Ab initio study of the unimolecular pyrolysis mechanisms of formic acid: additional comments based on refined calculations

Role of water in formic acid decomposition

“…One way to address this issue of water's potential catalytic role is theoretical investigation. Several ab initio quantum chemical calculations for formic acid and its decomposition have been reported (Ruelle et al, 1986;Ruelle, 1987;Melius et al, 1990;Goddard et al, 1992;Francisco, 1992;Kumaresan and Kolandaivel, 1995). Francisco (1992) and Goddard et al (1992) studied the gas-phase reaction in the absence of water and showed that the activation energy for decarboxylation was slightly higher than that for dehydration, which is consistent with the higher yield of CO observed in gas-phase experiments.…”

Accurate Calculations of Rate Constants for the Forward and Reverse H2O + CO ↔ HCOOH Reactions

“…In addition, Ruelle et al . and Ruelle suggested that these CO/CO 2 values can be explained in gas phase by means of a dependence of reaction (1) on reaction (2). Hence, some of the H 2 O molecules produced in the second process could work as catalysts for the first reaction.…”

“…Besides, Goddard et al [8] commented that the reaction (2) is the predominant chemical pathway in agreement with experimental observations of Saito et al [6] , whose also noticed a low contribution from reaction (1) along the temperature range of 1370-2000 K. Furthermore, other experimental investigations focused on HCOOH decomposition point out values of at least 10 for the CO/CO 2 abundance ratios. [2,10,11] In addition, Ruelle et al [5] and Ruelle [12] suggested that these CO/CO 2 values can be explained in gas phase by means of a dependence of reaction (1) on reaction (2). Hence, some of the H 2 O molecules produced in the second process could work as catalysts for the first reaction.…”

A Computational Study on the Decomposition of Formic Acid Catalyzed by (H2O)x, x = 0−3: Comparison of the Gas-Phase and Aqueous-Phase Results

“…3,15,16 To explain the difference between the gas and aqueous phases, water as a homogeneous catalyst has been studied by several theoretical researchers. 11,12,14,17, 18 Ruelle et al 10,11 showed that using water as a catalyst reduces the activation barrier of the decarboxylation reaction. Later, Melius et al, 14 Akiya et al, 19 and Wang et al 12 studied the effect of water on both dehydration and decarboxylation and illustrated those pathways are catalyzed by water.…”