Enzymatic biodiesel: Challenges and opportunities

Extremophiles find uses

Simultaneous esterification and transesterification of waste phoenix seed oil with a high free fatty acid content using a free lipase catalyst to prepare biodiesel

Chapter 6 - Sustainable Waste-to-Energy Technologies: Transesterification

The diminution of edible oils and increasing cost of edible oils and biodiesel have gained the interest of many researchers for non-edible oils as biodiesel feed stock. The major hurdle in the commercialization of biodiesel is the high cost of feedstock. Due to fast mushrooming of fast food centers, waste cooking oil is one of the most economical feedstock available for the biodiesel production. The high free fatty acid contents and moisture in the waste cooking oil hinders the homogenous transesterification for the commercial purposes. Mixed oxides of Cu with Ni and Ce were synthesized by co-precipitation method and their efficacy for the production of biodiesel from the waste cooking oil was inspected. The acid catalyzed heterogeneous transesterification of waste cooking oil was performed in the sealed container. It was also interesting to mention that no pre-treatment was executed for the waste cooking oil conversion to biodiesel. It was investigated that mixed oxide catalyst CuO-CeO2 proved to be the potential candidate in pilot scale biodiesel production from waste cooking oil having about 92% conversion rate. Comprehensive chemical analysis of biodiesel including NMR, GC-MS, and FT-IR supports our result.

Biodiesel is a clean, renewable fuel and may be considered as a potential option to supplement fossil-based fuels. It is deduced from a variety of edible and non-edible vegetable oils, animal fats, waste cooking oil and animal fat, etc. Non-edible vegetable oils are second generation feedstocks and a better alternative to edible feed crops for biodiesel production.This paper deals with production of Biodiesel from the oils of Sesame (Sesamum indicum L.) and Neem (Azadirachta indica) which are available in India and other parts of the world. Neem oil is non edible oil having very high free fatty acid (FFA) content. It requires pre-treatment neutralization step before undergoing the alkali catalyzed transesterification process, very high alcohol to oil molar ratio and comparatively larger reaction time needed to obtain sustainable yield of biodiesel. Sesame oil is an edible oil mainly used in pharmaceuticals due to its medicinal properties and has low FFA content. These two oils, one having very high FFA content and other having low FFA content are mixed in suitable proportions and this mixture is transesterified without the pre-treatment process at a molar ratio of 6:1. A significant conversion yield is achieved by mixing the feedstocks before transesterification reaction.

Homogeneous, heterogeneous and enzymatic catalysis for transesterification of high free fatty acid oil (waste cooking oil) to biodiesel: A review

Biodiesel production from waste cooking oil (WCO) using heterogeneous sodium silicate catalyst is presented in this article. The conversion of WCO to biodiesel exploited the potential of the catalyst to convert high free fatty acid (FFA) content feedstock to biodiesel directly, thereby by-passing the esterification state whereby FFA content of the feedstock is reduced prior to transesterification reaction. In the study, effect of reaction temperature and reaction time on the activity of the catalyst during transesterification of WCO to biodiesel was investigated. The transesterification reaction was conducted in a batch reactor with 2.51 g of the catalysts and at WCO to methanol ratio of 1:6. In addition, the reaction temperature was varied between 25 o C to 63 o C, and the reaction time was varied from 0 to 180 minutes at a 30 minute step increase. The fatty acid methyl ester (FAME) yield increased with reaction time and reaction temperature and the highest FAME yield of 30% was obtained at 63 o C after 180 minutes. However, further studies are required for in-depth understanding of the activity and kinetics of the catalyst for biodiesel production from WCO.

This study explores the use of a novel heterogeneous CoZnFe4O8 nanocatalyst for biodiesel production from a sustainable and innovative blend of waste cooking oil and neem oil feedstock. Utilizing waste cooking oil and inedible neem oil feedstock to produce biodiesel provides a green and economical way to produce renewable and environmentally friendly fuel while simultaneously reducing waste and valorizing inedible oils. Additionally, this feedstock blend does not threaten food or land resources as opposed to feedstocks obtained from edible resources. To fulfill the rising demand for biodiesel and address issues related to lower ester yields, particularly when utilizing waste cooking oils with high free fatty acid concentration, there is an urgent need for more effective processes, including two-stage transesterification. The novel CoZnFe4O8 nanocatalyst employed in this study demonstrated high efficiency in biodiesel production thanks to its high surface area, mesoporous structure, and catalytic properties. The effect of key process parameters, including catalyst concentration, reaction time, alcohol-to-oil molar ratio, and oil blend ratio, was investigated to evaluate the performance of the nanocatalyst and optimize the biodiesel yield with the help of Response Surface Methodology (RSM). The optimized process achieved a yield of 94.23% under optimum parameters of 2.13 wt% catalyst, 6.80:1 methanol-to-oil ratio, 4 h, and a ratio of waste cooking oil to neem oil of 98.32:1.68. The predicted and experimental values were in close agreement, indicating that the model was adequate. Additionally, detailed catalyst characterization, including analysis of the surface area, structure, and thermal stability, was carried out. Similarly, the biodiesel was characterized to assess its quality through heating value, density, Fourier Transform Infrared (FTIR) spectroscopy, and ultimate analysis. The recovery and reusability of the nanocatalyst were also investigated, highlighting its potential for multiple reaction cycles. The novel CoZnFe4O8 nanocatalyst and innovative feedstock blend demonstrated high efficiency in biodiesel production comparable to other nanocatalysts and feedstocks reported in the literature, highlighting their potential as an efficient and sustainable method to produce biofuels.

Transesterification of waste cooking oil using pyrolysis residue supported eggshell catalyst

The world is gradually moving toward a severe energy crisis due to depletion of fossil fuels. Biodiesel is one of the technically and economically feasible options to solve the aforesaid problem. However, the overall costs of biodiesel production associated with the increasing market price of its feedstock clearly influence the profitability of the process. Therefore, biodiesel production has been directed toward waste materials as feedstock such as waste cooking oil (WCO). On the other hands, WCO is dealing with high free fatty acids (FFA) contents which gives a significant effect to the transesterification reaction, resulting in a lower biodiesel production. Therefore, a viable catalyst is needed for wide industrial usage in biodiesel synthesis from WCO. CaO is one of the promising heterogeneous catalyst for the transesterification reaction. However, CaO is deals with some limitations that need to overcome. This research paper deals with the synthesis of heterogeneous calcium titanate (CT) catalyst from calcium oxide (CaO) and titanium precursor by a sol-gel method for pilot evaluation in biodiesel production. CT catalyst was produced under different calcination temperature (200 °C, 400 °C, 600°C, 800 °C). The synthesized catalysts were evaluated for performance in transesterification reaction of methanol with WCO. BET surface area, XRD, and SEM were measured to correlate the activity with the structural features of the catalysts. The results exhibited that the calcination temperature of 400 °C is more preferable in terms of technical and economic feasibility. A biodiesel yield of 80.0 % was observed with a methanol to oil molar ratio of 15:1 and 1 wt. % of CT catalyst loading amount in 1 h at 65 °C which is comparative with commercial CaO catalyst calcined at 400 °C (60.0 % of biodiesel yield) at the same reaction conditions.

Biodiesel is a diesel replacement and renewable fuel that is manufactured from vegetable oils, animal fats or waste cooking oils. The production of biodiesel from edible oil is currently much more expensive than hydrocarbon-based fuel, due to the relatively high cost of edible oils. The cost of biodiesel can be reduced by using non-edible oils instead of edible oils. The purpose of the present study was to develop a method of esterification of non-edible oil like rubber seed oil (Hevea brasiliensis). The high free fatty acid content oil reacts quickly with alkaline catalysts to form soap, which prevents the separation of biodiesel and glycerol. A two-step process was used instead of the simple alkaline catalysed transesterification process. It consisted of an acid catalysed pre-processing followed by the usual alkaline catalysed process. The physical and chemical properties of biodiesel were analysed. The quantification of methyl esters were done by high-performance liquid chromatography.

Food waste, including non-reusable materials like chicken bones, forms a significant portion of solid waste. In Malaysia, approximately 540,000 tons of waste cooking oil (WCO) is discarded annually without proper treatment. Chicken bones, rich in calcium, can be utilized as a heterogeneous catalyst in biodiesel production, addressing waste management issues. However, the use of chicken bone as a catalyst presents challenges such as the unmodified chicken bones often require a pre-treatment step to reduce high free fatty acid (FFA) content in WCO to prevent saponification, limiting their efficiency. Hence, this research endeavors to innovate by converting WCO into biodiesel via a transesterification reaction, leveraging waste chicken bones as a catalyst. The calcined waste chicken bone (CB) was modified to form 5 wt% Fe-CB, and 10 wt% Fe-CB. The catalysts were found to have similar physical characteristics in terms of the structure and surface morphology observed from XRD, N2 adsorption-desorption, and SEM analysis. Among the catalysts, 10 wt% Fe-CB, produced the highest yield of fatty acid methyl esters (FAME), reaching 72.52%, under mild reaction conditions (10:1 methanol-to-WCO molar ratio, 1 wt% catalyst loading, 60 oC reaction temperature and 4 h reaction time). The capability of 10 wt% Fe-CB to produce a higher fatty acid methyl esters (FAME) yield than 5 wt% Fe-CB and calcined CB was due to the presence of CaO with binary transition metal oxides providing both acidic and basic sites, allowing for more efficient WCO conversion.

Palm cooking oil consumption in Indonesia is very high, and as a result, the used cooking oil which mostly ends up as the waste is also high. Direct discharge of waste cooking oil (WCO) into the environment causes serious environmental pollution problems. WCO contains triglyceride and free fatty acid, which can be converted into biodiesel. In this study, the conversion of WCO into biodiesel was conducted using non-catalytic subcritical methanol process. The effect of the ratio of WCO to methanol (w/v), temperature, and pressure on the recovery of biodiesel was investigated under constant reaction time of 4 h. Based on the Response Surface Methodology (RSM); temperature, pressure, and WCO to methanol ratio (w/v) gave a significant effect on the recovery of fatty acid methyl ester (FAME). From the experimental result, the maximum FAME recovery obtained was 93.29% with the purity up to 97% (200 °C, 5.5 MPa, 3:10), while the predicted recovery calculated by RSM was 91.93% with the optimum condition: 200 °C, 5.5 MPa for WCO to methanol ratio 0.3061 (w/v). The experimental verification showed satisfactory agreement between the observed and predicted values with only 1.36% of error. Therefore, subcritical methanol has good prospects to be applied further in lieu of conventional process to utilize waste oil with high free fatty acid content.

Biodiesel production from waste cooking oil: An efficient technique to convert waste into biodiesel

Continuous production of biodiesel from waste cooking oil in a reactive distillation column catalyzed by solid heteropolyacid: Optimization using response surface methodology (RSM)