Systems and methods of reducing refinery carbon dioxide emissions by increasing synthesis gas production in a fluid catalytic cracking unit having a reactor and a regenerator are disclosed. In one example, a method comprises separating spent catalyst from a hydrocarbon product in the reactor, the spent catalyst having trapped hydrocarbon thereon. The method further comprises reacting an additional feed with the spent catalyst in the reactor to deposit additional coke on the spent catalyst, defining a gas product. The method further separating the gas product and the trapped hydrocarbon from the spent catalyst with a stripping gas. The method further comprises removing coke from the spent catalyst in the regenerator, thereby increasing the amount of synthesis gas production.