(254c) Catalytic Conversion of Bioresource to Graphene-Based Materials

Graphene is a bidimensional material with one atomic layer as thickness. Graphene sheets are highly organized in graphitic structure or randomly oriented in turbostratic structure, leading to the formation of carbon nanotubes, carbon fibers, carbon black. Depending on the characteristics such as the length and the orientation of the graphene sheets, various properties could be developed: electrical conductivity, mechanical or thermal resistance. Therefore, graphene is considered as a high-performance material, in applications such as batteries, energy storage, electronics, and biology. Currently, materials are produced from petroleum-based industries (exfoliation or chemical vapor deposition) leading to a high negative environmental impact.

Graphene production from carbon resources requires the progressive organization of carbon atoms into fused benzene rings (namely basic structural units), then the coalescence for larger graphene sheets over 2000°C. Their organization (graphitic, turbostratic) will impact the final properties of the designed material. Aromatization and coalescence phenomena are strongly related to the original feedstock, and resources are sorted into graphitizable and non-graphitizable materials.

The aim is to use bioresources (biomass polymers), non-graphitizable carbons, to enhance the quantity and the quality of graphenic domains during catalytic pyrolysis up to 1800°C. For this purpose, the catalysts are more likely selected among inherent biomass minerals providing a green approach for graphene synthesis.

This study investigates the impact of catalyst on the evolution of the graphenic structure, texture and nanotexture in biochars. Graphitization experiments have been carried out in a high-temperature furnace (1800°C) with raw materials (lignin or cellulose) either impregnated or not with Ca or P catalysts. The remaining biochar was characterized to evaluate the quality of graphitization using combined techniques: HRTEM, Raman Spectroscopy and XRD. The impregnation of raw materials significantly improved the graphitization parameters such as length of basal sheets, stacking and significantly reduced the amount of amorphous carbon.