Maintenance of a Highly Active Solid Acid Catalyst in Sugar Beet Molasses for Levulinic Acid Production

A strongly acidic cation exchange resin (Amberlyst-36™) was used as a heterogeneous acid catalyst in a sugar beet molasses solution for levulinic acid production. The solid acid catalyst was quickly deactivated during the reaction, in a large portion due to the non-sugar components (cations, proteins and alkaline compounds) in sugar beet molasses. In order to keep the catalyst active for reuse, the sugar beet molasses solution was pretreated in a column packed with the resin pellets for selective removal of the impurities that might cause the deactivation. The ion-exchange solution not only gave a high levulinic acid yield, but also maintained the heterogeneous catalyst active for repeated reuse under the reaction conditions. The saturated resin pellets discharged from the ion-exchange pretreatment could be conveniently regenerated under ambient conditions. In contrast, the catalyst deactivated in the reaction had to be regenerated in harsh conditions involving re-sulfonation, in which the catalyst had a gradual permanent activity loss in repeated regenerations. The ion-exchange pretreatment of sugar beet molasses solution can therefore maintain a high catalytic activity of Amberlyst-36™ and reduce the cost of the solid catalyst in levulinic acid production.