Rational design of bifunctional hierarchical Pd/SAPO-5 for the synthesis of tetrahydrofuran derivatives from furfural

The one-pot aldol condensation/crotonization reaction between furfural and methyl isobutyl ketone (MIBK), followed by hydrogenation with molecular H-2, was implemented for preparing tetrahydrofuran derivatives. To this aim, we developed a robust Pd/HPSAPO-5 catalyst based on the crystalline silicoaluminophosphate SAPO-5 with hierarchical porosity and optimized silicon content. The hierarchical HPSAPO-5 catalyst was synthesized using a bottom-up method starting from pre-synthesized MCM41, with the surfactant (CTAB) inside the mesopores, serving both as Si source and mesoporogen. NH3-TPD and FT-IR spectroscopy of adsorbed probe molecules combined with solid-state H-1 MAS NMR were used to assess the nature, strength and accessibility of the acid sites. The structural and textural properties of the catalysts were investigated using X-ray diffraction (XRD) and N-2 adsorption. HR-TEM was used to assess the dispersion and location of Pd nanoparticles on HPSAPO-5. The spent catalyst could be restored and reused after calcination. (C) 2021 Elsevier Inc. All rights reserved.