Evaluation of crude bio-oil production from green tea waste (GTW) through pyrolysis over clamshell waste as a natural catalyst

The present study aimed to evaluate the effect of clamshell waste (CSW) as a natural catalyst to enhance the bio-oil yield and composition through pyrolysis with green tea waste (GTW). Initially, volatiles from GTW pyrolysis were allowed to pass through a capsule filled with CSW, which showed insignificant changes in bio-oil yield with 31.6%, 12.3%, 23.5%, and 11.6% increase in hydrocarbons, esters, alkanes/alkenes, and phenols, respectively. Further, CSW was directly mixed with GTW at ratios of 2.5%, 5.0%, 7.5%, and 10.0% (w/w) in comparison with the control (using GTW only). Results showed that caffeine was the dominant component in the bio-oil, representing 39.9% in the control, which could be used to enhance the process feasibility through biorefinery approach. Using 7.5% CSW enhanced the bio-oil yield by 10.2% over the control. In addition, CSW application showed desirable composition of the bio-oil. Nitrogen-containing compounds proportion of the bio-oil produced at 10% CSW represented 20.3% lower than that of the control. In addition, hydrocarbons, esters, and alkanes/alkenes proportions increased by 38.4%, 37.7%, and 71.6%, respectively, over the control. The present study introduces CSW as a natural catalyst for enhanced bio-oil yield and characteristics that could be used in many future applications.