We are trying to preparing ferrierite by hydrothermal synthesis and I think charge compenstation from presence of aluminium in the structure should be done by alkali metal, sodium in my case. That means atomic ratio of sodium and aluminium should be unity after synthesis of zeolite but amount of sodium is much lower than aluminium indicating presence of proton bot sodium. Is it possible? and if it is possible, why alkali metal is essential for synthesis of zeolite?
I think the +1 and +3 metals ions is essential to get on different electrepositivity this process in order to produce an varies active site for synthesis of zeolite.
Regards
Is this synthesis performed in presence of an organic template (such as pyrrolydine) ? If yes, the template (its protonated form, pKa=11.3) may also play a role in the charge compensation of the Al (and, on the calcined sample, the charge compensating organic cation will be likely replaced by H+).In absence of an organic template, all framework aluminum should be charge compensated by a cation, so one would indeed expect a Na+/Al ratio of one. If the ratio is significantly lower, it might be due to : (i) presence of a large fraction of extraframework Al (you could check this using 27Al MAS NMR); (ii) partial exchange of sodium by H+ during the washing step (if the water you use for washing is slighlty acidic (carbonated) and you performed a very thorough washing).
Dear
Thanks to your answers
I prepared sample with organic template and also prepared by using re-crystallization with as-made zeolite (without SDA). firstly prepared zeolite with organic template showed lower crystallinity so it showed much lower Na/Al ratio, but re-crystallized zeolite with highly crystalline one showed higher Na/Al ratio but it wasn't also unity. Anyway, I figure out water washing step can affect to the sodium exchange now. Thanks a lot.