Comparison of Lewis Acidity between Al-MCM-41 Pure Chemicals and Al-MCM-41 Synthesized from Bentonite

Tewfik Ali-Dahmane (Laboratoire de Chimie des Matériaux L.C.M, Université Oran1, BP-1524 El-Mnaouer, 31000 Oran|Algeria École Supérieure en Sciences Appliquées de Tlemcen (ESSAT), BP 165 RP Bel horizon, 13000 Tlemcen)
Lamia Brahmi (Laboratoire de Chimie fine L.C.F., Université Oran1, BP-1524 El-Mnaouer, 31000 Oran|Algeria Université A Belkaid, B.P 119, 22 rue Abi Ayad Abdelkrim, Fg Pasteur, 13000 Tlemcen)
Rachida Hamacha (Laboratoire de Chimie des Matériaux L.C.M, Université Oran1, BP-1524 El-Mnaouer, 31000 Oran)
Salih Hacini (Laboratoire de Chimie fine L.C.F., Université Oran1, BP-1524 El-Mnaouer, 31000 Oran)
Abdelkader Bengueddach (Laboratoire de Chimie des Matériaux L.C.M, Université Oran1, BP-1524 El-Mnaouer, 31000 Oran)

Bulletin of Chemical Reaction Engineering & Catalysis
2019: BCREC Volume 14 Issue 2 Year 2019 (August 2019)

This study focused on the Lewis acidity of Al-MCM-41 prepared from bentonite (Al-MCM-bentonite) as silica and aluminum source simultaneously. This acidity was compared with Al-MCM-41 synthesized from pure chemicals reagents (Al-MCM-standard). Structural analysis showed that the substitution of the silicon atom by the aluminum atom decreases the structural order of Al-MCM-standard, whereas Al-MCM-bentonite has a better structural organization. The Lewis acidity of the Al-MCM-bentonite was evaluated in allylation reaction of benzaldehyde with allyltrimethylsilane and pyridine adsorption experiments. The results showed that the difference in acidity between Al-MCM-standard and Al-MCM-bentonite is due to the amount of aluminum incorporated into the framework of our mesoporous materials. According to the EDX analysis, the incorporation of aluminum in Al-MCM-standard (Si/Al = 13.47) is more important than in Al-MCM-bentonite (Si/Al = 43.64). This explains the low acidity of Al-MCM-bentonite, and the moderate yields in the allylation reactions of benzaldehyde with allyltrimethylsilane.