Plasma Pyrolysis of Methane to Hydrogen and Carbon Black

Abstract

The plasma-driven gas-phase thermal decomposition of methane yielding hydrogen and solid-phase carbon has been suggested as an environmentally friendly alternative to conventional methods of producing hydrogen from natural gas. The advantage of the process is that hydrogen is obtained directly from methane without producing CO2 as a byproduct. The process was experimentally examined using a modified version of a dc plasma reactor originally developed for the conversion of methane to acetylene. Carbon yields of 30%, a factor of 6 increase, with a corresponding decrease in acetylene yield were obtained by simply increasing the residence or reaction time. A detailed kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons through benzene is described. A model for solid carbon nucleation and growth is included. The model is compared to experimental results and is used to examine process optimization.

Production of hydrogen and carbon black by methane decomposition using DC-RF hybrid thermal plasmas

“…Recently, Fincke et al developed a kinetic model by employing simplified soot formation mechanism for the methane decomposition and carbon particle generation in dc thermal plasmas [9]. For the simulations of solid carbon nucleation and growth, it is assumed that primary soot particles are generated from benzene and increase their mass continuously via the adsorption of acetylene on their surfaces .…”

“…For this reason, a simplified approach is adopted in this simulation work for the convenience and for getting useful information with reasonable accuracy. This chemical kinetic model incorporated with the simplified soot formation mechanism is based on the semiempirical model of Lindstedt et al [22] and well discussed in the Fincke et al paper [9].…”

“…Recently, numerous studies have been conducted on the synthesis of carbon black and/or hydrogen, mainly focused on finding new technology of their production of the best quality and purity. Among the variety of such synthesis methods, thermal plasma technology has become popular in the materials and environmental industries because of its high performance and environmentally clean process [4]- [9]. Conventional processes for hydrogen and carbon black production are based on an incomplete combustion of natural gases or heavy oils, and subject to poor product yields, low price values, and high level emission of pollutants.…”

“…The dc thermal plasma process (carbon black and hydrogen process) for producing carbon black was developed and commercialized by Kvaerner Engineering Company [5], [6]. Fincke et al also demonstrated dc thermal plasma pyrolysis of methane into hydrogen and carbon black by introducing specially designed reactor geometries for providing supersonic expansion of thermal plasma jet through a converging-diverging nozzle to increase its quenching effect on the synthesized product [9]. Furthermore, effects of operation parameters, such as temperature, pressure, and residence time of the process gases, are investigated through detailed chemical reaction simulations to optimize processing conditions and to maximize the yield of carbon products.…”

“…It is generally known that the reaction temperature and residence time play a crucial role in determining product yields and synthesis qualities like surface morphologies. In the work by Fincke et al [9], the optimization of process was accomplished simply by increasing residence or reaction time by adopting longer reactor geometries. Fulcheri et al have intensively investigated the relationships between reaction temperature and texture of carbon blacks [15], [16], and finally concluded that higher temperature and longer reaction time in the process results in highly developed graphitic structures at the surface of carbon particles.…”