| Autor: |
Grönke, Martin, Arrozi, Ubed S. F., Bronkalla, Nadine, Schmidt, Peer, Valldor, Martin, Oswald, Steffen, Woodcock, Thomas G., Eckert, Victoria, Hao, Qi, Plüschke, Laura, Lederer, Albena, Nielsch, Kornelius, Büchner, Bernd, Kaskel, Stefan, Hampel, Silke |
| Zdroj: |
Chemistry of Materials; 20240101, Issue: Preprints |
| Abstrakt: |
The transition metal halide α-titanium(III) chloride (α-TiCl3) is a layered two-dimensional compound and a well-established Ziegler–Natta catalyst for the polymerization of ethylene. A new synthesis technique is used to obtain thin sheets of α-TiCl3that show exceptional physical properties in contrast to their bulk counterparts, due to an enlarged surface-to-volume ratio. Chemical vapor transport (CVT) of α-titanium(III) chloride directly on substrates results in microsheets that exhibit an improved catalytic effect. For rational planning of synthesis conditions, thermodynamic simulations of occurring gas-phase equilibria were performed. Based on these calculation results, crystal growth was achieved by adding GaCl3via pure short term CVT in a temperature gradient of 700–600 K on yttrium-stabilized zirconia (YSZ) substrates. Phase pure, as-grown, single crystal sheets with high crystallinity and a thickness of around 4 μm were obtained. These thin sheets of α-TiCl3on YSZ substrates were implemented as catalysts for the ethylene polymerization reaction. A significant improvement of catalytic activity of 16% was achieved, probably due to an increased surface-to-volume ratio. As a highlight, the as-grown microsheets were exfoliated subsequently to a thickness lower than 200 nm and an even higher catalytic activity of up to 24% was confirmed experimentally due to delamination effects. This is the first time that an improved catalytic effect of α-TiCl3is observed as a result of downscaling from bulk to microsheets by CVT. |
| Databáze: |
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