first of all KSF & K10 are commercial samples, usually mineral acid treated samples, having less acidity and due reduced CEC, but untreated bentonite has higher CEC.

More the CEC more will be the acidity, in clays majority of the acidity from interlayer cations (polarizabilty of the cations).

Bentonite is better one for further modification...

Thanks a lot for your answer. So what is exactly the difference between K10 and KSF? If I treat bentonite with sodium chloride I found out that surface area and catalyst adsorption is better. Is is true?

K10 as more surface area compare to KSF, and CEC play major role for the adsorption, what type of adsorbate you are using. normally NaCl does not increase the surface area. if lower the CEC layer swelling is more so we can expect increased adsorption

I am trying to load silicotungstic acid. I am trying to compare these two papers to chose the best way to load this acid: 

Silicotungstic Acid Modified Bentonite: An Efficient Catalyst for Synthesis of Acetal Derivatives of Aldehydes and Ketones

Synthesis of ethyl acetate by esterification of acetic acid with

ethanol over a heteropolyacid on montmorillonite K10

Thanks once more

If you need more information especially regarding the physical and chemical properties of K10 and Bentonite, you can peruse the attached files.

Article Pillared montmorillonite supported ferric oxalate as heterog...

Article Catalytic activity of copper modified bentonite supported fe...

Are there any details of physical and chemical properties of K10 and KSF ?

K10 and KSF were obtained by treatment of montmorillonite with sulfuric acid. The KSF clay was obtained using a soft treatment.

I experienced some differences in catalytic properties non-dried and dried M-KSF and M-K10. For instance, phenyl prenyl ethers undergo 1,3-sigmatropic rearrangement with normal (wet) M-KSF. If dried at 100 deg. Cel. overnight, cleavage of ether dominate. This makes sense as Montmorillonites absorb and retain large amount of water.

For more details please see

https://www.researchgate.net/publication/8562575_Synthesis_molecular_modeling_and_evaluation_of_nonphenolic_indole_analogs_of_mycophenolic_acid

For catalyst support, I prefer to use MK10. Sometimes, bentonite contens some minerals impurities not only a montmorillonite.

K10 is not a montmorillonite, It was probably in the beginning of the process. Currently it a mixture of oxides derived from the chemical acid activation and thermal treatment and contains mica and quartz as contaminants. Similar materials can be obtained from acid activation of several clay minerals, see for examples the reference: Article Acid-activated montmorillonites as heterogeneous catalysts f...