Co-pyrolysis of corn cobs and polypropylene for production of biofuel similar to gasoline at low heating rate

Abstract

Co-pyrolysis between corncobs and polypropylene has a synergetic effect that transforms part of polar fraction of bio-oil into non-polar fraction containing non-oxygenate compounds as precursor for synthesis of bio-fuel. In the present work, pyrolysis of the nonpolar fraction of bio-oil was led to produce bio-oil with viscosity similar to that of gasoline and contained non-oxygenated compounds. The pyrolysis was carried out in 2 stages, where the first-stage was co-pyrolysis to produce non-polar bio-oil and the second-stage was pyrolysis of non-polar fraction from the first stage to reduce its viscosity similar to that of gasoline. The first and second-stage pyrolysis was carried out in a stirred tank reactor at heating rate of 5˚C/min using nitrogen as carrier gas with the second-stage pyrolysis final temperature varied. The resulting bio-oil product was characterized by FT-IR, GC-MS, H-NMR, viscometer and LC-MS. The results show that bio-oil viscosity and yield of the second-stage pyrolysis heavily depended on its final temperature, in which the higher the temperature, the higher was the viscosity, yet the higher was the bio-oil yield. Final temperature of 300°C was the optimal one for obtaining bio-oil similar to gasoline regarding its close viscosity despite of low yield of bio-oil. Pyrolysis of bio-oil may be performed coinciding with attempting of reducing branching index to reduce its viscosity.