This research introduces an innovative reactor design for the production of synthetic natural gas (SNG) through CO2 methanation, thermally integrated with methanol steam reforming (MSR) to generate hydrogen. The primary innovation involves leveraging the exothermic heat generated from CO2 methanation to drive the endothermic methanol synthesis reaction, thereby simplifying hydrogen production and lowering the methanation hotspot temperature by 10 °C. Simulations indicate that the coupled system exhibits superior performance, achieving 98 % CO2 conversion, an 11 % reduction in net carbon emissions, and a 64 % decrease in utility consumption, alongside a 40 % methanol conversion rate. A multi-objective optimization was conducted to improve operational flexibility by customizing reactor performance, with the goals of maximizing fuel production (SNG and H2) and minimizing CO2 yield. Two operational modes are identified from the Pareto front. The sustainable Mode optimizes environmental outcomes, decreasing CO2 emissions to 4 % and enhancing methane yield from 19 % to 25 %. The Maximum Fuel Production Mode optimizes energy output, resulting in yields of 35 % methane and 40 % hydrogen, though it entails increased CO2 processing intensity. Adjusting variables such as feed temperature, pressure, and flow rates along an optimal pathway enables this dual-mode approach to provide a flexible and adaptable solution for optimizing reactor operation, thereby enhancing the efficiency and sustainability of synthetic fuel production.

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