Light-Reinforced Key Intermediate for Anticoking To Boost Highly Durable Methane Dry Reforming over Single Atom Ni Active Sites on CeO2

Dry reforming of methane (DRM) has been investigated for more than a century; the paramount stumbling block in its industrial application is the inevitable sintering of catalysts and excessive carbon emissions at high temperatures. However, the low-temperature DRM process still suffered from poor reactivity and severe catalyst deactivation from coking. Herein, we proposed a concept that highly durable DRM could be achieved at low temperatures via fabricating the active site integration with light irradiation. The active sites with Ni-O coordination (Ni-SA/CeO2) and Ni-Ni coordination (Ni-NP/CeO2) on CeO2, respectively, were successfully constructed to obtain two targeted reaction paths that produced the key intermediate (CH3O*) for anticoking during DRM. In particular, the operando diffuse reflectance infrared Fourier transform spectroscopy coupling with steady-state isotopic transient kinetic analysis (operando DRIFTS-SSITKA) was utilized and successfully tracked the anticoking paths during the DRM process. It was found that the path from CH3* to CH3O* over Ni-SA/CeO2 was the key path for anticoking. Furthermore, the targeted reaction path from CH3* to CH3O* was reinforced by light irradiation during the DRM process. Hence, the Ni-SA/CeO2 catalyst exhibits excellent stability with negligible carbon deposition for 230 h under thermo-photo catalytic DRM at a low temperature of 472 degrees C, while Ni-NP/CeO2 shows apparent coke deposition behavior after 0.5 h in solely thermal-driven DRM. The findings are vital as they provide critical insights into the simultaneous achievement of low-temperature and anticoking DRM process through distinguishing and directionally regulating the key intermediate species.

Automated summary

In this study, highly durable dry reforming of methane (DRM) at low temperatures was achieved through the integration of light irradiation and active site engineering. Two targeted reaction paths for the production of the key intermediate (CH3O*) were successfully constructed by fabricating active sites with Ni-O coordination and Ni-Ni coordination, respectively. The operando diffuse reflectance infrared Fourier transform spectroscopy coupled with steady-state isotopic transient kinetic analysis (operando DRIFTS-SSITKA) was used to track the anticoking paths during the DRM process. The findings provide critical insights into the simultaneous achievement of low-temperature and anticoking DRM process.