Methods of the present disclosure may comprise: introducing a first effluent and a second effluent in a gasifier of a partial oxidation unit to produce a waste gas, wherein the first effluent comprises one or more hydrocarbon containing feeds and the second effluent comprises air, enriched air with oxygen or oxygen; selectively removing hydrogen sulfide (H2S) from the waste gas; combining the waste gas and steam in a water-gas shift unit to produce a shift gas comprising hydrogen and carbon dioxide; separating the carbon dioxide from the shift gas in a carbon capture unit to produce a carbon dioxide-enriched effluent and an effluent comprising a hydrogen- and nitrogen-enriched mixture; and recovering the carbon dioxide from the carbon dioxide-enriched effluent.