Palm Oil-based Trimethylolpropane Ester Research Articles

Enzymatic synthesis of palm oil-based trimethylolpropane ester as biolubricant base stock catalyzed by Lipozyme 435

The application of enzymes in the organic synthesis of polyol esters for biolubricants is one of the initiatives in the development of sustainable processes in the oil palm industry. In this study, trimethylolpropane (TMP) ester was synthesized from high oleic palm methyl ester (HO-PME) via enzymatic transesterification. Lipozyme 435, which is an immobilized form of lipase B from Candida antarctica (CALB), was investigated as a substitute for chemical catalyst in the production of palm oil-based lubricant. Response surface methodology (RSM) via Central Composite Rotatable Design was employed to optimize the reaction conditions. The results showed that only 3% (w/w) enzyme dosage was required to obtain the highest triester of 82% without purification. The optimum process conditions predicted by RSM were 3.45:1 M ratio of HO-PME: TMP, 15.25 mbar pressure, and 48 h reaction time. The TMP ester exhibited excellent lubricant properties. This study demonstrated a reduction in overall production cost including waste management due to the elimination of the product purification step. As compared to chemical catalyst, milder reaction conditions and no formation of side products were observed in this study. The physicochemical characteristics of the TMP ester synthesized via enzymatic transesterification complied satisfactorily with the requirements of biolubricant base stock. Our findings offer a greener and economical approach for producing high-performance biolubricant, which can be applied for scale-up production.

Nano-tribological characterisation of palm oil-based trimethylolpropane ester for application as boundary lubricant

Abstract To isolate shearing of boundary film from direct surface-to-surface asperity interactions, the study determines boundary lubrication properties of palm oil-based TMPE (PTMPE) using Lateral Force Microscopy coupled with fluid imaging. PTMPE is produced through a series of 3-step transesterification processes, converting palm oil (PO) into palm methyl ester (PME) and finally into PTMPE. It is shown that PME generates the lowest friction. However, using Eyring thermal activation energy approach, PME is shown to possess less desirable load bearing property, portraying a form of stiction or adhesive nature. Even though friction is higher, PTMPE exhibits better load bearing ability, demonstrating the onset of lubricant laminar flow due to increased hydrodynamic effect, which is not observed for the PO and PME measurements.

Synthesis of high oleic palm oil-based trimethylolpropane esters in a vacuum operated pulsed loop reactor

The experimental studies have shown that a pulsed loop reactor can be used to successfully reduce the reaction time for the transesterification of oils and fats. In the present study, the transesterification of palm methyl ester (PME) and trimethylolpropane (TMP) to produce palm oil based TMP ester was conducted using the vacuum operated pulsed loop reactor. The reaction was catalyzed with sodium methoxide solution in methanol. The influences of five operating variables such as vacuum pressure, catalyst loading, molar ratio of high oleic PME to TMP, reaction temperature and oscillatory speed on the yield of TMP esters and unwanted fatty soap formation were examined. The optimum conditions for the reaction were found at 120°C, 20mbar, 3.9:1M ratio of PME:TMP, 1.0wt% catalyst solution and 180rpm oscillatory speed. The product containing 95wt% TMP triester was successfully synthesized in 1h with 167mg/g of fatty soap. The physicochemical properties of the TMP esters obtained using pulse reactor were comparable to characteristics of high oleic TMP esters.

Synthesis of palm oil-based trimethylolpropane ester as potential biolubricant: Chemical kinetics modeling

The environmental impact of large amounts of lubricants from mineral oils has become an increasingly important issue. The use of rapidly biodegradable lubricants, vegetable products as well as modified vegetable oil esters, could significantly reduce the environmental pollution compared to mineral oils. A kinetic/mathematical model describing chemical transesterification of palm oil-based methyl esters (POMEs) with trimethylolpropane (TMP) to polyol esters has been developed. The kinetics of the transesterification reaction was modeled as three distinct elementary reversible series–parallel reaction mechanisms. The model considers the transesterification reaction to take place in both forward and reverse directions. The resulting kinetics equations were solved using ode45 solver function in MATLAB, where the rate constants of the proposed kinetic model were determined by minimization of errors based on the optimum criteria of statistical analysis and by comparing the component concentrations at maximum and at equilibrium. The forward and reverse rate constants of all three steps involved in the transesterification reaction were reported. The validity of the model was tested by comparing the observed experimental values with the theoretical calculated data. A good correlation between simulated results and experimental data was observed, confirming that the model was able to predict the rate constants with plausible accuracy. The new proposed kinetic model would facilitate the design of a pilot-scale chemical reactor for the transesterification of POME with TMP to obtain palm oil-based polyol esters as a potential biolubricant.

Response Surface Methodology for Optimization of Epoxidized Trimethylolpropane Ester Synthesis from Palm Oil

To improve the oxidative stability of the palm oil-based biolubricant, the fatty acid double bonds in palm oil-based trimethylolpropane ester (TMP ester) was converted into an oxirane ring via an in-situ epoxidation method. The epoxidized TMP ester was produced from a reaction between TMP ester and peracetic acid which was prepared in-situ by reacting glacial acetic acid with hydrogen peroxide in the presence of concentrated sulphuric acid. The response surface methodology was applied using a central composite design technique to optimize the conditions of the epoxidation reaction to produce the epoxidized TMP ester. The effects of four independent variables namely concentration of acetic acid (0-2 mol), concentration of hydrogen peroxide (1.5-9.5 mol), temperature of reaction (30-110°C) and reaction time (0.5-26.5 h) on the three dependent variables; percentage of oxirane oxygen, iodine value, and hydroxyl value were studied. A second-order polynomial multiple regression model was employed to predict the three dependent variables under optimum conditions of 0.59 mol of glacial acetic acid, 7.5 mol of hydrogen peroxide concentration, at temperature of 50°C and reaction times of 7 h. The optimum values of percentage of oxirane oxygen, iodine value, and hydroxyl value were 4.01%, 1.94%, and 0.43% respectively. The analysis of variance yielded a high coefficient of determination value of 0.9395-0.9880, hence indicating the fitness of the second-order regression model to the experimental data.

Response Surface Methodology for Optimization of Epoxidized Trimethylolpropane Ester Synthesis from Palm Oil

To improve the oxidative stability of the palm oil-based biolubricant, the fatty acid double bonds in palm oil-based trimethylolpropane ester (TMP ester) was converted into an oxirane ring via an in-situ epoxidation method. The epoxidized TMP ester was produced from a reaction between TMP ester and peracetic acid which was prepared in-situ by reacting glacial acetic acid with hydrogen peroxide in the presence of concentrated sulphuric acid. The response surface methodology was applied using a central composite design technique to optimize the conditions of the epoxidation reaction to produce the epoxidized TMP ester. The effects of four independent variables namely concentration of acetic acid (0-2 mol), concentration of hydrogen peroxide (1.5-9.5 mol), temperature of reaction (30-110°C) and reaction time (0.5-26.5 h) on the three dependent variables; percentage of oxirane oxygen, iodine value, and hydroxyl value were studied. A second-order polynomial multiple regression model was employed to predict the three dependent variables under optimum conditions of 0.59 mol of glacial acetic acid, 7.5 mol of hydrogen peroxide concentration, at temperature of 50°C and reaction times of 7 h. The optimum values of percentage of oxirane oxygen, iodine value, and hydroxyl value were 4.01%, 1.94%, and 0.43% respectively. The analysis of variance yielded a high coefficient of determination value of 0.9395-0.9880, hence indicating the fitness of the second-order regression model to the experimental data.

Synthesis of Palm Oil Based Trimethylolpropane Esters with Improved Pour Points

Palm oil based trimethylolpropane (TMP) esters are potential biodegradable base stocks for environmentally friendly lubricants. To improve the low-temperature properties of palm oil based TMP esters, which are well below the requirements set by the lubricants' manufacturers, the high oleic content palm oil based TMP ester with a pour point between −10 and −32 °C was synthesized. The synthesis of palm oil polyol esters was performed by transesterification of fractionated palm oil methyl esters with TMP using sodium methoxide as a catalyst. Nearly complete conversion to palm TMP triesters (98% w/w) was obtained. The palm oil methyl esters were fractionated at 150−180 °C and 0.1 mbar prior to the synthesis to reduce the saturated fatty acid content. The fractionation and reaction took place using the same experimental setup. The effects of composition on pour points, viscosity, and viscosity index of the high oleic content palm oil based TMP esters were also evaluated. The concentration of C16:0 methyl ester...