Hierarchical FAU/ZIF-8 Hybrid Materials as Highly Efficient Acid–Base Catalysts for Aldol Condensation

Abstract

The composite of hierarchical faujasite nanosheets and zeolitic imidazolate framework-8 (Hie-FAU-ZIF-8) has been successfully prepared via a stepwise deposition of ZIF-8 on modified zeolite surfaces. Compared to the direct deposition of metal organic frameworks (MOFs) on zeolite surfaces, ZIF-8 nanospheres were selectively attached to the external surfaces of the MOF ligand-grafted FAU crystals because of the enhancing interaction between the zeolite and MOF in the composite. In addition, the degree of surface functionalization can be greatly enhanced because of the presence of hierarchical structures. This behavior leads to an increase in the deposited MOF content, improving the hydrophobic properties of the zeolite surfaces. Interestingly, the designed hierarchical composite exhibits outstanding catalytic properties as an acid-base catalyst for the aldol condensation of 5-hydroxymethylfurfural with acetone. Compared to the isolated FAU and ZIF-8, a high yield of the product, 4-[5-(hydroxymethyl)furan-2-yl]but-3-en-2-one (67%), can be observed in the composite because of the synergistic effect between the Na-stabilized zeolite framework and the imidazolate linkers bearing basic nitrogen functions. This opens up interesting perspectives for the development of new organic and inorganic hybrid materials as heterogeneous acid-base catalysts.

Advances in porous and nanoscale catalysts for viable biomass conversion

“…The selective anchoring of metal organic framework (MOF) nanospheres on a hierarchical zeolite (FAU) assisted to improve its hydrophobic nature, due to the surface functionalization of the zeolite. 520 The degree of surface functionalization and hydrophobicity can be easily tuned by optimizing the amount of deposited MOF and the number of deposition cycles. Zeoliteencapsulated metal nanoparticles may contain contaminated water because of the hydrothermal conditions used for their synthesis.…”

Tuning the Catalytic Performance of Novel Composites Based on ZIF‐8 and Nafen through Dimensional and Concentration Effects in the Synthesis of Propylene Glycol Methyl Ether

“…Moreover, this material contains both Lewis acid sites attributed to Zn 2+ ions (LAS) and basic sites associated with the imidazole units in its framework . Because of these properties, ZIF‐8 was successfully used as the catalyst for the conversion of CO 2 to cyclic carbonates,, Knoevenagel reactions, aldol condensation and trans‐esterification of vegetable oil with alcohols . Therefore, this material is a good candidate for the synthesis of PGME from PO and methanol.…”

“…This phenomenon can contribute essentially to the activity and selectivity control. Actually, the size effect was demonstrated for the inorganic solid acid catalysts, such as SAPO‐34, and H‐ZSM‐5 , . In general, the reduction of the particle size from the micrometer to the nanometer scale leads to significant changes in physicochemical properties of a solid catalyst as well as in its performance.…”

ZIF‐8‐Nanocrystalline Zirconosilicate Integrated Porous Material for the Activation and Utilization of CO2 in Insertion Reactions

“…MOF based catalysts are relatively unstable under liquid phase conditions. Therefore, efforts are being made to develop hybrid and stable porous MOF‐zeolite or MOF‐silica catalysts for various catalytic applications . Zeolite and MOF based hybrid porous materials would be suitable for the CO 2 insertion reaction.…”

“…Therefore, efforts are being made to develop hybrid and stable porous MOF-zeolite or MOF-silica catalysts for various catalytic applications. [33][34][35][36] Zeolite and MOF based hybrid porous materials would be suitable for the CO 2 insertion reaction. Zeolites have the capability to adsorb CO 2 whereas certain MOFs have the capability to adsorb and activate CO 2 .…”