A novel hierarchically structured siliceous packing to boost the performance of rotating bed enzymatic reactors

- Engineering of silica pellets with hierarchical pore structure devised and tested.
- Effective immobilization of model enzyme to obtain structured biocatalysts.
- Rotating bed (SpinChem) reactor performance boosted ten-fold against benchmark.

In this paper we demonstrate exceptional performance of a new type of packing made of the siliceous pellets with hierarchical pore structure in micrometric and nanometric scales, devised for the application in SpinChem® reactors. Rotating bed (enzymatic) reactors of SpinChem® type emerge as a new type of very effective, small catalytic reactors designed for the synthesis of fine chemicals. The pellets/catalysts of two sizes and two hierarchical pore structures were fabricated using sol-gel method combined with phase separation and pore templating, and after covalent attachment of a model enzyme (invertase) tested in a sucrose hydrolysis reaction. For the same enzyme load, the pellets/catalysts of ca. 3.5-5.5 mm in size with pore structure predominated by flow-through macropores of 20-50 μm (pore volume ca. 2.5-3 cm3/g) and mesopores of about 30 nm (pore volume > 1 cm3/g) appeared to be more active than somewhat smaller ones with the same pore structure, and 6-7 times more active than those of the same size but with macropores of 10-12 μm, and nearly ten times more active than prepared using mesopores predominated Kieselgel 60 (considered as benchmark). Nearly full (99%) conversion was obtained in 75 min reaction time using the proposed structured catalysts/pellets, whereas for the benchmark it was 26%. The catalysts were shown to be stable in ten reaction runs and the pellets of used catalysts could be regenerated by calcinations. The regenerated pellets could also be reused at least 4-5 times as supports for the new/fresh enzyme.

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