Preparation Of Amorphous Co-La-B Catalyst And Its Catalytic Performance In Liquid Phase Hydrogenation Of Ethyl Lactate To 1,2-propanediol

1,2-propanediol(1,2-PDO) is a widely used chemical product, it can be used in pharmaceuticals, cosmetics and food production. For example, it can be used as the solvent of unsaturated polyester resin, the precursor of polyether, the antifreeze an solvent in food processing and softener in the skin care products, and can also be used as de-icing fluid and tablets excipient. The traditional production of 1,2-propanediol is mainly through the oxidation and hydration of the propylene from the fossil raw material, this process involves a hydrogen peroxide chemical process and a chloride ethanol process of hypochlorous acid.However, with the impact of rising prices of fossil raw material and serious global warming resulted from the greenhouse effect, the biomass-derived platform molecule as the raw material will get more attention of the society.Lactic acid(LA), also known as 2-hydroxy acid, mainly generated by the fermentation of carbohydrates, such as glucose, maltose, sucrose, lactose and the like. In addition, the emergence of modern membrane separation and purification technology,especially the micro(ultra) filtration and electrodialysis made not only low-cost production of lactic acid into a reality, but also avoid the process-related environmental issues resulted from traditional production of lactic acid, and therefore the rapid growth of annual output lactic acid make it a high potential platform molecule derived from biomass molecules.Therefore, the direct hydrogenation of lactic acid or lactate to the 1,2-propanediol become an green and environmental protection route alternative to petroleum-based production.Because the activity of carbonyl group in the the acid is lower than the corresponding esters and it may generate other esters with side reactions, the direct hydrogenation of lactate to the 1,2-propanediol would possess more development prospects.A series of metal additives(La, Ni, W, Mo, Cu, Fe, Zn) doped Co-B amorphous alloy catalysts were prepared by chemical reduction with NaBH4 in this text. The effect of the amount of La in Co-B catalysts on catalyst behevier in selective hydrogenation of lactate to1,2-propanediol was investigated, and the catalyst samples were characterized by XRD,TEM, DSC, BET, ICP, XPS, H2-TPD, etc.The results showed that the active ingredient Co exists in elemental and oxidized state respectively in the Co-La-B amorphous alloy catalysts, and there is a electron shift from B to Co which is electron-rich and is beneficial to activate hydrogen. However, the additive La exists in only oxidized state, and La3+not only promote the electron transfer in Co-B alloy, but also contribute to the C=O group activation in the ethyl lactate, thus make it easier to adsorb activated hydrogen. An appropriate amount of La doping can significantlyreduce the particle size of the catalyst and improve the particle dispersion and thermal stability of the catalyst. There exists more uniform Co active sites in 0.5%Co-La-B catalyst,which increased opportunities for ethyl lactate contact with the Co active sites on the surface of catalyst. The hydrogenation results shows that hydrogenation of ethyl lactate exhibits optimum catalytic properties on 0.2 g 0.5%Co-La-B catalyst in the n-heptane solvent under 433 K and 6 MPa after 9 h, while the ethyl lactate conversion of 99.7% and selectivity to 1,2-propanediol of 98.5% is obtained.