Amino Compounds as Inhibitors of De Novo Synthesis of Chlorobenzenes

The inhibitory effects of four amino compounds on the formation of chlorobenzenes (CBzs) - dioxin precursors and indicators, and the inhibitory mechanisms were explored. The results show NH(4)H(2)PO(4) can decrease the total yields of CBzs (1,2di-CBz, 1,3di-CBz, 1,4di-CBz, penta-CBz and hexa-CBz) by 98.1%±1.6% and 96.1%±0.7% under air and nitrogen flow. The inhibitory effects indicated by the total yields of CBzs follow the order NH(4)H(2)PO(4) > NH(4)HF(2) > (NH(4))(2)SO(4) > NH(4)Br under air flow and NH(4)H(2)PO(4) ≈ (NH(4))(2)SO(4) ≈ NH(4)HF(2) >NH(4)Br under nitrogen flow. The inhibition mechanism revealed by thermal analysis that CuCl(2) was converted to CuPO(3) by reacting with NH(4)H(2)PO(4) below 200 °C, which can block the transfer of chlorine and formation of C–Cl bonds at 350 °C. The effects of the other three inhibitors were weaker because their reactions with CuCl(2), which form other copper compounds, and the reaction of CuCl(2) with carbon, which forms C–Cl bonds, were almost simultaneous and competitive. Oxygen influenced the yield of CBzs obviously, and the total yield of five CBzs sharply increased with oxygen. Because of their high efficiency, low environmental impact, low cost, and availability, amino compounds - especially NH(4)H(2)PO(4) - can be utilized as inhibitors of CBzs during incineration.