Pyrolysis of dibenzodioxin, dibenzofuran and 1,2,3,4-tetrabromodibenzodioxin with different chlorine donors and catalysts

Abstract

Dibenzodioxin, dibenzofuran and 1,2,3,4-T 4BrDD were pyrolysed with conc. HCl, NaCl or PVC at 800°C and 900°C for 10 min in an open quartz tube. Dibenzodioxin and dibenzofuran were also pyrolysed with conc. HCl and catalysts such as AlCl 3, CuCl 2 and extracted fly ash. The residues were dissolved in toluene and analysed by HRGC/MS. Only MCDD was detected when dibenzodioxin was pyrolysed using conc. HCl, conc. HCl AlCl 3 or conc. HCl/fly ash. MCDD, DCDD, T 3CDD and T 4CDD were detected in the pyrolysate of dibenzodioxin with conc. HCl CuCl 2 . Only MCDF was found in the pyrolysate of dibenzofuran with conc. HCl AlCl 3 and conc. HCl CuCl 2 . Low chlorinated dioxins were formed in the pyrolysis of dibenzofuran with conc. HCl, conc. HCl AlCl 3 and conc. HCl CuCl 2 . In all reactions of 1,2,3,4-T 4BrDD, an exchange of bromine for chlorine was observed. Pyrolysis of 1,2,3,4-T 4BrDD at 800°C with PVC, resulted in 46% of the starting material being transformed to brominated/chlorinated dioxins (Br/Cl-DD) (39.7%) and 1,2,3,4-T 4CDD (6.3%). The yield of Br/Cl-DD and 1,2,3,4-T 4CDD at 900°C was 69%, and 34.7% conversion to 1,2,3,4-T 4CDD was observed. In the reaction with HCl (T=900°C), 49.2% Br/Cl-DD and 1,2,3,4-T 4CDD were formed. Pyrolysis with NaCl at 900°C yielded 10.5% conversion to Br/Cl-DD or 1,2,3,4-T 4CDD.