An Introduction to the Combustion of Carbon Materials

Abstract

Combustion is arguably as old as homo sapiens ability to observe and use fire. Despite the long tradition of using carbon combustion for energy production, this reaction is still not fully understood. This can be related to several facts that are intertwined and complicate the investigation, such as the large variety of possible carbon structures, the actual surface structure, porosity, the solid-gas nature of this reaction, diffusion limitation and fundamental reaction steps. In this review, a brief history of carbon combustion science is given, followed by a detailed discussion of the most important aspects of carbon combustion. Special attention is given to limitations for example diffusion. In carbon combustion, kinetic control can rarely be observed. The literature of the fundamental reaction steps actually occurring on the carbon framework is reviewed and it becomes apparent that the reaction is occurring primarily on defects on the basal plane. Thus, the reaction between oxygen and carbon may be used as an analytical tool to provide further insights into novel materials, for example synthetic carbon materials, fibres and graphene type materials. Mastering the combustion reaction in all its complexity may prove to be very valuable in the future.

Burning Graphite Faster than Carbon Black: A Case of Diffusion Control

“…Carbon combustion reaction is a well‐known illustration, being of a solid–gas type. It is recognized for its complexity and diffusion limitation is a major concern [8,9] . To describe the impact of different diffusion processes on the apparent reaction rate, Walker and co‐workers summarized in their 1959 review paper, a model based on Wicke and Rossberg works, [10,11] to distinguish 5 different zones for the carbon combustion reaction (kinetic (I), internal (II) and external (III) diffusion and 2 transition regimes) which is still today widely used [12] .…”

“…Experimentally, only the global reaction rate can be measured and corresponds to the rate of the slowest chemical step (kinetic regime) or physical process (other regimes). Even if the carbon combustion reaction has sometimes been studied in the total diffusion limited (TD−L) regime (zone III, also called external diffusion regime), [12,13] it has caught less attention than the reaction in the regime I or II and intermediates [9] . While some applications for the use of selective internal diffusion exists, e.g.…”

Burn Them Right! Determining the Optimal Temperature for the Purification of Carbon Materials by Combustion

“…One central aspect of combustion is the possibility for the reaction to occur under diffusion regimes [13,14,30,31]. As for all solid-gas reactions, the gaseous reactant has to reach the solid surface by passing through a boundary layer, by diffusion.…”

“…In fact, stirring the material during the combustion reduces the diffusion limitations versus an immobile powder. While it has been shown over and over that the carbon combustion can easily suffer diffusional limitation [14], the use of "low" temperature, i.e., temperature close to the ignition temperature, favors the kinetic regime [13,31]. In the CRTA program, the temperature at which the apparatus will stabilize first (first isothermal step), depends on the choice of the criterion for the weight-loss rate.…”

Nanoarchitectonics of RGO‐Wrapped CNF/GO Aerogels with Controlled Pore Structures by PVA‐Assisted Freeze‐Casting Approach for Efficient Sound and Microwave Absorption**

“…As a typical 2D material, graphene oxide has a great potential as a novel aerogel with a low density, large specific surface area and desirable stiffness and elasticity. [8] It was reported that the microstructure of GO aerogel can be adjusted through various routes, such as CVD, freeze-casting, solution self-assembly and 3D printing. Among these methods, icetemplate method is widely applied due to its simple process, diversified materials and environmental friendliness.…”