Lamellar Aluminosilicate acidity in the presence and absence of water

• Grant number: 22/05743-0
• Support Opportunities: Scholarships in Brazil - Master
• Effective date (Start): December 01, 2022
• Effective date (End): April 30, 2024
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Heloise de Oliveira Pastore
• Grantee: Paulla Beatriz França de Sousa
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Zeolites are microporous crystalline solids that offer a number of advantages for catalytic reactions, mostly because they present shape selectivity to reactants and products. However, the access to the acid sites by voluminous molecules is hindered by the channels and cages limitations. Contrarily, lamellar silicates are known by their ion exchange properties and by the possibility to isomorphously substitution of a part of the layer atoms by heteroatoms which can give the 2D-materials acidic properties to be used in catalysis. For this work, the lamellar silicate Na-[Al]-RUB-18 where the silicon isomorphous substitution by aluminum in the structure is known, with a range of Si:Al molar ratios, to determine similarities and differences between the acidic properties in anhydrous and humid conditions, and correctly direct the solids to the specific catalytic reactions with large molecules such as biomass conversions. For that, aluminum will be incorporated by hydrothermal post synthesis method and a deep characterization of the as prepared aluminosilicates will be performed. In the identification of structure, textural and morphological characteristics as well as chemical composition, X-rays diffraction and fluorescence, N2 cryogenic adsorption, scanning electron microscopy and 29Si and 27Al-nuclear magnetic resonance will be performed. Nature, strength and quantification of acidic sites will be studied by Fourier transformed infrared spectroscopy using pyridine as probe-molecule, ammonia thermoprogrammed desorption and 27Al nuclear magnetic resonance, as well as 31P-NMR of trialkylphosphine oxide adsorbed onto the solids surface.