Ultra-selective carbon molecular sieve membranes for natural gas separations based on a carbon-rich intrinsically microporous polyimide precursor
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KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Biological and Environmental Sciences and Engineering (BESE) Division
Chemical Engineering Program
Chemical Science Program
Functional Polymer Membranes Group, Thuwal, 23955, Saudi Arabia
Nanostructured Functional Materials (NFM) laboratory
Physical Science and Engineering (PSE) Division
KAUST Grant NumberBAS/1/13223-01-01
Online Publication Date2019-05-10
Print Publication Date2019-09
Permanent link to this recordhttp://hdl.handle.net/10754/652881
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AbstractA highly contorted, carbon-rich intrinsically microporous polyimide (PIM-PI) made from spirobifluorene dianhydride and 3,3-dimethylnaphthidine (SBFDA-DMN) was employed as a precursor for the formation of carbon molecular sieve (CMS) membranes at pyrolysis temperatures from 550 to 1000 °C. The high carbon content of SBFDA-DMN (∼84%) resulted in only 28% total weight loss during pyrolysis under a nitrogen atmosphere at 1000 °C. The development of the various microstructural textures was characterized by gas sorption analysis, Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction, Raman spectroscopy, electrical conductivity, and gas transport properties. Heat treatment of a pristine SBFDA-DMN membrane at 550 °C resulted in reduced permeability for all gases (e.g.: PCO2 dropped from 4700 to 1500 barrer) as well as lower BET surface area from 621 to 545 m2 g−1. At 600 °C, new pores induced by pyrolysis increased the BET surface area to nearly that of the precursor and significantly improved gas separation performance. Above 600 °C, a progressive collapse of the micropores became evident with CMS membranes showing higher gas-pair selectivity but lower permeability. At 1000 °C, ultra-micropores comparable in size with the kinetic diameter of CH4 emerged and induced a prominent molecular sieving effect resulting in very high CH4 rejection. This strong size exclusion effect, further supported by gravimetric gas sorption measurements, resulted in unusually high N2/CH4 and CO2/CH4 selectivities of 35 and 1475, respectively.
CitationHazazi K, Ma X, Wang Y, Ogieglo W, Alhazmi A, et al. (2019) Ultra-selective carbon molecular sieve membranes for natural gas separations based on a carbon-rich intrinsically microporous polyimide precursor. Journal of Membrane Science. Available: http://dx.doi.org/10.1016/j.memsci.2019.05.020.
SponsorsThis research was supported by funding (BAS/1/13223-01-01) from King Abdullah University of Science and Technology.
JournalJournal of Membrane Science