【摘要】 通过浸渍法制备了不同Cu/Zn比的γ Al2 O3 和改性γ Al2 O3 负载的Cu Zn催化剂 ,并用XRD ,XPS和SEM等手段对催化剂进行了表征 .XRD表征结果表明 ,还原活化前催化剂中的Cu和Zn分别以CuO和ZnO的形式存在 ;还原活化后Cu以单质的形式存在 ;催化剂失活后 ,单质Cu又转变成CuO .XPS和SEM分析结果表明 ,催化剂中金属的价态及颗粒的形貌在反应前后发生了变化 .所制备的催化剂在糠醛加氢制糠醇反应中表现出较高的选择性 .用Co改性的γ Al2 O3 负载的Cu Zn催化剂不仅具有较高的催化活性和选择性 ,而且还呈现出较长的寿命 .催化剂中的Cu晶相是催化活性中心 ;催化剂中的Cu晶相转变成CuO和烧结是催化剂失活的主要原因更多还原

【Abstract】 The Cu Zn catalysts supported on γ Al 2O 3 and modified γ Al 2O 3 were prepared and their catalytic performance for hydrogenation of furfural to furfuryl alcohol was studied. All of the catalysts show high selectivity for furfuryl alcohol. X ray diffraction (XRD), X ray photoelectron spectrometry (XPS) and scanning electron microscope (SEM) were used to characterize the catalysts. It was found that the catalytic activity of the catalysts is directly related to the copper crystal. Copper and zinc in the as prepared catalysts existed as CuO and ZnO respectively, and the CuO turned into Cu crystal after reduction and activation at 443 K, and the formed Cu is the catalytic active phase. The catalyst Cu Zn/ γ Al 2O 3 lost its catalytic activity as the Cu crystal became CuO. Compared with Cu Zn/ γ Al 2O 3, the Cu Zn supported on cobalt modified γ Al 2O 3 had higher activity and longer longevity. The XPS results showed that the cobalt used to modify γ Al 2O 3 had two different valences, Co 2+ and Co 3+ , in which Co 2+ species stabilized the Cu crystal of Cu Zn/modified γ Al 2O 3. The difference of SEM images of the fresh and the used Cu Zn/ γ Al 2O 3 indicated that the sintering is one of the causes resulting in deactivation of the catalysts.更多还原