Dry reforming of methane by LaNiO3 perovskite oxide: Cu-substituted improving reactivity and stability

The conversion of greenhouse gases is pivotal for mitigating environmental pollution. Dry reforming of methane is an attractive technological process as it facilitates the conversion of both CO(2 )and CH4 into a suitable syngas. However, the coke deposition inhabits the development of Ni-based catalyst. In this study, the effects of Cusubstituted in LaNi1-xCuxO3 (x = 0, 0.2, 0.4 and 0.6) perovskites were investigated. In comparison with the LaNiO3 sample, the Cu-substituted samples exhibit enhanced stability and resistance to coke deposition; However, a marginal decrease is observed in the conversion of CH4. In the case of Cu-substituted samples, the weight loss rates due to coke deposition are below than 3.9%, with LaNi0.4Cu0.6O3 showing a particularly low rate during the 3h reaction. This improvement in coke resistance is more than 22 times greater compared to the LaNiO3 sample. LaNi0.8Cu0.2O3 demonstrated the highest conversion rates for both CO2 and CH4 among all Cusubstituted samples. Characterization results have demonstrated that the Cu-substituted sample promotes the formation of Ni-Cu alloy particles. Notably, there is a pronounced tendency for Ni-Cu particle to aggregate when x equals 0.4 and 0.6. The LaNi0.8Cu0.2O3 sample has been subjected to further investigation across a range of temperatures from 600 to 750 degrees C. It has been observed that the conversion of CH4 and CO2 is notably enhanced at temperatures exceeding 700 degrees C. The results indicate that the optimal reaction temperature is 700 degrees C, yielding a favorable H-2/CO ratio of approximately 1, which is suitable for syngas production. Characterization results indicate a tendency for the Ni-Cu alloy to segregate into Ni and CuO phases. Furthermore, the activity of La2O2CO3 is enhanced, which contributes to a reduction in coke deposition. In an 8h stability test, the LaNi0.8Cu0.2O3 sample demonstrated a relatively stable performance in terms of CH4 conversion, CO2 conversion, and H-2/CO ratio.