Facile construction of non-crystalline ZrO₂ as an active yet durable catalyst for methane oxychlorination

An amorphous ZrO₂ mesoporous material was prepared by propylene oxide (PO)-assisted sol-gel process and was first evaluated in CH₄ oxychlorination. Various characterizations were conducted including XRD, N₂ adsorption–desorption, NH₃-TPD, CO₂-TPD, SEM, and TEM. Results showed the amorphous ZrO₂ with mesoporosity and large SSA exhibited abundant surface acid and base sites. As a non-redox catalyst, the amorphous ZrO₂ unexpectedly delivered much higher activity and better stability in CH₄ oxychlorination than conventional ZrO₂. The CH₄ conversion was 18.6% and the selectivity of CH₃Cl and CO reached 47.6% and 30.2% at 490 °C, respectively. The amorphous ZrO₂ could stably operate at 470 °C for 50 h without significant deactivation. Kinetic studies revealed that the CH₄ activation on the surface of the amorphous ZrO₂ was the rate-determining step. [Figure not available: see fulltext.].