Co-upgrading of biomass and plastic volatiles via metal-modified HZSM-5 coupled with NTP: deterioration and in situ recovery of the catalyst†
Co-upgrading of biomass and plastic pyrolysis volatiles was conducted over metal-modified HZSM-5 coupled with NTP technology. Three aspects were investigated: (I) the effects of different metals (Ru, Mo, Ti, and Sn) on the organic yield and grade, active radicals and catalyst coking were analyzed, (II) the effects of plastic to biomass ratios on coking characteristics were evaluated, and (III) in situ regeneration of the spent catalyst by NTP was conducted and the performance of the regenerated catalyst was evaluated. The results showed that Mo and Ti modifications had a stronger promotion effect on the formation of active radicals, increasing the organic yield and fuel-grade obviously, and the metal modified versions coupled with NTP had more advantages in anti-coking. Graphite carbon increased with the increase of the plastic proportion, showing that co-upgrading synergized with NTP broke through the limitation of plastic proportion. Although dehydrogenated carbon and graphite-like carbon co-existed, the textural properties of the spent catalyst were better retained in a higher plastic proportion. Lower temperature led to insufficient activation of coke and precursors, while higher temperature intensified the elimination effect of plasma, and the coked catalyst could be regenerated at a lower temperature and in a shorter time. The properties of the spent catalyst were efficiently recovered, and reutilization of the regenerated catalyst was effective by comparison. This study laid the experimental and theoretical foundations of catalyst deterioration and provided a new cycle method for sustainability.