Rapid Pyrolysis of Olive Residue. 2. Effect of Catalytic Upgrading of Pyrolysis Vapors in a Two-Stage Fixed-Bed Reactor

Abstract

The upgrading of the rapid pyrolysis vapors was performed using various catalysts (clinoptilolite (a natural zeolite, NZ), ZSM-5, H-Y) with catalyst/feed ratios of 0.05, 0.1, 0.15, 0.20, and 0.25 in the catalyst bed temperature range of 350-500 degrees C on the product distributions. The catalytic treatment with synthetic zeolites provided enhancement of the gas yields and reduction of the oil yields. Moreover, the high catalyst/feed ratio was favored to increase of gas yields. ZSM-5 was very effective in gas production, whereas NZ was in bio-oil production without any severe coking, compared to synthetic zeolites. H-Y showed a higher tendency of formation of coke and tar. Moreover, a catalyst bed temperature of >450 degrees C caused enhancement of the gas yields and reduction of the oil yields. After application of catalytic treatment, the long chains of alkanes and alkenes of the pyrolysis oil were converted to lower-weight hydrocarbons. An increase of aliphatics, aromatics, and olefins and a sharp decrease of asphaltenes and polar groups (highly oxygenated groups) were determined. NZ was determined to be very effective in aliphatic production, whereas ZSM-5 produced more aromatics. Consequently, comparing the natural zeolite with synthetics on bio-oil production, NZ exhibited better performance.