Upgrading the corn cob pyrolysis vapors by processing over catalysts based on aluminium slag and the assessment of the produced bio-oil

Abstract

In this paper the processing of corn cob pyrolysis vapors (CCPV) over catalysts based on aluminium slag (AS) was studied as a new route to produce bio-oil with improved quality. The processing of the CCPV was performed in a lab-scale fixed bed reactor applying raw and modified aluminium slag as catalysts and also without catalyst and the resulted bio-oils were compared.The proportion of the oxygenated compounds in bio-oil phase obtained without catalyst was increased compared with bio-oil phase obtained with catalysts, in which the concentrations of the compounds free of oxygen or with low oxygen content was predominant.The degree of deoxygenation (DOD) for bio-oils produced catalytically after five consecutive processing/regeneration cycles was in the range of 59.38–64.02 %,depending on the catalyst used, the highest DOD of 64.02 % was obtained for the bio-oil produced with NaAS as catalyst. During the CCPV processing on the catalyst was deposited coke leading to a possible its deactivation.The deposited coke amount was determined, the catalyst was regenerated by coke combustion and then reused in the five cycles. It could be observed that after five cycles of processing the amount of deposited coke remained almost the same(in the range 0.051–0.085 g) which indicated a good regeneration and a stable behavior of the catalyst. As such, the CCPV processing with catalysts based on AS represents an economically attractive alternative to more expensive catalysts such as zeolites for production of bio-oil with good quality, which may be further processed in conventional refineries or directly applied as a renewable fuel.