Selective conversion of lactic acid into acrylic acid over hydroxyapatite catalysts

Lactic acid conversion into acrylic acid was carried out over Ca-HAP catalysts at 623 K. Stoichiometric Ca-HAP catalyst gave a high acrylic acid yield of about 60 C-%. Furthermore, non-stoichiometric calcium deficient Ca-HAP catalysts containing the specific amounts of sodium ions, which were prepared under hydrothermal conditions, exhibited remarkably high acrylic acid yields of about 80 C-%. In contrast, non-stoichiometric Ca-HAP catalysts with vacancy sites and Ca-HAP catalysts with excess amounts of sodium species showed relatively low acrylic acid yields and high selectivities into acetaldehyde and 2,3-pentanedione. (C) 2014 Elsevier B.V. All rights reserved.