High Jolt-Resistance CuO-CeO₂/AlOOH/Al-fiber Monolithic Catalyst For CO Preferential Oxidation

The preferential oxidation of CO in H₂-rich stream（CO-PROX）is one of the best ways to purify hydrogen fuel of proton exchange membrane fuel cell（PEMFC）.Given that the inevitable bumps of PEMFC in portable and vehicle-mounted power applications,the CO-PROX catalyst must be high jolt resistance.Moreover,both the oxidation of CO and H₂ are exothermic reactions,and the increase of bed temperature will not only aggravate the oxidation of H₂,reduce the reaction selectivity,but also easily generate“hot spots”to deactivate the catalyst.The structured catalysts based on metal fiber/foam are characteristic of low pressure drop at high-throughput operation and excellent mass and heat transfer performance,which can effectively solve these problems.In this paper,Al-fiber was used as substrate with in-situ growth of AlOOH nanosheets on its surface by steam oxidation method and then loaded with CuO-CeO₂catalytic active components.Finally,the CuO-CeO₂/AlOOH/Al-fiber monolithic catalyst was obtained for CO-PROX reaction,achieving high activity and high jolt resistance.The main research contents of this paper are as follows:The preparation and reaction conditions of CuO-CeO₂/AlOOH/Al-fiber monolithic catalyst were optimized,and the optimal catalyst preparation conditions was obtained:CuO/CeO₂ weight ratio of 7/3,total CuO-CeO₂ loading of 8 wt%,Cu-Ce co-impregnation,AlOOH/Al-fiber calcined at 100 ^oC,and catalyst calcination temperature of 350 ^oC.The preferred catalyst delivered 100%CO conversion and81%selectivity at 140 ^oC with a gas hourly space velocity of 12000 m L g^-1 h^-1 and the composition of gas feed of CO/O₂/H₂/N₂（0.5/0.5/49.5/49.5）.After 120-hour stability test,the catalyst was not deactivated.The effect of calcination temperature on AlOOH/Al-fiber carrier was investigated by characterization and correlated with catalytic performance.The results illustrated the changed surface morphology of the catalysts prepared with different AlOOH/Al-fiber carriers that were calcined at different temperatures of 200-600 ^oC,while the specific surface area and CuO-CeO₂ dispersion were decreased.However,the catalyst prepared with uncalcined-AlOOH/Al-fiber（i.e.,Cu-Ce-AlOOH-100）showed the lowest activation energy and highest activity.The Cu-Ce-AlOOH-100catalyst is rich in surface hydroxyl groups,which are conducive to promoting the CuO-CeO₂ dispersion.The XPS and H₂-TPR results indicated that the Cu-Ce-AlOOH-100 catalyst produced Cu⁺/Cu~0 species during the reaction,with the strongest Cu-Ce interaction.In addition,the hydroxyls can also influence the reaction pathways via promoting the formation of intermediate species.