程序升温-漫反射红外光谱考察SAPO-34分子筛表面酸性质

Investigation of the Character of Surface Acidity of SAPO-34Molecular Sieve by Programmed Temperature-Diffuse Reflectance IR-FTS

将程序升温 -漫反射红外光谱用于表征磷酸硅铝分子筛SAPO_34表面酸性质 ;结果表明 ,SAPO_34分子筛中的桥联羟基Si—OH—Al具有较强的热稳定性 ;结合NH3 探针考察表明 ,SAPO_34分子筛具有B酸和L酸两种酸中心 ,其中B酸较强 ,是SAPO_34酸性的主要部分 ,而L酸中心较弱。

The character of surface acidity of SAPO-34molecular sieve was investigated by a newin-situ technique,the programmed temperature-diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).The results showthat the bridged Si—OH—Al groups in SAPO-34have higher heat stability(873K).This method coupled with NH 3 molecular probes indicates that SAPO-34has both Br⒐nsted and Lewis acidic centers.It was found that the Bronsted acidic center is stronger than the Lewis acidic center and is the main source of the acidity of molecular sieve.