In silico study on the effects of carbonyl groups on chemical equilibrium of reactions with a polar product occurring under confinement in pores of activated carbons

Abstract

This work has presented the results of the first systematic reactive Monte Carlo studies on the influence of oxygen surface groups on the equilibria of reaction leading to the polar product in pores of activated carbons. Carbonyl groups have been chosen as the simple representative of the oxygen functionalities. It should be noted that the effects of the chemical nature of carbon surface on the studied phenomenon are not sufficiently known. The results of our theoretical studies have provided some general regularities which can be adapted to the real processes and show the direction of synthesis/modification of carbon to maximize the yield of reaction. Firstly, it has been shown that oxidation of carbonaceous surface significantly increases the amount of formed product when it is quite polar, i.e., its dipole moment is equal to 1.25 Debye which is the value comparable with the polarity of hydrochloride or ammonia molecules. Next, it has been examined how polar the product should be to observe significant effects of the surface functionalities. It has been found that the yield is only slightly raised when the dipole moment does not exceed 0.5 Debye. The increase of polarity above this value is connected with a rapid non-linear increase of the product amount in the pores. The obtained results have proven that the effects of confinement in carbonaceous pores for the considered class of reaction can be emphasized by the choice of highly microporous carbons and the oxidation of their surface.