Abstract: The present disclosure provides a process for controlling syngas composition from an internal combustion engine-based syngas generator. While air is typically used as an oxidant, with nitrogen (N2) as a diluent, this results in expensive downstream compression, and low feedstock conversion efficiencies. This disclosure provides CO2 as a diluent to reduce N2 concentration in the syngas. In some embodiments, the CO2 diluent may be from either a biogas processing coupled with methanol, DME, and/or hydrocarbon production; or natural gas processing coupled with Fischer-Tropsch (FT) synthesis and/or other hydrocarbon synthesis.