Phosphorus and nitrogen-doped palladium nanomaterials support on coral-like carbon materials as the catalyst for semi-hydrogenation of phenylacetylene and mechanism study

In this work, two types of polyporous and coral-like materials (CN) with high specific surface area are prepared using sodium glutamate as a carrier. At the same time, a CN-supported phosphorus-nitrogen-doped palladium nanomaterial CN-P-Pd is synthesized and applied to the preparation of styrene by selective hydrogenation of phenylacetylene under mild conditions. As shown in the TEM images, Pd nano-particles with a particle size of about 4.4 nm are uniformly dispersed on the surface of the carrier. The results of N-2 adsorption-desorption reveal that the surface area of the prepared catalyst (CN-P-Pd) is 1307 m(2)g(-1). In addition, the experimental exploration shows the intervention of P in carbon-nitrogen materials can contribute to improve the selectivity of the reaction, which can be attributed to the fact that P element can change the electron density of Pd. Meanwhile, it is found that the solvent not only affects the activity of catalyst, but also the selectivity of the reaction. Kinetic study shows the activation energy of the reaction is 4.5 kJ/mol. With the increase of the reaction temperature, the dissolution rate of hydrogen in the solvent gradually slows down, which inhibits the progress of the reduction reaction. Mechanistic studies demonstrate that the carbon-nitrogen materials have strong adsorption capacity for substrates, and also provide more adsorption sites for phenylacetylene. Additionally, the optimal catalyst (CN-P-Pd) also has high reaction activity to other alkynes and the conversion can reach at 95%. Moreover, the optimal catalyst can be reused several times without significant reduction in reaction activity. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, two types of high specific surface area polyporous and coral-like materials were prepared using sodium glutamate as a carrier. A CN-supported phosphorus-nitrogen-doped palladium nanomaterial CN-P-Pd was synthesized and used in the selective hydrogenation of phenylacetylene to produce styrene. The intervention of phosphorus in carbon-nitrogen materials improved the reaction selectivity by changing the electron density of Pd. The optimal catalyst showed high activity for other alkynes and could be reused multiple times without significant loss in activity.