Energy Conversion and Management, Vol.155, 175-181, 2018
Controlled regeneration of ZSM-5 catalysts in the combined oxygen and steam atmosphere used for catalytic pyrolysis of biomass-derivates
Catalyst deactivation by coke deposition was the main barrier in the catalytic pyrolysis of biomass for hydrocarbons, thus deactivated catalysts should be regenerated timely. In this study, several measures were applied in the regeneration process to obtain higher yield of hydrocarbons in the catalytic conversion of biomass-derivates. The effect of oxygen concentration in the regeneration atmosphere on catalytic performance was firstly investigated, and then steam was introduced on the basis of the optimal oxygen concentration to further decrease the internal temperature of catalyst particle. Finally the deactivated catalysts were partially regenerated by retaining some coke. The results showed that 15% was the optimal oxygen concentration, at which the catalysts still showed steady production of olefins and aromatics after 30 cycles of catalysis-regeneration. When 15% oxygen and 5% steam was combined in the regeneration atmosphere, the temperature of catalyst bed was reduced efficiently. The stable yield of hydrocarbons by combined regeneration method was boosted by 31.3% compared with pure 15% oxygen. At retaining coke amount of 2.18%, yield of hydrocarbons was promoted by 27.4% compared with completely regenerated. With the combined oxygen/steam atmosphere and controlled regeneration, the temperature of catalyst particles was well regulated and stable catalysis-regeneration process to produce hydrocarbons via thermochemical utilization of biomass can be realized.