Tuning the A‐site Element in LaCo0.8Fe0.2O3 Perovskite‐based Catalyst for High Temperature N2O Decomposition in Nitric Acid Plant

Abstract

AbstractThe effect of La‐deficiency and Ce/Sr‐substitution in the benchmark LaCo0.8Fe0.2O3 has been investigated for the decomposition of N2O between 500 and 900 °C. Real inlet gas composition and space velocity reveal that La‐deficiency and Ce/Sr‐substitution can improve the thermal stability of catalyst, while La1‐xSrxCo0.8Fe0.2O3 with x≥0.1 was highlighted as a promising formula due to the strongest resistance to deactivation and suppressed undesired NOx decomposition at high space velocity. This phenomenon is mainly ascribed to the incorporation of Sr2+ into the perovskite lattice during the reaction consequently stabilizing the Co3+ species and creating the oxygen vacancies in La1‐xSrxCoO3‐δ. On the contrary, the loss of activity on Ce‐substituted LaCo0.8Fe0.2O3 has been preferentially related to the cobalt exsolution to extra framework of perovskite making the catalytic cycle with Co3+ unfavorable. All these bulk and surface changes are accompanied with opposite evolution of apparent activation energy and pre‐exponential factor which can be discussed based on a redox mechanism.