Selective Hydrogenation of Ethyl Lactate to 1,2-Propanediol over the La-doped Co-B Amorphous Catalyst

The La-doped Co-B amorphous alloy catalyst( Co-La-B) was prepared by the chemical reduction method for liquid phase hydrogenation of ethyl lactate to 1,2-propanediol( 1,2-PDO). The Co-La-B catalysts were characterized using X-ray diffraction( XRD),transmission electron microscopy( TEM),physical adsorption( BET),differential scanning calorimetry( DSC),inductively coupled plasma atomic emission spectrometry( ICP-AES),Xray photoelectron spectroscopy( XPS),hydrogen chemisorption and H2temperature-programmed desorption( H2-TPD). The effects of the La content on the hydrogenation of ethyl lactate were investigated. At a suitable La content,the Co-La-B amorphous alloy catalyst exhibited higher activity and selectivity than the Co-B catalyst in the hydrogenation. With the increase of La,the activity first increased and then decreased. The optimum theoretical La content was 0. 5%( mole ratio),at which the conversion of ethyl lactate could reach 99. 7% and the selectivity of1,2-propanediol could reach 98. 5%. The promoting effect of the La-dopant could be attributed to the dispersing effect that resulted in the higher thermal stability and appropriate particle size,unique Co active sites and electron transfer effect between Co and B.