Phase equilibria of aqueous solutions of formaldehyde and methanol: Improved approach using UNIQUAC coupled to chemical equilibria

Abstract

This is an author's version published in: http://oatao.univ-toulouse.fr/20334 a b s t r a c tThe study of the phase equilibria involving formaldehyde is still relevant because of its presence in new processes where biomass is the raw material. The coupling between physical phase equilibria and chemical reactions makes its thermodynamic description a challenging task. In this work, an improved approach using UNIQUAC coupled to chemical equilibria was developed and compared with experimental data from the literature. The first application was done for the phase equilibria of the formaldehyde-water system and distribution of oligomers in the liquid phase was computed. The second and the third applications respectively considered the phase equilibria of the formaldehyde-methanol system and the formaldehyde-water-methanol system.

A mathematical analysis of carbon fixing materials that grow, reinforce, and self-heal from atmospheric carbon dioxide

“…Formaldehyde oligomerization reactions rates are multiple orders of magnitude higher than the formaldehyde production reaction rates, guaranteeing the continuous conversion of formaldehyde upon production in the solution with minimal mass loss. 52,[58][59][60] For the catalytic conversion of CO 2 , the initial reduction of CO 2 to either formic acid or carbon monoxide is the rate-limiting step, having rate constants two to three orders of magnitude smaller than all other photocatalytic reaction steps. The subsequent reaction of photocatalytically produced formaldehyde is fast, and the hydration of formaldehyde will outcompete its subsequent reduction to methanol.…”

Generalized Chemical Equilibrium Constant of Formaldehyde Oligomerization

“…Figure 5, also holds for other temperatures. The values of the reaction enthalpies of the first addition reaction of formaldehyde to the different solvents, as determined from the correlations shown in Table 3 using Equation (10), lie between -27 kJ mol −1 and -31 kJ mol −1 . Hence, the first addition of formaldehyde is mildly exothermal, similar to the chain prolongation reaction.…”

“…they have to be considered for describing the vapor-liquid equilibrium. [3][4][5][6][7][8][9][10] In the literature, information on the chemical equilibrium of mixtures of formaldehyde with water, [11][12][13][14] with the mono-alcohols methanol, 12,15,16 ethanol, 17 and 1-butanol 18,19 as well as with the diols ethylene glycol 17 and 1,4-butynediol 20 is available. In the present work, the entire set of available data on the oligomerization reactions of formaldehyde was analyzed.…”

Prediction of the Vapor–Liquid Equilibrium of Formaldehyde–Water–Trioxane Ternary System by the Conductor-Like Screening Model for Real Solvents

“…Based on the early work of Klamt, a conductor-like screening model for real solutions (COSMO-RS) [11] was proposed in 1995, and has been intensively developed over the past decades [12]- [16]. COSMO-RS is a statistical thermodynamics theory based on COSMO polarization charge densities, which overcomes many of the limitations and theoretical shortcomings of dielectric continuum models.…”