Effect of temperature on the enrichment and volatility of 18 elements during pyrolysis of biomass, coal, and tires

Abstract

The effect of temperature on the enrichment and volatility of elements during pyrolysis of brown coal, biomass pellets, and used tires was evaluated. The elements investigated included barium (Ba), bromine (Br), calcium (Ca), chlorine (Cl), chromium (Cr), copper (Cu), iron (Fe), potassium (K), manganese (Mn), phosphorus (P), lead (Pb), rubidium (Rb), sulfur (S), silicon (Si), strontium (Sr), titanium (Ti), yttrium (Y), and zinc (Zn). The pyrolysis experiments were conducted in a semi-continuously operated triple-screw reactor at four temperatures: 500, 550, 600, and 650 °C. An enhancement in the total contents of elements was observed in all materials due to pyrolysis. The highest enrichment of elements was observed in char from pyrolysis of coal, followed by biochar, and char from pyrolysis of tires. Differences between investigated materials were also observed regarding volatility of elements and they were attributed primarily to (i) discrepancies in the composition of raw materials, (ii) secondary reactions of chars, and (iii) the affinity and occurrence of elements.