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采用离子交换法制备负载型纳米HZSM-5分子筛,采用负压-沉积沉淀法制备负载型纳米Au/HZSM-5催化剂,对载体及催化剂进行XRD、UV-Vis、TEM、XPS、NH3-TPD和FT-IR等表征,并评价催化剂的甲烷吸附性能。XRD与TEM表征结果表明,N2气氛焙烧的2.0%Au/HZSM-5催化剂金粒子尺寸较小,为(5~10)nm;UV-Vis表征结果表明,焙烧导致负载金的价态由离子态转为零价态,且N2气氛焙烧的2.0%Au/HZSM-5催化剂上零价金的吸收峰较弱,即相应的颗粒度较小;XPS表征结果表明,金负载量越高,催化剂上零价金占总金的比例越高;NH3-TPD表征结果表明,金负载量较小时,催化剂强酸中心峰面积较载体下降,负载量较大时,强酸和弱酸中心峰面积均下降;FT-IR表征结果表明,低温下金催化剂能将甲烷转化为含有烯烃双键的吸附物种,显示出载金催化剂对甲烷较强的C—H键活化能力。
The supported nano-sized HZSM-5 zeolite was prepared by ion exchange method. The supported nano-Au / HZSM-5 catalyst was prepared by vacuum-precipitation deposition method. XRD, UV-Vis, TEM, XPS, NH3-TPD and FT-IR and other characterization, and evaluate the methane adsorption performance of the catalyst. The results of XRD and TEM showed that the size of gold particles calcined at 2.0% Au / HZSM-5 in N2 atmosphere was small (5 ~ 10) nm. The UV-Vis characterization results indicated that the valence states of the supported gold from the ionic state To zero valence state, and the zero-valent gold absorption peak of 2.0% Au / HZSM-5 catalyst calcined in N2 atmosphere is weaker, that is, the corresponding particle size is smaller. The XPS characterization results show that the higher the gold loading, NH3-TPD characterization results show that when the gold loading is small, the peak area of strong acid center of the catalyst is lower than that of the carrier, and when the loading is large, the peak areas of strong acid and weak acid decrease; FT- IR characterization results show that the gold catalyst can convert methane into olefinic double bond-containing adsorption species at low temperature, indicating the strong C-H bond activation ability of the supported gold catalyst to methane.