中文摘要：

使用浸渍法制备不同负载量的Cr/γ-Al2O3催化剂,研究乙酸乙酯的催化燃烧.BET,XRD结果表明,Cr在γ-Al2O3上负载存在分散阈值效应,负载量在阈值以下时呈单层分散形式,在超过阈值时Cr形成结晶,实验测得单层分散阈值与理论计算一致.Raman结果表明Cr在单层分散时为Cr6＋,而在非单层分散时为Cr2O3.催化乙酸乙酯燃烧的活性研究显示,阈值效应对催化活性有显著影响：催化活性在单层分散阈值时最好,此时活化能最高,指前因子最大.

英文摘要：

Cr/γ-Al2O3 catalysts with different loadings were prepared by the impregnation method and were used for catalytic ethyl acetate combustion. Dispersion threshold were observed using BET and XRD when chromium was supported on T-AlO3. Below threshold, Cr was dispersed in monolayer state. Above threshold Cr crystals were found. The monolayer dispersion threshold of Cr/γ-Al2O3 estimated from experimental data is in good agreement with the results calculated from the model. Raman results show that Cr6＋ appears in monolayer dispersion and Cr/O3 appears when chromium loading is above the monolayer dispersion threshold. Catalytic activity is the highest at the monolayer dispersion threshold and the highest activation energy and pre-exponential factor are also obtained.