Homogeneous Base Catalysts Research Articles

Comparative Studies on Methyl Ester Production from Pretreated Sludge Palm Oil Using Homogeneous and Heterogeneous Base Catalysts

A heterogeneous base catalyst transesterification process with a calcium oxide (CaO) catalyst was performed to produce high-purity methyl ester (ME) from pretreated sludge palm oil (PSPO) derived from sludge palm oil (SPO). Additionally, a comparative analysis was conducted with potassium hydroxide (KOH) as a homogeneous base catalyst to assess the distinctions between heterogeneous and homogeneous base catalysts. The response surface methodology (RSM) was utilized to determine the optimal and recommended conditions for both transesterification processes. For heterogeneous transesterification, a varying CaO catalyst loading (10–60 wt.%), methanol (25–65 wt.%), and reaction time (60–180 min) were essential parameters. Meanwhile, homogeneous transesterification involved investigating the KOH catalyst loading (1–3 wt.%), methanol (1.8–5.5 wt.%), and reaction time (20–60 min). For the heterogeneous-base-catalyzed reaction, the recommended conditions were as follows: a molar ratio of methanol to oil of 5.83:1 (41.61 wt.%), 31.3 wt.% CaO, and a reaction time of 119.0 min, which resulted in a ME purity of 96.51 wt.%. The optimal conditions for homogeneous transesterification were a molar ratio of methanol to oil of 0.49:1 (3.45 wt.%), a 40 min reaction time, and a 1.39 wt.% KOH concentration, which achieved 96.59 wt.% ME and met the standard.

Efficient and Sustainable Biodiesel Production via Transesterification: Catalysts and Operating Conditions

Biodiesel has received tremendous attention as a sustainable energy source. This review presents an overview of various catalysts utilized in biodiesel production and compares their potential for producing biodiesel. Presented here are the excellent features of the various catalysts while highlighting their drawbacks. For instance, production of biodiesel with homogeneous base catalysts is easy but it can only be used with refined oils having low levels of free fatty acid (FFAs). When homogeneous acid is used in esterification, it causes reactor corrosion. Water and FFAs do not affect heterogeneous acid catalysts. Thus, transesterification of triglycerides into biodiesel and converting FFAs into biodiesel through esterification can be catalyzed more efficiently using a heterogeneous acid catalyst. Biocatalysts are also being used to produce biodiesel from oils with high FFAs. However, heterogeneous acid catalysts and biocatalysts are not suitable for industrial application due to serious mass transfer limitations. Biodiesel yield and conversion were compared over various catalysts in this paper. Also presented are the effects of different reaction parameters on biodiesel yield over different catalysts. The correct interplay of factors like reaction temperature, time, alcohol-to-oil molar ratio, and catalyst loading produces optimal process conditions that give the highest biodiesel yield.

Liquid-Liquid Equilibrium of Sesame Fatty Acid (Ethyl and Methyl) Ester + Glycerol + Ethanol/Methanol Mixtures at Different Temperatures.

This study aimed to investigate the liquid-liquid equilibrium (LLE) behavior of sesame fatty acid ethyl ester (FAEE) and methyl ester (FAME) in combination with glycerol and the co-solvents ethanol and methanol. FAEE and FAME were produced through the transesterification of mechanically extracted and purified sesame oil, using potassium hydroxide (KOH) as a homogeneous base catalyst. The reactions were conducted in ethanol and methanol to produce FAEE and FAME, respectively. Post-reaction, the products were separated and purified, followed by an analysis of the LLE behavior at 313.15 K and 323.15 K under atmospheric pressure (101.3 kPa). The experimental process for the miscibility analysis utilized a jacketed glass cell adapted for this study. Miscibility limits or binodal curves were determined using the turbidity-point method. Tie lines were constructed by preparing mixtures of known concentrations within the two-phase region, which allowed the phases to separate after agitation. Samples from both phases were analyzed to determine their composition. This study revealed that higher temperatures promoted greater phase separation and enhanced the biodiesel purification process. The NRTL model effectively correlated the activity coefficients with the experimental data, showing good agreement, with a root-mean-square deviation of 3.5%. Additionally, the data quality was validated using Marcilla's method, which yielded an R2 value close to 1. Attraction factors and distribution coefficients were also calculated to evaluate the efficiency of the co-solvents as extraction agents. The findings indicated higher selectivity for methanol than for ethanol, with varying degrees of distribution among the co-solvents. These results offer significant insights into enhancing biodiesel production processes by considering the effects of co-solvents on the LLE properties of mixtures, ultimately contributing to more efficient and cost-effective biodiesel production.

Liquid Hot Water (LHW) and Hydrothermal Carbonization (HTC) of Coffee Berry Waste: Kinetics, Catalysis, and Optimization for the Synthesis of Platform Chemicals

Colombia is the world’s leading producer of mildly washed arabica coffee and produces 12.6 million bags of green coffee, but at the same time, 784,000 tons of waste biomass are dumped in open fields, of which only 5% is recovered or used. The objective of this project was to evaluate the production of platform chemicals from these coffee wastes for sustainable resource management. To achieve this, biomass characterization was carried out using proximate analysis, ultimate analysis, and structural analysis. Hydrothermal valorization was carried out at a temperature range of 120–180 °C (LHW) and 180–260 °C (HTC) for one hour. The platform chemicals obtained were quantified by HPLC-RI and monitored by pH and conductivity, and the solid fraction was characterized by monitoring the functional groups in IR spectroscopy and elemental analysis. Hydrolysis processes were obtained at 150 °C, production of platform chemicals at 180 °C, and maximum concentration at 180 °C-4 h; over 200 °C, degradation of the products in the liquid fraction starts to take place. Homogeneous basic and acid catalysts were used to improve the yields of the reaction. The kinetics of the hydrolysis of lignocellulosic structures to sugars were also analyzed and described, and reaction orders of 1 (LHW), 3 (HTC), and their respective reaction rate equations were reported.

Biodiesel Production from Waste Cooking Oil Using Extracted Catalyst from Plantain Banana Stem via RSM and ANN Optimization for Sustainable Development

Biodiesel is a promising sector worldwide and is experiencing significant and rapid growth. Several studies have been undertaken to utilize homogeneous base catalysts in the form of KOH to develop biodiesel in order to establish a commercially viable and sustainable biodiesel industry. This research centers around extracting potassium hydroxide (KOH) from banana trunks and employing it in the transesterification reaction to generate biodiesel from waste cooking oil (WCO). Various operational factors were analyzed for their relative impact on biodiesel output, and after optimizing the reaction parameters, a conversion rate of 95.33% was achieved while maintaining a reaction period of 2.5 h, a methanol-to-oil molar ratio of 15:1, and a catalyst quantity of 5 wt%. Response surface methodology (RSM) and artificial neural network (ANN) models were implemented to improve and optimize these reaction parameters for the purpose of obtaining the maximum biodiesel output. Consequently, remarkably higher yields of 95.33% and 95.53% were achieved by RSM and ANN, respectively, with a quite little margin of error of 0.0003%. This study showcases immense promise for the large-scale commercial production of biodiesel.

Enabling Catalysts for Biodiesel Production via Transesterification

With the rapid development of industry and the increasing demand for transportation, traditional sources of energy have been excessively consumed. Biodiesel as an alternative energy source has become a research focus. The most common method for biodiesel production is transesterification, in which lipid and low carbon alcohol are commonly used as raw materials, in the presence of a catalyst. In the process of transesterification, the performance of the catalyst is the key factor of the biodiesel yield. This paper reviews the recent research progress on homogeneous and heterogeneous catalysts in biodiesel production. The advantages and disadvantages of current homogeneous acid catalysts and homogeneous base catalysts are discussed, and heteropolyacid heterogeneous catalysts and biomass-derived base catalysts are described. The applications of the homogeneous and heterogeneous catalyst derivatives ionic liquids/deep eutectic solvents and nanocatalysts/magnetic catalysts in biodiesel production are reviewed. The mechanism and economic cost of current homogeneous acid catalysts and homogeneous base catalysts are also analyzed. The unique advantages of each type of catalyst are compared to better understand the microscopic details behind biodiesel. Finally, some challenges of current biodiesel catalysts are summarized, and future research directions are presented. This review will provide general and in-depth knowledge on the achievements, directions, and research priorities in developing novel homogeneous/heterogeneous catalysts for the green and cost-effective production of biodiesel.

Advancements in Basic Zeolites for Biodiesel Production via Transesterification

The excessive utilization of petroleum diesel has led to the depletion of fossil resources and severe environmental pollution. Biodiesel produced from renewable triglycerides (TGs) or waste lipids is a low-emission fuel substitute for diesel. Biodiesel is mainly produced by transesterification reactions over homogeneous base catalysts with excellent activity and low cost. In comparison, solid base catalysts are more attractive due to their lower environmental impact and simpler production and purification processes. It remains a challenge to further improve the stability and activity of solid base catalysts. Because of the high surface area, superior stability, and tunable basicity, basic zeolites, especially two-dimensional zeolites, have emerged as promising solid basic catalysts for the transesterification of TGs. In this review, we present recent advancements in the synthesis, characterization, and catalytic performance of basic zeolites for the transesterification of TGs. Challenges and development prospects of basic zeolites for biodiesel production via transesterification are also pointed out. We expect that this review will inspire the more efficient and rational design of zeolites for sustainable fuel production.

Transesterification of Algae Oil and Little Amount of Waste Cooking Oil Blend at Low Temperature in the Presence of NaOH

The present study describes the single-step transesterification method of biodiesel production from high free fatty acid (FFA) waste cooking oil blended with algae oil using a homogeneous base catalyst. Due to high FFA contents, two step transesterification is needed to convert oil into biodiesel and therefore the high FFA content of waste cooking oil is decreased by blending it with low FFA content algae oil, which would further lead only to single step transesterification of low FFA oil. The design and optimization studies were conducted using Response Surface Methodology (RSM). The box-Behnken design technique is applied to optimize the three process parameters, i.e., catalyst concentration (0–2 wt%), methanol concentration (v/v) (20–60%) and reaction time (60–180 min) at a uniform reaction temperature of 50 °C. The result of the current study indicates that an effective biodiesel yield of 92% can be obtained at the optimized condition of catalyst concentration of 1.5% (w/w), methanol/oil ratio of 21:1 and reaction time of 110 min at a constant reaction temperature of 50 °C. This analysis clearly shows that this study can resolve the storage problem of high FFA oils from different feedstock and RSM can be successfully used to model the reaction to maximize the biodiesel yield.

Homogeneous base catalyst with high activity and stability for synthesis of dimethyl carbonate by transesterification.

In the synthesis of dimethyl carbonate (DMC) by transesterification, CH3ONa has been commonly applied as a homogeneous catalyst due to its high catalytic activity, but its stability is unsatisfactory. Here, by studying the influence of ionic liquid base strength on transesterification, we prepared an organic base catalyst, potassium imidazole (KIm), with high catalytic activity and stability, which solved the problem of catalyst deactivation in transesterification. The results showed that when KIm was used in the synthesis of DMC from propylene carbonate (PC) and methanol (MeOH), the chemical equilibrium could be reached within 3 minutes and the yield of DMC reached 73.03%, indicating that KIm performed better in transesterification than the majority of previously reported catalysts. In addition, the activity of the catalyst had hardly decreased after ten cycles of reaction, which can well meet the requirements of industrial production.

State-of-the-art catalysts for clean fuel (methyl esters) production—a comprehensive review

There has been growing and recent interest in using non-edible feedstocks, such as waste animal fats, as an alternative to vegetable oils in biodiesel production to address the food versus fuel debate. Waste animal fats are cost effective and yield good quality biodiesel. Therefore, waste animal fats are appealing and excellent feedstocks to produce biodiesel. Commercially, the biodiesel is obtained by transesterification reaction of triglycerides present in oil/fat with alcohol in the presence of homogeneous base catalysts. However, free fatty acids found in low-quality oil feedstocks are particularly sensitive to homogeneous base catalysts, necessitating extra acid pretreatment and neutralization procedures that not only raise the overall expense of producing biodiesel but also create environmental contamination. Optimistically, the use of solid catalysts can offer an environmentally friendly, cost-effective and practical route for the manufacture of biodiesel from inexpensive oil feedstocks, including waste animal fat. The present review article covers catalyzed transesterification/esterification using various catalysts with particular focus on the use of heterogeneous catalysts when using waste animal fat as feedstock for biodiesel production. In particular, the properties of biodiesel obtained from waste animal fats are also compared to the biodiesel properties of standard organizations, such as the European Committee for Standardization (ISO) and the American Society for Testing and Materials (ASTM). Moreover, this paper also offers future research directions that can direct researchers to fill in knowledge gaps impeding the creation of efficient heterogeneous catalysts for long-term biodiesel generation. To the best of our knowledge, the valorization of waste animal fats from slaughterhouses is not feasible and has some techno-economic concerns. However, this technology is more desirable considering the environmental point of view to address the pollution problems caused by these wastes.

Direct and rapid production of biodiesel from algae foamate using a homogeneous base catalyst as part of an intensified process

• Continuous air flotation was used to harvest microalgae for transesterification. • KOH-catalysed in situ transesterification used to convert biomass into biodiesel. • Transesterification was not adversely affected by moisture of up to 80% in algae. • A 97% yield of biodiesel (FAME) was obtained in 10 minutes. • Energy savings were achieved by in situ transesterification of algae feedstock. Microalgae are important biodiesel feedstocks because of their high lipid content and low land requirement for cultivation. One method of harvesting and concentrating algal biomass is by means of a foam column using surfactant CTAB as a collector and foaming agent, however, the downstream treatments for the “foamate” produced have not yet been investigated. Here, the freshwater microalgae strain, Chlorella vulgaris , was harvested by a continuous dispersed air flotation column and the foamate obtained was used as the feedstock for conversion to biodiesel via in situ reactive extraction using KOH as the catalyst. The process variables were methanol: oil molar ratio (100:1 to 1000:1), reaction temperature (40–60°C) and reaction time (5–10 min). The maximum biodiesel yield from the foamate produced of 97% from C. vulgaris microalgae was accomplished at a molar ratio (methanol to oil) of 1000:1, a 60°C temperature of reaction and a 10 min time of reaction. Longer reaction times resulted in reduced fatty acid methyl ester (FAME) yield due to saponification, converting the FAME to soap. High FAME yields were obtained despite the presence of significant quantities of free fatty acids (6% lipid) in the C. vulgaris biomass. The method also exhibited greater tolerance to water than that observed in conventional transesterification conditions. At a methanol: oil molar ratio of 1000:1, the method was not adversely affected by the presence of up to 80% level of moisture in the microalgae. Hence, a viable, FFA-tolerant, water-tolerant process has been demonstrated for direct conversion of microalgae foamate to biodiesel, at mild conditions (60°C and below) in a short residence time (10 min).

Boosting the Transesterification Reaction by Adding a Single Na Atom into g-C3N4 Catalyst for Biodiesel Production: A First-Principles Study

Increasing environmental problems and the energy crisis have led to interest in the development of alternative energy. One of the most promising sustainable alternatives to fossil fuel is biodiesel which is typically produced from the transesterification of refined vegetable oils using a homogeneous base catalyst. However, the current process limitations and steep production costs associated with the use of homogeneous catalysts have limited the global-wide acceptance of biodiesel. Heterogeneous catalysts have been considered suitable alternatives, but they still suffer from low catalytic activity. In this study, by using density functional theory (DFT) calculations, we examined the electronic and catalytic activity of the single Na-doped graphitic carbon nitrides (indicated by Na-doped g-C3N4) toward the efficient biodiesel (acetic acid methyl ester) production via the transesterification of triglyceride (triacetin). Our DFT calculation on reaction energetics and barriers revealed the enhancement of biodiesel productivity in the Na-doped catalyst compared to the pristine g-C3N4 catalyst. This was related to the large reduction of the barrier in the rate-limiting step. In addition, we investigated the acidity/basicity and electron distribution and density of state for the Na-doped and pristine g-C3N4 catalysts to better understand the role of the Na atom in determining the transesterification reaction. This study highlights the importance of the dopant in a g-C3N4 catalyst in determining the transesterification reaction, which may open new routes to improve biodiesel production.

Highly thermally stable multi-porous calcium aluminum hydrotalcite catalyst for efficient carbonate synthesis

In the context of a carbon–neutral era, conversion of greenhouse gas CO2via chemical catalysis is a powerful means. Using CO2and petroleum-derived alkylene oxide as the raw materials to produce high-value carbonate substances has been considered a green and economic path for carbon reduction and energy transition. We discovered a multi-porous calcium aluminum hydrotalcite material (Ca-Al HT), and found that it performs excellent catalytic ability on transesterification (an important reaction in the synthesis of carbonates). Being different from homogeneous basic catalysts such as soluble metal hydroxides and organic halide salts, and well-known solid basic catalyst CaO, which are difficult to recycle and suffer severe deactivation in long-term catalytic process, the robust Ca12Al14O33crystal phase in Ca-Al HT catalyst behaves much more stable catalytic performance during 4000 min efficient catalysis (63 % conversion and 100 % selectivity). The special crystal phase structure of Ca12Al14O33remains stable at even a very high temperature of 900 °C. In contrast, CaO as the reference catalyst is very sensitive to trace H2O in catalytic system, and deactivates immediately. The outstanding catalytic ability of Ca-Al HT is attributed to its super-strong alkali strength, large alkali amount, and quick mass transfer originating from the hierarchical pore system.

Highly thermally stable multi-porous calcium aluminum hydrotalcite catalyst for efficient carbonate synthesis

<h2>Abstract</h2> In the context of a carbon-neutral era, conversion of greenhouse gas CO₂ via chemical catalysis is a powerful means. Using CO₂ and petroleum-derived alkylene oxide as the raw materials to produce high-value carbonate substances has been considered a green and economic path for carbon reduction and energy transition. We discovered a multi-porous calcium aluminum hydrotalcite material (Ca-Al HT), and found that it performs excellent catalytic ability on transesterification (an important reaction in the synthesis of carbonates). Being different from homogeneous basic catalysts such as soluble metal hydroxides and organic halide salts, and well-known solid basic catalyst CaO, which are difficult to recycle and suffer severe deactivation in long-term catalytic process, the robust Ca₁₂Al₁₄O₃₃ crystal phase in Ca-Al HT catalyst behaves much more stable catalytic performance during 4000 min efficient catalysis (63% conversion and 100% selectivity). The special crystal phase structure of Ca₁₂Al₁₄O₃₃ maintains stability at even a very high temperature of 900 °C. In contrast, CaO as the reference catalyst is very sensitive to trace H₂O in catalytic system, and deactivates immediately. The outstanding catalytic ability of Ca-Al HT is attributed to its super-strong alkali strength, large alkali amount, and quick mass transfer originating from the hierarchical pore system.

Ionic Liquids as Homogeneous Catalysts for Glycerol Oligomerization.

Ionic liquids (ILs) were used for the first time as catalysts for the glycerin condensation reaction. A series of imidazolium and ammonium ionic liquids differing in the length of the alkyl substituent (C2, C12, and C14) and the type of anion (Br−, CH3COO−, and NaHPO4−) were synthesized using a typical two-step method. The structure of the obtained ILs was confirmed by nuclear magnetic resonance 13C NMR, and their base power was determined on the basis of the Hammett function. The oligomerization of glycerin with the participation of the obtained ionic liquids and, for comparison, in the presence of a homogeneous basic catalyst Na2CO3, was carried out for 3 h at 180 °C, under a pressure of 0.4 bar, where the highest conversion, i.e., 92%, was obtained against 1-dodecyl-N,N,N-triethylammonium acetate. The course of the reaction was monitored using a reaction system coupled with a FTIR spectrometer, which allowed for the tracking of changes in product concentration over time and the assessment of glycerin oligomerization kinetics. The reaction products were analyzed by positive electrospray ionization mass spectrometry (ESI-MS), 13C NMR, and infrared absorption spectroscopy (FTIR).

Comparison of Performance of Various Homogeneous Alkali Catalysts in Transesterification of Waste Cooking Oil

Biodiesel is an excellent substitute for fossil diesel, which received a significant attention in recent decades. Catalyst methods are frequently used to produce biodiesel at low temperatures and pressures. The present work investigates the methanolysis of waste cooking oil with the acid value of 1.86 mg KOH/g employing a variety of homogeneous base catalysts, including KOH, NaOH, CH3OK and CH3ONa. Among the studied catalysts, CH3OK produced the highest biodiesel yield at 99.0%, followed by CH3ONa, KOH and NaOH under the identical reaction conditions. The reaction was carried out for 30 min at 600 ºC and a speed of 600 rpm with a molar ratio of 6:1 for methanol-to-waste cooking oil (WCO) and a 1 wt.% catalyst. However, the viscosity, flash point, density and acid value of the biodiesel all met ASTM criteria, indicating that biodiesel made from KOH, NaOH, CH3OK and CH3ONa is of high quality.

Sintesis Biodiesel dari Minyak Jelantah Menggunakan Katalis Bentonit, K-Bentonit Dan K-Bentonit Terimpregnasi CaO

Biodiesel is an alternative fuel for diesel engines produced by a transesterification reaction between vegetable oils or animal fats containing triglycerides and alcohol, one of which is methanol. The use of homogeneous base catalysts in the synthesis of biodiesel still poses a problem for the environment because it is difficult to separate, therefore, researchers use variations of heterogeneous base catalysts. The synthesis of biodiesel from used cooking oil was carried out through a transesterification reaction with technical methanol with a catalyst of CaO impregnated Bentonite, K-Bentonite and Bentonite using the reflux method at 65ºC for 2 hours. The ratio of the volume of oil, methanol, and catalyst used is 5:1:1%-w oil. Based on the research that has been done, the yield of each catalyst is 84.85% bentonite, 84.24% K-bentonite and 89.27% ​​K-bentonite-CaO. The characteristics of biodiesel obtained from each of these catalysts such as calorific value and density have met the quality requirements of the Indonesian National Standard (SNI 7182-2012), except for the acid number and kinematic viscosity which still exceed the quality requirements of SNI 7182-2012.

Amine Functionalized Dendronized Polymer as a Homogeneous Base Catalyst for the Synthesis of Polyhydroquinolines and 4-Arylidene-3-Methylisoxazol-5(4H)-Ones

Amine Functionalized Dendronized Polymer as a Homogeneous Base Catalyst for the Synthesis of Polyhydroquinolines and 4-Arylidene-3-Methylisoxazol-5(4H)-Ones

Trends in Widely Used Catalysts for Fatty Acid Methyl Esters (FAME) Production: A Review

The effective transesterification process to produce fatty acid methyl esters (FAME) requires the use of low-cost, less corrosive, environmentally friendly and effective catalysts. Currently, worldwide biodiesel production revolves around the use of alkaline and acidic catalysts employed in heterogeneous and homogeneous phases. Homogeneous catalysts (soluble catalysts) for FAME production have been widespread for a while, but solid catalysts (heterogeneous catalysts) are a newer development for FAME production. The rate of reaction is much increased when homogeneous basic catalysts are used, but the main drawback is the cost of the process which arises due to the separation of catalysts from the reaction media after product formation. A promising field for catalytic biodiesel production is the use of heteropoly acids (HPAs) and polyoxometalate compounds. The flexibility of their structures and super acidic properties can be enhanced by incorporation of polyoxometalate anions into the complex proton acids. This pseudo liquid phase makes it possible for nearly all mobile protons to take part in the catalysis process. Carbonaceous materials which are obtained after sulfonation show promising catalytic activity towards the transesterification process. Another promising heterogeneous acid catalyst used for FAME production is vanadium phosphate. Furthermore, biocatalysts are receiving attention for large-scale FAME production in which lipase is the most common one used successfully This review critically describes the most important homogeneous and heterogeneous catalysts used in the current FAME production, with future directions for their use.

Synthesis and characterization of SO42-/KCC-1 catalyst as an alternative candidate for simultaneous esterification and transesterification reactions

Sulfate-impregnated acid catalysts can be used to replace conventional homogeneous base catalysts which are very dangerous, corrosive and environmentally unfriendly. Sulfate impregnation on porous support material will increase the surface area of the catalyst. The use of KCC-1 as a supporting material can produce catalysts with excellent properties. The method used in this research is the hydrothermal method for the synthesis of KCC-1 and the direct impregnation method for the synthesis of SO42-/KCC-1. Characterization of the resulting material using X-ray diffraction (XRD), FTIR spectrometer, and low temperature emission scanning electron microscope (SEM). The characterization results showed that the synthesis of KCC-1 and SO42-/KCC-1 had been successfully carried out. This is evidenced by the formation of amorphous silica, the presence of peaks of silica and sulfate groups, and scanning electron microscope images showing nano-sized materials.©2021 JNSMR UIN Walisongo. All rights reserved.