Dear experts,
I have use XRD to identify zeolites in my research.However, i found out that several zeolites overlapped in several peaks. Is my zeolite not pure? May i report the mixed of zeolite that I obtained? I have repeated the lab work several times and I only got different peak of zeolites in XRD.
Do I need to clarify using other method of characterization such as BET surface area, SiO2/Al2O3 ratio, FTIR and FESEM? Which method give the most powerful evidence for zeolite I obtained?
Thank you for your assist.
Best methods are XRD and surface area
PXRD
Try to match it with JCPDS data available in the XRD instrument itself. It will show impurity peaks (if any). if you are getting those peaks try to identify those peaks by correlating it with the XRD of the probable impurity. Also you can measure crystal size using scherrer quation. Which also can be confirmed with the literature reports
Surface area
Surface area of the samples you prepare should be matched with the reported data available.
Dear Syafiqah,
The most common and most precise way to determine your zeolite structure is XRD. if you have several different phases in your sample Rietfeld refinement will help to determine your phases.
BET measurement is a very good technique for characterization of a catalysts, because the properties are highly influenced by this parameter, but the BET surface does not give you a information about your specific zeolite structure type. Several different zeolite structures could be found with similar or overlapping BET surface areas.
SiO2/Al2O3 ratio is important to determine the acidity of your sample. But it will normally not help you to specify your zeolite type. Most (or at least several) zeolites can have wide range of different SiO2/Al2O3 ratios. For example zeolite ZSM-5 (MFI) exists with SiO2/Al2O3 ratios from about 15 up to 1000 .
FTIR could give you information about your specific structure type. But it is hard to determine the structure vibrations and you will have to be very careful at analyzing the spectra. From my opinion it is harder to determine your structure type by FTIR compared to XRD (more overlapping bands for example).
SEM analysis will give you an idea of the morphology of your sample, but it will be hard to get real structure information. It could be a hint if you are searching for a zeolite with characteristic crystal shape (like the ZSM-5 with its coffin shaped crystals).
A good reference for zeolite characterization or determination is the attached book from Chester and Derouane.
Especially the introduction chapters of several other text book s could give you additional information of different zeolite structures and their determination.
http://link.springer.com/book/10.1007%2F978-1-4020-9678-5
You are welcome!
In the attached link you will find advise for quantification, if you have a mixture of different zeolite structures.
https://www.researchgate.net/post/How_to_calculate_each_phase_percentage_of_a_mixed_crystalline_material
You can analysis your XRD data by using a software named " PANalytical X’Pert HighScore Plus".
I did same for my mixture of zeolite LTA and zeolite X, http://pubs.acs.org.ezproxy1.lib.asu.edu/doi/abs/10.1021/acs.cgd.6b00133.
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