(50c) Mixed Matrix Membranes for Butanol Recovery Based on Zeolites As Macro-Crosslinkers

Mixed
matrix membranes for butanol recovery based on zeolites as macro-crosslinkers

Song Hu¹, Peiyong Qin^1,*

¹National energy R&D center for
biorefinery, Beijing University of Chemical
Technology, Beijing, China

Biobutanol
produced by biomass fermentation is critical for the development of sustainable
and renewable biofuel. Mixed matrix membrane (MMM) is considered to be a promising
choice for butanol recovery from fermentation via pervaporation.

In previous
work, methods for fabrication of MMM only focus on improving fillers¡¯ physical
compatibility and ignore the potential of chemical bridging between
polymer and fillers, thus it is still hard to obtain a sufficiently
thin selective membrane layer with high particles loading.

Herein, we
report a method for the fabrication of an efficient membrane for butanol
recovery using micron-sized particles of surface modified silicalite-1 as macro-crosslinkers
within a polydimethylsiloxane (PDMS) matrix (as shown in Fig. 1). In this
method, silicalite-1 of nano- and micron-sized
particles were synthesized and surface modified with a range of alkyloxysilanes in the fabrication of mixed matrix
membranes (MMMs) in order to minimize the undesirable voids. Moreover, silicalite-1 particles in MMMs have a double function which not
only provided
transport channels of high selectivity, but also reacted with the hydroxyl groups of PDMS during membrane
formation. The highest separation performance was obtained by
incorporating micron-sized n-propyltrimethoxysilane
(PTMS)-modified silicalite-1 into the PDMS membrane at a loading of 63 wt. %. A
high separation factor of 72.9 and a normalized total flux of 1156 g/m²h
were obtained in separating n-butanol from a 1.5 wt. % aqueous solution at 55 ^oC. Compared to the pure PDMS membrane, the
separation factor and normalized butanol flux were increased by 83.6 % and 19.7
%, respectively.

Fig. 1 Schematic diagram
of the strategies for improving the interactions and eliminating the
undesirable voids, and rheology of membranes in curing process.

Additionally,
MCM-41 (mesoporous) was also used as fillers in fabricating of mixed matrix
membrane via the same method. Compared to the pure PDMS membrane, the total
flux increased by 40 % when using PTMS-modifiled
MCM-41 as macro-crosslinker.