Synthesis of Al2O3-nanowhisker-based HKUST1 MOF composites

Highlights: • MOF composites based on MOF HKUST1 and nanowhiskers of modified Al₂O₃ were prepared. • The obtnaied materials are real composites and not just a physical mixture of these constituents. • The oxides affected the crystal growth of MOF HKUST1 changing the crystallinity. • The mesopores in the composites enable access for large molecules in catalysis applications. -- Abstract: This paper reports the synthesis of metal-organic framework (MOF) composites based on MOF HKUST1 and Al₂O₃ nanowhiskers (NWs), functionalized with different ratios of (3-aminopropyl)triethoxysilane (APTES). The effect of the Al₂O₃ NW content on the properties of the MOF HKUST1 composites was also reported. The synthesized materials were shown to be real composites and not a physical mixture of the constituents. In addition, the high Al₂O₃ content in the MOF HKUST1 matrix hampered the thermal and textural properties of the composite. This behavior may be related to the effects of APTES NWs on composite synthesis. The oxides affected the crystal growth of MOF HKUST1, changing the crystallinity of the composites. However, when the optimal amount of APTES NWs was used for the composite synthesis, i.e., 10% w/w (copper and APTES NWs), the main characteristic features of the MOF were retained by the composites, as demonstrated by X-ray diffraction, thermogravimetric analysis, and CO₂ uptake at 298 K.