Unraveling the lab-scaling up production of activated carbon from plastic-enriched waste

Abstract

This work explores the preparation of activated carbon from the pyrolysis char residues in two different scale scenarios, i.e. a laboratory furnace and a scaled-up version in a lab-pilot plant rotatory furnace. As the activating method, K2CO3 was added to the carbonaceous precursor. The activation temperature (700-800ºC) and the impregnation char: K2CO3 ratio (1:0.25-1:2) were modified in both setups, comparing the attained results of textural development and chemical composition by elemental analysis and XPS. The effect of the agitation during the activation process was also evaluated at the lab-pilot plant scale. The results pointed out a better definition of the textural properties at the lab-pilot plant scale, with an important influence on the agitation in the process. Thus, the optimum temperature was set as 750 ºC, and the char: K2CO3 ratio as 1:0.5, leading to a material with an area of ~1100 m2 g-1, and a pore volume of ~0.8 cm3 g-1. The resulting activated carbon could adsorb up to 270 mg CO2 g-1. Dynamic tests of CO2-CH4 mixtures (from 20:80 to 40:60) were carried out with the optimized material prepared at the lab-pilot plant scale, demonstrating the suitability of the valorized residue as activated carbon for biogas upgrading, with high stability in sequential reusing assays.