Not Just Another Methanation Catalyst: Depleted Uranium Meets Nickel for a High‐Performing Process Under Autothermal Regime

Abstract

Ni-based catalysts prepared through impregnation of depleted uranium oxides (DU) have successfully been employed as highly efficient, selective, and durable systems for CO 2 hydrogenation to substituted natural gas (SNG; CH 4 ) under an autothermal regime. The thermo-physical properties of DU and the unique electronic structure of f-block metal-oxides combined with a nickel active phase, generated an ideal catalytic assembly for turning waste energy back into useful energy for catalysis. In particular, Ni/UO x stood out for the capacity of DU matrix to control the extra heat (hot-spots) generated at its surface by the highly exothermic methanation process. At odds with the benchmark Ni/γ-Al 2 O 3 catalyst, the double action played by DU as a "thermal mass" and "dopant" for the nickel active phase unveiled the unique performance of Ni/UO x composites as CO 2 methanation catalysts. The ability of the weakly radioactive ceramic (UO x ) to harvest waste heat for more useful purposes was demonstrated in practice within a rare example of a highly effective and long-term methanation operated under autothermal regime (i. e., without any external heating source). This finding is an unprecedented example that allows a real stepforward in the intensification of "low-temperature" methanation with an effective reduction of energy wastes. At the same time, the proposed catalytic technology can be regarded as an original approach to recycle and bring to a second life a lesssevere nuclear by-product (DU), providing a valuable alternative to its more costly long-term storage or controlled disposal.

Ni‐Based Catalysts for CO2 Methanation: Exploring the Support Role in Structure‐Activity Relationships

“…Ru being a noble metal is uneconomical to be applied in high‐grid industrial applications. Ni is inexpensive and widely available, it also possesses high activity when used in CO 2 methanation [16–18] . A lot of research has been done on support materials for Ni‐based catalyst preparation and used in CO 2 methanation, and the most commonly used supports are CeO 2 , [19,20] Al 2 O 3 , [21,22] TiO 2 , [23,24] ZrO 2 , [25,26] Y 2 O 3 , [27,28] Sm 2 O 3 , [29,30] etc .…”

UV- and visible-light photocatalysis using Ni–Co bimetallic and monometallic hydrotalcite-like materials for enhanced CO2 methanation in sabatier reaction

“…Ni, Rh, Ru, Au, and Ag have been previously used as catalytic materials for CO 2 activation in both thermo- and photocatalytic reactions. The effect of different metal oxide supports (SiO 2 , Al 2 O 3 , CeO 2 , and TiO 2 ) on CO 2 hydrogenation depends on their surface area and oxygen vacancies as well as their ability to synthesize catalysts with well-dispersed active metals and strongly basic sites [ [4] , [5] , [6] , [7] , [8] ].…”