Effect of SnO2/Al2O3 ratio of Si-based MFI on its acidity and hydrophobicity: Application in selective hydroxyalkylation of p-cresol

• Silica based MFI type catalysts with various SnO2/Al2O3 ratios were synthesized.
• Al-free Sn-MFI catalyst showed excellent activity and complete product selectivity.
• Moderate acidity and hydrophobicity are necessary for highest activity–selectivity.
• Al-MFI having hydrophilic character gives lower activity and product selectivity.

Silica based MFI type molecular sieves with various SnO2/Al2O3 ratios were synthesized from gels having molar compositions SiO2:xSnO2:yAl2O3:0.23(TPA)2O:35H2O where 0 ≤ x ≤ 0.02 and 0 ≤ y ≤ 0.01. Recyclable, Al-free Sn-MFI catalyst showed 31% conversion of formaldehyde with 100% selectivity to 2,2′-methylenebis(4-methylphenol) in hydroxyalkylation of p-cresol with formaldehyde on account of moderate acidity and higher hydrophobicity.

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