Preparation of NH2-SH-GO/SWCNTs based on graphene oxide/single-walled carbon nanotubes for CO2 and N-2 separation from blast furnace gas

摘要

The traditional molecular sieve membrane for gas separation is mostly prepared by zeolite, MOFs and other materials. Nano-carbon materials such as graphene and carbon nanotubes have been studied in the field of gas separation in recent years which have large specific surface area and high porosity. The performance of carbon nanotubes and graphene can be effectively improved by adding corresponding groups. A novel molecular sieve membrane was synthesized by sulfhydryl and amino-modified graphene oxide/oxidized single-walled carbon nanotubes (NH2-SH-GO/SWCNTs). The composite material was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller specific surface area analyzers. The results reveal that laminated graphene oxide and tubular single-walled carbon nanotubes are intertwined and carbon nano tubes attach onto the surface of GO or intercalate into the GO sheets to form a spatial stereoscopic structure. TGA results demonstrate that the loading amount of amino and sulfydryl groups in NH2-SH-GO/SWCNTs is about 11.91 wt%. When the intake pressure of N-2 is 0.10 MPa, the permeability coefficient for N-2 passing through NH2SH-GO/SWCNTs is 1829 Barrer. With the increase of temperature, permeability coefficient for N-2 decreases, while it increases as the intake pressure rises. The experimental results for mixed gases passing through NH2-SHGO/SWCNTs show that, when P0 = 0.10 MPa and T = 323 K, the permeability coefficient for CO2 is 1896 Barrer, while that for CO is only 116 Barrer. At 323 K, selectivity for N-2/CO, CO2/CO and CO2/N-2 is 39.2, 46.3, and 9.3, respectively. These results indicate that NH2-SH-GO/SWCNTs may be a promising molecular sieve membrane for gas separation.