Dry HCl gas from muriatic and sulfuric acids conc.

[WillD]

Dripping an affordable muriatic acid (HCl aq 31%) over concentrated sulfuric acid (H2SO4) is one of the best methods for producing a dry gaseous HCl, if it is necessary to quickly scaling. The reaction rate and temperature is easily controlled. Capacities are easily and quickly cleaned, and if necessary, immediately launches with a new portion of reagents. The method is well suited when you need large volumes of dry HCl immediately and quickly. It is better to use glass or plastic reactor or handmade analogs (barrels and stirrer devices).

Muriatic acid slowly drops to stirred sulfuric acid. Sulfuric acid is dehydicing muriatic acid, releasing dry gas. The released HCl is preferably skipped over a small amount of sulfuric acid in an intermediate container to remove traces of water. The obtained dry gas can saturate the available isopropyl alcohol for storage as anhydrous solution. By weight of the solution, it is possible to determine the concentration of the resulting solution (no more than 25% for IPA)

Recommended amount of sulfuric acid - 2 parts per 1 muriatic (31%) acid. The stirred during all time. The reaction can be seen bubbles in the receiver. Plastic tubes are suitable for gas. With the right proportions, almost all HCl is removed from muriatic acid.

Example of an industrial reactor for this method

Example of a laboratory generator

 

[G.Patton]

CaCl2 is considerably safer to handle than concentrated H2SO4. It also is available at low cost, sometimes as a byproduct of the Solvay process. The standard assemblies for gas generation shown above are appropriate for the preparation of crude HCl(g).

It is able to fix enough water (over the 30% of its weight considering it hydrates only to CaCl2·2H2O, which is stable up to 150 °C) to deliver a significant amount of HCl gas. In a typical run, 100 g of 35% HCl were added over 100 g of granular CaCl2 at room temperature (the thermal effect is not significant), and 15 g of HCl(g) were obtained. This represents over 40% yield, which may be compared with the 80%, yield reported for the process represented in Eq. 2; however, it uses approximately a 1:3 weight ratio between H2SO4 and HCl(aq).

CaCl2 also is easier to dispose of than H2SO4, and less base is required to neutralize the final waste. An additional advantage of this procedure regarding those based on H2SO4 concerns educational aspects. By heating at 200 °C, the resulting waxy mixture (or crystalline mass to which it converts after a few hours), the anhydrous CaCl2, can be regenerated for re-use once a solution of HCl is obtained. In this case, some calcium oxychloride formed can be ignored.

Even though this may be without value from a practical viewpoint, it may be of educational significance because it attracts attention to topics of current interest such as optimizing of processes, recycling of chemicals, and reducing of wastes. To this end, the assembly shown in Fig. b is more appropriate than that in Fig. a because the resulting mixture is ready to be distilled.

UPD: An alternative way:​

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[Riot]

Hi , ım thinking the use fig. a but you mentioned water will decrease your yield how much decrease will drop , did ı suppose to use trapped hcı gas gen in smaller synteshis will make problem

Thanks.

 

[IM BATMAN]

could you please explain about a base needed to neutralize the final waste?
so, before to discard it should i do that?

 

[G.Patton]

You need to add alkali to make the pH neutral.

 

[IM BATMAN]

but for discard it? just when had all the gas needed?

 

[G.Patton]

I don't understand your question, reformulate please correctly in English.

 

[IM BATMAN]

haha..ok ok
i meant that if i have to basify the mix just for discard , of for another reason.
i suppose i should basify to stop the reaction etc, right?

 

[G.Patton]

yes

 

[IM BATMAN]

Tnx! always did the acidification in wet form... ill try for sure.

 

[Nitecore20]

Hello. Can anybody say, if a Check Valve in the Tubing set-up, can prevent any suckback? Something like this one

 

[G.Patton]

Yes, it can

 

[ASheSChem]

Hello,

i try to understand with all equipement i know how to do

after that i have done two "shema" , can you confirm me if all it's ok ?

Spoiler: shema 1

Spoiler: shema 2

for the CaCl2 route the shema 2 is ok or i need to do somthing like the first one?

I imagine that my set-up is not perfect, but made with what I find on amazon, be indulgent

 

[ASheSChem]

@William Dampier , @G.Patton
my schema are good for this operation :x

 

[G.Patton]

Hi, ASheSChem. You have to close your pressure-equalizing dropping funnel. Also, you have to emerge hose with gas into a free base solution. Better to use traps by reason that it will increase yield but not significantly.

 

[ASheSChem]

ok thanks;

in a freebase solution when it was in "stand by" ? before using to change the ph of my solution ?
what kind of free base solution ?

about the traps; the two (one bubble and one dry) are necessary ? only one can be use? more traps more yields?

thanks you so much

 

[G.Patton]

I told about 4-mmc or methamph syntheses, when you want to make HCl salt.

Yes, exactly. Water will dissolve product salt and yield will be lower.

 

[ASheSChem]

yes it's why i try to learn that; change my sulfate amph. to methamph

 

[ASheSChem]

do you speak something like this ? what reagent it is ? (in the red circle)

 

[G.Patton]

Yes
I can't say exactly what is used in this video. Probably CaCl2 and HCl acid. Syringe with CaCl2 is absorb water from gas. Empty syringe is used as gas volume indicator.

 

[ASheSChem]

thanks @G.Patton

he put the hose with gaz in the red circle when he don't use it or i don't understand ? ^^
it is water?