Continuous synthesis of 2,2,6,6-tetramethyl-4-piperidinol over CuCrSr/Al2O3: effect of Sr promoter

Abstract

A continuous process was developed for catalytic hydrogenation of triacetoneamine (TAA) to 2,2,6,6-tetramethyl-4-piperidinol (TMP), both of which are indispensable raw materials of hindered amine light stabilizers. A series of promoter-modified CuCr/Al₂O₃ catalysts were prepared by co-precipitation method and evaluated by the above reaction. The effect of promoter on the catalytic performance was explored by characterization tools, in which, CuCrSr/Al₂O₃ exhibited excellent catalytic performance with nearly complete conversion of TAA and over 97% selectivity of TMP at 120 °C. The characterization results indicated that the doped Sr could decrease the size of Cu nanoparticles to provide more active sites, improve the ratio of Cu⁺/Cu⁰ to promote the adsorption of substrates, and reduce the surface acidity to depress side reactions, thus remarkably enhancing catalytic performance. This work provides a low-cost, reliable and efficient strategy for the continuous industrial production of TMP.