Pyrolysis of Millettia (Pongamia) pinnata waste for bio-oil production using a fly ash derived ZSM-5 catalyst

Fast pyrolysis of Millettia (Pongamia) pinnata waste (PPW) was performed using a scaled-up 180-cm drop-tube pyrolyzer with fly ash (FA)-derived ZSM-5 (FA-ZSM-5) as a deoxygenation and denitrogenation catalyst to upgrade the liquid products. The oil from P. pinnata is typically extracted to produce bio-fuel leaving a large amount of PPW that has some 20% (v/v) oil content. Since the PPW is inedible, due to its toxicity from karanjin and di-ketone pongamol, it represents a potential non-food competing 'green' biofuel feedstock. The FA-ZSM-5 catalyst applied in this work was synthesized using alkali hydrothermal treatment of coal FA to yield FA-ZSM-5 with a 329 m(2)/g surface area and 37.18 angstrom pore diameter. Pyrolyzer-gas chromatography-mass spectrometry was used to locate the optimal operating window prior to executing a scaled-up reactor operation at 400-700 degrees C). A maximum bio-oil yield of 43.1% by proportion was obtained at 500 degrees C, while the solid and gas products were 32.5% and 24.4%, respectively. Oleic acid was a major component in the bio-oil obtained from the non-catalytic condition, while ketones were prominent (79.4%) when FA-ZSM-5 was used, albeit with a low hydrocarbon (HC) selectivity. From the carbon chain length analysis, thermal cracking to smaller molecules was dominant in the presence of the FA-ZSM-5 catalyst, inducing a low HC yield in the liquid product.