(351g) From Atom to Industrial Reactor: A Multi-Scale Simulation of Syngas Methanation

Natural gas has been the most-consumed fuel in the U.S. industrial sector and its usage is expected to grow in the future. It is a relatively clean energy source that produces less greenhouse gas and other pollutions than coal. Methane production from syngas methanation provides one solution to the tremendous demand for methane and is attracting world-wide attention. However, traditional syngas methanation process has several shortcomings including high power consumption, limited reactor production capacity, large equipment investment, short catalyst lifespan, and low product yield. Such disadvantages are partially due to the exothermic nature of the reaction, which requires high-volume product gas circulation and inter-stage cooling to keep the temperature in a traditional adiabatic reactor in the suitable zone.

In this work, we designed an isothermal fix-bed reactor and improved the syngas methanation process to overcome the above disadvantages. We applied a multi-scale simulation method in our development of the process: Density functional theory (DFT) method was used to determine the reaction mechanism and map the reaction network, from which kinetic parameters of the catalytic methanation reactions were obtained. Computational fluid dynamics (CFD) method with mean-field approximation was applied to simulate the flow of fluid, effect of diffusion, heat transfer, and surface reactions based on the kinetic parameters obtained from the DFT calculation. The effect of the shape and packing of the catalyst and the dimensions of the reactor on the reactor performance was also studied to provide necessary data for the reactor design. Finally, a process simulation was performed and provided detailed mass and energy balance.

By applying a multi-scale simulation, we were able to design the process from the atomic-scale up to the industrial scale using only computational methods. It shortened the time needed for the design compared to the traditional reactor design scheme, and provided information that was otherwise difficult to obtain. It was proved to be a faster, cheaper, and greener approach for a reactor and process design.