Acid properties and catalysis of USY zeolite with different extra-framework aluminum concentration

• USY zeolite was prepared for purifying the aromatics.
• The reason for the enhancement after modifying by citric acid was discussed.
• The paper established an effective method for quantifying Lewis acid by Si/Al ratio.

USY zeolite was treated by the citric acid. The properties and catalysis of the USY zeolite were studied. The X-ray diffraction has been used to identify and quantify extra framework aluminum (EFAL) in USY zeolite by EFAL extraction using citric acid. The acid character changed depending on the EFAL concentration. The Lewis acid sites can be obtained from the Si/Al ratio. The removing of trace olefins was carried out over kinds USY zeolites with different amount of EFAL. The catalytic performance was correlated with the Lewis acid sites of USY.

It showed the removal of aluminum from USY zeolite by citric acid treatment and the rearrangement of aluminosilicate framework. The positive charge sited on the extra framework AlO+ can make an enhancement of the Lewis acid sites. It had been proved that the modification was significantly improved the activity of USY.Figure optionsDownload as PowerPoint slide