The hydrolysis of formaldehyde [HCHO + H 2 O → H 2 C-(OH) 2 ] assisted by bimolecular acidic catalyst of X (X = H 2 SO 4 •••H 2 O and (H 2 SO 4 ) 2 ) under different concentrations of H 2 SO 4 and H 2 O was performed by quantum chemical calculations of CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/6-311++G(3df,3pd) and the master equation method. The calculated results show that the hydrolysis reaction of HCHO catalyzed by X can occur through both HCHO•••H 2 O + X (one-step reaction) and H 2 O•••X + HCHO (stepwise reaction) routes. The stepwise reaction assisted by H 2 SO 4 •••H 2 O is the most favorable reaction among all the hydrolysis reactions assisted by X, with its effective rate constant larger by at least 2 orders of magnitude. In comparison with the hydrolysis of HCHO without X, the favorable route for the hydrolysis of HCHO with H 2 SO 4 •••H 2 O can reduce the energy barrier by 32.0 kcal•mol −1 . Meanwhile, the energy barrier of this reaction is also lower by another 0.8−17.6 kcal•mol −1 than those of the hydrolysis reaction of HCHO assisted by H 2 SO 4 , HCOOH, HNO 3 , CH 3 COOH, H 2 O, and (H 2 O) 2 . From the viewpoint of the calculated effective rate constant k′, the hydrolysis of HCHO with H 2 SO 4 •••H 2 O {[H 2 SO 4 ] = 10 6 molecules•cm −3 and [H 2 O] at 40−100% relative humidity (RH) along with [H 2 SO 4 ] = 10 7 −10 8 molecules•cm −3 and [H 2 O] at 20−100% RH} is more effective than the hydrolysis reaction assisted by H 2 O, (H 2 O) 2 , HCOOH (0.01−10 ppbv), HNO 3 (10 9 −10 11 molecules•cm −3 ), and CH 3 COOH (1−5 ppbv) within the temperature range of 280−320 K. Under the same condition, the hydrolysis of HCHO with H 2 SO 4 •••H 2 O can compete well with the hydrolysis of HCHO assisted by H 2 SO 4 (10 6 −10 8 molecules•cm −3 ). Therefore, this work predicts that H 2 SO 4 •••H 2 O can play a significant role in the hydrolysis of HCHO in the condition of wet areas with relatively high H 2 SO 4 pollution.

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Liu et al. (Proc. Natl. Acad. Sci. U.S.A, 2019, 116, 24966-24971) showed that at an altitude of 0 km, the reaction of SO3 with CH3OH to form CH3OSO3H reduces the...

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