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

• Behavior of 18 elements is investigated during pyrolysis of biomass, coal and tires.
• Pyrolysis increases the total contents of elements in all materials investigated.
• Char from pyrolysis of coal exhibits the highest enrichment of elements.
• Element volatility is influenced by material composition and secondary reactions.
• The affinity of elements affects the volatility of elements.

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.