Mass transfer effects in the H2SO4 catalyzed pivalic acid synthesis

Abstract

The synthesis of carboxylic acids from alkenes, carbon monoxide and water according to the Koch process is usually carried out in a stirred gas-liquid-liquid multiphase reactor. Due to the complex reaction system with fast, equilibrium reactions and fast, irreversible reactions the yield and product distribution depend on a number of process parameters. The effect of some of these parameters was studied for the production of pivalic acid, using sulfuric acid as a catalyst. For the 96 wt.% sulfuric acid catalyst solution used the main reactions are relatively fast with respect to mass transfer and mixing. Therefore, aspects like the position of the injection point, inlet concentration, agitation intensity and injection rate all influence the yield obtained. The presence of an inert organic liquid phase was found to be beneficial, due to a combined effect of enhanced gas-liquid mass transfer and a 'local supply' effect for carbon monoxide near the hydrocarbon reactant inlet.

Gas-liquid-liquid reactions: Contacting mechanisms and effective process technologies

“…Brilman et al [37] also studied the synthesis of pivalic acid/carboxylic acid using other reactants comprising CO gas, iso-butene, tert-butanol, catalyst solution and heptane, as a second immiscible liquid. This was carried out under pressure (40 bars) in an autoclave reactor for 1 hour using an acid catalyst H2SO4 96 wt%.…”

“…A stirred tank reactor is well adapted to this scenario. The recommended impeller type for such an operation would be a disc turbine or pitched blade turbine since these are effective for bubble and drop generation (see for example the synthesis of pivalic acid [37]), as well as for global mixing of the system. Gas should be fed into the system through a ring or plate sparger.…”

Hydroesterification of tert-butyl alcohol in room temperature ionic liquids

“…2,3 The amount of acid medium used for the reaction is usually equal or even greater than that of iso-butylene or tert-butyl alcohol, resulting in serious corrosion of equipment, difficulties in product separation and formation of a large amount of acidic waste water. 4 Catalytic processes that involved using Cu þ , Ag þ and Pd 2þ as catalysts were conducted under relatively moderate reaction conditions, 5 but strong inorganic liquid acid medium was also inevitably employed and the above disadvantages still remained. In view of the increasing emphasis on the adoption of clean manufacturing processes, environmentally benign, simple and efficient catalytic technologies for chemical production are highly desirable.…”