Burning Used Automotive Tires for Activated Carbon

Abstract

Shredded tire, considered as a single compound in defining theoretical air/fuel ratio, was heated in a quartz reactor placed in an electric furnace under conditions of various excess air ratios, temperatures and heating rates; temperature of up to 1050°C, heating rate of 20, 50, and 80°C/min, and FR of 0.2-1.0. Mass of solid char decreased as the final reaction temperature was raised up to about 600°C around which it maintained a relatively constant value before beginning to increase again at the final reaction temperature of about 800°C. The two-phased decrease of solid char mass with a transition seems to be caused by different modes of combustion. The effects of heating rate and FR (Feed Ratio) were relatively smaller than that of temperature on the mass reduction of solid char, but were significant on the emission of CO and its oxidation to CO₂. The fraction of smaller pores in solid char grew bigger as the final reaction temperature went up, resulting in higher surface area. Surface area also increased with decreasing FR from 0.8 to 0.4. Water injection proved so effective in increasing the surface area that the BET value almost doubled when proper amount of water was injected during combustion.