Efficiently Catalytic Synthesis Of Acetaldehyde And Propionic Acid From Bio-lactic Acid

Under the guidance of green chemistry and sustainable development concept,this paper uses bio-based lactic acid as raw material,and under certain conditions,reacts with catalyst to prepare acetaldehyde and propionic acid respectively through decarbonylation and deoxidation.The preparation method,catalyst structure,surface properties and catalytic activity of the catalyst were systematically studied,which provided a theoretical basis for the preparation of acetaldehyde and propionic acid.According to the characteristics of lactic acid decarbonylation,the preparation and process conditions of the corresponding catalysts were designed in detail.The catalyst for decarbonylation of lactic acid to prepare acetaldehyde was carried out with ammonia-modified CePO₄,and a series of preparation conditions and optimization of process conditions during the reaction were carried out by a controlled variable method.It was found by characterization that the yttrium phosphate prepared by any of the precursors has a crystal form of CePO₄?JCPDS NO.83-0650?.Finally,the CePO₄ was adjusted with ammonia water.It was found that the catalyst obtained by using CePO₄ prepared by using ammonia water as the precursor of Na4P2O7enhanced the reactivity of decarbonylation of lactic acid,while the others remained unchanged or even decreased slightly.Stability experiments show that the catalyst has long-lasting stability and can be regenerated after calcination in an air atmosphere.Deoxidation of lactic acid to produce propionic acid is carried out by a synergistic reaction of MoO₃ dispersed by a dispersant and a Mo-Fe catalyst.For the former,different dispersants exhibit different properties.Under the influence of N element in the dispersant,MoO₃ in the in-situ hydrogen atmosphere is quickly reduced to MoO₂,and MoO₂ plays an important role in the catalytic conversion of propionic acid by lactic acid.Experiments have shown that propionic acid is directly formed by lactic acid as the main route,and hydrogenation of acrylic acid obtained by conversion of lactic acid is a secondary route.The catalysts have good catalytic activity,strong regeneration performance,and can be separated and purified to obtain98%natural bio-propionic acid.For the latter,a Mo-Fe catalyst was designed,which has the characteristics of Fe-based and Mo-based catalysts,and has excellent activity and stability.It has been found through experiments that the hydrogen required for the reaction process can be completely reformed from lactic acid vapor.