[B]MFI membrane: Synthesis, physico-chemical properties and catalytic behavior in the double-bond isomerization of 1-butene

An MFI type borosilicate, [B]MFI (Si/B = 56), membrane was synthesized on the external surface of tubular α-alumina support. The structure, morphology and acidity of the synthesized membrane were characterized by X-ray diffraction, SEM and FT-IR spectroscopy. A flow-through membrane reactor was constructed and the simultaneous catalytic and separation selectivity of the membrane was tested in the double-bond isomerization of 1-butene in the temperature range of 120–250 °C and at 1-butene partial pressure of 18 and 50 kPa. No product of skeletal isomerization was formed under these conditions. The catalytic selectivity is attributed to the low acid strength of the Brønsted sites generated by the framework boron. Equilibrium trans/cis-2-butenes ratio was obtained in the retentate stream (1.4–1.5), whereas, that ratio at the permeate stream was up to ∼2.2 at 250 °C. The high trans/cis ratio was attributed to the permeation selectivity of the MFI membrane for trans-2-butene.

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