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Boron‐substituted ZSM‐5 membranes: Preparation and separation performance
Author(s) -
Tuan Vu A.,
Noble Richard D.,
Falconer John L.
Publication year - 2000
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690460612
Subject(s) - membrane , boron , zeolite , chemistry , alkali metal , chemical engineering , silicon , porosity , chromatography , materials science , polymer chemistry , inorganic chemistry , organic chemistry , catalysis , biochemistry , engineering
ZSM‐5 zeolite membranes with boron substituted into the framework for silicon were prepared on porous stainless‐steel and α‐alumina tubular supports. These membranes had higher n‐C 4 H 10 /i‐C 4 H 10 separation selectivities, and effectively separated these isomer mixtures to higher temperatures than membranes with aluminum substituted into the framework. Membranes were prepared with Si/B ratios as low as 12, and the best membranes were prepared from alkali‐free gels. The highest n‐C 4 H 10 /i‐C 4 H 10 permselectivity at 473 K was 60, and the highest at 527 K was 24. For most alkali‐free membranes, the n‐C 4 H 10 /i‐C 4 H 10 permselectivities and separation selectivities increased with boron content, and membranes on α‐alumina supports had both higher permeances and separation selectivities. Membranes with the same permeances and selectivities can be reproducibly prepared, and they are stable at elevated temperatures.