Selective hydrogenation of aromatic carboxylic acids over basic N-doped mesoporous carbon supported palladium catalysts

•Pd NPs are supported on MCN that is prepared via polymerization between ethylenediamine and carbon tetrachloride.•N-Pd interaction affords high dispersion and durability of Pd NPs.•MCN shows higher adsorption capacity for acid substrates than AC and NAC.•High N content (18.5 wt%) leads to negative charge of MCN and much higher activity in water.•Pd/MCN shows better performance for hydrogenation of acidic compounds than Pd/AC and Pd/NAC.

Mesoporous carbon nitride (MCN) has been prepared through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach. The obtained MCN possesses high surface area (166.3 m2/g), average pore size of 9.2 nm and high N content (up to 18.5 wt%). The negative charge and the basicity on MCN surface are originated from its rich carbon nitride heterocycles, which notably improves the surface hydrophilicity and the adsorption of acidic molecules. Furthermore, MCN can be adopted as the proper support for highly dispersed Pd NPs with well-controlled size distribution. Compared with microporous N-doped active carbon with low N-content, the MCN-supported Pd catalyst shows an enhanced activity in water phase for the selective ring hydrogenation of benzoic acid, benzamide and phenol, in which 11.3 times higher activity in comparison to undoped catalyst is achieved. Wide characterizations reveal that big pore size, selective adsorption for acid substrate and strong interaction between N and Pd may lead to the high activity of Pd/MCN.

Graphical abstractPd NPs are supported on MCN that is prepared via polymerization between ethylenediamine and carbon tetrachloride. The negative charge and the basicity on MCN surface are originated from its rich carbon nitride heterocycles. The negative charge contributes to strong N-Pd interaction and the basicity generates higher adsorption capacity for acid substrates, both of which may lead to its high activity for selective ring hydrogenation of aromatic compounds.Figure optionsDownload full-size imageDownload high-quality image (164 K)Download as PowerPoint slide