Zeolith, verfahren zu dessen Herstellung und Verfahren zum Entfernen von Stickoxiden aus Gasen durch selektiven katalytischen Reduktion unter Verwendung des Zeolits

摘要

The hydrogen consumption corresponding to the peak of the second wave is equal to a half mole of hydrogen per mole of copper present in the solid. The first wave has two peaks, P1 and P2, resolved by Gaussian deconvolution. The ratio A1/A2 of the zones corresponding to the peaks P1 and P2 respectively are greater than 1.5. Mixed zeolite represented by the formula Cu(x)M'(y)M(z)Z, in which Z represents a zeolitic net with an atomic ratio Si/Al of between 0.9 and 20; M' is lithium and/or a metallic element with a valence of 2, 3 or 4, with an ionic diameter or between 0.12 and 0.30 nm; M is H+, Na+ and/or K+; and x, y, and z are the respective theoretical exchange rates of copper ions and M' and M ions expressed as a percentage of the total exchange capacity of the Faujasite, with the following values: 5=x=60; 20=y=70; z=100-x-y. The zeolite is agglomerated with a link to form grains with a mean size of at least 0.5mm. Z is an X or Y Faujasite. M is a calcium ion, a lanthanide ion or a mixture of lanthanide ions. Process for obtaining such a zeolite, by (a) exchanging some of the exchangeable sites of an M.Z zeolite in powder form with at least a first cation M', (b) agglomeration , (c) exchange of copper for part of the exchangeable cations in the zeolite and (d) heat treatment such as drying and activation. An additional drying and activation stage can be fitted between (b) and (c), or the zeolite can be agglomerated before cation exchange.