Theoretical study of partial oxidation of methane by non-equilibrium oxygen plasma to produce hydrogen rich syngas

Modeling study of the partial oxidation of methane and methane-steam blend in a model flow reactor with given length in order to produce hydrogen rich syngas via activation of oxygen by specially arranged electric discharge is presented. It has been shown that the minor length of methane and methane-steam conversion into syngas is achieved at reduced electric field of 10 Td, when excited O-2(a(1)Delta(g)) and O-2(b(1)Sigma(+)(g)) molecules are preferably generated in a discharge. The major yield of syngas due to methane partial oxidation takes place at CH4/O-2 equivalence ratio phi= 3 and can be as large as 89%, whereas the greatest ratio of H-2 mole fraction to CO one in syngas can be achieved at phi = 4, when the yield of syngas is notably smaller similar to 69-76%. The addition of steam to methane delays the conversion process and does not allow increasing the syngas mole fraction and H-2/CO ratio significantly at the flow reactor exit. The estimates of energy efficiency of the process showed that the major value of energy returned on energy invested is achieved for the plasma-chemical approach based on methane partial oxidation or a combination of partial oxidation with steam conversion. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.