Prominent Roles of Impurities in Ionic Liquid for Catalytic Conversion of Carbohydrates

Impurities present in commercially available ionic liquids display prominent catalytic functions toward carbohydrate conversion. Little conversion was observed at 180 °C with high purity [EMIM]Cl ionic liquid whereas significant conversion was observed for ionic liquids of lower purity levels. Addition of metal halides to high purity [EMIM]Cl catalyze cellulose conversion with drastically different product selectivities dependent on the metal ions. CuCl₂ is an active catalyst for hydrolyzing cellulose and further degrading the products. CrCl₂ is an active and a selective catalyst for the formation of 5-hydroxymethylfurfural (5-HMF). CrCl₂ also helps stabilize the 5-HMF product. FeCl₂ does not show catalytic activity. Metal impurities in ionic liquid correlate to the activities observed when similar metals were added to high purity ionic liquids.