K-Chabazite(K-CHA)zeolites were synthesized with an ultrafast procedure through an eco-friendly and cost-effective“one-pot”method.By solely employing colloidal silica and aluminum hydroxide in the K^(+)/Sr^(2+)syste...K-Chabazite(K-CHA)zeolites were synthesized with an ultrafast procedure through an eco-friendly and cost-effective“one-pot”method.By solely employing colloidal silica and aluminum hydroxide in the K^(+)/Sr^(2+)system without the assistance of seeds,fluorides or organic structure as directing agents,the K-CHA nano-aggregates were successfully synthesized in a few hours.The crystallization behavior of the gels with different SiO_(2)/Al_(2)O_(3) molar ratios(SARs)was investigated using X-ray diffraction(XRD);scanning electron microscope(SEM);X-ray fluorescence(XRF);27Al and 29Si magic angle spinning nuclear magnetic resonance(MAS NMR);Fourier-transform infrared spectra(FTIR);UV-Raman characterizations.As the nucleation rates were changed with the SARs,three kinds of K-CHA nano-aggregates,namely,hamburger-,disk-and walnut-shaped,were obtained.A possible formation mechanism of the K-CHA nano-aggregates was proposed.Additionally,the walnut-shaped sample with an SAR of 7 possessed the largest pore volume and specific surface area,resulting in the highest methane adsorption capacity.Furthermore,it exhibited a CH_(4)/N_(2) selectivity of more than 3 under relative pressures ranging from 0 to 0.6.This work offers guidance for modifying the stacking modes of other nano-sized zeolites.展开更多
基金supported by the National Natural Science Foundation of China(No.21276183).
文摘K-Chabazite(K-CHA)zeolites were synthesized with an ultrafast procedure through an eco-friendly and cost-effective“one-pot”method.By solely employing colloidal silica and aluminum hydroxide in the K^(+)/Sr^(2+)system without the assistance of seeds,fluorides or organic structure as directing agents,the K-CHA nano-aggregates were successfully synthesized in a few hours.The crystallization behavior of the gels with different SiO_(2)/Al_(2)O_(3) molar ratios(SARs)was investigated using X-ray diffraction(XRD);scanning electron microscope(SEM);X-ray fluorescence(XRF);27Al and 29Si magic angle spinning nuclear magnetic resonance(MAS NMR);Fourier-transform infrared spectra(FTIR);UV-Raman characterizations.As the nucleation rates were changed with the SARs,three kinds of K-CHA nano-aggregates,namely,hamburger-,disk-and walnut-shaped,were obtained.A possible formation mechanism of the K-CHA nano-aggregates was proposed.Additionally,the walnut-shaped sample with an SAR of 7 possessed the largest pore volume and specific surface area,resulting in the highest methane adsorption capacity.Furthermore,it exhibited a CH_(4)/N_(2) selectivity of more than 3 under relative pressures ranging from 0 to 0.6.This work offers guidance for modifying the stacking modes of other nano-sized zeolites.
