Selective catalytic conversion of tea waste biomass into phenolic-rich bio-oil and subsequent extraction

Fast pyrolysis has appeared as a promising technology for bio-fuels and bio-based chemicals production. This paper reports tea waste (TW) as a promising source of phenolic-rich bio-oil production via catalytic fast pyrolysis in fluidized bed reactor. TG-FTIR analysis is applied to optimize pyrolysis temperature for phenolic-rich bio-oil production and maximum phenols yield (17.3 %) was obtained at 500 degrees C. Meanwhile, bio-oils are produced at each corresponding temperatures of TG-FTIR analysis and GC-MS analysis is performed to examine consistency and authenticity of TG-FTIR results. Moreover, catalytic effect of activated carbon + KOH (AC-K) with different biomass-to-catalyst ratio was examined to optimize most efficient ratio at 500 degrees C and maximum phenol contents (39.72 %) were obtained at 1:6 ratio of biomass-to-catalyst as compared to non-catalytic pyrolysis (23.85 %). Moreover, effect of temperature on product distribution was examined and maximum liquid yield (40.7 %) was obtained at 500 degrees C. Furthermore, switchable hydrophilic solvents (SHS) were used to isolate phenols from bio-oil with 95.02 % yield calculated by GC-MS analysis. The elemental analysis and high heating value (HHV) of the crude and residue bio-oil were determined. The carbon contents and HHV of residue bio-oil were increased to 67.3 % and 13.7 MJ/Kg from 46.2 % and 10.38 MJ/Kg respectively while; oxygen contents were decreased to 19.7 from 45.3 % demonstrating its potential for fuel application.

Automated summary

This paper explores the production of phenolic-rich bio-oil from tea waste through catalytic fast pyrolysis. By analyzing different conditions, it is found that the use of activated carbon + KOH as catalyst at 500 degrees C results in the highest phenol yield. Switchable hydrophilic solvents are effective in extracting phenols from bio-oil.