Unconventional, highly selective CO2 adsorption in zeolite SSZ-13.

Low-pressure adsorption of carbon dioxide and nitrogen was studied in both acidic and copper-exchanged forms of SSZ-13, a zeolite containing an 8-ring window. Under ideal conditions for industrial separations of CO(2) from N(2), the ideal adsorbed solution theory selectivity is >70 in each compound. For low gas coverage, the isosteric heat of adsorption for CO(2) was found to be 33.

Isolated Cu2+ ions: active sites for selective catalytic reduction of NO.

Cu chabazite catalysts show remarkable low temperature activity in selective catalytic reduction (SCR) of NO. This high activity is due to the unique character of the zeolite framework that allows only the presence of one type of isolated mononuclear Cu(2+) species. These Cu(2+) species are the active sites for SCR.

Initial stages of self-organization of silica-alumina gels in zeolite synthesis.

We report the effect of aluminum on the formation and structure of silica nanoparticles formed in basic solutions of small organic and inorganic cations using a combination of small-angle X-ray scattering, conductivity, pH, and 27Al NMR spectroscopy methods. At low silica concentrations, our observations agree with previous reports and show the formation of small oligomers ((HO)4-nAl(OSi(OH)3)n)- that can be modeled qualitatively using a simple aqueous speciation model. We also find that aluminum drastically reduces the concentration of silica at which nanoparticles are formed.