Switchable Catalysts for Chemical CO₂ Recycling: A Step Forward in the Methanation and Reverse Water–Gas Shift Reactions

Abstract

Advanced catalytic technologies are crucial to enable the transition toward a low-carbon industry with minimized CO 2 emissions. This paper showcases the application of highly effective Ru-promoted Ni-based catalysts for gas-phase CO 2 upgrading: CO 2 methanation and reverse water−gas shift. The addition of small amounts of Ru results in a remarkable enhancement of CO 2 conversion and selectivity. The bimetallic Ru-Ni catalyst displays greater metallic dispersion, tuned electronic properties and outstanding stability for long-term runs, a mandatory requisite for its implementation in actual CO 2 conversion units. The singularity of our advanced catalyst lays on its capacity to work effectively for both the CO 2 methanation and the reverse water−gas shift, allowing end-product flexibility by adjusting the reactor temperature. Such versatility opens a big range of possibilities to adapt this technology in heavy carbon industries whose net CO 2 emissions represent a big share in the global greenhouse gases emissions.

Bimetallic Ni-Based Catalysts for CO2 Methanation: A Review

“…Pastor-Pérez et al [ 69 ] prepared Fe and Co modified Ni catalysts supported on CeO 2 -ZrO 2 and observed a negative effect of Fe addition, since the 3% Fe, 15% Ni/CeO 2 -ZrO 2 catalyst exhibited lower values for CO 2 conversion and CH 4 selectivity compared to the monometallic Ni catalyst. Likewise, le Saché et al [ 70 ] observed that Fe addition on a Ni/CeO 2 -ZrO 2 catalyst led to a drop in CO 2 conversion and CH 4 selectivity. Furthermore, Frontera et al [ 71 ] also reported a drop in CO 2 methanation activity upon Fe alloying over Ni catalysts supported on Gd-doped CeO 2 (GDC).…”

“…Renda et al [108] also showed that using ruthenium acetylacetonate instead of ruthenium chloride as the Ru precursor salt could improve the dispersion of the active metals, due to the templating effect of the precursor salt, leading to an enhanced methanation performance. In another interesting study, le Saché et al [70] reported that Ru addition on a Ni/CeO2-ZrO2 catalyst could improve the dispersion of Ni and increase the overall intrinsic activity for the reduction of CO2. The bimetallic NiRu catalyst exhibited enhanced CO2 methanation performance in terms of CO2 conversion and CH4 selectivity at lower temperatures compared to the monometallic Ni catalyst.…”

Recent Advances in Supported Metal Catalysts and Oxide Catalysts for the Reverse Water-Gas Shift Reaction

“…It is reasonable for the Ni species with the electron deficient state to possess high catalytic performance for RWGSR when Ni is added as a second metal component to the Mo/Al 2 O 3 catalyst (Kharaji et al, 2014). As for RuNi/CeZr catalyst, the addition of Ru enhances the Ni reducibility and leads to greater Ni dispersion on the catalyst surface, thus promoting overall activity and CO selectivity for the RWGSR (Sache et al, 2020). Typically, MOF-74 plays a role in helping adsorb and deliver electrons, whereas the low amount of Au@Pd NPs in Au@Pd@MOF-74 results in the poor photon adsorption strength of the Au@Pd active sites.…”

Ru and Ni—Privileged Metal Combination for Environmental Nanocatalysis

“…Ruthenium is one of the most used noble metals for this purpose. The addition of Ru to an Ni catalyst enhances the Ni reducibility and dispersion on the catalyst surface [76,77] and increases the catalytic activity at a low temperature in CO 2 methanation [53,74]. In dry reforming of methane (DRM), the addition of Ru modifies the interaction between Ni and the support, improving catalyst stability and catalytic performance.…”

“…However, they did have some important advantages. The 1% Ru-15% Ni/CeZr system can be used in both CO 2 methanation and RWGS reactions [77]. It is extremely stable and maintained a CO 2 conversion of 53% at 350 • C in methanation (selectivity to CH4: 93%), while maintaining a CO 2 conversion of 72% at 700 • C in a RWGS reaction (selectivity to CO: 91%).…”