Transesterification Reaction Of Oil Research Articles

Utilising magnetite and heteropoly acid to modify silica foam and consider catalytic activity for esterification and transesterification procedure

Silica foam can be helpful substrate to tailoring heterogenous catalyst in various shapes and size. In this work, we have successfully prepared and modified Silica Foam that modified by magnetite nanoparticle (FM) and heteropoly acid (FMH). These new composites were characterized by FT-IR, XRD, SEM, TGA, DTG, NH3-TPD, and VSM. The result confirms that fine dispersity of magnetite nano particle and heteropoly acid into silica foam and without any significant change in structure of materials. The synthesized composites FM and FMH were used as catalysts for the esterification reaction of acetic acid with five different alcohols and the transesterification reaction of sunflower, animal fats, and waste oils. The results show that the efficiency of the esterification reaction for the FMH catalyst is about 98.8% and 78.8% for the transesterification reaction.

Catalysis of the Transesterification Reaction of Alkyl Benzoates and Vegetable Oils by Carbonates, Carbene, and Anionite

Catalysis of the Transesterification Reaction of Alkyl Benzoates and Vegetable Oils by Carbonates, Carbene, and Anionite

Enhanced Biodiesel Production from Waste Cooking Oil Using Potash-Enriched Natural Base Catalyst

The transesterification reaction of waste cooking oil with methanol using a sugar apple peel ash catalyst has been reported. Under optimized conditions, the reaction of the oil with methanol in a molar ratio of 1:10, in the presence of a catalyst (2 g) at 60 °C temperature offered a 94.5% yield of biodiesel within 120 min. The heterogeneous catalyst was developed via a straightforward calcination process using fruit processing industry waste peels of sugar apples. The characterization of the catalyst by FTIR, EDS, SEM, XRD, N2 sorption, and XRF analysis revealed a higher concentration of potassium species which is possibly responsible for the promotion of the transesterification reaction more efficiently. This approach offers cost competitiveness, reusability of the catalyst, simplicity of operation, and high biodiesel yields. This study underscores the potential of utilizing waste materials for sustainable biodiesel production, contributing to environmental preservation and economic viability.

Modeling and simulation of biodiesel synthesis in fixed bed and packed bed membrane reactors using heterogeneous catalyst: a comparative study

In this study, modeling and simulation of biodiesel synthesis through transesterification of triglyceride (TG) over a heterogeneous catalyst in a packed bed membrane reactor (PBMR) was performed using a solid catalyst and compared with a fixed bed reactor (FBR). The kinetic data for the transesterification reaction of canola oil and methanol in the presence of solid tungstophosphoric acid catalyst was extracted from the published open literature. The effect of reaction temperature, feed flow rate, disproportionation of the reactants, and reactor length on the product performance was investigated. Two-dimensional and heterogeneous modeling was applied to PBMR and the resultant equations were solved by the Matlab software. Moreover, the velocity profile in the membrane reactor was obtained. The results showed the best conditions for this reaction are 180 °C, the molar ratio of methanol to oil equal 15:1, and the input flow rate of 0.5 mL/min. In this condition, a conversion of 99.94% for the TG can be achieved in the PBMR with a length of 86 cm while a length of 2.75 m is required to achieve this conversion of the FBR. Finally, the energy consumption for the production of 8000 ton/y biodiesel in a production plant using the PBMR and the FBR was obtained as is 1313.24 and 1352.44 kW, respectively.

A Novel PETG Microchannel Reactor for Microwave-Powered Biodiesel Production

Biodiesel stands at the forefront as a replacement for fossil diesel in compression ignition engines, particularly in the transportation sector where diesel engines are the primary movers. However, biodiesel production is hampered by poor heat and mass transfer during the transesterification reaction, leading to long production times and high costs due to inefficient energy utilisation. This study targets heat and mass transfer issues during the production of biodiesel via a synergic approach that combines microwave-assisted heating and microfluidics via a polyethylene terephthalate glycol (PETG) microchannel reactor. The transesterification reaction of palm oil and methanol was investigated using a full factorial design of experiments (DOE) method. Biodiesel yield was quantified via gas chromatographic analysis, and the results were optimised using statistical analysis. Optical analysis of slug quantification within the microchannel revealed that small slugs, smaller than 1 mm, accelerated the transesterification reaction. The composite-optimised experimental results, aimed at minimising energy costs and environmental impacts while maximising fatty acid methyl ester (FAME) yield, indicate a reaction temperature of 50 °C, a catalyst loading of 1.0 wt.%, and a 3:1 methanol to oil molar ratio. Regression analysis revealed that the reaction temperature was statistically insignificant when utilising the PETG microchannel reactor. This key finding positively impacts biodiesel production as it relates to significantly reduced energy intensity, costs, and emissions. Overall, this research work paves a pathway toward an energy-efficient and sub-minute rapid transesterification reaction, highlighting the effectiveness of microwave heat delivery and effects of microfluidics via the PETG microchannel reactor in overcoming heat and mass transfer barriers in biodiesel production.

Preparation of CaO@CeO2 Solid Base Catalysts Used for Biodiesel Production

The study investigated the use of CeO2 extracted from monazite with calcium oxide (CaO) as a solid catalyst for biodiesel production. The wet impregnation method was used to produce CaO@CeO2 mixed-oxide catalysts with 0–50 wt.% CaO. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and a Fourier transform infrared spectrometer (FTIR) was used to characterize the catalysts. In order to determine the optimal preparation conditions, the effect of different CaO compositions on the performance of CaO@CeO2 mixed-oxide catalysts was examined. The catalytic activity of the CaO@CeO2 catalyst for the transesterification reaction of palm oil to produce biodiesel was studied. The results show that the optimum yield of biodiesel can reach 97% fatty acid methyl ester over the 30CaO@CeO2 catalyst at the reaction conditions of 5 wt.% catalysts, methanol-to-oil molar ratio of 9:1, with a reaction temperature of 65 °C within 30 min. The results show that the high catalytic activity and stability of the CaO@CeO2 catalyst make it a promising candidate for industrial-scale biodiesel production. Further study is needed to improve the stability and efficiency of catalysts in transesterification reactions to achieve a high FAME yield using long-life-span catalysts. Moreover, it is necessary to investigate the economic feasibility of this process for application in large-scale biodiesel production.

Indirect Measurement of Variables in a Heterogeneous Reaction for Biodiesel Production.

This research focuses on the development of a state observer for performing indirect measurements of the main variables involved in the soybean oil transesterification reaction with a guishe biochar-based heterogeneous catalyst; the studied reaction takes place in a batch reactor. The mathematical model required for the observer design includes the triglycerides' conversion rate, and the reaction temperature. Since these variables are represented by nonlinear differential equations, the model is linearized around an operation point; after that, the pole placement and linear quadratic regulator (LQR) methods are considered for calculating the observer gain vector L(x). Then, the estimation of the conversion rate and the reaction temperature provided by the observer are used to indirectly measure other variables such as esters, alcohol, and byproducts. The observer performance is evaluated with three error indexes considering initial condition variations up to 30%. With both methods, a fast convergence (less than 3 h in the worst case) of the observer is remarked.

Biodiesel Production by Methanolysis of Rapeseed Oil-Influence of SiO2/Al2O3 Ratio in BEA Zeolite Structure on Physicochemical and Catalytic Properties of Zeolite Systems with Alkaline Earth Oxides (MgO, CaO, SrO).

Alkaline earth metal oxide (MgO, CaO, SrO) catalysts supported on BEA zeolite were prepared by a wet impregnation method and tested in the transesterification reaction of rapeseed oil with methanol towards the formation of biodiesel (FAMEs-fatty acid methyl esters). To assess the influence of the SiO2/Al2O3 ratio on the catalytic activity in the tested reaction, a BEA zeolite carrier material with different Si/Al ratios was used. The prepared catalysts were tested in the transesterification reaction at temperatures of 180 °C and 220 °C using a molar ratio of methanol/oil reagents of 9:1. The transesterification process was carried out for 2 h with the catalyst mass of 0.5 g. The oil conversion value and efficiency towards FAME formation were determined using the HPLC technique. The physicochemical properties of the catalysts were determined using the following research techniques: CO2-TPD, XRD, BET, FTIR, and SEM-EDS. The results of the catalytic activity showed that higher activity in the tested process was confirmed for the catalysts supported on the BEA zeolite characterized by the highest silica/alumina ratio for the reaction carried out at a temperature of 220 °C. The most active zeolite catalyst was the 10% CaO/BEA system (Si/Al = 300), which showed the highest triglyceride (TG) conversion of 90.5% and the second highest FAME yield of 94.6% in the transesterification reaction carried out at 220 °C. The high activity of this system is associated with its alkalinity, high value of the specific surface area, the size of the active phase crystallites, and its characteristic sorption properties in relation to methanol.

Synthesis and characterization of NaY@ZIF‐8 composite by the ship‐in‐bottle method as a catalyst for esterification and transesterification reactions

AbstractZeolite imidazolate frameworks (ZIFs) were composited with NaY zeolite using two different approaches to the ship‐in‐bottle method. The two synthesized nanocatalysts showed that the ZIF‐8 composite with NaY zeolite could stabilize their structure as catalysts in an acidic environment. The NaY@ZIF‐8 nanocomposites that were prepared were investigated using Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), elemental mapping (MAP), thermogravimetric (TGA), temperature‐programmed desorption of ammonia (NH3‐TPD), and inductively coupled plasma analyses. The synthesized composites were used as catalysts for the esterification reaction of acetic acid with four different alcohols and the transesterification reaction of animal fats, vegetable oils, and waste oils. The results show that the efficiency of the esterification reactions for the two catalytic composites was 98.5% and 94.3%, respectively, and 78.1% for the transesterification reaction.

Synthesizing a transesterification catalyst via a condensation reaction and assessment of the mechanism using density functional theory

AbstractBACKGROUNDA solid acid (SPEI–EN–OHCMs) having dendritic –NH2 groups was prepared via oxidation of hydrothermal carbon microspheres (OHCMs) followed by a condensation reaction with the –NH2 groups of polyethyleneimine and sulfonation. The mechanism by which –COOH groups on the surfaces of OHCMs reacted with these –NH2 groups was assessed using density functional theory (DFT).RESULTActivation using a combination of 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS) was found to promote the formation of amide bonds such that –NH2 groups were bonded to the microsphere surfaces. This effect provided more bonding sites for –SO3H groups. The DFT results indicated that the energy barrier on the potential energy surface in the presence of EDC and NHS was lowered by 18.1 kcal mol−1. X‐ray photoelectron spectroscopy analyses also confirmed the introduction of –NH2 groups followed by –SO3H groups onto the surfaces of the OHCMs. The concentration of surface acid sites on SPEI–EN–OHCMs was found to be as high as 11.8 mmol g−1. Thermogravimetric data and elemental analysis results showed that the –SO3H groups on the SPEI–EN–OHCM surfaces were thermally stable below 180 °C.CONCLUSIONThe SPEI–EN–OHCMs catalyst was used to promote the transesterification reaction of waste frying oil with methanol. A trial with a methanol‐to‐oil molar ratio of 10:1 at 110 °C for 4 h gave a fatty acid methyl ester (FAME) yield of 92.3%. After four reuses, an SPEI–EN–OHCMs specimen provided a FAME yield of 54.3%. © 2024 Society of Chemical Industry (SCI).

Biodiesel production from waste cooking oil using an innovative magnetic solid acid catalyst based on Ni–Fe ferrite: RSM-BBD optimization approach

In the present study, a novel solid acid magnetic catalyst composed of nickel ferrite (NiFe2O4) and impregnated with molybdenum oxide (MoO3) was synthesized by wet method and applied in the production of biodiesel from the methyl transesterification reaction of waste cooking oil (WCO). The catalyst was characterized by the following techniques: surface acidity, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Vibrating Sample Magnetometry (VSM). The optimization of the variables of the methyl transesterification reaction was carried out through the Box-Behnken 24 experimental design (BBD) and the response surface methodology (RSM). The optimized experimental results led to the obtainment of a biodiesel with 95.4 % conversion to esters under the following reaction conditions: 168 °C temperature, 30:1 methanol:WCO molar ratio, 10 wt% catalyst amount, and 1 h reaction time. The mathematical model developed showed an error of less than 5 % between the observed and predicted values. In addition, the catalyst showed bifunctional character (catalytic and magnetic) and high stability after seven reaction cycles, with conversion to esters above 90.3 %, as well as high versatility in the presence of various raw materials, indicating its high potential for development and application.

Pregled proizvodnje biodizela transesterifikacijom esterifikovanog ulja Carica Papaia (CSO)

As a result of global urbanization and modernization, the use of petroleum (fossil fuel) is on the increase and there are growing concerns among stakeholders in the oil and gas industry over the depletion rate of petroleum reserves and its rising cost. The conversion of readily available sources of biomass to produce different types of biofuels to address the future energy crisis is one of the preferred attractive choices. Biodiesel is generally produced by the transesterification reaction of vegetable oils, waste vegetable oil or animal fats in the presence of a suitable catalyst. The choice of biodiesel as a preferred renewable source of energy was based on its biodegradability, non-toxic, lower emissions, sulphur free, low levels of polycyclic aromatic hydrocarbons (PAHs) and their nitrated compounds. This alternative source of energy is environmentally friendly and could be used in the existing diesel engines with little or no modifications. This will reduce the world's dependence on fossil fuels that are non-renewable with the attendant environmental benefits to mankind. However, the use of these edible vegetable oils will put pressure on the food uses of such oil which will result to fuel-food crisis in the future. This impending crisis can be readily averted by exploring non-edible crops/agricultural waste biomass that can be grown or harnessed domestically and capable of producing oils as valuable raw materials for the emerging industry. A free fatty acid (FFA) lower than 3% is necessary to carry out the base catalysed reaction to end. For biodiesel production, the higher the acid value of the oil, the lesser the conversion efficiency hence the need for esterification process. Papaya seed contains 27.3% to 28.3% protein, 28.2% to 30.7% lipids, and 19.1% to 22.6% crude fibers, it is not economically used. The majority of seeds are produced as residues and discarded as agricultural waste during fruit processing, generating environmental issues. Oil is abundant in papaya seeds (13.9% to 40.0%), which is rich in monounsaturated fatty acids and beneficial phytochemicals as tocopherol, carotene, and phenolics. This provides information on how to reduce pollution and make waste seeds lucrative. As a result, the CPSO is receiving an increasing amount of attention.

A review of the use of SrO in catalysts for biodiesel production

AbstractSrO has attracted attention for its use as a heterogeneous catalyst in producing biodiesel from transesterification owing to its high alkaline character and low solubility in methanol. In studies conducted in this decade, reaction conditions such as the methanol–oil molar ratio, reaction time, catalyst loading and temperature have been optimized in these systems. Furthermore, several works have been carried out to improve the physicochemical properties and increase the leaching resistance of this material. Thus, the new trends in using SrO in transesterification reactions are that this oxide should be supported or combined with Al2O3, TiO2, ZrO2, or Fe2O3, CaO, metal–organic frameworks, zeolites or La2O3. It has been observed that strontium can form mixed crystalline phases with these oxides by increasing the (M2+O2−) pairs and Lewis basicity of the oxygens, resulting in increased basicity and catalytic activity. Moreover, the transition metal oxides may provide Lewis acidity. Hence, these strontium‐containing catalytic systems have demonstrated a bifunctionality that can perform esterification and transesterification reactions at the same time. In addition, the combination of these oxides decreases the leaching of the catalyst. Other materials such as metal–organic frameworks, zeolites, and La2O3 have been studied as SrO supports, showing that they can be used in oil transesterification reactions.

Boosting biodiesel production of waste frying oil using solid magnetic acid catalyst from agro-industrial waste

In the present study, a new magnetic acid solid catalyst composed of an agro-industrial waste (rice husk ash-RHA) magnetized with cobalt ferrite (CoFe2O4) and impregnated with MoO3 was synthesized and applied in the methyl transesterification reaction of waste frying oil (WFO) for biodiesel production. The catalyst was synthesized by wet impregnation method and characterized by the following techniques: surface acidity, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), and vibrating sample magnetometer (VSM). The one variable at time (OVAT) technique was used to optimize the variables of the transesterification reaction in the following ranges: temperature (130.0–170.0 °C), methanol:oil molar ratio (10:1–50:1), catalyst amount (2.0–10.0 wt%), and reaction time (1.0–5.0 h). The results demonstrate that the application of the MoO3/RHA-CoFe2O4 synthesized catalyst resulted in the attainment a biodiesel with ester content of 94.6 % under the optimized reaction conditions: temperature of 160.0 °C, methanol:oil molar ratio of 20:1, catalyst amount of 6.0 wt%, and reaction time of 3.0 h. The biodiesel produced was characterized and presented physicochemical properties in accordance with the limits established by the international standards ASTM D6751 and EN 14214. The kinetic study of the transesterification process revealed that the pseudo-first order model is the most suitable with an activation energy of 27.3 kJ mol−1. In addition, the catalyst showed bifunctional character (catalytic and magnetic), as well as high catalytic stability after ten reaction cycles, maintaining the production of biodiesel with ester content above 70.0 %, indicating its high potential for development and application.

Biodiesel production via transesterification reaction

Global warming, climate change, local air pollution, ozone depletion, acid rain and depletion of fossil fuel are the major global environmental issues. Presently, non-renewable fossil fuels meet up to 80% of the world’s energy demand. Rapid consumption of fossil fuels as well as rising environmental pollution caused by extreme CO2 emissions, sulphur dioxide, and aromatic hydrocarbons has become crucial in searching for a clean and renewable energy source such as biodiesel. With continuous growth in the world’s population, rapid industrialization, urbanization, and economic growth, fossil fuel consumption is escalating to meet the global energy demand. Biodiesel is renewable, non-toxic, environment-friendly and an economically feasible options to tackle the depleting fossil fuels and its negative environmental impact. Biodiesel is an alternative fuel made by transesterification reaction of oil and alcohol under the influence of catalyst. Biodiesel is an alcoholic ester of various fatty acids, also known as FAME (Fatty Acid Methyl Esters). In the process of transesterification, the performance of the catalyst is the key factor of the biodiesel yield. Catalysts used in biodiesel production are classified as homogeneous, heterogeneous, and enzymatic catalysts. The incorporation of a catalysis-based transesterification reaction generally increases the rate of reaction and enhances the yield of the end product. In case of homogeneous catalysts, there are problems of catalyst poisoning and contamination. Heterogeneous acid catalysis has a lesser toxic effect and gives rise to fewer environmental problems compared to the homogeneous mode. The cost of each specific catalyst depends on various factors, including the source, synthesis method, and its reusability. Generally, using waste or biomass as sources of catalysts may reduce the price of commercially available solid catalysts.

EFFECT OF POTASSIUM HYDROXIDE CONCENTRATION AS A CATALYST ON THE YIELD OF COCONUT OIL (Cocos nucifera) TRANSESTERIFICATION

Research has been carried out on the effect of potassium hydroxide catalyst concentration on the yield of coconut oil (Cocos nucifera) transesterification and continued to characterize the reaction results. The concentration of potassium hydroxide used was 1, 2, and 3% by weight of coconut oil with ethanol as the reactant. The data processing used was the one-way analysis of variation and its characterization from a physicochemical perspective, followed by the analysis of gas chromatography-mass spectroscopy (GCSM) and infrared spectrophotometry. Based on the data processing results, potassium hydroxide concentrations of 1, 2, and 3% did not affect the yield of the transesterification reaction of coconut oil, and the results were 74.5264%, 71.9330%, and 69.0420%. The characterization results show that the physicochemical properties of the reaction products, such as acid number, density, and viscosity, comply with the Indonesian National Standard (SNI) for biodiesel. The results of the GCMS analysis showed that nine peaks were dominated by ethyl laurate.

BaO as a heterogeneous nanoparticle catalyst in oil transesterification for the production of FAME fuel

Metal oxide-based catalysts play an important role in the transesterification reaction of vegetable oils for fatty acid methyl ester (FAME) production. Additionally, nanocatalysts demonstrate high efficiency due to their increased surface area, higher catalytic activity, and easy operational procedures. Thus, the main objective of this work is to investigate FAME production from sunflower oil using barium oxide (BaO) nanoparticles. BaO was synthesized through one-pot sol–gel reactions and was analysed by several techniques, such as X-ray diffraction (XRD), transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence(EDXRF), N2 adsorption–desorption of liquid nitrogen at 77 K [Brunner–Emmett–Teller (BET)] for surface area measurement and UV–Vis spectroscopy. BaO behaved as an efficient catalyst in the transesterification of oils into FAMEs. Furthermore, the impacts of a variety of reaction parameters on the biofuel yield were explored. The catalyst with 4.7 wt% has the maximum yield of 78.38 % achieved under the optimized reaction conditions (70 °C, 1:20 M ratio of oil:methanol). The characteristics of the resulting methyl ester partially agreed with international FAME standards, making it suitable for use as a blend with petroleum diesel in proportions defined by volume according to the specifications of the American Society for Testing and Materials(ASTM). The catalyst was also evaluated for reusability tests, and the reusability through the reaction showed less than a 7 % conversion drop after 3 runs and 14.6 % after 5 runs.

Optimization of microreactor-intensified transesterification reaction of sesame cake oil (sesame waste) for biodiesel production using magnetically immobilized lipase nano-biocatalyst

Enzyme-catalyzed transesterification to produce biodiesel is a time-consuming reaction. This study aimed to use a recoverable nanomagnetic immobilized enzyme and microreactor-intensified process to design a significantly rapid transesterification reaction. Immobilization of Candida Rugosa lipase (CRL) on GO-Fe3O4@TiO2 nanocomposite was optimized using response surface methodology-box–Behnken design (RSM-BBD). Results showed the highest immobilization efficiency of 92.73% at the optimum condition of CRL concentration of 2.59 mg/mL, time of 4.96 h, and temperature of 37.61 °C. Newly synthesized GO-Fe3O4@TiO2@CRL nano-biocatalyst (NBC) was characterized using FTIR, XRD, VSM, FE-SEM, EDX and elemental mapping. Immobilized CRL showed improved stability under different parameters, including pH, thermal, and methanol medium compared to free CRL. Freshly synthesized NBC was used in a microreactor to intensify the transesterification reaction of sesame cake oil to produce biodiesel. The RSM-BBD optimization of the transesterification reaction showed a maximum conversion rate of 97.03%, achieved at the NBC amount of 4.47 wt%, residence time of 13.29 min, and Me/oil molar ratio of 4.28. The generated biodiesel has all characteristics well within the ASTM D6751, demonstrating its good quality. The results of this study showed that using a microreactor could sufficiently intensify the transesterification reaction and reduce the reaction time using GO-Fe3O4@TiO2@CRL NBC.

Lubricity Performance of Ethylene Glycol Ester from Soybean Oil as a Lubricity Enhancer Bio-Additive for Low-Sulfur Diesel Fuel

The present study aims to show the tribological properties of soybean oil's ethylene glycol ester (SOEGE) and its effect on low-sulfur diesel fuel lubrication. The SOEGE or 2-hydroxyethyl ester was synthesized by a transesterification reaction of soybean oil and ethylene glycol with a potassium carbonate catalyst. The product was characterized using Gas Chromatography-Mass Spectrometry (GC-MS). Then, the lubricity of commercial diesel fuel (Pertadex) and SOEGE were tested alone using the High-Frequency Reciprocating Rig (HFRR) machine. Its mixture form with various product doses in Pertadex (0.2, 0.4, 0.6, 0.8, and 1% v/v) was also tested with the same apparatus. This study showed that the product's coefficient of friction and Wear Scar Diameters (WSD) were 0.057 and 154.4 m, respectively. This value is lower than Pertadex and Fatty Acids Methyl Ester (FAME) of Soybean oil from the literature. Furthermore, adding products into Pertadex can reduce the coefficient of friction and WSD of Pertadex. The Pertadex coefficient of friction was reduced from 0.161 to 0.135 after the addition of 0.8% product. At a concentration of 1% product, WSD Pertadex was successfully reduced by 39.42%. These phenomena imply that ester ethylene glycol has an excellent lubricating effect on low-sulfur diesel. This work's findings open opportunities for other researchers to develop alternative lubricating bio-additives for low-sulfur diesel through the in-depth study of tribochemistry or tribosurface.

Bimetallic Zrx-Aly-KIT-6 modified with sulfate as acidic catalyst for biodiesel production from low-grade acidic oils

For the purpose of fabricating an efficient solid acid catalyst for biodiesel production from low-grade acidic oils, bimetallic silica mesoporous composites with different Zr/Al molar ratios were initially synthesized via a facile one-step hydrothermal method, and then sulfated with sulfuric acid at different concentrations to get a series of sulfated Zrx-Aly-KIT-6 catalysts (denoted as SZA-K, where x/y represents the molar ratio of Zr to Al). The sulfated bimetallic solid catalysts were fully characterized by using XRD, FT-IR, TEM, SEM, EDS, NH3-TPD, and nitrogen porosimetry measurements. Results showed that the remarkable amount of acidic sites in the catalysts was derived from the Zr and Al incorporation and further sulfation, and specifically, the Zr4+ and Al3+ could afford abundant weak acid sites while the inductive effect of SO42− species greatly influences the acidic strength of this solid catalyst. In combination with the enhancement in mass transfer resulting from the inherent interconnected mesoporous structure, the SZA-K catalyst could facilitate the transesterification reaction to take place efficiently. The sulfated Zr5–Al1-KIT-6 catalyst (Zr/Al molar ratio of 5/1, treated using 0.75 mol/L sulfuric acid for 12 h) exhibited enhanced acid strength with larger number of acidic sites (7.81 mmol/g), resulting in a high catalytic performance to the oil transesterification reaction. An oil conversion of 96.3% was attained for the transesterification reaction performed at 120 °C for 7 h by using a methanol/oil molar ratio of 20:1 and a catalyst dosage of 6 wt%. Further, this solid catalyst exhibited better acid and water-resistance capacity with above 80% of oil conversion even with 10% of free fatty acid (FFA) and 2% of moisture present in the low-grade acidic oils. Meanwhile, the good reusability was shown for this catalyst with 80.1% conversion even after reusing for three cycles. The good stability of the solid catalyst was resulted from the strong interactions between the acidic species and the bimetallic composite support.