Study On Tert-Butyl Acetate Synthesis

The thermodynamics properties of acetic acid and isobutylene esterification to tert-butyl acetate (TBA) system were calculated and compared. The theory results were used to select of the optimal process conditions. According to the results, isobutylene in liquid phase and temperature range from 273.15 K to 373.15 K, the main reaction and side reactions are exothermic and spontaneous, low temperature is benefit for the main reaction. In this situation the main reaction Kp is far more than that under atmospheric. So it is necessary for the syetem to assure isobutylene to be liquid. Through selecting chromatographic column, searching for analytic conditions, investigating qualitative methods and determining calibration factors for products, the analytical method for TBA and sec-butyl acetate synthesis with acetic acid and isobutylene or 1-butylene gas phase chromatography was established.The effects of temperature, pressure, space velocity and acid to isobutylene ratio for acetic acid and isobutylene synthesis TBA on three strongly acidic resins as catalysts respectively were investigated. The results show that process conditions have less effect on the contents of dissolving isobutylene and tert-butanol in products, as well as isobutylene conversion. Pressure and space velocity have little influence on acetic acid conversion and TBA and isobutylene low polymers selectivities. Large acetic acid to isobutylene ratio is benefit for TBA and inhibits to isobutylene low polymers. Low temperature is favorable for esterification to TBA. As to the results, catalyst A10 is the best. The suitable process conditions for TBA synthesis system as follows:space velocity 4-5 h-1, acetic acid to isobutylene ratio 4-5:1, reaction temperature≤25℃, and must guarantee a liquid reaction system. In addition, the methods to reducing isobutylene low polymers were also explored, the results show that adding water or tert-butanol in acetic acid can suppress the low polymers production and improve TBA selectivity. Considering acetic acid conversion, isobutylene conversion, TBA selectivity, isobutylene low polymers selectivity, product separation and the operating cost, the method of adding water in acetic acsid is more feasible than that of adding tert-butanol in acetic acid, the suitable water amount in acetic acid is 0.5-1.5%.