Optimization And Kinetics Study Of Calcium Formate Production By Calcium Hydroxide Carbonylation

Calcium formate is widely used as sulphur flue gas desulfurization additives,intermediates for preparing oxalic acid, and feed additives. However, there are somedrawbacks related to the current methods, such as cost-in effective, severeenvironmental pollution, and the bottleneck of the throughout. The pathway for theformulation of calcium formate by calcium hydroxide shows the advantage withrespect to economy and environment protection.In this paper, the synthesis of calcium formte by calcium hydroxide reaction in ahigh-pressure stirred tank was conducted as a semi-continuous way. Through theanalysis of reaction thermodynamics and the product analysis by XRD, it isdemonstrated that the reaction mechanism is that carbon monoxide firstly reacts withwater to produce formic acid, which reacts with the dissolved calcium hydroxide toform calcium formate. At the same time, the water-gas shift reaction takes placeassociated with the main reaction to generate carbon dioxide, which could beneglected during the study of the kinetics due to the relatively less amount.In order to calculate the yield and convert ratio of the reaction, a simple methodwas set up to detect the concentration of the formate ion. The effects of stirring speed,the initial calcium hydroxide concentration, temperature, pressure and solutionvolume on the yield of calcium formate have been investigated, from which thesuitable operating parameters are determined i.e. stirring speed of1000rpm, initialconcentration of calcium hydroxide of0.097g/mL, pressure of2.0~3.0MPa andtemperature of423~463K.The kinetics of the calcium hydroxide carbonylation was studied in ahigh-pressure stirred tank operated as semi-continuous way. The mathematical modelis developed based on the duel-film theory and the parameters of the kinetics areregressed based on the experimental data. The deviations of reaction rate obtained bythe kinetics from the experimental result are within10%, which validated theeffectiveness of the established kinetics. Furthermore, the obtained kinetics forcalcium formate production can lay a solid foundation for industrial application.