Efficient acrylic acid production through bio lactic acid dehydration over NaY zeolite modified by alkali phosphates

Alkali phosphates-modified NaY zeolites were developed as catalysts for efficient conversion of lactic acid to acrylic acid. The catalytic performance was optimized in terms of the type and loading of alkali phosphates, reaction temperature, liquid hourly space velocity, and lactic acid concentration. A high acrylic acid yield of 58.4% was achieved at 340 °C over 14 wt % Na ₂HPO₄/NaY. The physicochemical properties of the catalysts were investigated by various techniques including NH₃-TPD, pyridine adsorption-FTIR, Raman, and MAS ³¹P NMR. Introduction of alkali phosphates to NaY zeolite results in a decline of surface acidity. The results of FTIR, Raman, and MAS ³¹P NMR investigations on the fresh and used catalysts suggest that sodium phosphate is largely transformed to sodium lactate during the reaction. The phosphates and the in situ generated sodium lactate function as highly active species for the target reaction.