Improved biodiesel production from waste cooking oil with mixed methanol–ethanol using enhanced eggshell-derived CaO nano-catalyst

Abstract

In this report, the utilization of mixed methanol–ethanol system for the production of biodiesel from waste cooking oil (WCO) using enhanced eggshell-derived calcium oxide (CaO) nano-catalyst was investigated. CaO nano-catalyst was produced by calcination of eggshell powder at 900 °C and followed by hydration-dehydration treatment to improve its catalytic activity. The particle size, morphology, and elemental composition of a catalyst were characterized by using XRD, SEM, and EDX techniques, respectively. After hydration-dehydration the shape of a catalyst was changed from a rod-like to honeycomb-like porous microstructure. Likewise, average particle size was reduced from 21.30 to 13.53 nm, as a result, its surface area increases. The main factors affecting the biodiesel yield were investigated, accordingly, an optimal biodiesel yield of 94% was obtained at 1:12 oil to methanol molar ratio, 2.5 wt% catalyst loading, 60 °C, and 120-min reaction time. A biodiesel yield of 88% was obtained using 6:6 equimolar ratio of methanol to ethanol, the yield even increased to 91% by increasing the catalyst loading to 3.5 wt%. Moreover, by slightly increasing the share of methanol in the mixture, at 8:4 ratio, the maximum biodiesel yield could reach 92%. Therefore, we suggest the utilization of methanol–ethanol mixture as a reactant and eggshell-derived CaO as a catalyst for enhanced conversion of WCO into biodiesel. It is a very promising approach for the development of low-cost and environmentally friendly technology. Properties of the biodiesel were also found in good agreement with the American (ASTM D6571) fuel standards.

Biomass‐based heterogeneous catalysts for biodiesel production: A comprehensive review

“…On the other hand, researchers have tested nano CaO as a catalyst for biodiesel synthesis 45‐47 . Its large specific surface area and high catalytic activity constitute its favorable properties for its application in heterogeneously catalyzed biodiesel synthesis 72 .…”

“…On the other hand, researchers have tested nano CaO as a catalyst for biodiesel synthesis. [45][46][47] Its large specific surface area and high catalytic activity constitute its favorable properties for its application in heterogeneously catalyzed biodiesel synthesis. 72 Pandit and Fulekar 47 achieved the formation of newly synthesized eggshell-derived CaO nanoparticles with a size of 75 nm and a surface area of 16.4 m 2 /g.…”

Effect of Hydrothermal Treatment on the Properties of Calcium Oxide from Eggshells Used as a Biodiesel Catalyst

“…However, this important alternative fuel was found to be more costly than its petroleum‐based counterpart, mainly because of the high cost of the starting raw materials, particularly vegetable oil feedstocks 15, 16. As a result, a number of research interests are currently focused on the use of waste (used) cooking oil in an effort to make biodiesel production economically competitive and environmentally friendly 15–17. The use of waste (used) cooking oil is expected to bring down the cost of biodiesel production, since this oil is far less expensive than pure vegetable oil 16–18.…”

“…As a result, a number of research interests are currently focused on the use of waste (used) cooking oil in an effort to make biodiesel production economically competitive and environmentally friendly 15–17. The use of waste (used) cooking oil is expected to bring down the cost of biodiesel production, since this oil is far less expensive than pure vegetable oil 16–18. Although the quantity of these oils that can be obtained in Nigeria cannot meet the demand for diesel in the country, it would partly reduce the reliance on petroleum‐based diesel 16.…”

“…Among the most popular solid catalysts reported for biodiesel production, calcium oxide (CaO) has the highest potential because of its outstanding catalytic activity and lower solubility in biodiesel 16. It is also inexpensive, environmentally friendly, and reusable; has low solubility in methanol; and can be obtained from a variety of natural sources, such as bones and shells 17.…”