【摘要】 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ε1460厘米-1L/ε1545厘米-1B=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εL=4.87厘米/微摩尔εB=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。更多还原

【Abstract】 The H+ mordenite sample was prepared by hydrochloric acid exchange. It was calcined under vacuum at 400℃ for 24 hr, cooled to room temperature and then allowed to adsorb pyridine vapour for 30 min. The absorption bands of pyridine adsorbed on H+ mordenite surface were observed at relatively low temperature, after calcination in vacuum the temperatures of calcination being 250°, 300°, 350°, and 400℃.The characteristic absorption band 1545 cm-1 was due to adsorption of pyridine on Bronsted acid site, and band 1460 cm-1 was due to adsorption on Lewis acid site. The intensity of adsorption band 1545cm-1 decreased and that of band 1460cm-1 increased linearly as the calcination temperature was increased from 250° to 400℃. Thus, it made possible to determine the ratio of differential absorbance （⊿A） and relative molecular extinction coefficient （ε） in the differential temperature ranges if each Bronsted site was converted into one Lewis site and if the sample disc thickness was uniform. Then, the relative molecular extinction coefficient was given by(ε1460cm-1L)/ε1545cm-1B)=(⊿A1460cm-1L/⊿1545cm-1B)=1.44±0.10Under similar conditions, the total amount of adsorption of pyridine was measured by poisoning titration method. The values of molecular exitinction coefficients could be obtained by infrared spectra coupled with poisoning titration method. These values wereε1545cm-1B=3.38 cm/μ mole for Brnsted siteand ε1460cm-1L=4.87 cm/μ mole for Lewis site.The surface acid centers of H+ mordenite have been measured by this method. It has been found that the Brnsted acid centers decreased as calcination temperature was increased and the activity of disproportion ation of toluene was dependant only on Brntsed acid centers present.更多还原