Possible atmospheric source of NH2SO3H: the hydrolysis of HNSO2 in the presence of neutral, basic, and acidic catalysts

Abstract

NH₂SO₃H can directly participate in H₂SO₄–(CH₃)₂NH-based cluster formation, and thereby substantially enhance the cluster formation rate. Herein, the reaction mechanisms and kinetics for the formation of NH₂SO₃H from the hydrolysis of HNSO₂ without and with neutral (H₂O, (H₂O)₂, and (H₂O)₃), basic (NH₃ and CH₃NH₂), and acidic (HCOOH, H₂SO₄, H₂SO₄⋯H₂O, and (H₂SO₄)₂) catalysts were studied theoretically at the CCSD(T)-F12/cc-pVDZ-F12//M06-2X/6-311+G(2df,2pd) level. The calculated results showed that neutral, basic, and acidic catalysts decrease the energy barrier by over 18.1 kcal mol⁻¹; meanwhile, the product formation of NH₂SO₃H was more strongly bonded to neutral, basic, and acidic catalysts than to the reactants HNSO₂ and H₂O. This reveals that the reported neutral, basic, and acidic catalysts promote the formation of NH₂SO₃H from the hydrolysis of HNSO₂ both kinetically and thermodynamically. Kinetic calculations using the master equation showed that (H₂O)₂ (100% RH) dominate over the other catalysts within the range of 0–10 km altitudes and 230–320 K with its rate ratio larger by at least 2.98 times, whereas HCOOH (3.2 × 10⁹ molecules cm⁻³) is the most favorable catalysts at 15 km altitude in the troposphere. Overall, the present results will provide a definitive example that neutral, basic, and acidic catalysts have important influences on atmospheric reactions.