Synthesis of biodiesel via methanolysis of waste frying oil by biowaste-derived catalyst: process optimization and biodiesel blends characterization

Heterogeneously catalyzed transesterification reaction is known to be the most appropriate process for producing biodiesel from triglyceride-containing feedstock as it ensures catalyst reusability and easy product separation, lowers production costs, and makes biodiesel affordable. This work investigates the influence of calcination temperature (700-1000 degrees C) on the performance of CaO catalyst obtained from eggshells for biodiesel synthesis from waste frying oil (WFO). The prepared CaO catalyst was characterized using various techniques (TGA/DTA, N-2 adsorption-desorption isotherm (BET), FTIR, CO2-TPD, XRF, XRD, and SEM). Taguchi optimization method with an orthogonal array was used to investigate the effect of process parameters (time, catalyst amount, methanol/oil ratio, and temperature). Reaction time was observed to be the most influential variable according to the design. Under the optimal transesterification conditions (i.e., at 50 degrees C for 3 h using WFO/methanol molar ratio of 1:10 with catalyst dosage of 0.75 wt.%), the biodiesel yield attained 90.81% when eggshell derived-catalyst calcined at 850 degrees C (CEG-850) was used. The remarkable performance of the CEG-850 could be attributed to its high basic strength (749 mu mol/g), improved surface area (15.4 m(2)/g), and dominance of basic sites on its surface. The blended fuel with 10% by volume biodiesel (B10) exhibited improved fuel properties compared to blended fuel with 50% by volume biodiesel (B50), which confirmed the suitability of a low-level biodiesel blend in the diesel engine. More than 54% biodiesel yield was achieved after the seventh cycle, depicting better stability.

Automated summary

This study investigates the effect of calcination temperature on the performance of CaO catalyst obtained from eggshells for biodiesel synthesis. By optimizing the transesterification conditions, a high biodiesel yield of 90.81% was achieved using the CaO catalyst calcined at 850 degrees C. The study also reveals the improved fuel properties of low-level biodiesel blends in diesel engines.