Synthesis and catalytic applications of novel mesoporous aluminosilicate molecular sieves

Four different aluminum compounds are examined as Al source in the hydrothermal synthesis of the mesoporous aluminosilicates of MCM-41 type, including pseudo boehmite, aluminum sulfate, aluminum isopropoxide and sodium aluminate. X-ray diffraction results show that there are differences in the d₁₀₀ spacings for the samples prepared with different Al sources: sodium aluminate>Al isopropoxide>Al sulfate>pseudo boehmite. Such differences reveal that Al incorporation in the framework increases in the following order: pseudo boehmite<Al sulfate<Al isopropoxide<sodium aluminate. ²⁷Al NMR and ²⁹Si NMR reveal that most of the Al species in the samples prepared with pseudo boehmite are present in octahedral coordination.