Tailoring the accessibility and amphiphilicity of MWW zeolites for two-phase glycerol ketalization

Author(s)

Lima, Diego S. D. ; Silva, Laura L. L. ; Zapelini, Iago W. W. ; Mintova, Svetlana ; Martins, Leandro

• Document type: Journal article
• Source: INORGANIC CHEMISTRY FRONTIERS; v. 10, n. 19, p. 13-pg., 2023-08-23.

Abstract

Two MWW zeolite catalysts, purely microporous MCM-22 (3D) and hierarchical ITQ-2 (2D), were synthesized and functionalized with dodecyltriethoxysilane. The functionalized zeolites were employed in a two-phase glycerol ketalization reaction with acetone. There are two crucial factors to consider in this reaction: (i) the kinetic diameter of glycerol is comparable to the size of catalyst pores, limiting its accessibility to the active sites and (ii) glycerol exhibits poor solubility in acetone, causing the reaction to predominantly occur at the interfaces. Therefore, it is essential to focus on enhancing the accessibility of chemicals to the inner catalyst pores and adjusting the hydrophilic-hydrophobic balance of the functionalized catalysts to improve the reaction performance. The accessibility of the catalysts was indirectly evaluated by the chemisorption of pyridine and 2,6-di-tert-butylpyridine, which confirmed that ITQ-2 had a superior capacity to accommodate bulkier chemicals. Moreover, contact angle measurements of glycerol on ITQ-2 zeolites indicated that the functionalized materials exhibited reduced interaction with glycerol due to their increased hydrophobic nature. As a result, the functionalized materials tended to accumulate in the interfacial region, facilitating the dispersion of glycerol droplets within the reaction medium and eliminating the need for an additional solvent to homogenize the system. However, the hydrophobic characteristic played a more significant role at the beginning of the reaction since, after reaching 25% conversion, the system transitioned into a single phase as the product acted as a solvent. (AU)

• FAPESP's process: 17/21965-5 - Synthesis and catalytic uses of embryonic zeolites possessing acidic ou basic sites
• Grantee: Laura Lorena da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/01789-6 - Lamellar and amphiphilic zeolitic catalysts for reaction with bulky molecules in immiscible systems
• Grantee: Diego Sarmento Duncan Lima
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 21/08326-9 - Effects of crystallinity and different amines on the acid-base catalytic properties of amine-grafted H-aluminosilicates
• Grantee: Iago William Zapelini
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products
• Grantee: José Maria Correa Bueno
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/12486-1 - Multi-User Equipment approved in grant 2018/01258-5: gas chromatograph
• Grantee: Leandro Pierroni Martins
• Support Opportunities: Multi-user Equipment Program