Kinetics measurement of ethylene-carbonate synthesis via a fast transesterification by microreactors

High-purity ethylene carbonate (EC) is widely used as battery electrolyte, polycarbonate monomer, organic intermediate, and so on. An economical and sustainable route to synthesize high-purity ethylene carbonate (EC) via the transesterification of dimethyl carbonate (DMC) with ethylene glycol (EG) is provided in this work. However, this reaction is so fast that the reaction kinetics, which is essential for the industrial design, is hard to get by the traditional measuring method. In this work, an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst. The effects of flow rate, microreactor diameter, catalyst concentration, reaction temperature, and reactant molar ratio were investigated. An activity-based pseudo-homogeneous kinetic model, which considered the non-ideal properties of reaction system, was established to describe the transesterification of DMC with EG. Detailed kinetics data were collected in the first 5 min. Using these data, the parameters of the kinetic model were correlated with the maximum average error of 11.19%. Using this kinetic model, the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%, suggesting its satisfactory prediction performance.     

Experimental and Kinetic Studies on a Homogeneous System for Diethyl Carbonate Synthesis by Transesterification

A synthesis of diethyl carbonate through transesterification of propylene carbonate and ethanol, coproducing useful propylene glycol, was carried out in the presence of sodium ethoxide as catalyst. The effects of reaction parameters such as catalyst concentration, mole ratio of ethanol to propylene carbonate and reaction temperature on the transesterfication reaction were investigated. The results showed that the reaction is reversible with a propylene carbonate equilibrium conversion of about 64 % at an ethanol to propylene carbonate mole ratio of 8.0 and a reaction temperature of 303 K. A kinetic model was proposed based on the reaction mechanism. The model parameters were estimated by the Runge‐Kutta method. The statistical test showed that the model calculation results were in good agreement with the experimental data.     

Bio-diesel production by alkali catalyzed transesterification of dairy waste scum

The potential of using dairy waste scum as a feed stock for bio-diesel production was investigated. Present study optimized the parameters involved in transesterification process of Dairy Waste Scum Oil. Gas chromatography was used to determine the fatty acid composition of Dairy Waste Scum Oil. Results revealed that the low free fatty acid content was a notorious parameter to determine the viability of alkaline transesterification. The yield of bio-diesel reached 96.7% when 1.2 wt.% of Potassium Hydroxide, reaction temperature of 75 °C, 30 min of time and 6:1 Methanol oil ratio at 350 rpm. Thermo gravimetric analysis followed the evaluation of transesterification process. The present analysis confirms that bio-diesel from dairy waste scum is quit suitable as an alternative to petroleum diesel with recommended fuel properties as per ASTM standards. This new way for using dairy waste scum reduces the cost of production of bio-diesel and the problem related to the disposal of Dairy scum.     

Biodiesel production from highly unsaturated feedstock via simultaneous transesterification and partial hydrogenation in supercritical methanol

In this study, a supercritical one-pot process combining transesterification and partial hydrogenation was proposed to test its technical feasibility. Simultaneous transesterification of soybean oil and partial hydrogenation of polyunsaturated compounds over Cu catalyst in supercritical methanol was performed at 320 °C and 20 MPa. Hydrogenation proceeded simultaneously during the transesterification of soybean oil in supercritical methanol, and hydrogenation occurred during the reaction despite the absence of hydrogen gas. The polyunsaturated methyl esters obtained in the biodiesel were mainly converted to monounsaturated methyl esters by partial hydrogenation. Key properties of the partially hydrogenated methyl esters were improved and complied with standard specifications for biodiesel.     

Advances on the development of novel heterogeneous catalysts for transesterification of triglycerides in biodiesel

This paper describes experimental work done towards the search for more profitable and sustainable alternatives regarding biodiesel production, using heterogeneous catalysts instead of the conventional homogenous alkaline catalysts, such as NaOH, KOH or sodium methoxide, for the methanolysis reaction. This experimental work is a first stage on the development and optimization of new solid catalysts, able to produce biodiesel from vegetable oils. The heterogeneous catalytic process has many differences from the currently used in industry homogeneous process. The main advantage is that, it requires lower investment costs, since no need for separation steps of methanol/catalyst, biodiesel/catalyst and glycerine/catalyst. This work resulted in the selection of CaO and CaO modified with Li catalysts, which showed very good catalytic performances with high activity and stability. In fact FAME yields higher than 92% were observed in two consecutive reaction batches without expensive intermediate reactivation procedures. Therefore, those catalysts appear to be suitable for biodiesel production.     

生物柴油及其生产技术的进展

介绍了由可再生油脂原料衍生的环保燃料生物柴油在国内外应用现状,重点介绍了酯交换法制备生物柴油技术研究进展情况,展望了生物柴油产业在我国的发展前景。     

Synthesis of dimethyl carbonate from propylene carbonate and methanol using CaO–ZrO2 solid solutions as highly stable catalysts

CaO–ZrO₂ catalysts were prepared by coprecipitation and their catalytic performances were evaluated in the synthesis of dimethyl carbonate from propylene carbonate and methanol. The characterization by XRD, N₂ adsorption, XPS and CO₂–TPD indicated that Ca²⁺ ion substituted for Zr⁴⁺ ions in the host lattice to form homogeneous CaO–ZrO₂ solid solution when Ca/(Ca + Zr) ratio changed from 0.1 to 0.3, and CaO segregated at grain boundaries with Ca/(Ca + Zr) ratio from 0.4 to 0.5. As a result, the catalysts showed different activity and stability towards the transesterification of propylene carbonate and methanol into dimethyl carbonate. The activity of catalysts was improved with increase in Ca content, whereas high stability was shown with Ca/(Ca + Zr) ratio below 0.3. The formation of homogeneous CaO–ZrO₂ solid solution was responsible for the stability of catalysts.     

Transesterification of sunflower oil catalyzed by flyash-based solid catalysts

Flyash-based base catalyst was used in the transesterification of sunflower oil with methanol to methyl esters in a heterogeneous manner. Catalyst preparation variables such as, the KNO₃ loading amount and calcination temperature were optimized. The catalysts were characterized by powder XRD. The catalyst prepared by loading of 5 wt.% KNO₃ on flyash followed by its calcination at 773 K has exhibited maximum oil conversion (87.5 wt.%). The influence of various reaction parameters such as % catalyst loading, methanol to oil molar ratio, reaction time, temperature, reusability of the catalyst on the catalytic activity was investigated. K₂O derived from KNO₃ might be an essential component in the catalyst for its efficiency.     

Production of biodiesel from palm oil (Elaeis guineensis) using heterogeneous catalyst: An optimized process

Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the three important reaction variables — methanol/oil molar ratio (x₁), reaction time (x₂) and amount of catalyst (x₃) for production of biodiesel from palm oil using KF/ZnO catalyst. Based on the CCD, a quadratic model was developed to correlate the reaction variables to the biodiesel yield. From the analysis of variance (ANOVA), the most influential factor on the experimental design response was identified. The predicted yield after process optimization was found to agree satisfactory with the experimental value. The optimum conditions for biodiesel production were found as follows: methanol/oil ratio of 11.43, reaction time of 9.72 h and catalyst amount of 5.52 wt%. The optimum biodiesel yield was 89.23%.     

A Transesterification Double Step Process — TDSP for biodiesel preparation from fatty acids triglycerides

This study introduces a two consecutive steps basic–acid transesterification process, (denominated Transesterification Double Step Process — TDSP) for biodiesel production from vegetable oils. The process involves homogeneous consecutive basic–acid catalysis steps and is characterized by formation of well-defined phases, easy separation procedures, high reaction velocity and high conversion efficiency. The proposed TDSP is different in relation to other traditional two-step procedures which normally include acid esterification followed by basic transesterification, or enzymatic or even supercritical transesterification conditions. The biodiesel (fatty acid methyl esters) was analyzed by standard biodiesel techniques in addition to ¹H-NMR, indicating high quality and purity biodiesel products. The transesterification of sunflower and linseed oils resulted in oil conversions higher than 97% corresponding to yields of 85%. A probable reaction mechanism responsible for the process is presented.