Hydrolysis of Sucrose over Sulfonic Acid Resins

Abstract

Sucrose hydrolysis on acidic ion‐exchange resins is a long‐established process in the sugar industry, but the formation of side products is less understood. A resin typically used in the industrial process (C124SH, Purolite) was investigated in a broad range of sucrose concentration (7 to 75\u2009% w/w) and temperatures from 25 to 80\u2009°C. Fructose is converted to 5‐hydroxymethylfurfural (HMF) due to a 1/2 order reaction. This is explained by the formation of a fructose disaccharide (monoanhydride) as an intermediate decomposing to HMF and fructose. Difructose dianhydrides (DFAs) are separately formed as prevailing by‐products. The color of the product mixture is correlated to HMF and found to be reduced by size exclusion inside the resins. Diffusional limitations of the total reaction are investigated by comparison of the entire resin bead with its size‐reduced forms obtained by milling. Without diffusion limitation the catalytic activity increases with the sugar concentration while the diffusion control leads to a maximal activity around 40\u2009% w/w sugar. Diffusion coefficients of sucrose are calculated.