Parkia speciosa: A basic heterogeneous catalyst for production of soybean oil-based biodiesel

A green heterogeneous catalyst was fabricated for the biodiesel synthesis via transesterification of soybean oil. The catalyst was generated by simple calcination of the biomass Parkia speciosa (Manipuri beans) at 700 degrees C. Characterization techniques like TGA, FT-IR, XRD, SEM, BET, TEM, STEM, EDS, XPS, and CO2-TPD were employed to analyse the catalyst. The results showed the existence of significant amount of potassium (K) with some amount of calcium (Ca) in the form of oxides and carbonates which serves as active catalytic sites for accelerating the process of transesterification. The highest biodiesel yield of 96.4 % was achieved at 40 degrees C, when reaction was performed for 3 h with catalyst loading of 5 wt%, 1:15 M ratio of oil to methanol and 20 wt% of co-solvent. The catalyst has also proved to be truly heterogeneous at low temperature as its efficiency remains intact even after five successive cycles. Thus, the biomass-derived catalyst can be seen as a potentially viable alternative for the conventional homogeneous catalyst.