Solid base catalysis of calcium oxide for a reaction to convert vegetable oil into biodiesel

Calcium oxide as a promising heterogeneous catalyst for biodiesel production: Current state and perspectives

“…Concerning methanolysis of vegetable oils over CaO, some researchers believe that calcium methoxide functions as the substantial solid active species under the reacting condition [44,69,[114][115][116], but some others think that CaO is combined not only with methanol but also with by-produced glycerol, depending on the methanolysis reaction phase [3,36,49,74,114,115,[117][118][119][120]. Based on this, calcium methoxide [44,114,116,121], diglyceroxide [36,74,114,117,120] and glycerolate [74] have been tested as solid catalysts in transesterification reactions.…”

A review on recent advancement in catalytic materials for biodiesel production

“…The CaO-glycerin complex was considered to function as a chief catalyst to accelerate the transesterification reaction. Kouzu et al [113] investigated the reaction mechanism for the CaO-catalyzed transesterification between soybean oil and methanol. It was proposed that methanol, with the help of basic sites on the CaO surface, produces methoxide anions which serves as a nucleophile and effectively initiates the transesterification reaction.…”

Supercritical fluid technology in biodiesel production

“…Numerous studies have been performed employing various oils, different alcohols (methanol, ethanol, butanol), as well as different catalysts, including homogeneous ones, such as sodium hydroxide (NaOH) [8], potassium hydroxide (KOH) [9,10], and sulfuric acid [11], and heterogeneous ones such as lipases, calcium oxide (CaO) [12][13][14] and magnesium oxide (MgO) [15]. …”

“…However, the concentration of Ca in the final product was 3065 ppm, which exceeds the allowable range of mineral content in standard biodiesel. In a different study by the same group [13], the catalyst was collected after the reaction and analyzed with X-ray diffraction, scanning electron microscopy, and nuclear magnetic resonance: the results showed that the collected catalyst contained calcium glyceroxide, due to the reaction between CaO and glycerol. This led to the decrease in catalytic activity demonstrated by the yield of FAME, which reached 70% after 1 h. By contrast, the transformation of catalyst brings a tolerance to air-exposure, which was effective when the reaction was successfully repeated with regeneration of the collected catalyst.…”