Thermal and photocatalytic cascade one-pot synthesis of secondary amine using multifunctional Pd decorated MOF-derived CeO2

Abstract

The use of a single catalyst to perform thermal and photochemical N-alkylation of amine is challenging work. Herein, Pd decorated MOF-derived CeO₂ was prepared for the cascade one-pot synthesis of secondary amine by thermal and photocatalytic routes. Among the designed catalysts, Pd(0.5%)/CeO₂-300 exhibited the best activity for thermal and photocatalytic one-pot secondary amine synthesis involving benzyl alcohol and aniline. The physicochemical characteristics of Pd(0.5%)/CeO₂-300 suited for the oxidation of benzyl alcohol followed by condensation with aniline to form an imine. Further, reduction of imine over Pd NPs decorated on CeO₂-300 took place to form secondary amine. An excellent conversion of benzyl alcohol and secondary amine selectivity was observed thermally at 100 °C in 26 h. The Pd(0.5%)/CeO₂-300 exhibited excellent activity in white LED. Interestingly, more activity was achieved in sunlight. The Pd(0.5%)/CeO₂-300 demonstrated excellent stability under thermal and photocatalytic conditions and was recycled 5 times without losing any significant activity. The surface area, acidity, and elemental compositions were characterized by various physicochemical techniques. The light absorption property, bandgap, charge carrier separation, and photocurrent measurements were carried out by photoelectrochemical and optoelectronic analysis. The reaction mechanism and structural activity relationship correlated with control experiments, catalytic activity data, physicochemical, and optoelectronic characterization. One catalyst affording efficient activity in conventional thermal and photocatalytic conditions, especially sunlight, would be exciting to researchers and industrial practitioners.

Keywords: Cascade one-pot synthesis; CeO(2); MOF-derived metal oxide; Photocatalysis; Secondary amine.