Spinel copper–iron-oxide magnetic nanoparticles with cooperative Cu(i) and Cu(ii) sites for enhancing the catalytic transformation of 1, 2-propanediol to lactic acid under anaerobic conditions. Issue 23 (23rd October 2020) - Feng, Yonghai
Abstract : The synergy between Cu(i ) and Cu(ii ) sites in spinel CuFeO x magnetic nanoparticles contributes to the significant enhancement in catalytic 1, 2-propanediol transformation into lactic acid. Abstract : The aerobic catalytic oxidation of 1, 2-propanediol (PDO) over non-noble metal ( e.g. Cu) based catalysts usually suffers serious C3 product dissociation at high temperature, thus showing low lactic acid (LA) selectivity. Here, an alternative anaerobic catalysis strategy over spinel copper–iron-oxide magnetic nanoparticles (CuFeO x MNs) with the coexistence of Cu(i ) and Cu(ii ) dual sites is developed for the catalytic transformation of PDO to LA with a quantitative yield of co-product H2 in basic aqueous solution. The absence of O2 is beneficial for enhancing LA production in comparison with the presence of O2 . The synergy between Cu(i ) and Cu(ii ) sites in CuFeO x MNs is vital for improving the catalytic performance as compared to Cu2 O or CuO catalysts with Cu(i ) or Cu(ii ) sites alone. Cu1 Fe1 O x MNs with a Cu/Fe mole ratio of 1/1 exhibit 94.5% LA selectivity and 72.6% PDO conversion at 160 °C for 8 h. Experimental results and DFT calculations suggest that the spinel CuFeO x MN based catalytic PDO transformation follows a favorable pathway of PDO → hydroxyacetone → lactaldehyde → lactic acid for LA production. In addition to the catalytic PDO transformation, the use of CuFeO x MNs can be extended to favor high activity and selectivity in the catalytic transformation of glycerol to LA (98.5% selectivity) and ethylene glycol to glyceric acid (97.8% selectivity). This work highlights the design of an alternative non-noble metal-based CuFeO x MN catalyst for efficiently catalyzing the transformation of bio-based polyols into value-added carboxylic acids.