改进型XC502低压甲醇合成催化剂的研究Ⅱ.催化剂的活性位

Abstract

采用XPS-AugEr、Xrd和fTIr等方法，对5组分Cu-zn-Al-M1-M2改进XC502铜基低压甲醇合成催化剂进行了表征。XPS-AugEr结果表明，XC502催化剂出现主峰为336.4EV（Cu＋），而Cu-zn-Al催化剂主峰为334.9EV（Cu0）；Xrd结果表明，两种工作态催化剂比氧化态新增峰的2θ分别为36.5°（Cu＋）和43.3°（Cu0），XC502催化剂这两峰的强度比I36.5/I43.3是Cu-zn-Al催化剂的2.1倍，说明工作态XC502催化剂单位Cu0中的Cu＋含量比Cu-zn-Al催化剂多；fTIr谱显示，XC502和Cu-zn-Al两种工作态催化剂新增波数分别为622CM-1和627CM-1的振动峰，此新增峰可能是Cu＋-O或Cu＋-O-zn2＋的振动峰。改进型铜基甲醇合成催化剂的活性位可能是Cu0-Cu＋-O-zn2＋/Al2O3-MOX。

pectroscopic characterization of the active site of a modiFied low pressure copperbased catalyst XC502, prepared by adding a small amount of metal oxides of the VI B and VB groups to a CuZnAl catalyst For methanol synthesis, is carried out by XPSAuger, XRD and FTIR.The main peaks are detected by XPSAuger to be 336.4eV(Cu+) and 334.9eV(Cu0) on the surFaces of XC502 and the CuZnAl catalyst, respectively.The XRD result shows that two new peaks appear at 2θ=36.5°(Cu+) and 43.3°(Cu0) For those Functioning catalysts, but I36.5/I43.3 of XC502 is twice as large as that of the CuZnAl catalyst, showing that the surFace of the Functioning XC502 catalyst has higher Cu+/Cu0 ratio and valence stability than those of the CuZnAl catalyst.By applying FTIR spectroscopy, bands at 622 cm-1 and 627cm-1 are observed on the Functioning XC502 and CuZnAl catalysts, respectively, and the band may be assigned to Cu+OZn2+ bond vibration.In light of the above results, it is suggested that the active site on the Functioning XC502 copperbased catalyst For methanol synthesis at low pressure is probably Cu0Cu+OZn2+/Al2O3MOx.