Nonstoichiometric calcium pyrophosphate: a highly efficient and selective catalyst for dehydration of lactic acid to acrylic acid

摘要: Calcium phosphate catalysts were prepared by co-precipitation method using calcium nitrate and mixtures of ammonium different sodium phosphates as precursors, respectively. Depending on the precursor, pH synthesis mixture changed during catalyst precipitation. The characterisation XRD ICP revealed formation a pyrophosphate structure with varying Ca/P ratio from 1.02 to 0.76 which could be correlated solutions. Vapour phase dehydration lactic acid acrylic was carried out these catalysts. Non-stoichiometric found most efficient among synthesized series 100% conversion 78% selectivity at 375 °C. higher for has been increased acidity reduced basicity non-stoichiometric compared other stoichiometric pyrophosphates. In situ FTIR studies showed amount lactate leading acid.