Determination of the positions of aluminum atoms introduced into SSZ-35 and the catalytic properties of the generated Brønsted acid sites

Abstract

The positions of aluminum (Al) atoms in SSZ-35 together with the characteristics of the generated protons were investigated by Al multiple quantum magic-angle spinning (MQ-MAS),Si MAS, and H MAS NMR data analyses accompanied by a variable temperatureH MAS NMR analysis. The origin of the acidic -OH groups (Brønsted acid sites) generated by introducing Al atoms into the T sites was investigated and the T sites introduced into the Al atoms were revealed. To further determine the catalytic properties of the acidic protons generated in SSZ-35, the influence of the concentration of the Al atoms on the catalytic activity and selectivity during the transformation of toluene was examined.

Control of Al Distribution in the CHA-Type Aluminosilicate Zeolites and Its Impact on the Hydrothermal Stability and Catalytic Properties

“…The distribution of Al atoms in the zeolite framework has been recognized as an important factor for catalytic activity and selectivity, and its control and evaluation have been extensively tackled by many research groups. − In aluminosilicate zeolites, to balance the charge, Al 3+ atoms in silica framework, (SiO 4 ) 4– , are located near cations, including inorganic cations, e.g., Na + and K + , and/or organic ones. We have reported the control of the Al distribution in the MFI framework based on the rational choice of inorganic and/or organic cations and the use of alcohols as the pore-filling agent. − …”