Design And Synthesis Of CuO-CeO₂/UiO-66 Catalyst And The Investigation Between Cu-Ce Structure-Activity Relationship Based On Co Oxidation

In the past two decades,heterogeneous catalysts based on MOFs have attracted significant attention.In the early days,efforts on MOF catalysis primarily focused on the synthesis of fine chemicals.In recent years,MOF-based catalysts for solid-gas phase catalysis have also been extensively studied.CuO-CeO₂,as a non-precious metal catalyst with low cost and excellent storage and release oxygen ability and CO adsorption capacity,exhibits good performance in CO oxidation.In this paper,a Zr-based MOF material UiO-66 with high specific surface area and high stability was used to support the CuO-CeO₂ catalyst by impregnation method for CO catalytic oxidation.The effects of Cu/Ce ratio?wt/wt?,Cu+Ce?wt%?content and calcination temperature were investigated.Finally,a series of CuO-CeO₂ catalysts with low CuO loading were prepared.The effects of thermal treatment temperature on the structure and catalytic activity of the catalyst were investigated.The catalysts were characterized by low temperature N₂ adsorption and desorption,PXRD,XPS,H₂-TPR,CO-TPD,TEM and in situ DRIFT.The kinetics of some catalysts were tested.The structure-activity relationship and mechanism of CuO-CeO₂ catalysis was study.The main results are as follows:1.A group of 30-CCU-a/b catalysts were prepared by calcining at 250°C.The results show that the best Cu/Ce ratio is 3:7.The CeO₂ particles in the catalysts can be evenly distributed by UiO-66.and the content of highly dispersed CuO,Cu⁺and Ce³⁺is the highest.2.The results of the investigation of Cu+Ce load showed that,with the increase of Cu+Ce load,the activity of the catalysts showed an increasing trend.The characterization results showed that the total content of active sites increased gradually,while the proportion of them were decreased.Finally,the apparent activation energy gradually decreased with the increase of Cu⁺content.3.Taking 20-CCU-3/7 as the research object,the effects of calcination temperatures on the performance of the catalyst were investigated.The results showed that the catalyst calcined at 600°C has the highest activity because of the highly dispersed CuO species.4.A series of CuO/CeO₂ catalysts with low CuO loading?0.5 wt%⁵ wt%?were prepared.The structure and catalytic performance of the catalysts calcined at 500°C and 800°C were compared.The results show that calcination at 800°C results in a decrease in specific surface area and the increase in particle size,however,increases the activity of the catalysts with the CuO loading less than 3 wt%.Kinetic tests verified that the CO oxidation catalyzed by CuO-CeO₂ followed the MVK mechanism.