Dry Reforming of Methane over A-Site Ca Doping of Ni/La ₂ Ce ₂ O ₇ Catalyst

Dry reforming of methane is a prospective technology that converts greenhouse gases into valuable products, attracting significant research interest due to its environmental benefits. However, its industrial application is hindered by catalyst deactivation, primarily due to coking and sintering. This work thoroughly explored the impact of alkaline earth metal (specifically, Ca, Sr, Ba) doping and varying Ca doping levels on the activity of Ni catalysts supported by La2Ce2O7 pyrochlore. The 7.5NLC0.6C catalyst was identified as the best-performing catalyst and showed high conversion rates (95.1% for CH4 and 93.0% for CO2), high product yields (90.2% for H2 and 93.4% for CO) at 800 °C, atmospheric pressure, and a weight hourly space velocity of 30,000 mL·g–1cat·h–1, with a near-unity H2/CO ratio (0.97). Furthermore, the 7.5NLC0.6C catalyst exhibited a lower deactivation rate than the undoped sample during a 15 h stability test. Physicochemical characterization analysis demonstrated that Ca2+ successfully incorporates into the pyrochlore lattice without forming impurities, increasing oxygen vacancy concentration, reducing active Ni particle size, strengthening the Ni-pyrochlore interaction, and enhancing surface basicity. Additionally, thermogravimetric and Raman results indicated that the 7.5NLC0.6C catalyst exhibits significantly lower coking levels and graphitization than the undoped sample, demonstrating excellent anticoking properties. Consequently, the 7.5NLC0.6C catalyst exhibited superior activity and stability. This work offers a straightforward and efficient strategy for enhancing the performance of Ni/pyrochlore catalysts.