Partial Oxidation of Methane to Nitrogen Free Synthesis Gas Using Air as Oxidant

Abstract

In order to generate synthesis gas or hydrogen free from nitrogen by partial oxidation of methane using air as an oxidant, gas–solid reactions of methane and a metal oxide and/or mixed metal oxides were carried out. The background of the gas–solid reaction was briefly reviewed and then a series of the present author’s studies was described. As metal oxides Fe₂O₃ and NiO were active, but the reaction with methane and these oxides afforded complete oxidation to give H₂O and CO₂. To both oxides, addition of Cr- and Mg- oxides promoted the following reaction to give synthesis gas.

$$ {\text{CH}}_{ 4} + {\text{ MM}}'{\text{O}}_{\text{x}} \to {\text{CO }} + {\text{ 2H}}_{ 2} + {\text{ MM}}^{\prime}{\text{O}}_{{{\text{x}} - 1}} $$

After the reaction with methane, mixed oxides were reduced to lower valence state oxides and they were regenerated by the oxidation with air.

$$ {\text{MM}}^{\prime}{\text{O}}_{{{\text{x}} - 1}} + {\text{ Air}} \to {\text{MM}}'{\text{O}}_{\text{x}} + {\text{ N}}_{ 2} $$

Up to 10 repeated reaction and regeneration cycles did not or only slightly decreased the activity of the mixed oxides. By switching two or more reactors, the reaction and the regeneration were carried out to give synthesis gas continuously.