Effect Of Rehydration On Structure Evolution And Ammonia Adsorption-Desorption Of Calcined Palygorskite

Palygorskite is a hydrated magnesium aluminium phyllosilicate of layer chain structure. Due to its special nano-rod crystal structure and properties, so that this type of clay has many special application performance, Which the adsorption properties is one of the many important features. The Palygorskite development of microporous channels and huge surface area, NH3molecules are free to enter into the pore, which is one of the sources of Palygorskite adsorption properties of small polar molecules. NH3is also a basic probe molecules, By NH3adsorption-desorption experiments of different temperature calcined Palygorskite can detect different types of acid sites as well as surface acidity changes on the Palygorskite.About the evolution of the structure on heated Palygorskite during dehydration have been reported, the results show that the appropriate heat treatment to improve their physical and chemical properties, but very few studies about the surface properties change in the hydration of heat treatment Palygorskite. In this thesis, the structure recovery of the heated Palygorskite rehydration and the adsorption and desorption of NH3, reveals the NH3adsorption mechanism. Mechanism of Adsorption of small gas molecules to provide the necessary experimental basis and theoretical guidance.By a small line mass spectrometer as the main analytical tools, through temperature-programmed control furnace fixed bed reactor evaluate NH3adsorption-desorption performance of different temperature calcined Palygorskite, combined with the X-ray diffraction, X-ray fluorescence analysis and specific surface area analysis and other modern analytical techniques to study the structure evolution, changes in the specific surface area, surface properties of NH3adsorption and desorption performance of two different causes of palygorskite calcined in different temperature.The results showed that, with the increase of the calcination temperature, the palygorskite surface adsorbed water and pore adsorbed water removal step by step, specific surface area first increase and then decrease, and100℃is calcined palygorskite adsorption of NH3activation temperature point, having largest specific surface area. With the removal of crystal water and structural water within the palygorskite pore, The structure of the folding collapse, the pore folding temperature between250～300℃, only less than300℃calcined palygorskite after rehydration the pore folding can restore.palygorskite after200～300℃calcination, rehydration treatment, a significant increase in the NH3adsorption than unhandled palygorskite,250℃is NH3adsorption of calcined palygorskite rehydration treatment best temperature point.