Impact of tailored chemical and textural properties on the performance of nanoporous borazine-linked polymers in small gas uptake and selective binding

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2013, Vol.15 (1), p.1, Article 1368
• Main Authors: Reich, Thomas E., El-Kaderi, Hani M.
• Format: Article
• Language: English
• Subjects: Adsorption; Benzene; Boron; Carbon dioxide; Characterization and Evaluation of Materials; Chemical synthesis methods; Chemistry and Materials Science; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; health and environment; Inorganic Chemistry; Lasers; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials Science; Methane; Methods of nanofabrication; Nanomaterials in energy; Nanoparticles; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Polymers; Research Paper; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal properties of condensed matter; Thermal properties of small particles, nanocrystals, nanotubes
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-012-1368-5

Six borazine-linked polymers (BLPs) have been synthesized through the thermolysis reaction of p -phenylenediamine, 1,3,5-tris-(4-aminophenyl)benzene, benzidine, or tetra-(4-aminophenyl)methane with boron tribromide or boron trichloride. Each product exists as an amorphous polymer whose chemical connectivity was confirmed by FT-IR and elemental analysis while thermogravimetric analysis revealed moderate thermal stabilities up to about 200 °C under nitrogen atmosphere. All BLPs possess high surface areas with chlorinated BLPs exhibiting higher values than brominated BLPs (1,174–1,569 vs. 503–849 m 2 /g, respectively). Gas storage capabilities were investigated as well. BLPs possess good hydrogen uptakes (0.68–1.75 wt% at 77 K) and zero-coverage isosteric heat of adsorption, Q st , (7.06–7.65 kJ/mol) as calculated by the virial method. The uptakes and heat of adsorption for carbon dioxide (51–141 mg/g at 273 K with Q st : 22.2–31.7 kJ/mol) are also attractive. BLPs do not, however, appear to exhibit significant methane storage capacities (1.9–15.2 mg/g at 273 K with Q st : 17.1–21.7 kJ/mol). Accordingly, CO 2 /CH 4 selectivity studies were performed using the ideal adsorbed solution theory and further supported by initial slope calculations. The results indicate that BLP-1(Br) and BLP-2(Br) exhibit very high CO 2 /CH 4 selectivities 23 and 26, respectively, which make them attractive for small gas separation applications.