Temperature Effect on 1H Chemical Shift of Hydroxyl Groups in Zeolites

用298~673K的变温1H魔角旋转核磁共振(1H MAS)谱研究了温度对H+交换分子筛(ZSM-5型分子筛，包括硅沸石、丝光沸石和Y型分子筛)中羟基引起的1H化学位移的影响。根据变温~1H-MAS核磁共振法测定了沸石分子筛的~1H化学位移与分子筛中羟基的酸强度之间的关系，根据已报道的热分析数据，如NH3程序升温脱附法测定了NH_3的吸附热，以及对乙醇和1-己烯转化的催化活性，讨论了分子筛的~1H化学位移与分子筛中羟基的酸强度的关系。

The influence of temperature on 1H chemical shift due to hydroxyl groups in H+-exchanged any kinds of zeolites (ZSM-5 type zeolites including silicalite, mordenite and Y zeolites) was examined by variable temperatures 1H magic-angle spinning nuclear magnetic resonance (1H MAS NMR) spectroscopy measured from 298 to 673 K. The temperature dependence of the 1H chemical shift due to the bridging hydroxyl groups was more pronounced than that due to the terminal silanol groups and also the nest silanol groups. The relationship between the 1H chemical shift and the acid strength of the hydroxyl groups in zeolites was discussed on the basis of the variable temperature 1H MAS NMR measurements of zeolites, previously reported thermal analysis data, such as the heat of NH3 adsorption measured by NH3 temperature-programmed desorption, and also the catalytic activity for the conversion of ethanol and 1-hexene.