SO₂-Enhanced Nitration of Fluoranthene and Pyrene Adsorbed on Particulate Matter in the Heterogeneous Reaction in the Presence of NO₂

Abstract

Heterogeneous photoreaction of fluoranthene (FL) or pyrene (PY) adsorbed on solid support under 10 ppm NO₂-air in the presence or absence of SO₂ was investigated in order to clarify the effect of SO₂ on nitroarene formation. Formation yield of nitrofluoranthenes (NFs) and nitropyrenes (NPs) were increased by the addition of SO₂ to reaction atmosphere. 1-, 2-, 7-, and 8-NFs were formed in the presence of SO₂ while 1-, 2-, and 7-NF were detected in the absence of SO₂. After the reaction for 4 h, yield of 2-NF in the presence of 10 ppm of SO₂ was 1.5 times as large as that in the absence of SO₂. 1-NP and 1,3-, 1,6-, 1,8-dinitropyrenes (DNPs) were formed both in the presence and in the absence of SO₂. After the reaction for 2 h, yields of 1-NP and DNPs in the presence of 10 ppm of SO₂ were about three times and twice as large as those in the absence of SO₂, respectively. While the yield of 1-NP and degradation rate of PY were hardly affected by the concentration of SO₂, the yield of DNPs increased with the increase in SO₂ concentration. The isomer distributions of NFs and NPs indicated that NFs and NPs were formed by non-electrophilic nitration and electrophilic nitration, respectively.

Key Words:

• nitrofluoranthene
• nitropyrene
• heterogeneous nitration
• nitrogen dioxide
• sulfur dioxde
• photoirradiation