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用量热滴定法、电位滴定法、脉冲色谱法等技术测定了各种热分解NH_4Y型沸石的总酸度、质子酸度、最高酸强度以及催化裂解反应活性,并对上述沸石的吸附吡啶进行了DTA—TG和N(1s)电子能谱的研究。结果表明,沸石的弱结合Al(16—17Al/U.C.)移去后,其总酸度略有下降,酸强度稍有增加,异丙苯裂解活性未发现明显变化。随着脱Al量的递增,吸附吡啶量降低。XPS图显示出,未脱Al的NH_4Y型沸石和脱Al沸石经焙烧后的差别,近乎是在“很薄”的表面层范围内。表面Al(OH)_(3-x)~(x+)阳离子不是沸石酸性和催化活性的决定因素,热分解NH_4Y型沸石的酸性主要来源于其骨架质子。
The total acidity, proton acidity, the highest acid strength and the catalytic cracking reactivity of various pyrolyzed NH_4Y zeolites were determined by thermometric titration, potentiometric titration and pulse chromatography. The adsorption of pyridine on these zeolites was characterized by DTA- Study of TG and N (1s) Electron Energy Spectrum. The results showed that the total acidity of Al (16-17Al / U.C.), Which is a weak bond of zeolite, decreased slightly, the acid strength increased slightly, and no obvious change of cumene cracking activity was found. As the amount of de-Al increases, the amount of pyridine adsorbed decreases. The XPS pattern shows that the difference between the non-Al-converted NH 4 Y zeolite and the de-Al zeolite after calcination is almost within the “very thin” surface layer range. The surface Al (OH) _ (3-x) ~ (x +) cations are not the decisive factors for the acidity and catalytic activity of zeolites. The thermal decomposition of NH_4Y zeolites mainly comes from their backbone protons.