MeOH Ratio Research Articles

Enhancing biodiesel production in stirred tank reactors through the implementation of a baffle array: Creating a reactor with unique characteristics

This study focuses on enhancing biodiesel production from expired refined palm oil by implementing baffle arrays with a suitable dimension ratio into a conventional stirred tank reactor. This reactor functions as a deglycerolizing reactor at low agitation speeds (250 rpm), or an intensive mixing at high agitation speeds (500 rpm). With these unique characteristics, this reactor outperformed its traditional counterparts and could produce biodiesel via a simplified, single-step transesterification process. The optimal reaction condition was 1:6 oil to MeOH ratio, 1.0 wt% KOCH3, 30-minute reaction time and 60 °C reaction temperature. Ester content of 98.13 wt% was obtained in the deglycerolizing reactor and 98.54 wt% in the intensive mixing reactor with the number of baffles of 16. This achievement represents a 50 % reaction time reduction and 30 % reactor cost reduction compared to the conventional reactor with similar reaction condition and production capability.

Optimization of HPLC[sbnd]CAD method for simultaneous analysis of different lipids in lipid nanoparticles with analytical QbD

Since lipid nanoparticles (LNP) have emerged as a potent drug delivery system, the objective of this study was to develop and optimize a robust high-performance liquid chromatography with charged aerosol detectors (HPLCCAD) method to simultaneously quantify different lipids in LNPs using the analytical quality by design (AQbD) approach. After defining analytical target profile (ATP), critical method attributes (CMAs) were established as a resolution between the closely eluting lipid peaks and the total analysis time. Thus, potential high-risk method parameters were identified through the initial risk assessment. These parameters were screened using Plackett–Burman design, and three critical method parameters (CMPs)—MeOH ratio, flow rate, and column temperature—were selected for further optimization. Box–Behnken design was employed to develop the quadratic models that explain the relationship between the CMPs and CMAs and to determine the optimal operating conditions. Moreover, to ensure the robustness of the developed method, a method operable design region (MODR) was established using the Monte Carlo simulation. The MODR was identified within the probability map, where the risk of failure to achieve the desired CMAs was less than 1%. The optimized method was validated according to the ICH guidelines (linearity: R2 > 0.995, accuracy: 97.15–100.48% recovery, precision: RSD < 5%) and successfully applied for the analysis of the lipid in the LNP samples. The development of the analytical method to quantify the lipids is essential for the formulation development and quality control of LNP-based drugs since the potency of LNPs is significantly dependent on the compositions and contents of the lipids in the formation.

Thermodynamic Study of One-step Production from Isobutene to Methyl Methacrylate

Methyl methacrylate (MMA) has emerged as an essential industrial monomer. However, the toxic by-production and shortage supply of MMA in the global market has gained great attention. Herein, a one-step synthesis to produce MMA from isobutene via a direct oxidative esterification process has been demonstrated to curb the aforementioned downsides. Thermodynamic analysis via Gibbs free energy minimization method proved the feasibility of this route via the equilibrium constant. Despite tert-butanol and isobutane showed higher equilibrium constant than isobutene, they should be avoided. Isobutane is highly flammable while the precursor of tert-butanol is exorbitant. Thus, isobutene was selected for the equilibrium compositions screening. Isobutene conversion was 90% and 15% MMA yield at 700 °C and IBN: O2: MeOH ratio with 1:7:1. This route is mainly limited by the generation of side reactions from the reaction of CH3OH and O2. By varying the feedstock ratio at 1:2:1, the MMA yield increased to ~25%. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Processing wet microalgae for direct biodiesel production: optimization of the two-stage process assisted by radio frequency heating

ABSTRACT A two-stage biodiesel production directly from wet microalgae (Chlorella vulgaris) assisted by radio frequency (RF) heating was optimized in this study with the response surface methodology (RSM) applied to both two steps. In order to apply RSM to the two stages rather than to a one-step reaction, a three-variable, five-level central composite design (CCD) was employed to evaluate the effects of three key parameters, i.e. HCl to MeOH ratio (v/v), MeOH volume, and RF heating time. Two regression equations (one regression equation for each stage) were obtained, and two sets of optimized production conditions with a slight difference were also determined. The best predicted FAME yield of 93.1% was obtained at a HCl to MeOH ratio of 4.27 (v/v), a MeOH volume of 28.5 mL, and a RF heating time of 19.2 min. Although the second stage of conversion increased the FAME yield from 82.9% to 93.1%, this process would cause additional consumption of time, solvent, and energy. Verification experiments were carried out at the optimized point and resulted in a yield of 92.7 ± 0.1%, which validated the reliability of the prediction model. All processing steps, including cell destruction, esterification, and transesterification, were carried out at temperatures below 100°C and atmospheric pressure. Therefore, no pressure-proof nor high-temperature apparatus was required. The procedure shows great potential for industrial application because of its high FAME yield, simple operation, low chemical consumption, and short processing time. The principles of the procedure can also be applied to other microalgae with high lipid contents.

Carbon material@Chitosan composite as catalyst on the synthesis of FAME from used-cooking oil with electrocatalytic process

The conversion of fatty acid methyl ester (FAME) from soybean oil with a carbon@chitosan composite as alkaline catalyst using electrolysis process had been investigated. The carbon was added onto chitosan through sol-gel method. Carbon material@chitosan, featured with high electrical conductivity and large surface area and Scanning electron microscopy equipped with an energy dispersive spectroscope (EDS) detector was performed to characterize the microstructures as-prepared alcolgels composite. The evaluation of the synthesis process was followed by GC-MS, determining the fatty acid methyl ester (FAME) ratio at different operation variables (e.g oil:MeOH molar ratio at 1:6, THF:MeOH ratio at 1:1 v/v, 10 V and 60 mins). The results showed that the incorporation of carbon resulted in an observable change in the porous structure and an obvious increase in the conductivity strength. When compared with graphite@chitosan composite as catalyst, the carbon@chitosan composite exhibits remarkably FAME yields of 100% in 20 wt.% catalyst loading. The application of those processes was also evaluated when using used-cooking oil as a feedstock of biodiesel production.

Microwave-Assisted Rapid Synthesis of γ-Cyclodextrin Metal–Organic Frameworks for Size Control and Efficient Drug Loading

The micron and nanometer-sized γ-cyclodextrin metal–organic frameworks (γ-CD-MOFs) were successfully synthesized using the microwave technique for the first time for rapid and facile synthesis. Polyethylene glycol 20000 (PEG 20000) was used as surfactant to control the size and morphology of γ-CD-MOFs. The as-synthesized γ-CD-MOFs were characterized using various techniques, including X-ray powder diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2 adsorption. The increment in the reaction time and MeOH ratio dramatically damaged the crystalline integrity of γ-CD-MOFs. Fenbufen was selected as a model drug to evaluate the loading characteristics of γ-CD-MOF crystals. As a result, the nanometer sized γ-CD-MOFs (100–300 nm) showed rapid and higher adsorption (196 mg g–1) of Fenbufen in EtOH when compared with the micron crystals. The adsorption parameters fitted well to a pseudo-second-order kinetic model and chemisorption of Fenbufen was further supported by molecular docking illustrations. In summary, the controlled synthesis of γ-CD-MOFs was successfully achieved by microwave assisted method and resultant crystals were further evaluated for potential drug delivery applications.

Reaction kinetics and equilibrium parameters for the production of oxymethylene dimethyl ethers (OME) from methanol and formaldehyde

A catalyst screening comprising zeolites and ion exchange resins for the synthesis of oligomeric oxymethylene dimethyl ethers (OME) from methanol (MeOH) and formaldehyde (FA) has been carried out. All catalysts led to the same product spectrum and parameters for chemical equilibrium have been determined. The ion exchange resin Dowex50Wx2 showed highest activity and reaction kinetics has been investigated employing this catalyst. The influence of the FA:MeOH ratio and water as well as refeeding of OMEs with undesired chain lengths have been considered in the kinetic model, which is based on a hyperbolic approach. Experiments have been carried out in the temperature range between 40 and 120°C and variable FA:MeOH ratios from 0.5 to 1.5g/g have been employed. Regarding water, up to 23wt.% have been added to the reaction mixtures to investigate its influence on yield and reaction rate. Low water contents lead to high OME selectivities. By varying the FA:MeOH ratio, chain lengths of the OMEs can be influenced. Regarding the most active catalyst Dowex50Wx2, 90% of equilibrium conversion is reached after 5min at 60°C employing a catalyst loading of 1wt.%. A study on the long term performance of the catalyst has been carried out and after 17days the decrease of activity was below 10% while selectivity remained the same. For different Dowex catalysts a general kinetic model could be developed, which is not limited to Dowex50Wx2.

Multipodal dynamic coordination involving cation-π interactions to control the structure of helical polymers.

A precise tuning of the four possible states of a helix (P/M helical sense and stretched/compressed helical backbone) is attained by controlling the complexation between Li+ and a poly(phenylacetylene) that bears amide, ester and phenyl ring functionalities at the pendant group. Depending on the MeOH ratio that is present as a cosolvent, different coordination sites are involved in interactions leading to complexes I-III, each one with a characteristic structure (tri-, bi-, and unipodal) and an associated helical state. This dynamic coordination allows the selective modification of the helical sense or the stretching/compression backbone of a helical polymer.

Energy Analysis of Hydrogen Production from Methanol under Atmospheric Pressure and Supercritical Water Conditions

The energy analysis of hydrogen production from the methanol reforming and oxidation under atmospheric (ATM) pressure and supercritical water (SCW) conditions was performed. The equilibrium hydrogen was investigated by the minimization of the Gibbs free energy based on Peng-Robinson equation of state for high pressure and ideal gas equation for atmospheric pressure. An objective of this study was to obtain the optimum operating conditions to maximize the net hydrogen yield, defined as the hydrogen yield taking into account also the methanol consumed by combustion to generate heat. This was done by investigating the effect of operating parameters over the following ranges: temperatures between 773 and 1273 K, pressures between 0.1 and 25.0 MPa, water-to-methanol (H2O:MeOH) ratios between 1 and 5, and oxygen-to-methanol (O2:MeOH) ratios between 0 and 1.05. At ATM pressure, it was found that the equilibrium hydrogen yield increases with increasing H2O:MeOH ratio but the peak of equilibrium H2 yield is at 973 K for higher H2O:MeOH ratio than 1:1. Additionally, the total heat load increases significantly as the reaction temperature and the water amount increase. Therefore, the optimum net H2 yield is at the H2O:MeOH ratio of 2:1 and the reaction temperature at 973 K. Under SCW conditions, an increase of temperature and water amount in the system constantly increases the equilibrium H2 yield. It means that the high H2O:MeOH ratio and temperature are required in SCW. The presence of oxygen in hydrogen production was investigated that an increase of O2:MeOH ratio constantly decreases the H2 yield and also the net H2 yield for reaction at ATM pressure whereas under SCW conditions, the equilibrium H2 yield and the net H2 yield increase with increasing oxygen up to 0.42 and 0.84, respectively.

Thermodynamic Analysis of Hydrogen Production from Methanol Reforming in Supercritical Water

The hydrogen production via methanol reforming in supercritical water (SCW) condition has been thermodynamically investigated by a Gibbs free energy minimization method to determine equilibrium yields and energy requirements in fuel processor over the temperature range between 673 and 1273 K and water-to-methanol (H2O:MeOH) ratio of 1 – 5 corresponding to the methanol concentration from 64 to 26 wt%, respectively. In this research, the main objective is to compare the influence of operating pressure from atmospheric (ATM) pressure to SCW condition on the product yields. At ATM pressure, a hydrogen production increases with increasing reaction temperature up to 973 K while under SCW condition, an increase of temperature constantly increases the formation of hydrogen. As the reaction temperature increases, the hydrogen production and the total heat load increase but the hydrogen to carbon monoxide (H2/CO) ratio decreases. Although the hydrogen yield is constantly higher at ATM pressure than under SCW condition, the H2/CO ratios are always greater in SCW at temperatures above approximately 700 K. The amount of hydrogen and the heat load of both the preheater and the reactor also increase significantly as the H2O:MeOH ratio increases.

Enhanced hydrogen selectivity via photo-engineered surface defects for methanol steam reformation using zinc oxide–copper nanocomposite catalysts

Methanol steam reformation (MSR) to produce hydrogen (H2) gas using copper on zinc oxide (Cu/ZnO) supported catalysts is attractive due to the simple and low cost preparation process of the catalyst. H2 yield from MSR is proportional to total catalyst loading which can be tuned during catalyst preparation. By creating UV-c light induced surface defects on ZnO nanorods, we have shown improved copper (Cu) nano-particle distribution on the ZnO nanorods leading to better H2 yield. Increase in Cu nanoparticle adsorption is achieved by in situ reduction of Cu ions by photo-generated electrons, facilitated by ZnO surface defects that act as high energy sites favorable for Cu ion adsorption and their subsequent growth into nanoparticles. The modulated Cu/ZnO catalyst increases H2 selectivity by 57% along with a corresponding increase in CO content, which can be controlled by adjusting H2O:MeOH ratio in the precursor solution.

A thermogravimetric study of the partial oxidation of methanol for hydrogen production over a Cu/ZnO/Al2O3 catalyst

The partial oxidation of methanol for the production of hydrogen was investigated in both a fixed-bed microreactor and in a thermogravimetric analyzer (TG-FTIR) from 180°C to 250°C using a commercial Cu/ZnO/Al2O3 catalyst. In the microreactor, a hot spot in the undiluted catalyst bed of 4K and 32K was observed at 180°C and 220°C, respectively. Methanol conversion was strongly accelerated between 180°C and 220°C. In the TG-FTIR experiments, the reduced copper was completely oxidized to cuprite, Cu2O, with increasing time-on-stream in the presence of oxygen and methanol (O2/MeOH=0.5) at 180°C. The selectivity to formaldehyde increased in the same manner as the catalyst was oxidized to cuprite. In contrast, at 250°C the catalyst remained completely reduced for the same O2/MeOH ratio. Two main reaction pathways are proposed explaining the influence of the copper oxidation state on the product distribution.

Steam reforming of methanol over Cu/ZnO/Al2O3 modified with hydrotalcites

Dilution of a commercial Cu/ZnO/Al 2 O 3 (CZA) catalyst by well-crystallized MgAl hydrotalcite nitrate (HTNO 3 ) and chloride (HTCl) resulted in the formation of the modified samples CZA–HTN and CZA–HTCl, respectively. The samples were characterized by N 2 sorption and XRD measurements. The structures of the CZA–HT materials proved to be more compact than those of the pristine clays. The modified samples were investigated as catalysts for the steam reforming of methanol under steady state conditions. The catalytic activity and the long-term stability of CZA–HT were found to depend strongly on the nature of the interlamellar anion of HT. CZA–HTN exhibited a marked catalytic activity and an enhanced thermal stability. It was pointed out that dilution with HTNO 3 improved the catalytic performance of CZA by increasing the methanol conversion and decreasing the CO production. The moderate increase in the methanol conversion for CZA–HTN during time-on-stream was attributed to partial delamination of the HT structure under SRM conditions. The application of an enhanced H 2 O:MeOH ratio of 1.3 for CZA–HTN was found to decrease both the methanol conversion and the CO formation to an appreciable extent.

Thermodynamic analysis of carbon formation in a solid oxide fuel cell with a direct internal reformer fuelled by methanol

A detailed thermodynamic analysis is undertaken for carbon formation in a solid oxide fuel cell (SOFC) with a direct internal reformer (DIR) fuelled by methanol. Two types of fuel cell electrolyte, i.e. oxygen- and hydrogen-conducting, are considered. Equilibrium calculations are performed to find the range of inlet steam methanol (H 2O:MeOH) ratio where carbon formation is thermodynamically unfavourable in the temperature range of 500 to 1200 K. The key parameters that determine the boundary of carbon formation are temperature, type of solid electrolyte, and the extent of the electrochemical reaction of hydrogen. The minimum H 2O:MeOH ratio for which carbon formation is thermodynamically unfavoured decreases with increasing temperature. Comparison between the two types of electrolyte reveals that the hydrogen-conducting electrolyte is impractical for use given the tendency for carbon formation. This is mainly due to the water formed by the electrochemical reaction at the electrodes.