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盐酸交换的氢型丝光沸石(HM),经400℃煅烧,室温吸附吡啶后,在低于400℃温度下进行脱附。吡啶在Lewis酸,Bronsted酸位置的光吸收,随脱附温度有线性变化。Lewis酸光吸收增强,Bronsted酸光吸收减弱。从光吸收改变量直接求得两种酸的消光系数比值ε_(1460厘米~(-1))~L/ε_(1545厘米~(-1))~B=1.44±0.10。用脉冲色谱中毒技术,测定吡啶吸附总量后,可得到摩尔消光系数ε~L=4.87厘米/微摩尔ε~B=3.38厘米/微摩尔采用上述方法,测定了HM表面上的酸分布。结果表明:Bronsted酸的浓度随煅烧温度的增加而下降,甲苯歧化的活性只与Bronsted酸的存在有关。
Hydrochloric acid-exchanged hydrogen type mordenite (HM) is calcined at 400 ° C, pyridine is adsorbed at room temperature, and desorption is performed at a temperature lower than 400 ° C. The absorption of pyridine in Lewis acid and Bronsted acid sites changes linearly with desorption temperature. Lewis acid absorption increased, Bronsted acid absorption decreased. The extinction coefficient ratio ε_ (1460 cm -1) ~ L / ε_ (1545 cm -1) ~ B = 1.44 ± 0.10) of the two acids was directly calculated from the change of light absorption. Using a pulse chromatography poisoning technique, the molar extinction coefficient, ε-L = 4.87 cm / micromolar ε-B = 3.38 cm / micromolar, was determined after total pyridine adsorption. The acid distribution on the HM surface was determined by the above method. The results showed that the Bronsted acid concentration decreased with the increase of calcination temperature. The activity of toluene disproportionation was only related to the presence of Bronsted acid.