what is the meaning of (1) Zeolite Y, hydrogen (2) Zeolite Y, ammonium (3) Zeolite ZSM-5, ammonium. I know they have different silica/alumina ratio but I'm particularly looking for the meaning of hydrogen, ammonium etc.
Hi,
Basically, there are counter-ions in the zeolite structures. These ions can vary and be exchanged (Na+,Ca2+,Li+,K+,H+,Mg2+ ....). Therefore, to fully characterize the structure of the zeolite, you have to specify the kind of ions in the structure e.g.: NaY, NaX, LiLSX, H-ZSM5 ...
Best regards
Faujasite is a mineral group in the zeolite family of silicate minerals. Depending on the silica-to-alumina ratio of their framework, synthetic faujasite zeolites are divided into X and Y zeolites. In X zeolites that ratio is between 2 and 3, while in Y zeolites it is 3 or higher.Zeolite Y is used as a cracking catalyst in petroleum refinery catalytic cracking units to convert high-boiling fractions of petroleum crude to more valuable gasoline, diesel and other products. Zeolite Y, ammonium is synthesized by introducing Ammonium ions in place of Aluminium. Same way introducing Hydrogen will give Zeolite Y, Hydrogen. ZSM-5, Zeolite Socony Mobil–5 (is an aluminosilicate zeolite belonging to the pentasil family of zeolites.
The cations in the zeolite are charge compensating the Al in tetrahedral substitution in the zeolite framework. Ammonium form are very usual because, to transform a Na-zeolite in a H-zeolite, one usually proceeds by ion exchange of Na+ by NH4+ (and not by H+, which would imply exposing the zeolite to too acidic solution) followed by calcination (formation of the H form and release of NH3).
Zeolite is a cation exchanger which exchanges its loosely bound ions like sodium ions if iit is chemically hydrated sodium aluminosilicate with other ions. hydrogen ions substitute say sodium ions during regeneration of zeolite.. However aluminium ions can be substituted to different degrees by other cations to get synthetically derived varieties of zeolites.
Shrikaant's answer should note the differences between the natural aluminosilicate faujasite mineral and it's synthetic analogues , Zeolites X and Y. The conversion to HY is as is explained by Juliette were by the ammonium exchanged form of Y is heated so as to decompose the ammonium form to the hydrogen form(HY)
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