14 - Acrylic Acid

Abstract

The case study deals with the conceptual design of a sustainable process for acrylic acid production, starting from glycerol. The renewable feedstock is available today in large amounts and at low cost from biodiesel manufacturing. The chemistry considers two steps: dehydration of glycerol to acrolein and further oxidation of acrolein to acrylic acid. The central problem is finding an active but robust catalyst for glycerol dehydration. Heteropoly acids (HPA) and zeolites catalysts have interesting performance, but a regeneration method must be included in the reactor design. The study examines three alternatives: bubbling fluidized bed, circulating turbulent fluidized bed, and circulating fluidized bed. The first two are suitable for lower and moderate activity catalyst, as HPA, the last for very fast zeolite catalysts. Two alternatives for separating the acrylic acid–acetic acid–water mixture are developed, using azeotropic distillation and liquid–liquid extraction. The exothermal oxidation reaction gives good opportunities for energy saving by heat integration. The capital costs are dominated by the reactors. The sustainability analysis indicates that manufacturing acrylic acid from glycerol is a viable green alternative to the petrochemical process.