【摘要】 用红外光谱法考察了HY,CaHY,LaHY及相应的经超稳化处理的USY,CaUSY,LaUSY分子筛。也对比了HY,USY及其进一步用NH₄⁺交换的USYH分子筛。USY的3700cm^-1特征谱带强度不仅与Na⁺含量有关,也与其它阳离子如Ca²⁺,La³⁺的含量有关。从OH基伸缩振动区的谱带看到,La有稳定结构羟基和抑制脱铝的作用。观察了各超稳化分子筛的各个OH基谱带及它们在不同吡啶脱附温度下的变化。HY,USY刚USYH的酸量及其强度有很大差别,它们的B酸强度不同,USYH的L酸强度出乎预料地高。正癸烷裂化活性与B酸有较好对应关系。讨论了超稳化处理、阳离子性质、后NH₄⁺交换等因素对分子筛的酸性、稳定性和酸中心可接近性的影响。更多还原

【Abstract】 HY, CaHY, LaHY and the corresponding ultrastable treated USY, CaUSY, LaUSY zeolites were studied by means of infrared spectroscopy. In comparison with HY and USY, USYH obtained by further NH4+ ion exchange of USY was also examined.It was found that the intensity of 3700cm-1 band of MeUSY depended not only on the content of Na+, but also on the content of other cations, such as Ca2+ and La3 + . Spectra in the region of OH stretching vibration showed that the presence of La3+ stabilized the skeletal OH groups in zeolites. The intensity of spectral band around 1545 and 1455cm-1 and its change at different desorption temperatures of pyridine were examined for characterizing the quantity and the strength of acidity of zeolites. It was revealed that HY, USY and USYH behaved quite differently in this respect. Their Bronsted acid strength are of three different levels and the Lewis acid strength of USYH is unexpectedly high. A better corresponding relation between the cracking activity for n-decane and Bronsted acid strength is found. These three, zeolites samples, in acidity, may be taken as representatives of zeolites investigated in this paper.Discussion on the effect of ultrastable treatment, the properties of cations and subsequent NH4+ exchange on the stability of zeolites, the nature and accessibility of the acid sites was given.更多还原