Palladium Nanoparticles Anchored on COFs Prepared by Simple Calcination for Phenol Hydrogenation

Abstract

Covalent organic frameworks (COFs) used as supports for metal nanoparticles (MNPs) show high efficiency in heterogeneous catalysis. Developing a green and efficient way to synthesize COFs remains a great challenge. Herein, an imine COF (TpPa-1) was prepared via a green and convenient calcination method under low temperature, and then Pd nanoparticles (NPs) were loaded to prepare Pd@COFs catalysts for the selective phenol hydrogenation to cyclohexanone. XRD and FTIR results confirm the successful synthesis of TpPa-1 by a simple calcination method. A suitable calcination temperature (280 °C) is conducive to the synthesis of TpPa-1 (COF-280) with higher crystallinity, larger BET surface area, higher mesoporous proportion, and uniform spherical morphology. These characteristics of COF-280 increase the Pd loading, promote the formation of Pd with higher Pd0 proportion on the catalyst surface, and enhance the mass transfer, thereby improving the catalytic properties of Pd@COF-280 for the phenol hydrogenation, with a catalytic activity increased by 2 times compared to Pd@COF-220. The addition of p-toluenesulfonamide during the synthesis can affect the crystallinity and morphology of TpPa-1 and the corresponding catalytic performance. Furthermore, Pd@COF-280 shows good reusability during four reaction cycles. The work provides a green approach for preparing imine-COFs and their efficient applications in heterogeneous catalysis.

Hierarchical Pd@PC-COFs as Efficient Catalysts for Phenol Hydrogenation

“…However, the use of raw materials (1,3,5-triformylphloroglucinol, p -phenylenediamine) with very high price limited its application. Very recently, TpPa-1 was prepared by a simple calcination method in our group, and the as-prepared Pd@COF-280-9 catalyst showed good catalytic performance, with a cyclohexanone selectivity of 99.1% and a phenol conversion of 95.3% under mild reaction conditions (90 °C, H 2 1 bar) . Unfortunately, the catalytic activity of Pd@COF-280-9 slightly decreased during four reaction cycles due to the leaching of Pd and the increase in the Pd size.…”

“…Very recently, TpPa-1 was prepared by a simple calcination method in our group, and the as-prepared Pd@COF-280-9 catalyst showed good catalytic performance, with a cyclohexanone selectivity of 99.1% and a phenol conversion of 95.3% under mild reaction conditions (90 °C, H 2 1 bar). 47 Unfortunately, the catalytic activity of Pd@COF-280-9 slightly decreased during four reaction cycles due to the leaching of Pd and the increase in the Pd size. In addition, the addition of p-toluenesulfonamide during the synthesis of TpPa-1 for improving the crystallinity increased the cost.…”

Activation of Carbonyl Groups via Weak Interactions in Pt/COF/SiO2 Catalyzed Selective Hydrogenation

“…Recently, covalent organic frameworks (COFs) have been used as crystalline porous polymers to support metal NPs in hydrogenation reactions. , COFs with a high Brunauer–Emmett–Teller (BET) surface area can stabilize ultrafine metal NPs even with high metal loading . Furthermore, the π–π interactions in COFs can improve the activity of Pd NPs in the selective hydrogenation of polar aromatic compounds; however, the synergistic catalysis of COFs and metal NPs has been rarely reported.…”

Covalent organic framework supported palladium catalysts

“…The catalytic activity of Pd@COF-280, as the best catalyst investigated at a hydrogen pressure of 0.1 MPa and a reaction temperature of 80 °C, showed excellent conversion and selectivity for the hydrogenation of phenol to cyclohexanone. 36…”