Effect of Al sources on the synthesis and acidic characteristics of mesoporous aluminosilicates of MCM-41 type

This paper reports the synthesis of four series of mesoporous aluminosilicates (Al-MCM-41) and their acidic characteristics. Four different Al compounds were examined as Al source in the hydrothermal synthesis of Al-MCM-41, including pseudo boehmite, aluminum sulfate, aluminum isopropoxide, and sodium aluminate. Synthesized samples were characterized by XRD, chemical analysis, nitrogen adsorption, and ²⁷Al MAS NMR. The acidic characteristics of the Al-MCM-41 samples were characterized using temperature-programmed desorption of n-butylamine, and probe hydrocracking reactions of 1,3,5-triisopropylbenzene and 1,3,5-tri-t-butylbenzene. The results clearly indicate that the Al source used for synthesizing Al-MCM-41 samples has a major impact on the Al incorporation in their framework and their acidic properties. Al-MCM-41 prepared with Al isopropoxide and sodium aluminate showed improved acidic properties than those with pseudo boehmite and Al sulfate.