Short contact time catalytic partial oxidation of biogas – A comprehensive study on CO2 and N2 dilution

• Dilution of CH4 by CO2 decreases CH4 conversion & H2 selectivity more than by N2.
• Partial oxidation of a biogas surrogate yields a product stream ideal for pyrolysis.
• Effects of flow rate on product composition are smaller under dilute conditions.
• Effects of fed ratio on product composition are smaller under dilute conditions.

The short contact time catalytic partial oxidation of methane diluted with nitrogen and/or carbon dioxide to act as a surrogate for biogas conversion was carried out. Experiments were carried out under varying operating conditions to determine the possible use of the products in pyrolysis.Carbon dioxide has a larger effect on the product selectivities and back face temperature of the catalyst compared to nitrogen for equal dilutions. Carbon dioxide is consumed in the reactor whereas nitrogen is not. Since carbon dioxide likely takes part in endothermic reactions, the temperature of the catalyst is lower as is the conversion of methane and selectivity to carbon monoxide and hydrogen.The product stream is at an appropriate composition and temperature for subsequent use in a pyrolysis reactor. The presence of hydrogen and carbon monoxide will result in the removal of oxygen from bio-oils that are produced in the pyrolysis reactor.