Nitrogen-Doped Graphene Monolith Catalysts for Oxidative Dehydrogenation of Propane.

Weijie Liu,Xingyu Lu,Fan Li,Xueya Dai,Wei Qi,Yunli Bai,Tianlong Cao

doi:10.3389/fchem.2021.759936

Abstract

It’s of paramount importance to develop renewable nanocarbon materials to replace conventional precious metal catalysts in alkane dehydrogenation reactions. Graphene-based materials with high surface area have great potential for light alkane dehydrogenation. However, the powder-like state of the graphene-based materials seriously limits their potential industrial applications. In the present work, a new synthetic route is designed to fabricate nitrogen-doped graphene-based monolith catalysts for oxidative dehydrogenation of propane. The synthetic strategy combines the hydrothermal-aerogel and the post thermo-treatment procedures with urea and graphene as precursors. The structural characterization and kinetic analysis show that the monolithic catalyst well maintains the structural advantages of graphene with relatively high surface area and excellent thermal stability. The homogeneous distributed nitrogen species can effectively improve the yield of propylene (5.3% vs. 1.9%) and lower the activation energy (62.6 kJ mol−1 vs. 80.1 kJ mol−1) in oxidative dehydrogenation of propane reaction comparing with un-doped graphene monolith. An optimized doping amount at 1:1 weight content of the graphene to urea precursors could exhibit the best catalytic performance. The present work paves the way for developing novel and efficient nitrogen-doped graphene monolithic catalysts for oxidative dehydrogenation reactions of propane.

Highlights

Propylene is one of the most important industrial building blocks, which can be used extensively to produce a variety of high value-added petrochemical products. (Sattler et al, 2014)
A certain amount of urea was highly dispersed into graphene oxide (GO) water dispersion under ultrasonic treatment, and a homogeneous suspension of GO and urea could be obtained, which was chemically stable in the few hours
The suspension was heated under high pressure via the hydrothermal treatment in which graphene oxide sheets were reduced and self-assembled through the strong π-conjugated and Van der Waals interactions between the functional groups to form a 3D graphene network with finely dispersed nitrogen element

Summary

INTRODUCTION

Propylene is one of the most important industrial building blocks, which can be used extensively to produce a variety of high value-added petrochemical products. (Sattler et al, 2014). Nano Carbon Catalyst materials are usually in the form of powder, which seriously limits their industrial applications in gas-phase heterogeneous catalysis due to the obvious pressure drop in the fixed-bed reactor and the difficulty in mass and heat transfer (Garcia-Bordeje et al, 2006; Liu et al, 2014). The nanocarbon materials usually have a decent catalytic activity with surface defects and oxygen-containing functional groups as catalytic activity sites comparing with the conventional metal-based industrial catalysts. Aiming at above scientific challenges, we fabricated a series of porous nitrogen doped graphene monolith catalyst (NG) with GO and urea as precursors through self-assembly and hydrothermal method. The as-prepared NG aerogel monolith catalyst exhibits excellent thermal stability and high catalytic performance in the oxidative dehydrogenation reaction of propane.

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT