Biodiesel production by a highly effective renewable catalyst from pyrolytic rice husk

High efficiency and stable CaO-based catalysts which used rice husk biochar as a carrier were utilized to catalyze transesterification of vegetable oil with methanol. The properties of the synthesized catalyst were determined using XRD, TGA, FT-IR, SEM, EDX, N2 adsorption/desorption, XPS and the Hammett indicator method. The influences of catalyst preparation, reaction parameters and reusability of catalyst were also investigated. The results indicated that the catalyst activity mainly depended on the pretreatment temperature, structure and basicity of the catalysts. The maximum yield could reach 93.4% under the prepared conditions of 30% CaO loading and 700 °C calcination temperature. Meanwhile, after being reused for 10 cycles, there was no noticeable loss of catalyst activity in biodiesel yield (above 85%). The appearance of CaOSi bond on the catalyst surface was the main reason for high stability. The findings suggested that the rice husk biochar based catalyst was a very promising choice for biodiesel production.