Application Of Amorphous Co-B/γ-Al₂O₃ Catalyst In Liquid Phase Hydrogenation Of Ethyl Lactate To 1,2-propanediol

Bio-based organic acids and esters containing a plurality of reactive functional groups, is an important raw material for the production of chemicals. Facing with an increasingly serious energy crisis and environmental pollution problems, bio-based organic acids and esters have many advantages, such as the low price, the green production process. There is a tendency to gradually replace petroleum-based products, and its practical application is increasing. Lactic acid is one of important bio-based organic acid, and from renewable carbohydrate fermentation. With the mature fermentation and purification technology of lactic acid, its commercialization progress can be bright.Mainly used in the pharmaceutical, chemical industry chemical solvents and common reagents,1,2-PDO is widely used, has a huge demand every year. The production of 1,2-PDO from selective hydrogenation of lactic acid and its derivatives, provides a green, economical and environmentally friendly non-petrochemical production line. This eased the dependence on propylene oxide which is raw material of the 1,2-PDO traditional production process, and environmental pollution generated in the production and refining process. This is in line with the requirements of the green and sustainable development strategy. Ethyl lactate can be producted by esterification of lactic acid. Its sources are rich, and its hydrogenation reaction is easy. Therefore, preparation of 1,2-PDO from catalytic hydrogenation of ethyl lactate is of great significance.In the paper loading modified Co-B/7-Al2O3 amorphous alloy catalysts were prepared for selective hydrogenation of ethyl lactate production and 1,2-PDO reaction. The prepared catalysts were characterized by ICP, XRD, TEM, SAED, DSC, XPS and other means to determinant the composition, structure and chemical nature of the catalysts. The effects of preparation conditions of Co-B/γ-Al2O3 catalysts and reaction conditions on the hydrogenation of ethyl lactate were examined.The results showed that, γ-Al2O3 as the best carrier to determine the Co-B/γ-Al2O3 catalysts. Co-B/γ-Al2O3 catalysts prepared by impregnation-chemical reduction method show excellent catalytic performance. The most appropriate solution pioneer Co ion concentration is 0.2 mol/L.All the fresh catalysts showed an amorphous structure and Co-B particles are dispersed uniformly on γ-Al2O3 support. The thermal stability of the amorphous catalyst and Co/B atomic ratio of surface composition increased with increasing Co content. The optimum reaction conditions for the Co-B/γ-Al2O3 amorphous catalyst lactate hydrogenation reaction of 1,2-PDO:metal Co loading of 30%(mass fraction, w), n-heptane as solvent, catalyst dosage of 0.25 g, the reaction temperature of 160℃, a hydrogen pressure of 6 MPa, reaction time of 9 h. Under the optimum preparation and reaction conditions, The Co-B/γ-Al2O3 amorphous catalyst showed the highest catalytic activity, the ethyl lactate turnover frequency (TOF), conversion and the selectivity, yield to 1,2-PDO reached 1.41 h-1,93.63% and of 96.10%,89.98%, respectively. The higher catalytic performance of 30%(w) Co-B/γ-Al2O3 supported amorphous catalyst is attributed to its highly dispersing Co-B particles, the higher Co/B atomic ratio of surface composition and electronic effect between Co and B.