Liquid Phase Aldol Condensation Of Formaldehyde And Isobutyraldehyde Over Solid Base Catalysts

Neopentyl glycol is an important chemical intermediate in the manufacture of various synthetic resins, alkyd resins, polycarbonate resins, plasticizers, adhesives and synthetic lubricants, which was synthesized from formaldehyde and isobutyraldehyde. There are two main industrial production technologies:(1) Cannizzaro technology:in the presence of strong bases such as NaOH, formaldehyde and isobutyraldehyde occurred aldol condensation, then followed by Cannizzaro reaction; (2) Aldol condensation followed by hydrogenation technology:the condensation of formaldehyde and isobutyraldehyde is carried out in the presence of weak bases such as tertiary amines, then the aldol product hydrogenates on catalyst.In this work, we want to prepare a metal/solid base bifunctional catalyst by loading hydrogenation active metal on a solid base which can catalyze the aldol-condensation of formaldehyde and isobutyraldehyde and the following hydrogenation of aldol adduct in a single-reactor. The study of this paper includes two parts:1. Synthesized different solid base catalysts, such as hydroxyapatite, Mg-Al hydrotalcite, Mg-Zr oxide and evaluated their catalytic activity. We focused on the aldol condensation of formaldehyde and isobutyraldehyde over reconstructed hydrotalcite and Mg-Zr oxide catalysts, investigated the effect of feed ratio, solvent, phase transfer catalyst and other factors on the aldolization. Mg-Zr oxide exhibited excellent catalytic activity, comparable to tertiary amine and better than anion exchange resin with 95%conversion and 92% yield.2. Different characterization techniques, including XRD, BET, ICP, CO2-TPD, CO2-DRIFTS and XPS were used to characterize the structure and surface properties of Mg-Zr oxide catalysts, which made a better understanding of the aldol condensation mechanism on the solid base catalysts and lay a foundation for bifunctional catalyst synthesis and hydrogenation reaction.