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在前文研究天然Stilbite沸石(CXN沸石)水热稳定性影响因素的基础上,以27Al与29Si MAS NMR,NH3-TPD和低温氮吸附等详细研究了铵型CXN沸石骨架铝配位状态和硅配位状态,表面酸性与孔性质等与水蒸汽处理温度的关系.随温度升高,沸石骨架硅铝比逐渐提高,并伴随硅羟基缺陷增多.经750℃水蒸汽处理3 h后沸石骨架硅铝比可达到21.3.沸石总酸量随水蒸汽处理温度的提高而降低,沸石骨架铝脱除造成沸石孔道部分被堵塞,但同时形成有利于分子扩散的介孔.
Based on the previous studies on the factors that affect the hydrothermal stability of natural Stilbite zeolites (CXN zeolites), the aluminum coordination states and the silicon distributions of ammonium-type CXN zeolites were studied in detail by 27Al and 29Si MAS NMR, NH3-TPD and low temperature nitrogen adsorption. The state of the surface acidity and the nature of the pore and the temperature of water vapor treatment.With the increase of temperature, the ratio of silica to aluminum of the zeolite framework increases gradually with the increase of the defects of silanol groups.After treated with steam at 750 ℃ for 3 h, Than the maximum achievable 21.3.The total acidity of zeolite decreased with the increase of steam treatment temperature. The removal of zeolite framework aluminum resulted in the blockage of zeolite pores, but at the same time, mesopores were formed which were favorable for molecular diffusion.