flame propagation and NO generation were conducted, and 3D computational fluid dynamics (CFD) modeling was also established with the simplified mechanism simultaneously to investigate the impact of methanol addition and ammonia cracking in the lean-burn mode. The findings showed that methanol addition and ammonia cracking can significantly improve the combustion rate, and 60%ammonia/40%methanol with ammonia cracking ratio of 90% (N60R90) at equivalence ratio (ER) of 0.7 yields the similar LBV as pure methanol at ER of 1.0 in laminar burning condition. Its ER can be extended to 0.4 to obtain the similar level of LBV as pure ammonia at 1.0. The experiments and 3D simulations revealed that N60R90 at 0.4 yields the equivalent level of combustion rate as N60R0 at 0.8, while obtaining much lower NO emission. In addition, N60R100 at 0.4 without fuel-NO formation during the combustion can get ultra-low NO emission. This study provides the insights on low-carbon combustion strategy for ammonia cracking with low NO.

Catalytic activity of modified silica gel adsorbents under conditions of methanol conversion from water-methanol waste of natural gas

The work is devoted to the analysis of factors affecting the catalytic activity of modified silica gel adsorbents under conditions of methanol conversion to dimethyl ether. The objects of the study were the initial and modified silica gel adsorbents ASM, ASM VS, BASF KC-Trockenperlen H and BASF KC-Trockenperlen WS used in the purification of methanol from water‒methanol waste of natural gas. The purpose of this paper is to study the effect of the specific surface area, elemental and phase composition, and operating time of adsorbents on the catalytic activity of modified silica gel adsorbents under conditions of methanol conversion to dimethyl ether. The composition and structural characteristics of the samples were determined by X‒ray fluorescence, X-ray diffraction analysis and low-temperature nitrogen adsorption. Based on the results of IR‒spectrometric and thermal studies, changes in the structure of the surfaces of adsorbents during their operation by various components of organic origin were evaluated. The catalytic activity of silica gel adsorbents in methanol conversion was studied in a fixed bed reactor at atmospheric pressure in the range of 120-290°C and an optimized rate of methanol-saturated nitrogen flow of 1200 ml/min. The methanol conversion process was controlled by gas‒liquid chromatography. An increase of the catalytic activity of adsorbents in methanol conversion to dimethyl ether was found in the range of ASM VS < BASF KC-Trockenperlen WS < BASF KC-Trockenperlen H < ASM. The maximum catalytic activity at 290°C was shown by the adsorbent ASM with 4.2% aluminum oxide and an amorphous structure, which significantly reduces methanol emissions into the atmosphere. For crystalline adsorbents ASM VS with an alumina content of 13.2%, the catalytic activity was minimal. It is shown that the decrease in the catalytic activity of adsorbents in gas treatment unit during operation is associated with a decrease in the value of the specific surface area of samples with a constant content of aluminum oxide and phase state, which is associated with the possible blocking of the catalytic centers of adsorbents due to the accumulation of components of organic origin in the process of natural gas purification. The establishment of factors affecting the methanol conversion to dimethyl ether on modified silica gel adsorbents will allow managing environmental risks, as well as reducing risks to humans during transportation and disposal of water-methanol waste from natural gas purification.

Effects of Different Solvents on the Extraction of Phenolic and Flavonoid Compounds, and Antioxidant Activities, in Scutellaria baicalensis Hairy Roots

The hairy roots (HRs) of Scutellaria baicalensis are widely used and consumed worldwide as a medicine, especially in Asian countries, due to their biological and pharmacological activities. The HRs of this plant are rich in secondary metabolites. However, the optimal method and solvents for the extraction of secondary metabolites from S. baicalensis HRs have not been well studied. Therefore, in this study, S. baicalensis HRs were extracted with different solvents, including water (WE), 99.9% pure methanol (PM), 70% aqueous methanol (AM), 99.9% pure ethanol (PE), and 70% aqueous ethanol (AE). The phenolic and flavonoid compounds and various antioxidant activities of each extract were measured. The AE extract (16.85 ± 0.15%) had a higher yield, which led to the highest accumulation of total phenolic content (TPC) and total flavonoid content (TFC), and antioxidant activity. The TPC and TFC were highest in AE (66.03 ± 0.44 mg GAE/g and 40.11 ± 1.31 mg QE/g, respectively), whereas WE, PM, and PE showed lower values in all assays. In addition, the highest antioxidant activities, such as DPPH, ABTS, and SOD-like scavenging activities and reducing power, were achieved in the AE extract compared to the other solvent extracts. Based on these results, the AE extract showed the highest phenolic and flavonoid accumulation and antioxidant activities, highlighting its potential use in the manufacture of useful materials from S. baicalensis HRs and its novel applications.

Mechanism of poly(N-isopropylacrylamide) cononsolvency in aqueous methanol solutions explored via oxygen K-edge X-ray absorption spectroscopy.

The cononsolvency mechanism of poly(N-isopropylacrylamide) (PNIPAM), dissolving in pure methanol (MeOH) and water (H2O) but being insoluble in MeOH-H2O mixtures, was investigated by O K-edge X-ray absorption spectroscopy (XAS). The cononsolvency emerges from the aggregation of PNIPAM with MeOH clusters, leading to the collapse of the hydrophobic hydration of PNIPAM.

Utilizing EPR spectroscopy to investigate the liquid adsorption properties of bimetallic MIL-53(Al/Cr) MOF.

The flexibility of the MIL-53(M) metal-organic framework (MOF) has been elucidated through various characterization methodologies, particularly in gas and liquid adsorption processes. However, to the best of our knowledge, there has been no prior electron paramagnetic resonance (EPR) characterization of liquid-phase adsorption in the MOF MIL-53(M), which offers insights into local geometric changes at the oxygen octahedron containing the metal ions of the framework. In this study, we investigate, for the first time, the pore transformations within the MIL-53(Al0.99Cr0.01) framework during liquid-phase adsorption using EPR spectroscopy. Our investigation concentrates explicitly on the adsorption of pure solvents, including water, methanol, ethanol, isopropanol, pyridine, and mixed water/methanol phases. The EPR spectroscopy on the (Al0.99Cr0.01) MOF has allowed us to witness and comprehend the transitions between the narrow pore and large pore phases by examining changes in the zero-field splitting parameters of the S = 3/2 Cr(iii) species. Of all the solvents examined, a robust and distinct spectral feature observed during methanol adsorption unequivocally indicates the pore opening.

Methanol recovery: potential of nanolaminate organic solvent nanofiltration (OSN) membranes.

Researchers have made a significant breakthrough by merging the energy-saving attribute of organic solvent nanofiltration (OSN) with the remarkable solvent permeance and solute rejection of two-dimensional (2D) laminated membranes. This innovative approach brings forth a new era of sustainable and cost-effective separation techniques, presenting a promising solution to the issue of industrial solvents contaminating the environment. This development paves the way for new opportunities in building a sustainable future. Specifically, our mini-review has cast a spotlight on the separation and recovery of methanol-a solvent abundantly used in industrial processes. We systematically evaluated a diverse array of free-standing 2D nanolaminate OSN membranes. The analysis encompasses the assessment of pure methanol permeance, solute rejection capabilities, and the simultaneous evaluation of methanol permeance and solute rejection performance. Notably, this study sheds light on the considerable potential of 2D laminated OSN membranes in revolutionizing separation processes for the industrial use of methanol.

Comparative Evaluation of the Power-to-Methanol Process Configurations and Assessment of Process Flexibility

This paper compares different power-to-methanol process configurations encompassing electrolyser, adiabatic reactor (s) and methanol purification configurations. Twelve different power-to-methanol configurations based on direct CO2 hydrogenation with H2 derived from H2O-electrolysis...

Effects of Injection Parameters and EHN Mixing on the Combustion Characteristics of Fueling Pure Methanol in a Compression Ignition Engine

As one of the most ideal alternative fuels for internal combustion engines, methanol can achieve near-zero carbon emissions. The main problem of methanol application in compression combustion engines is the phase lag caused by its poor combustion characteristics, but under low load conditions, the fuel activity can be improved by adding the cetane number improver EHN (Isooctyl nitrate), and the dependence on intake heating can be reduced to a certain extent. Based on a three-dimensional CFD simulation, the effects of methanol injection parameters and the addition of EHN on the combustion characteristics of a four-stroke exhaust turbocharged diesel engine were studied in this paper. With or without EHN, the increase in injection pressure and the advance in injection timing lead to an increase in the peak temperature, pressure, and heat release rate, as well as a shortening of the combustion duration. Adding EHN witnesses reduced requirements for methanol ignition, including a decreased peak temperature, pressure, and heat release rate, a significantly shortened ignition delay period, and an extended combustion duration, which thus results in a reduced indicated thermal efficiency. This study innovatively develops a 3D model of a compression combustion engine applicable to in-cylinder direct injection pure methanol fuel and EHN under small load conditions, which provides a reference for future research and development of small-load pure methanol compression combustion engines and has certain guiding significance.

Antinociceptive and antiinflammatory activities of crude leave extract and solvent fractions of Commelina latifolia Hochst. ex C.B.Clarke (Commelinaceae) leaves in murine model.

Ethnopharmacological relevance: In the past, Ethiopian traditional medicine employed the leaves of the native Commelina latifolia Hochst. ex C.B. Clarke plant to treat wounds, pain, and malaria. Aim of the study: The crude extract and solvent fractions of C. latifolia Hochst. ex C.B. Clarke leaves were examined in the present investigation to determine their ability to have an antiinflammatory effect and provide an antinociceptive effect in animal models. Materials and methods: The leaves of C. latifolia were extracted with 80% methanol, and the CL crude extract was further fractionated with chloroform, pure methanol, and distilled water. The carrageenan-induced paw edema model was used to test the extracts' ability to reduce inflammation. The hotplate model and the acetic acid-induced writhing test on rodents were used to test the extracts' potential antinociceptive effect to reduce pain. Results: Inflammation was decreased by 64.59% with CL crude extract (400mg/kg); 56.34% (400mg/kg) of methanol fraction, 64.59% of aqueous fraction (400mg/kg), and 38.27% of chloroform fraction in the carrageenan-induced inflammatory model. All extracts demonstrated a considerable lengthening of the nociception reaction time in the hot plate test, with a maximum antinociceptive effect of 78.98% (crude extract) and 71.65% (solvent fractions). At a dosage of 400mg/kg, the natural C. latifolia crude extract and aqueous fraction demonstrated considerable antinociceptive effects against acetylsalicylic acid (ASA) during the writhing test (48.83% and 45.37than%, respectively). The current findings support Ethiopia's traditional user's assertions that the herb can alleviate inflammation and pain.

Computational study of added H2 impacts on mixture formation, OH radical and unregulated emissions of spark-ignition methanol engine under various boundary parameters

Numerical simulations of hydrogen (H2) impacts on mixture formation, OH radical generation, and formaldehyde (HCHO) and unburned methanol (CH3OH) emissions of spark-ignition (SI) methanol engine based methanol late-injection strategy under different methanol injection timings (MIT), ignition timings (IT), excess air ratios (λ) and added H2 ratios (RH2) boundary parameters were conducted. The simulation results show that the ideal methanol concentration distribution is obtained at the MIT = 85°CA BTDC. The OH radical plays a dominant role in methanol oxidation. The OHPMF (peak OH radical mass fraction) of RH2 = 9 % ≫ OHPMF of RH2 = 6 % > OHPMF of RH2 = 3 % > OHPMF of RH2 = 0 % at MIT = 85°CA BTDC. Compared with IT and λ, the RH2 is more decisive for the generation of OH radical. The HCHO is a major intermediate and an important unregulated emission of methanol engine. In the initial stage of methanol reaction, added H2 can accelerate the generation of OH radical, further promote the oxidation of methanol, and greatly raise the generation of HCHO. The peak HCHO mass fraction increases with the increase of RH2. At MIT = 85°CA BTDC and exhaust valve opening, the HCHO emission of RH2 = 3 %, 6 %, and 9 % is approximately 51 %, 76.5 % and 89.4 % lower than that of RH2 = 0 %, respectively. The generation and post-oxidation of HCHO mainly depended on average in-cylinder temperature. There is a lowest CH3OH emission at MIT = 85°CA BTDC, IT = 28°CA BTDC, λ = 1.4 and pure methanol. At MIT = 85°CA BTDC, λ = 1.4 and exhaust valve opening, the CH3OH emission of RH2 = 3 %, 6 %, and 9 % is approximately 52.8 %, 75.5 % and 92.5 % lower than that of RH2 = 0 %, respectively.