Reducing Reaction Temperature, Steam Requirements, and Coke Formation During Methane Steam Reforming Using Electric Fields: A Microkinetic Modeling and Experimental Study

摘要

In this study, we approach several common problems with the Ni-catalyzed methane steam reformation reaction (MSR) using a two-pronged approach combining density functional theory (DFT) calculations with experimental work. Specifically, we look at the deactivation of a Ni catalyst due to coke formation, its high operating temperature requirements, and the high steam to methane (H2O/CH4) ratio needed for proper MSR operation. A DFTbased microkinetic model was developed in the presence and absence of electric fields, and the results were compared with experimental results. The microkinetic model shows that, under various electric fields, the most favorable MSR mechanism changed slightly. It also shows that the presence of a positive electric field decreases the surface coverage of carbon, increases the water coverage, accelerates the rate-limiting step of the C-H bond cleavage in methane, and increases the desorption rates of the syngas product (CO + H-2) during MSR Consequently, for a given methane conversion, a positive electric field allows for significantly lower H2O/CH4 ratio and operating temperatures in comparison to systems without an electric field. These findings correspond well with experimental tests under a variety of operating conditions. In addition, improvement in the catalytic activity due to the presence of a positive electric field remained significant even at industrially relevant applied pressures-improving the hydrogen yield greatly. Overall, we find that an applied electric field can play a significant role in improving the catalytic activity of heterogeneous reactions. This information can guide the design of heterogeneous reactions in the presence of an electric field. By utilizing the electric field generated by various renewable energy sources, electric-field-assisted heterogeneous reactions can open up a paradigm in future energy research.