Sciencemadness Discussion Board

Manganese Dioxide from Manganese Sulphate

RU_KLO - 7-7-2023 at 04:55

I need "better" (purer) manganese dioxide, that the one from batteries.

I have already made manganese sulphate from batteries (from der Alte process), which I think they are more or less pure (2 crystallizations step). Also have purchased some.

Which route should I follow?

This are some thinking:
1) manganse sulphate to manganese nitrate -> heating -> manganese dioxide
2) found this in internet:

The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to yield high density manganese dioxide.

https://www.osti.gov/biblio/6894198#:~:text=The%20manganese%...

I do not have sodium peroxodisulfate, but do have Ammonium persulfate and Potassium persulfate. Could this be used instead?


3) any other better route? maybe temp decomposition?

When carbon is added to MnS04 in a mole ratio between 0.5 and 1 .O, the thermal decomposition of MnS04 is substantially promoted, yielding good rates (-60% conversion in 1 h) in the range 1250-1300 OF. The products
of decomposition consist of almost pure manganous oxide, MnO, and a gas phase containing average values of 67 YO SO2 and 33 YO COP. Increasing the carbon ratio above 0.5 (up to 1 .O) gives an increased decomposition reaction rate but does not alter the ratio of SO2 to COP in the product gases. The overall decomposition kinetics may be described by a multiple step model which includes a sulfate pre-reduction step

this route gives MnO and need MnO2....

also it seems difficult for me working with high controlled temperatures? or maybe putting in a can in an coal fire (barbacue) is enogh? how about purity?


"https://doi.org/10.1021/i260059a002"


This is to make then Potassium permanganate (from Keras post as he ask for higher purity reagents)

https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

Thanks

Alkoholvergiftung - 7-7-2023 at 10:57

wouldnt it be better to treat the MnSO4 with an mix of Ammonia and H2O2. it forms Mangandioxidhydrate thats more reactive than MnO2.

RU_KLO - 7-7-2023 at 16:21

dont know, process asks for MnO2. Will it work?

Bedlasky - 9-7-2023 at 09:51

Hydrated manganese dioxide will do the same work as anhydrous MnO2. If you are using it for something like thermite, it would be better to dehydrate it first (just by simple heating).

Grizli7 - 17-12-2023 at 06:37

A pure preparation for analysis can be obtained using the following method:
In a porcelain cup, Mn(NO3)2x6H2O, pure for analysis, is heated under draft to 100 degrees Celsius and the temperature is gradually increased to 160 degrees. The result is a black powdery mass. The product is cooled and wetted with HNO3 dens 1.34 pfa. Stir until it becomes a liquid slurry and heat again to 160 degrees. After cooling, the mass is sucked off using a funnel with a porous glass plate and washed 2 times with HNO3 (dens 1.62 pfa). And again it is heated twice with HNO3 to 160 degrees. Then the mass is sucked off using a Buchner funnel, washed 3-4 times with HNO3 and dried at 150 degrees. The yield of MnO2 is almost 100%. To obtain 100 g of MnO2, about 400 ml of HNO3 dens1.34 are consumed.

Texium - 18-12-2023 at 10:16

If you have permanganate, the most reliable method is the comproportionation reaction of MnSO4 and KMnO4. I've attached the e-EROS entry for MnO2 which contains several preparation procedures. I have used the procedure titled "Preparation of gamma-MnO2" and can confirm it produces a nicely reactive product.


Attachment: Manganese dioxide.pdf (2MB)
This file has been downloaded 188 times

clearly_not_atara - 19-12-2023 at 08:09

I think that potassium persulfate should work fine. The main difference is that K2S2O8 is highly insoluble (1.75% w/w) at low temperature.

This might also be a useful prep of sulfuric acid, if I'm getting this right:

MnSO4 + K2S2O8 + 2 H2O >> 2 KHSO4 + MnO2 + H2SO4

Separating H2SO4 from the bisulfate byproduct will require vacuum distillation.

But MnO2 is a usually nonstoichiometric material (MnO(2-x)) with several allotropes, not all of which display the desired reactivity in organic synthesis.

RU_KLO - 19-12-2023 at 08:50

Quote: Originally posted by Texium  
If you have permanganate, the most reliable method is the comproportionation reaction of MnSO4 and KMnO4. I've attached the e-EROS entry for MnO2 which contains several preparation procedures. I have used the procedure titled "Preparation of gamma-MnO2" and can confirm it produces a nicely reactive product.




the idea of getting MnO2 is for permanganate synthesis.

But if MnSO4 + H2O2 + Ammonia wil give me MnO2, then I will proceed this way.
Why Ammonia is needed? (will not H2O2 oxidize MnSO4 directly?)
How much ammonia is needed?

RU_KLO - 19-12-2023 at 09:22

Quote: Originally posted by clearly_not_atara  
I think that potassium persulfate should work fine. The main difference is that K2S2O8 is highly insoluble (1.75% w/w) at low temperature.

This might also be a useful prep of sulfuric acid, if I'm getting this right:

MnSO4 + K2S2O8 + 2 H2O >> 2 KHSO4 + MnO2 + H2SO4

Separating H2SO4 from the bisulfate byproduct will require vacuum distillation.

But MnO2 is a usually nonstoichiometric material (MnO(2-x)) with several allotropes, not all of which display the desired reactivity in organic synthesis.


from patent: US 5277890

"An article by P. Strobel and J.C. Charenton (Revue de Chimie Minerale, Vol. 23 (1986), p. 125-137, at p. 130) discloses a reaction of potassium or ammonium peroxodisulfates (K2SOs or (NH4)2S2O8) with MnSO4 to yield mixtures of hollandite (alpha MnO2) and gamma MnO2. The reference states, at p. 129, that only potassium and ammonium peroxodisulfates are sufficiently stable for use in the reaction"

So potassium or ammonium persulfate could be used. If then I want to "recover" H2SO4 I think that ammonium would be better, because it decomposes: Ammonium sulfate decomposes upon heating above 250 °C (482 °F), first forming ammonium bisulfate. Heating at higher temperatures results in decomposition into ammonia, nitrogen, sulfur dioxide, and water.
(wiki) but those temp are near H2SO4 azeotrope and from other post after 70% aprox (aprox 175°) its no use to boil it further.

So I dont know if viable to recover H2SO4...

The reaction with sodium persulfate is stated as:
MnSO4 + Na2S2O8 + 2H2O -> MnO2 + Na2SO4 + 2H2SO4

So I think that with Ammoniun Persulfate should be :
MnSO4 + (Nh4)2S2O8 + 2H2O -> MnO2 + (NH4)2SO4 + 2H2SO4







Attachment: US5277890 MnO2.pdf (1.3MB)
This file has been downloaded 107 times

bnull - 17-1-2024 at 17:39

Apparently, the best manganese dioxide comes from electrolysis of aqueous solutions or molten salts. I found some patents that may help :US4048027A, US20040009400A1.

woelen - 18-1-2024 at 00:50

Precipitate Mn(OH)2 from a solution of MnSO4 or Mn(NO3)2.
To this, you can add any oxidizer, which does not leave insoluble residues. Suitable oxidizers are peroxodisulfates (a.k.a. persulfate, but that name is not sufficiently specific), oxone, together with additional NaoH, or H2O2. The latter must be added in small steps, while stirring very well. H2O2 also is catalytically decomposed by MnO2, and hence a lot of it may be lost.
The result is a very dark brown solid.

The solid must be filtered and rinsed well with distilled water. The latter can be done, by allowing it to settle, decant the colorless solution above it, add a lot of distilled water, shake and then let it settle again, and decant the liquid again. If you have real filtering equipment, then that of course if easier.

Finally, dry the solid and heat it in an over at 200 C or so for a while to make it really dry.

The MnO2 you make will either be somewhat deficient in oxygen (e.g. MnO1.95 instead of MnO2), or it contains some alkali ions, so that you get something like K0.05MnO2, or Na0.05MnO2. In both cases, the average oxidation state of the manganese is not +4, but a little below +4 (e.g. +3.9 or so). Even high grade commercial samples of MnO2 have this somewhat lower oxidation state of manganese. Really pure MnO2 is extremely rare and I doubt whether it even exists.

Admagistr - 18-1-2024 at 16:18

I have successfully used the reaction with KMnO4,Na2SO3 and H2O. This produces MnO2,Na2SO4 and KOH.