Characterization and development of a Ni-based catalysts for the conversion of methane into H2 and solid carbon
EMSL Project ID
60245
Abstract
The main objectives in this project are to continue our investigation into Ni/Cu bimetallic catalysts active for the thermocatalytic decomposition (TCD) of methane. Thermocatalytic decomposition (TCD) of methane provides an approach to produce CO2-free hydrogen and solid carbon co-product. This approach eliminates the requirement for CO2 capture, as is necessary with conventional steam methane reforming. Instead, it generates value-added solid carbon such as carbon nanotubes (CNTs), which have potential markets to reduce net costs for practical TCD processes on industrial scale. In this way, this work directly addresses the DOE’s Hydrogen Energy Earthshot of reducing the cost of clean hydrogen to $1/kg by 2030. In FY19 we investigated how Ni-based catalysts were active for methane pyrolysis (MP) and CNT formation in a continuous flow reactor at temperatures between 550 and 650°C. This is impactful as this discovery represents a novel route to generate low-cost CO2-free H2 by selling valuable CNT/CF as co-product. With additional investigation it was found that while small Ni nanoparticles favor the formation of graphitic sheets of carbon, large Ni nanoparticles (> 20 nm) favor CNT/CF formation. Further, we discovered that alloying Ni with other materials stabilized the catalytic performance for more than 6 h. Specifically, we tested a panel of Ni/Cu bimetallic catalysts in FY21, consisting of different Ni/Cu ratios, total metal loadings, and different reaction temperatures. In that work, we determined that a lower Ni/Cu ratio favors higher TCD activity and catalyst stability at temperatures above 600 ℃, compared to pure Ni. However, we still have more to learn about the active site and the CNT/CF growth mechanism in order to perfect a formulation with an economically relevant activity and stability while producing CNT/CFs of sufficient quality. EMSL’s powder XRD will be crucial in this effort, as XRD will provide information on the metal crystallite size before and after reaction, the existence of different alloy phases of different compositions, and confirm the growth of graphitic carbon. EMSL’s environmental transmission electron microscopy (ETEM) and scanning transmission electron microscopy (STEM) will also be crucial in determining the elemental dispersion of nickel and copper within the metal active sites and visualizing the growth of carbon nanotubes/nanofibers and the size of crystallites from which they grow. These findings will support the design of an improved catalyst system for the selective formation of CNTs and commercialization of catalytic methane to CO2-free H2 technology.
Project Details
Start Date
2021-10-13
End Date
2022-10-12
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members