Analysis of the Coke Precursor on Bio-oil Refining Catalyst and the Regeneration of the Deactivated Catalyst

In preparation of motor fuel, the bio-oil from pyrolysis of biomass must be further upgraded (catalytic cracking ) so as to improve its quality. However the catalyst used in the cracking reaction is easy to lose its activity due to being coked, so that it is important to study the coke formation and its effects on the catalyst activity in the cracking process. TGA, FTIR and CNMR were used to analyze the precursor of coke on the catalyst HZSM-5 used in upgrading and based on it the mechanism of coking was discussed too. The results indicates that precursors of coke deposited inside the pore of the molecular sieve are mainly aromatic hydrocarbons with the boiling points ranging from 350 °C to 650 °C. Those precursors on the outer surface of the catalyst were identified as saturated aliphatic hydrocarbons with the boiling points below 200 °C. The effect of regenerating the deactivated HZSM-5 through calcining it in air at 600°C was also studied. In terms of the yield of organic distillate and the formation rate of coke, the results show that reused catalytic activity changes moderately during the first 3 times of regeneration, while the reused catalyst is gradually deactivated after repeated regenerations more than 3 times.