engleski

Mechanochemical amorphization of MOF-74 catalyst for selective conversion of CO2 to methanol

Carbon capture and storage technologies can significantly decrease our demand for fossil fuels. Hydrogenation of CO2 over a mixed-metal Cu/ZnO/Al2O3 catalyst is a promising industrial process that can efficiently utilize CO2 by converting it to methanol.[1] However, new catalytic materials are being studied to improve process selectivity. Metal-organic frameworks (MOFs) are crystalline porous materials composed of metal-containing nodes and organic linkers, which have vast application potential. Due to the high level of tunability of their physicochemical properties, MOFs are good candidates for improving the selectivity of the aforementioned catalytic process. We wanted to determine whether the high porosity and accessibility of metal nodes in MOF- 74 make this MOF suitable for this catalytic purposes. The catalysts were prepared by ball milling, which was shown to allow stoichiometrically controlled preparation of bimetallic MOF-74 materials.[2] The catalytic performance of the prepared ZnCu-MOF-74, monometallic Cu-MOF-74, and industrial Cu/ZnO/Al2O3 catalyst was evaluated. Also, we were interested in how the introduction of defects and the collapse of the porous structure of MOF-74 by mechanochemical amorphization will affect the catalytic activity and selectivity for methanol in the given catalysts. Bimetallic ZnCu-MOF-74 was found to have better catalytic performance comparing to Cu-MOF-74. Post-synthetic mechanochemical amorphization of ZnCu-MOF-74 resulted in a significant rise in both the activity and selectivity despite the destruction of the ordered, porous MOF-74 structure.[3] The results emphasize the importance of defects for the MOF catalytic activity and the potential of amorphous MOFs to be considered as heterogeneous catalysts. Given that, we will further explore the prospect of the mechanochemical MOF transformations as a tool for MOF properties enhancement.

mechanochemistry ; MOF-74 ; amorphization ; catalysis ; CO2 hydrogenation

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