Efficient production of acrylic acid by dehydration of lactic acid over BaSO4 with crystal defects

Abstract

BaSO₄ catalysts with different micromorphologies and crystal texture were prepared and used to investigate the structure–activity relationship in the dehydration reaction of lactic acid (LA) to acrylic acid (AA). SEM and N₂ physisorption were used to study the micromorphology. XRD and photoluminescence spectra were employed to analyze the crystal texture of samples prepared with different methods and treatments. The results revealed that BaSO₄ with smaller crystals and more defects had higher activity and selectivity to AA. It was likely that the crystal defects provided the active acid sites for dehydration of LA to AA, as evidenced by XPS and NH₃-TPD measurements. Using ethanol as the solvent and ultrasound treatment during the preparation of BaSO₄, imperfect small crystals with more defects were formed, which increased the AA selectivity to 78.8%.