TY - JOUR
T1 - On the performance of c-oriented MFI zeolite Membranes treated by rapid thermal processing
AU - Lee, Taehee
AU - Choi, Jungkyu
AU - Tsapatsis, Michael
N1 - Funding Information:
This work was supported in part by the Initiative for Renewable Energy and Environment (IREE) and National Science Foundation (NSF , Grant NSF-NIRT CMMI 0707610 ), and also by the National Research Foundation (NRF) funded by the Korea government (MEST) ( 2012R1A1A1042450 ). Portions of this work were conducted at the University of Minnesota Characterization Facility, which receives partial support from the NSF through the NNIN program.
PY - 2013/6/1
Y1 - 2013/6/1
N2 - Rapid thermal processing (RTP) was shown to be effective in reducing defects, especially grain boundary defects in c-oriented MFI membranes (Choi et al., Science 325 (2009) 590-593). In this study, the xylene and butane separation performances of RTP-treated c-oriented MFI membranes, which were now synthesized with a shorter secondary growth time (from 2 d to 1 d), were investigated. These membranes achieved a good performance for separating both p-/. o-xylene (~88 separation factor (SF)) and n-/. i-butane (~30. SF) isomers. In addition, fluorescence confocal optical microscopy was conducted to explore the defect structure by varying the contact time with the dye solution. This characterization revealed that the accessibility of dye molecules to grain boundary defects at the molecular level can be correlated with separation performance. Finally, the fluxes of xylene and butane isomers across RTP-treated c-oriented MFI membranes were deciphered by the Maxwell-Stefan formulation to obtain their diffusion coefficients. The diffusivities of the slow permeating component (i.e., o-xylene) were estimated to be lower than the literature values obtained by a zero length column method; this accounted for the high p-/. o-xylene SF. We considered the combination of adsorbate-adsorbate and adsorbate-zeolite interactions to calculate the diffusivities of n-/. i-butane isomers.
AB - Rapid thermal processing (RTP) was shown to be effective in reducing defects, especially grain boundary defects in c-oriented MFI membranes (Choi et al., Science 325 (2009) 590-593). In this study, the xylene and butane separation performances of RTP-treated c-oriented MFI membranes, which were now synthesized with a shorter secondary growth time (from 2 d to 1 d), were investigated. These membranes achieved a good performance for separating both p-/. o-xylene (~88 separation factor (SF)) and n-/. i-butane (~30. SF) isomers. In addition, fluorescence confocal optical microscopy was conducted to explore the defect structure by varying the contact time with the dye solution. This characterization revealed that the accessibility of dye molecules to grain boundary defects at the molecular level can be correlated with separation performance. Finally, the fluxes of xylene and butane isomers across RTP-treated c-oriented MFI membranes were deciphered by the Maxwell-Stefan formulation to obtain their diffusion coefficients. The diffusivities of the slow permeating component (i.e., o-xylene) were estimated to be lower than the literature values obtained by a zero length column method; this accounted for the high p-/. o-xylene SF. We considered the combination of adsorbate-adsorbate and adsorbate-zeolite interactions to calculate the diffusivities of n-/. i-butane isomers.
KW - Butane
KW - MFI zeolite membranes
KW - Maxwell-Stefan diffusivities
KW - Rapid thermal processing
KW - Xylene
UR - http://www.scopus.com/inward/record.url?scp=84875249577&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2013.02.028
DO - 10.1016/j.memsci.2013.02.028
M3 - Article
AN - SCOPUS:84875249577
SN - 0376-7388
VL - 436
SP - 79
EP - 89
JO - Journal of Membrane Science
JF - Journal of Membrane Science
ER -