Syngas formation via chemical looping of methane process using Y1La0.6Gd0.4O3 as a novel oxygen carrier

Abstract

The performance of Y₁La_0.6Gd_0.4O₃ perovskite at the test temperature range from 800 to 900 ˚C, as an oxygen carrier in the methane (CH₄) chemical looping process has been investigated. Specifically, the O₂-TPD test suggested that Y₁La_0.6Gd_0.4O₃ served a pivotal role in oxygen donation, and such high oxygen donation could be beneficial for the redox reaction. The nano-scaled uniform porous (sponge-like) morphology of the fabricated catalyst offered a favorable chance to enhance its capability as an oxygen carrier. An increase in the selectivity and conversion of CH₄ (≥95 % with an optimal ratio of H₂/CO) confirmed that the Y₁La_0.6Gd_0.4O₃ as an oxygen carrier had a positive effect on the catalytic activity. The Y₁La_0.6Gd_0.4O₃ catalyst improves oxygen storage and donation capacity due to increased oxygen vacancy defects and accelerates the removal of deposited coke. Notably, the oxygen storage capacity for the Y₁La_0.6Gd_0.4O₃ oxygen carrier reached a maximum value of 3.85–4.2 (mmol O atoms g⁻¹ _cat). Also, due to the improved oxygen storage and high oxygen mobility, the time required to fill the oxygen carrier network with oxygen is reduced. Furthermore, DFT calculations revealed that the synergistic effect of Y, La, and Gd significantly reduces the energy required to create oxygen vacancies, it indicates the enhanced oxygen mobility in the Y₁La_0.6Gd_0.4O₃ oxygen carrier.