Small pore zeolites,due to pore size constraint,have limited applications.Post-modification on the materials is therefore important to widen their use.A CHA-type zeolite(SSZ-13)with a unique spongelike structure is ob...Small pore zeolites,due to pore size constraint,have limited applications.Post-modification on the materials is therefore important to widen their use.A CHA-type zeolite(SSZ-13)with a unique spongelike structure is obtained by fluoride leaching.The development of macroporosity started from the crystal surfaces and continued progressively into the crystal by prolonging the treatment.Nitrogen physisorption measurements showed an increase in micropore volume and specific surface area as a consequence of the dissolution of the low crystallinity part of the zeolite.The effect of etching on the accessibility through the pore network,evaluated by means of breakthrough experiments on CO_(2)/N_(2) and CO_(2)/CH_(4) binary mixtures,showed an improved accessibility thanks to the interconnected macropores which shorten the diffusion pathlength.The set of experimental data shows the sponge-like SSZ-13 crystals retaining the intrinsic zeolitic properties but having an improved accessibility and crystallinity.展开更多
基金the National Natural Science Foundation of China(21571079,21621001,21390394,21571076 and 21571078)for the financial supportfinancial support from the CARNOT project ESP 3DNANOZET 5281.
文摘Small pore zeolites,due to pore size constraint,have limited applications.Post-modification on the materials is therefore important to widen their use.A CHA-type zeolite(SSZ-13)with a unique spongelike structure is obtained by fluoride leaching.The development of macroporosity started from the crystal surfaces and continued progressively into the crystal by prolonging the treatment.Nitrogen physisorption measurements showed an increase in micropore volume and specific surface area as a consequence of the dissolution of the low crystallinity part of the zeolite.The effect of etching on the accessibility through the pore network,evaluated by means of breakthrough experiments on CO_(2)/N_(2) and CO_(2)/CH_(4) binary mixtures,showed an improved accessibility thanks to the interconnected macropores which shorten the diffusion pathlength.The set of experimental data shows the sponge-like SSZ-13 crystals retaining the intrinsic zeolitic properties but having an improved accessibility and crystallinity.
