Zeolite capillary microreactor by flow synthesis method
A catalytic layer of CsNaX zeolite film was deposited on quartz capillary tube by flow synthesis method under hydrothermal conditions. The procedure involved seeding of the capillary tube with zeolite nanocrystals followed by controlled zeolite regrowth and crystallization under flow conditions. The CsNaX capillary microreactor was employed in Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate. The sensitivity of the catalyst to water produced by the condensation reaction was remedied with the use of solvents. Ninety nine percent benzaldehyde conversions were obtained using a traditional solvent DMSO, but decreased with time as water accumulates and poisons the catalyst. Replacing the solvent with an ionic liquid (IL-BMIC) improves water absorption and the catalyst displayed better (i.e., >99%) and stable conversions.
Graphical abstractA continuous and uniform zeolite NaX film was successfully synthesized in a quartz capillary tube by flow synthesis to form a zeolite film microreactor. The capillary microreactor with CsNaX zeolite film catalyst exhibited higher catalytic performance for Knoevenagel condensation of benzaldehyde (BA) and ethyl cyanoacetate (ECA) by replacing the solvent DMSO with an ionic liquid (IL-BMIC).Figure optionsDownload full-size imageDownload high-quality image (195 K)Download as PowerPoint slideHighlights► A layer of zeolite film/membrane is formed in a quartz capillary by flow synthesis to construct a zeolite film microreactor. ► The zeolite film microreactor shows excellent performances in Knoevenagel reaction of BA and ECA. ► Replacing the solvent with an ionic liquid improves water absorption and the catalyst could display better and stable conversions.
Journal: Catalysis Today - Volume 193, Issue 1, 15 October 2012, Pages 221–225