Submitted to: Catalysts
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2021
Publication Date: 11/23/2021
Citation: Khan, K., Ul-Haq, N., Ur Rahman, W., Ali, M., Rashid, U., Ul-Haq, A., Jamil, F., Ahmed, A., Ahmed, F., Moser, B.R., Alsalme, A. 2021. Comprehensive comparison of hetero-homogeneous catalysts for fatty acid methyl ester production from non-edible Jatropha curcas oil. Catalysts. 11(12). Article 1420. https://doi.org/10.3390/catal11121420.
DOI: https://doi.org/10.3390/catal11121420

Interpretive Summary: Disadvantages of biodiesel include the use of edible oils for fuel production, generation of wastewater, and inability to recycle catalysts from the production process. The aim of this study was to utilize low-cost, inedible oil extracted from Jatropha (Jatropha curcas) seeds to produce biodiesel using a new catalyst that can be recovered and reused. This has the advantages of reducing production costs while also reducing wastewater generation. This research revealed that the seed oil from Jatropha is acceptable as an alternative, low-cost, nonfood feedstock for production of renewable biodiesel as an alternative to conventional diesel fuel. This research also revealed a new catalyst, calcium oxide, that has important advantages over currently used catalysts for commercial production of biodiesel, such as high yield and the ability to recover and reuse the catalyst again. Overall, the properties of biodiesel from Jatropha oil were comparable to that of soybean-based biodiesel, thus indicating its acceptability as a new source of biodiesel fuel. These results will be important to biodiesel producers, distributors, and end-users (customers) because a new biodiesel fuel and a new biodiesel catalyst were described that exhibit favorable properties. This research may ultimately improve market penetration, availability, and public perception of renewable agricultural fuels such as biodiesel, thus affording greater national independence from petroleum-based fuels.

Technical Abstract: The synthesis of biodiesel from Jatropha curcas by transesterification is kinetically controlled. It depends on the molar ratio, reaction time, and temperature, as well as the catalyst nature and quantity. The aim of this study was to explore the transesterification of low-cost, inedible J. curcas seed oil utilizing both homogenous (potassium hydroxide; KOH) and heterogenous (calcium oxide; CaO) catalysis. In this effort, two steps were used. First, free fatty acids in J. curcas oil were reduced from 12.4 to less than 1 wt.% with sulfuric acid-catalyzed pretreatment. Transesterification subsequently converted the oil to biodiesel. The yield of fatty acid methyl esters was optimized by varying the reaction time, catalyst load, and methanol-to-oil molar ratio. A maximum yield of 96% was obtained from CaO nanoparticles at a reaction time of 5.5 h with 4 wt.% of the catalyst and an 18:1 methanol-to-oil molar ratio. The optimum conditions for KOH were a molar ratio of methanol to oil of 9:1, 5 wt.% of the catalyst, and a reaction time of 3.5 h, and this returned a yield of 92%. The fuel properties of the optimized biodiesel were within the limits specified in ASTM D6751, the American biodiesel standard. In addition, the 5% blends in petroleum diesel were within the ranges prescribed in ASTM D975, the American diesel fuel standard.