Journal of Energy Bioscience 2025, Vol.16, No.5, 216-226 http://bioscipublisher.com/index.php/jeb 217 In recent years, researchers have been improving the production methods of rapeseed oil biodiesel. This includes choosing the appropriate catalyst, optimizing reaction conditions, and assessing its impact on the environment. These studies have promoted the industrialization process of rapeseed oil biodiesel. The objective of this review is to sort out and compare the raw material characteristics, process conditions, catalytic systems and fuel performance of rapeseed oil in biodiesel production. It also combines the latest research cases to explore the advantages and difficulties under different process paths. Through these analyses, it is hoped that references can be provided for optimizing production processes, improving fuel quality and promoting sustainable development. 2 Biodiesel Production Pathways 2.1 Overview of common feedstocks: vegetable oils, animal fats, waste oils There are three main raw materials for biodiesel: vegetable oil, animal fat and waste oil. Common vegetable oils include rapeseed oil, soybean oil and sunflower oil. Waste oils include waste cooking oil and food waste oil (Encinar et al., 2020; Santaraite et al., 2020; Szkudlarek et al., 2024). In Europe, rapeseed oil is widely used as a raw material for biodiesel due to its high oil content and suitable fatty acid composition (Encinar et al., 2020; Santaraite et al., 2020). In recent years, due to the increasingly fierce competition in food and fuel, low-quality rapeseed oil and waste oil have also drawn attention. This type of raw material is cheaper and can also reduce the contradiction with food (Sendikien et al., 2022). 2.2 Transesterification process and key chemical reactions Biodiesel is mainly produced through transesterification reactions. During this process, triglycerides in vegetable oil or animal fat react with methanol or ethanol in the presence of a catalyst to form fatty acid esters (that is, biodiesel) and glycerol (Rashid and Anwar, 2008; Georgogianni et al., 2009; Szkudlarek et al., 2024). Commonly used catalysts include base catalysts (NaOH, KOH), acid catalysts, solid base catalysts (CaO, MgO, etc.), and enzyme catalysts (Essamlali et al., 2019; Santaraite et al., 2020; Lazdovieca et al., 2023). The basic equation of the reaction is as follows: Triglyceride + 3-alcohol → 3-fatty acid ester (biodiesel) + glycerol 2.3 Factors influencing biodiesel yield and quality The yield and quality of biodiesel are influenced by many factors. Types and dosages of alcohols: Methanol is the most common, with a fast reaction speed and a low price. Ethanol is more environmentally friendly, but the yield may be slightly lower (Khan et al., 2023; Szkudlarek et al., 2024; Ferreira et al., 2025). The common molar ratio of alcohol to oil is 6:1 to 15:1. Too high or too low will affect the yield and the generation of by-products (Rashid and Anwar, 2008; Lazdovieca et al., 2023). Catalyst types and concentrations: Alkaline catalysts (NaOH, KOH) react quickly, but have high requirements for raw materials. Solid base catalysts (CaO, MgO) are easy to separate and reuse, and are more environmentally friendly (Rashid and Anwar, 2008; Georgogianni et al., 2009; Essamlali et al., 2019; Lazdovieca et al., 2023; Szkudlarek et al., 2024). Enzyme catalysts are suitable for raw materials with high free fatty acids. They are environmentally friendly but costly (Li et al., 2006; Jeong and Park, 2008; Santaraite et al., 2020). Reaction conditions: Temperature, stirring and time will all affect the result. The general optimal temperature is 50 ℃~65 ℃. The stirring and time should be adjusted according to the catalyst and raw materials (Azcan and Danisman, 2008; Rashid and Anwar, 2008; Khan et al., 2023; Lazdovieca et al., 2023). The quality of raw oil: If the content of free fatty acids in the raw oil is high, saponification reaction is likely to occur, resulting in a decrease in yield. This problem can be solved by enzymatic catalysis or two-step method (Li et al., 2006; Santaraite et al., 2020; Send and ikien et al., 2022). 3 Physicochemical Properties of Rapeseed Oil 3.1 Fatty acid profile (oleic, linoleic, linolenic content) Rapeseed oil is rich in unsaturated fatty acids, accounting for approximately 93%. Among them, oleic acid (C18:1) is the most abundant, followed by linoleic acid (C18:2) and alpha-linolenic acid (C18:3). The content of saturated
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