Utilization of renewable and sustainable basic heterogeneous catalyst from Heteropanax fragrans (Kesseru) for effective synthesis of biodiesel from Jatropha curcas oil

Abstract

This study explores the application and efficacy of the green catalyst derived from Heteropanax fragrans in the production of Jatropha curcas biodiesel. The catalyst was prepared by calcination of the ash at 550 and 850 °C for 2 h. Powder-XRD, BET, FT-IR, FESEM, EDX, XPS and HRTEM were employed for catalyst characterization. The characterization indicated that among the various metals present, potassium was found to be the highest being 14.69 wt% in UHC (uncalcined H. fragrans catalyst), 19.05 wt% in the CC-550 (catalyst calcined at 550 °C), and 19.27 wt% in the CC-850 (catalyst calcined at 850 °C). The BET analysis of UHC, CC-550 and CC-850 showed the appreciable surface areas of 96.57, 27.50, and 78.45 m2 g−1, respectively. The CC-550 with the highest basic character (pH value = 12.89 at 1:5 w/v) is exhibiting better performance producing a high biodiesel yield of 97.75% in 65 min with TOF (Turnover frequency) of 35.55 min−1 compared to the CC-850 (96.58%, 115 min) and UHC (96.61%, 110 min) with TOF of 27.71 and 29.47 min−1, respectively at the optimum experimental conditions of 12:1 MTOR (methanol to oil ratio), and 7 wt% of catalyst at 65 °C. Hammett method showed stronger basicity of CC-550 (0.423 mmol/g) representing the better efficacy for the catalysis in comparison to that of CC-850 (0.303 mmol/g) and UHC (0.298 mmol/g). The catalyst is reusable which could produce a high biodiesel yield (90.22%) even in the 3rd reaction cycle. The activation energy of H. fragrans catalyzed biodiesel synthesis is found to be 32.31 kJ mol−1. FT-IR, NMR, and GC–MS techniques were used to characterize J. curcas biodiesel. The properties of J. curcas biodiesel were found to be within the limits of international standards. The prepared catalyst is an environmental-friendly, renewable, inexpensive and highly efficient base catalyst. Thus, the utilization of this catalyst for biodiesel production will add an aspect in the biorefinery for exploring sustainable raw materials with the overall capacity of reduction in biodiesel-cost.