Hydrogenation of vanillin to vanillyl alcohol over Pd/PDA/Ni foam in micropacked bed reactors

The micropacked bed reactor (mu PBR) with monolithic catalyst hydrogenation technology has received widespread attention due to its high efficiency, continuous operation, and safety. In this study, the Pd/PDA/foam catalyst was prepared via impregnation method and vanillin (VL) hydrogenation was investigated in green water solution based on the mu PBRs. The effect of operating temperature, pressure, the number of foam catalyst block, VL concentration, liquid and H2 flow rate on VL conversion and VA yield was discussed. The highest conversion of VL was 99.4 % and product yield of vanillyl alcohol (VA) reached 84.9 % with 2.8 MPa, 120 degrees C, 22 blocks of Pd/PDA/Ni foam catalyst, H2 flow rate of 10 mL min- 1 and liquid flow rate of 0.1 mL min- 1, and short reaction time (0.106 h) in mu PBRs. The kinetic of hydrogenation VL to VA was established. The reaction rate constant and activation energy in mu PBRs were from 0.63 to 1.39 min- 1 and 16.94 kJ center dot mol-1. The STY of VA in mu PBRs was 0.0824 kg center dot L-1 center dot h-1 center dot g-1, which was bigger than that of batch hydrogenation devices.