Premium
Ordered Mesoporous Carbon Nitrides with Tuneable Nitrogen Contents and Basicity for Knoevenagel Condensation
Author(s) -
Ruban Sujanya Maria,
Sathish C. I.,
Ramadass Kavitha,
Joseph Stalin,
Kim Sungho,
Dasireddy Venkata D. B. C.,
Young Kim In,
AlMuhtaseb Ala'a H.,
Sugi Yoshihiro,
Vinu Ajayan
Publication year - 2021
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.202001434
Subject(s) - knoevenagel condensation , catalysis , malononitrile , mesoporous material , chemistry , calcination , triazine , carbon fibers , organic chemistry , inorganic chemistry , polymer chemistry , materials science , composite number , composite material
We report on the preparation of ordered mesoporous carbon nitrides (MCN) with a 3D porous structure, tuneable nitrogen contents and basicity and their basic catalytic activities on the Knoevenagel condensation of benzaldehyde with malononitrile. The chemical structure and the nitrogen contents of the materials are finely tuned with the simple adjustment of the calcination temperature from 350 to 550 °C. The samples prepared at 350 and 400 °C exhibit C 3 N 5 structures with 1‐amino/imino‐1,2,4‐triazole moieties, whereas the samples synthesised at 450, 500, and 550 °C possess C 3 N 4 structures with 2‐amino/imino‐1,3,5‐triazine moieties. The materials prepared at the temperature lower than 400 °C show much higher activity than those of the samples prepared at 450, 500 and 550 °C. The change in the catalytic activities of these materials is linked with the change of the structure, nitrogen contents and the functional groups on the surface of the materials prepared at different temperatures. CO 2 temperature programme desorption study reveals that 1‐amino/imino‐1,2,4‐triazole moieties in C 3 N 5 samples provide high basicity due to the strain in 5‐membered 1,2,4‐triazole rings; however, the samples with 1,3,5‐triazine moieties have limited basicity which significantly affects the catalytic activity of the material. The optimised C 3 N 5 catalyst shows an enhanced catalytic activity when compared to other mesoporous basic catalysts and C 3 N 4 . It is also found that the optimised catalysts are highly stable and can be recycled several times and no major change in the activity is observed.