Hydrocarbon pyrolysis with a methane focus: A review on the catalytic effect and the coke production

Abstract

Hydrocarbon pyrolysis has been widely studied since the 1900's for applications in aerospace as a fuel and/or coolant or for use with fuel cells and hydrogen production with a catalyst. In this context, the role of heterogeneous reactions with homogeneous phase chemistry is unclear despite the fact that it is obviously at the heart of coupled physico-chemical phenomena. In addition, the thermal formation of solid carbon particles-coke, which can be deposited on the structure, impacts the heterogeneous reactions. The aim of this work is to review the available literature on hydrocarbon pyrolysis involving reactions with solid surfaces and coke particles. The influent parameters such as the nature of the fluid, the temperature (up to 2000 K), the pressure (up to 100 bars), the residence time (µs order to min order), the reactor type (plug flow, batch, perfectly stirred reactor) and the type of catalyst (inert, metallic or more complex such as zeolites) are discussed. Then, a link between catalicity and coke production is addressed. This literature survey focuses in particular on methane because of the growing interest regarding the potential for hypersonic applications.

Evaluation of heat sink capability and deposition propensity of supercritical endothermic fuels in a minichannel

“…A chemical heat sink is produced after the thermal decomposition, and it may yield a gaseous product at bulk fluid temperatures above 500°C [12][13][14][15]. In these tests, the gaseous products at steady state were measured at room temperature, and the atmospheric pressure by weight of the liquid products was deducted from the total fuel fed into the system.…”

“…During pyrolysis of hydrocarbons, solid particles with high carbon content are produced and deposited on the inner surface of the test channel, which is called coking [15]. For the non-passivated nickel alloy tubing used in this study, catalytic coke growth on the wall can also occur [2].…”

“…The endothermic degradation of the fuel acted as a heat sink. In parallel, the thermal decomposition produced heavy aromatic compounds which could lead to the formation of coke deposits on the reactor surface [15].…”

“…It is a big challenge to find an endothermic fuel that can improve heat sink capability with limited coking to deal with the high heat flux and surface temperature in the supersonic combustion chamber. Many investigations of endothermic fuel have been conducted since 1990, including studies on heat sink measurement [5,6], heat transfer and coking behavior [7,8], the factors that influence pyrolysis and coking [4,[9][10][11][12][13][14][15], fluid flow instability and heat transfer [16], the hydraulic effect and thermal effect caused by coking [17] and the thermal physical properties of fuels [18][19][20][21].…”

Prediction of transient chemistry effect during fuel pyrolysis on the pressure drop through porous material using artificial neural networks

“…These reactions can be due to the thermal fluid decomposition and to the degradation of the material itself. The degree of decomposition is highly dependent on the operating conditions (temperature, pressure, type of flow, nature of reactor) [10,[12][13][14][15]. Thermal cracking of hydrocarbons have been widely studied in petrochemical industry [16][17][18][19][20] and in the context of chemical vapor infiltration for the preparation of carbon/carbon composites [21][22][23][24][25].…”