why do not use ultrasonic bath instead of stirring? is more efficient

At least for copper I have achieved quite good results (dispersions) by using very similar procedures.

Have you thoroughly washed your product before calcination? Perhaps there is an excess of copper which is not incorporated into the zeolite and leftover as bigger particles, which you found by SEM.

Your calcination procedure sounds quite short. I normally used a slow temperature ramp (5 or more hours up to 500 °C) followed by several hours at the calcination temperature.

What about the other metals? have you achieved poor dispersions as well? At least iron tends to form ironoxide particles or clusters.

Hi,

It looks your metal ions are exchanged with protons of zeolite since you have used very dilute solution for the ion exchange and at certain concentration/ not well washed that time  they may form oxide. I feel the calcination step is fine.

it would be good if I  know what you want to disperse the metal oxides on Zeolite or Metal ions on zeolites ? or Does the Ph playing a role in selective adsorption/dispersion  of metal ions ? increase the Concentration of metal ions to have good dispersion followed by sonication!

Hope it helped you 

I have another points that came to my mind:

Which cations are in your source material? Is t h-, NH_4- or Na-form? Or anything else? The different cations are differently bound and perhaps need special or at least longer treatment. From my experience NH_4-form is the best form to start ion exchange.

Could you explain your SEM results? How have you concluded the poor dispersion of Copper? Is it only SEM or additional EDX analysis? I expect, that a well dispersion and a low exchange degree will not or at least hard detectable by SEM. When you have found big cupper containing structures "outside" your zeolite it points to a poor washing step.

PH value does play a big role in ion exchange of zeolites! 

thank you for helping me. I worked with metal base such as Cu,Fe,Li,Na

with XRF test, I found amount metal on zeolite. after repeat XRF test for each metal , result were not the same. Besides, TPD-ammonia for zeolite and modified zeolite did not change a lot. Also according to FESEM test, particle of ,etal did not did not disperse uniform on zeolite.

but before calcination , i did not wash the modified zeolite. i think if i do that , i will get better results.

Dear Thomas Simons

I use a Na form of ZSM-5.

Could you give me a detail procedure for modified zeolite?

I do not understand clearly about role of PH. I adjusted  PH= 8 using a 0.8 M NH4OH solution for 2 hours.

Do you think temperature is important or not?

i attached the result of Cu-ZSM-5

Thanks again

Unfortunately I can not give you a detailed description of my procedure, because it was done a few years ago. And I do not have access to my lab notes, because I am no longer member of the institute since my graduation.

But very roughly/briefly:

About 5 g of NH4-ZSM-5 and 500 mL of Cu(NO3)2 solution (0.01 mol L-1) were mixed. The pH was controlled to be slightly alkaline. After stirring for 24 h at room temperature, the mixture was filtered. Then thoroughly washed with distilled water (several times, 1.5 L water in total), and dried overnight at 100 °C. The procedure was repeated to ensure a complete ion exchange. Afterwards calcination at 500 °C was performed.

Have a look in the literature aqueous ion exchange of zeolites is very common. 

Dear Thomas Simons

thanks a lot

I appreciate your help

From your description and SEM images I would suppose, that there is a left over of your cupper salt in your sample, because of the unwashed material.

After a perfect ion exchange you will not see any difference in your SEM images (compared to the source zeolite), because the copper will be distributed in a monomeric manner. Do you want to achieve a full exchange or a certain exchange degree?

Ammonia TPD will not change a lot after Cu-exchange. There will be additional Lewis-sites, but it is hard to discriminate these results.

The pH value is a important factor in ion exchange of zeolites, because zeolites are solid acids. So for every reaction/ion exchange their acidic properties have to be taken in account.

But from your procedure it could be, that you have exchanged your Na+ by NH4+ and only a very small amount of Cu+/2+ have been exchanged to the zeolite. A way could be to use the NH4-Form or H-form as starting material.   

Dear Thomas Simons

thanks a lot

I appreciate your help

I have seen, that one of my former colleagues has recently published a paper, where Cu-Ion exchange is described (briefly).

See attached link. 

P.S.: If you like my comments, do not forget to upvote ;-)

Article In situ monitoring of DeNOx-SCR on zeolite catalysts by mean...

It was very helpful.

thanks again

I upvoted for you

Cations such as Cu,Fe and Ni( Li is not a base metal) form oxide/hydroxide species on zeolite surfaces. See for example Wark,Lutz,Schulz-Ekloff,Dyer,Zeolites,13,1993, 273-289..