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HY型沸石经过400℃真空煅烧,150℃吸附吡啶,分别在150℃、200℃、250℃、300℃、350℃真空脱附,先由红外光谱测得吸附在Lewis酸(简称L酸)和Bronsted酸(简称B酸)中心的吡啶吸收峰消光度(频率分别为1453cm~(-1)和1543cm~(-1)),然后,由紫外光谱测定其吡啶含量。求得两个红外吸收峰的消光系数为:ε~L=0.095±0.005cm~2/μmol,εB=0.065±0.004cm~2/μmol,计算了两种酸的酸量。测定了HY沸石和超稳Y沸石表面酸的酸强度分布。HY沸石的总酸量比超稳Y高,超稳Y酸强度比HY强。稳定化过程使总酸量减小,酸强度增加。在HY沸石中,L酸酸量随煅烧温度升高而升高,B酸酸量在300℃左右煅烧时达到最大,总酸量在300—350℃煅烧时出现最大。这与HY沸石催化苯的烷基化反应转化率比较,催化活性和总酸量存在密切联系。
HY zeolite was vacuum calcined at 400 ℃ and pyridine was adsorbed at 150 ℃. The HY zeolite was vacuum desorbed at 150 ℃, 200 ℃, 250 ℃, 300 ℃ and 350 ℃, respectively. The adsorption of Lewis acid (L acid) and The pyridine absorption peak extinction (1453 cm -1 and 1543 cm -1, respectively) of the Bronsted acid center was determined. The pyridine content was determined by UV spectroscopy. The extinction coefficients of the two kinds of acids were calculated as follows: ε ~ L = 0.095 ± 0.005cm ~ 2 / μmol, εB = 0.065 ± 0.004cm ~ 2 / μmol. The acid strength distribution of the surface acid of HY zeolite and ultrastable Y zeolite was determined. The total acidity of HY zeolite is higher than that of ultrastable Y. The strength of ultrastable Y acid is stronger than that of HY. The stabilization process reduces the total acidity and the acid strength increases. In HY zeolite, the amount of L acid increased with the increase of calcination temperature, the amount of B acid reached the maximum when calcined at about 300 ℃, and the total acidity reached the maximum when calcined at 300-350 ℃. This HY zeolite catalyst benzene alkylation reaction conversion rate, the catalytic activity and the total amount of acid is closely linked.