【摘要】 采用等容浸渍法,制备了t-ZrO₂,m-ZrO₂,CeO₂和CexZr1-xO（x=0.05⁰.8）负载RuO_x催化剂,研究了载体对RuO_x物种的结构及其催化甲醇选择氧化反应性能的影响。通过XRD,Raman,XPS和H2-TPR等手段对这些催化剂进行表征,发现当Ru表面密度为0.23⁰.43Ru·nm-2时,RuO_x物种以高分散形式存在,该结构含有Ru=O键以及与载体之间的Ru-O-S（S表示载体阳离子）键,且其Ru 3d5/2结合能为281.6 e V。这些结果表明高分散RuO_x物种以Ru O2-4结构形式存在。H2-TPR结果表明,CeO₂和CexZr1-xO（x=0.05⁰.8）载体相比于tZrO₂和m-ZrO₂载体具有更加优异的氧化还原性能。RuO_x/CeO₂催化甲醇选择氧化反应活性显著优于RuO_x/t-ZrO₂和RuO_x/m-ZrO₂催化剂。随Ce含量增加,RuO_x/CexZr1-xO（x=0¹.0）催化反应活性逐渐增大,反映出氧化还原性载体能够促进高分散RuO_x催化剂的活性。同时,甲酸甲酯产物的选择性也随之升高,反应温度为100℃时,在²0%甲醇转化率下,甲酸甲酯选择性可达81.5%。更多还原

【Abstract】 RuO_xcatalysts supported on t-ZrO₂,m-ZrO₂,CeO₂ and CexZr1-xO（x = 0. 05 0. 8） were prepared by an incipient wetness impregnation method,and examined for selective oxidation of methanol to methyl formate（MF）. These catalysts were characterized by XRD,Raman,XPS,and H2-TPR,showing that the RuO_xspecies were highly dispersed on their support surfaces at the Ru surface densities of 0. 23 0. 43 Ru·nm-2. These dispersed RuO_xspecies possessed Ru = O and Ru-O-S（S denotes Ce4 +or Zr4 +from the supports） bonds in the Ru O2-4structures,as evidenced from their characteristic Raman bands at 972 992 cm-1and 702 712 cm-1,respectively,and the Ru 3d5/2binding energy at 281. 6 e V. CeO₂ and CexZr1-xO（x = 0. 05 0. 8） were more reducible than t-ZrO₂ and m-ZrO₂ from the H2-TPR results. The activities of RuO_x/CexZr1-xO（x = 0 1. 0） increased gradually with increasing their Ce contents,and RuO_x/CeO₂ were superior to RuO_x/t-ZrO₂ and RuO_x/m-ZrO₂ catalysts in the selective oxidation of methanol at 100 ℃. Such change in the activities for these catalysts is consistent with the reducibility of the RuO_xspecies and the underlying supports,clearly showing the promoting effect of the redox properties of the supports on the activities of the Ru O2-4species. The MF selectivities for these catalysts simultaneously increased with increasing their Ce contents,and a highest selectivity of 81. 5% was achieved on RuO_x/Ce0. 8Zr0. 2O at a methanol conversion of 20%.更多还原