Syngas production by methane tri-reforming: Effect of Ni/CeO2 synthesis method on oxygen vacancies and coke formation

The effect of carbon dioxide in the feed stream of tri-reforming of methane process compared to the partial oxidation of methane

In this work, we studied the effect of CO₂ in the feed stream of the TRM process performance of nickel supported on LaFeO₃ perovskite for hydrogen production compared to the POM reaction. The perovskite and nickel supported on LaFeO₃ were synthesized and characterized by thermogravimetric analysis (TGA/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and programmed reduction temperature (TPR). The catalytic tests were carried out in temperatures varying from 700 to 800 °C with feed flow of 350 cm³/min and 200 cm³/min for TRM and POM, respectively. The hydrogen selectivity for the tri-reforming was 78%, while for the partial oxidation reaction, only 55% H₂ at 700 °C. Results showed that the hydrogen selectivity for the Ni/LaFeO₃ catalyst is significantly higher for the tri-reforming process, suggesting that CO₂ enhanced the hydrogen selectivity compared to the partial oxidation of methane. Analyses by Raman spectroscopy and thermogravimetric calculations showed structural modifications of the catalysts after the reaction. The Raman spectrum showed segregated NiO and Fe₃O₄ and low carbon formation at 700 °C. The proposed mechanism suggests methane and oxygen adsorption, lattice oxygen and CO₂ on surface active sites, and vacancies for both reactions.

Ni/CeO2 Catalyst Prepared via Microimpinging Stream Reactor with High Catalytic Performance for CO2 Dry Reforming Methane

Methane reforming with carbon dioxide (DRM) is one promising way to achieve carbon neutrality and convert methane to syngas for high-value chemical production. Catalyst development with better performance is the key to its potential large-scale industrial application due to its deactivation caused by carbon deposition and metal sintering. Hence, a Ni/CeO2 catalyst (Ni/CeO2-M) with higher CO2 conversion and better stability is prepared, supported on CeO2 precipitated via a novel microimpinging stream reactor. A series of ex-situ or in-situ characterizations, such as CO titration measurements, two-step transient surface reaction (two-step TSR), CO2 and CH4 temperature-programmed surface reaction (CO2-TPSR and CH4-TPSR), X-ray absorption fine structure (XAFS), and in-situ Raman spectroscopy study, were used to investigate its structure and mechanism. In contrast to Ni supported on commercial CeO2 (Ni/CeO2-C), the Ni/CeO2-M catalyst with stronger lattice oxygen mobility and higher oxygen storage capacity enhances its CO2 activation ability and carbon deposition. The Ni particle size of the Ni/CeO2-M catalyst decreased, and a higher oxidation state was obtained due to the strong metal–support interaction. Besides the reaction performance improvement of the Ni/CeO2-M catalyst, the novel microimpinging stream reactor could achieve catalyst continuous production with a high preparation efficiency. This work provides a novel method for the high-performance catalyst preparation for DRM reaction and its mechanism study gives a deep insight into high-performance catalyst development via bottom-up study.