Sciencemadness Discussion Board - V2O5 catalyst for H2SO4 production.

V2O5 catalyst for H2SO4 production.

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vulture - 22-4-2004 at 12:51

IMHO, caro's acid should passivate Al.

axehandle - 22-4-2004 at 17:53

Quote:

Perhaps you may look again at the aluminum coil in aluminum block idea(it does seem elegant doesn't it?) , even if the aluminum pipe gets brittle or cracked in the bending, the Al block should take care of any leaks, also there would be remelting on the surface of the pipe. It would actually be annealed in the process.
...
Filling the pipe with powdered gypsum might be the trick. then blowing the gypsum coud be blown out with compressed air at a local filling station.

Believe me, I have already considered this. What would happen would be that the bent pipe would melt, and the gypsum would spread out and become an unevenly distributed suspension in Al.

I've reached a design decision: I'll use copper pipe "as is", and hope that the corrosion will be minimal (which, according to what I've read, it will be provided the burner is fed with dry air).

I think it will still meet the Longevity design goal, and it's better to replace an easily contructed part every 6 months than going through the pain of doing it right, only to double the lifespan of the component.

This thread is getting unmanageably large, and is now approaching technochemistry. I think I'll soon continue it in that section.

What do you all think? Is it still "apparatus aquisition" or is it specialized enough to merit a move to technochemistry?

Oooh, 500th post!

[Edited on 2004-4-23 by axehandle]

It was always technochemistry...

Hermes_Trismegistus - 22-4-2004 at 18:25

Buying a plastic funnel from the hardware store is aquistition
Cutting open an old battery for the lead plate is aquisition,

Fashioning a sophisticated apparatus from materials only one step removed from the raw ore is about six steps past....

The_Davster - 22-4-2004 at 18:28

Well technochemistry does state; Chemistry with special equipment: arc furnaces, microwaves, catalyst tubes, electrochemical cells, etc.
I have gotten used to remembering that this thread is in the reagents and aparatus acquistion area, so to me it does not really matter where it goes.

Hmm.

axehandle - 22-4-2004 at 18:38

Quote:

Fashioning a sophisticated apparatus from materials only one step removed from the raw ore is about six steps past....

Yes.... there's not really any section that it fits in.

Quote:

Well technochemistry does state; Chemistry with special equipment: arc furnaces, microwaves, catalyst tubes, electrochemical cells, etc. I have gotten used to remembering that this thread is in the reagents and aparatus acquistion area, so to me it does not really matter where it goes.

Well, it surely fits w.r.t. "special equipment". I'm leaning towards technochemistry... but then the title of the thread should be renamed to "H2SO4 production using the contact process".

[Edited on 2004-4-23 by axehandle]

Al Koholic - 22-4-2004 at 21:51

Screw putting this in another section. It needs its OWN section! :-)

axehandle - 22-4-2004 at 22:31

Thanks for the praise, but I'm sure there are lots of people who have planned to make their own contact plant. I just happen to be crazy enough to actually go farther than the planning stage.....

Edit1: Phew. Mixing casting sand by hand is no fun at all. Think I'll need some more bentonite as well...

I have this new idea about casting the burner in 1 piece. Unfortunately that means cutting the old one into pieces with a hacksaw. Good exercise, I suppose...

Edit2: Think I'll dedicate this entire day to casting. Gonna practice with lead first. Tonight my girlfriend comes, but then she can melt the aluminum for me.... hmmm hehe.

Edit3: Righty righty --- away to buy M20 threaders, a very long 8mm drill, and perhaps more bentonite just in case.

Edit4: There, much better. The little thingie in the bottom is a bimetal thermostat, btw. It will control a servo controlling a coolant fluid valve. However, now I'm really broke and won't get more aluminum until Tuesday (money). And I don't really feel like cutting up the old burner --- it makes a very good ashtray for visitors. So there will be no interesting updates until Tuesday; well, perhaps some drawings.

[Edited on 2004-4-23 by axehandle]

Damned!

axehandle - 28-4-2004 at 03:45

Woke up too late today to buy aluminum (they close early). I'll have to get it tomorrow. Think I'll buy 10kg of pure Al plate.

The casting sand is ready. I used 90% SiO2, 10% bentonite and a liberal amount of water. It seems to hold its own.

Edit1: On second thought, I'll now try to cut up the old burner half with a hacksaw. Then I will have about 3kg of Al, today. And I can cast it --- today.

Edit2: Hmm, the hacksaw idea was too tedious, so I mashed the vessel in my hydraulic press instead. Now it remains to be seen whether my furnace can melt such a huge block.

Edit3: There we go, almost completely molten... but alas I'll have to get a refill for my propane tank. I really have to build a more efficient melting furnace. I've used up 10kg of propane in notime...

[Edited on 2004-4-28 by axehandle]

[Edited on 2004-4-28 by axehandle]

Hermes_Trismegistus - 28-4-2004 at 08:25

Quote:

Originally posted by axehandle Think I'll buy 10kg of pure Al plate.

Don't they make soda and beer cans out of aluminum there?

Maybe you might want to consider raiding the recycling bins eh?

also, as I remeber the old screen doors and aluminum sidings are made out of aluminum, why not try a junk yard or a garbage bin on a constructruction/demolition site.

(just a thought to save you some money)

axehandle - 28-4-2004 at 09:35

Thanks for the suggestion. I know you mean well, but there are several things wrong with your suggestion.

1) Beer cans are so thin that they oxidize before they melt.
2) Scrap yard aluminum is usually not pure Al, and for this project I'll use nothing else. It would probably work with, say, Al/Mg/Mn alloy, but I'm very corrosion wary when it comes to building a machine that contains within it a flow of superheated (900C-ish after the catalyst pass) SO3.

OK, progress.

axehandle - 28-4-2004 at 17:55

Here's the core I just cast for the burner vessel. It's cast of pure KCl, and will look a lot better once I've sanded it smooth. I'll cast Al around that, drill, thread, and then dissolve the core with water. But not until tomorrow, it's 03:54 here...

OK

axehandle - 29-4-2004 at 05:38

Time for some serious bench grinder work. Although I must admit I'm a bit hesitant to grind KCl with my fingers all filled with small wounds. But then again, that which does not kill makes you stronger.

Edit1: Having immense troubles with making a core. I'm now trying drying out a beer can filled with KCl + some water in the oven....

Edit2: No no no no no. Didn't dry it out enough. Here's number 3, this time I'm repeating it with a taller glass vessel. Once it looks dry (it's on a hotplate) into the oven it goes, where I intend to heat it in 3 1-hour steps to avoid glass breakage (100-->200-->300) and hold it at 300C overnight.

The metal thing coming out the top is an M16 threaded rod going through the salt cylinder. It will be used to hold the core in place in the casting sand, after which I'll drill it out and make an M20 threaded hole where it once entered the cast burner vessel.

Here's the casting plan:

[Edited on 2004-4-30 by axehandle]

Here we go, the finished core.

axehandle - 1-5-2004 at 05:54

Now it remains to be seen whether it cooling down to room temperature makes it crack. If it does, I have yet another idea (tm) for a core: Water, bentonite and perlite, all dried out completely. But we'll see. I hope this one doesn't crack, I'm getting sick of making failed casting cores now.

Edit1: Oh yessssss, precioussssss..... it didn't crack. And it probably wont crack from molten Al either if I pre-heat it to 300C ---- KCl has lousy thermal conductivity.
Here it is, cooled to room temp. It's a bit "bubbly" on the surface (hard to avoid considering the manufacturing method). I won't cast the burner until tomorrow, since I'm going to a party tonight. Heating aluminum to 800C and pouring it is not wisely done in a drunken state.

[Edited on 2004-5-1 by axehandle]

Casting shall be done not today but tomorrow.

axehandle - 2-5-2004 at 07:08

I little mishap slowed me down a little, though. I picked up ceramic pot shards from the bottom of the furnace, and, as usual, I cut myself. So now there's blood all over the furnace, on the kitchen floor, on a chisel I used trying to pry loose the last shards, etcetera. It's amazing how such small a wound can bleed so much. I'll have to wait until it stops before I make the sand mold. SiO2 particles inside a wound are painful.

Edit: No, my current casting sand is useless. I made it from atomized SiO2 and bentonite and water. Research I just did suggests using sifted sandbox sand, bentonite and water. My current mix simply isn't porous enough, so the bentonite and water lumps together, not blending properly with the "sand". Tomorrow I'll get a couple of kgs of bentonite and raid the childrens' sandbox once it's become dark. I hope there are no dog turds in it....

.

I'll also get a 20mm diameter wooden rod to form molds for the aluminum piping, casting the burner and some Al rods in one go.

Pictures will come tomorrow. I'm really tired now.

Edit2: There there, 10kg of bentonite are safely in a bag. Now I only have to wait until it's dark, then I'll go out with a bucket and loot the childrens' sandbox. Hehe.

Edit3: Sand stolen. But it's too wet because of rain. Typical.

Edit4: But VERY good sand, nethertheless. Very uniform particle size. I'm drying+disinfecting it at 275C now. I don't want to mix dog turd and cat piss infected sand with my wounded hands.

[Edited on 2004-5-3 by axehandle]

OK

axehandle - 4-5-2004 at 04:40

I've mixed the casting sand with 15% bentonite, and added some water. It's supposed to sit now for a while so the water will distribute itself cleanly.

I can share a warning though: Wear breathing protection when working with bentonite or silica! I've gotten myself a nasty cough by ignoring precautions. If done often, it can lead to silicosis, which is a horrible way to go.

Tacho - 4-5-2004 at 06:50

Just curious, is this the usual way to do molding sand for al foundry work or just a recipe you are trying?

I have seen casting sand be molded DRY and I always wandered why did it stick together.

Sand.

axehandle - 4-5-2004 at 07:02

There are two types of sand used for sand casting: Water bonded and oil bonded. The oil bonded kind uses a petroleum based binder with suspicious properties. Water based sand is just silica, clay and a minimal amount of water. The porosity of the sand lets the water vapors out, the clay is what's holding it together.

Edit: What you saw was probably the oil bonded CO2 hardened sand type.

My arms are aching.... mixing this stuff by hand is hard work... but it seems to hold itself together quite well:

21:37 Melting Al !!!
22:19 FUCK! The crucible developed a hole. The entire furnace is filled with molten Al. I'll have to build a new one. As a bonus, I trod in a puddle of molten Al. Ouch!!!
22:22 Yup, a 3rd degreer right under my foot. Great. Just fucking great.

[Edited on 2004-5-4 by axehandle]

Fucking hell.

axehandle - 4-5-2004 at 13:03

It stings a bit.

The only upside is that I planned to build a new furnace anyway, and purchased all the needed materials 5 days ago.

Edit: And on the bright side, I got a little Al down the sand mold. The sand works. That's always something. Now I'm going to go out and buy some beer and food in order to forget my aching foot.

Edit2: I'll construct the new furnace tomorrow. It will have a larger capacity and a better refractory formula (higher percentage of perlite and bentonite). So I guess the accident was all for the best, although it will take 4 days before the refractory has dehydrated enough for usage. Now, where do I get hold of cast iron crucibles capable of taking 3kg of aluminium???

Ah, I've found the perfect vessel for my new furnace. Sometimes even IKEA makes something useful:

Dimensions: dia 47cm, height 44cm, all galvanized steel.
And it comes with a lid! I only have to put refractory comp on the topside and inside and mount a hinge for the lid!

Edit3: I now have all materials needed. Jewelry casting cement, the bucket in the picture, a hinge, machine nuts and bolts, angle iron mounts for the refractory that will cover the underside of the lid, and a cubic metre of perlite. Plus a plastic bucket to serve as a mold, inside the metal bucket. Now I only need to regain some energy, then it's casting time. Unfortunately I'll need a refill of propane --- again :mad:

. My burner gobbles propane, I think I'll replace the 0.8mm nipple with a 0.6mm nipple.

[Edited on 2004-5-6 by axehandle]

Drying of SO2 inlet

Dagor - 6-5-2004 at 12:02

Hi there, congratz on your interesting project. We had labwork today for chemical engineering; the oxidation of SO2 to SO3, under catalysis of vanadiumpentoxide.
We had only one problem; vanadiumpentoxide was expired so we were down to 18% of the theoretical value, instead of 50%. Now my question for you guys is, does anyone know how vanadiumpentoxide can expire? It was in analytical concentration, stored in a closed jar.

Some ideas that might help; you speak of drying the inlet of air with CaCl2, why not use H2SO4, since it will certainly give less contamination and it is verry hygroscopic.

Our setup; a membrane airpump (like for an aquarium was connected to a big flasc partially filled with water, to give a more stable stream of air. a tube comes out of this flask and leads the air to a flasc with SO2 in it. Similar to the one to stabilize the air-flow. Then the air filled with SO2 is lead trough a washing-flask (like those for testing CO2 in air with chalkwater), filled with H2SO4, so the air is dryed. then it is lead trough a pipe of porcelain (like china-potterymaterial I know my English is bad). This pipe is about 40cm long and sealed with rubber stoppers. It is this pipe that goes trough the oven. Only a small part is heated, so the ends stay cool and the rubber stoppers don't melt. A small long recipient filled with pure vanadiumpentaoxide is placed in the pipe at the point where it is heated. As the "air"flow comes out of this pipe, you should have 50% SO3 formed. again sorry for my bad english, and can anybody help with how vanadiumpentoxide can expire, maybe chemical reactions? (It came from across and costs about €50,00 for 0,250kg), I'll mention your name in my labreport (not that anyone interesting would read it, but it may help as a reference if someone else is trying to patent stuff you came up with, you never know (and no, I am not serious, I have been standing next to an alcohol destiller the whole day). Be carefull if you try to get the product out of the pipe when it is still hot; the pipes break easilly and the fumes very unpleasant to inhale. I still have a head-ache from doing so and it's believed to be carcinogenic. About the oven; I can ask technical specifications if you are interested, but I believe it is just an electric resistor winded around a tube. Don't know about the thermostat, probably a thermocouple. It goes up to 800°C, about the double of the optimal temperature of about 400°C.
Thx and good luck

BTW; ACROSS does not sell to individuals, it was just for info on the product we used, in case you hoped for a new selling adress, I tried it too before.

[Edited on 6-5-2004 by Dagor]

vulture - 6-5-2004 at 13:17

The "expiring" you encountered is a very common effect in surface chemistry.

Crystals or particles will automatically "redissolve" and crystallize out as bigger particles, reducing the surface area.

Making ammoniumvanadate of the V2O5, or buying the ammoniumvanadate and pyrolysing that onto the cat base will have far superior catalyzing properties.

axehandle - 6-5-2004 at 13:44

Thanks for the experiment report. I'll try to answer some of the questions:

1) Dehydration. Yes, H2SO4 would be more efficient, but the reason for me trying to make H2SO4 is that H2SO4 is restricted here. As soon as my machine has produced 1 litre or so, I'll swap from CaCl2 to H2SO4. It's a catch-22.

2) I really like your buffer flasks idea. Consider it stolen

.

3) Heating. I'll use a cylindrical aluminium block with an embedded, 2 metres long canal to heat the SO2/air mix before it enters the catalyst chamber. The block will be insulated on all but one side, and heated by hotplate. As a thermometer, I'm going to use a molten salt thermostat (eutectic mix). I will aim for 450C, optimal for V2O5.

4) Catalyst. You were ripped off, I got mine from a ceramics supplier for less than half of that price. Sorry.

5) Catalyst loss. Vulture pretty much described it. I have deposited V2O5 on a substrate (pumice to be exact) by soaking the pumice pieces in NH4VO3 (aq + ammonia) solution, boiling it in and then heating the pieces enough for the NH4VO3 to convert to V2O5. It should be pretty stationary on the substrate.

BTW, NH4VO3 can be made by tossing V2O5 into strong ammonia, then boiling it in. It's smelly, and NH4VO3 is rather poisonous, so beware.

If for some obscure reason the V2O5 catalyst shouldn't work, I'll use Pt-on-kieselguhr instead.

thx

Dagor - 6-5-2004 at 20:49

Thx a lot, I'm gonna check out on the surface area. Maybe I can calculate the surface reduction by the reduction of efficiency. That 's gonna be an interesting report to write. Well, gotta go or I'll miss my train

Found you Vulture

Dagor - 12-5-2004 at 07:11

How am I supposed to get an independend verification of these results if you are interfering on chemixtry? ;-)

axehandle - 12-5-2004 at 11:12

My work on the machine has NOT stagnated, it's just awaiting me finishing my new Al melting furnace, which I document step by step here: http://www.sciencemadness.org/talk/viewthread.php?tid=1968

froot - 13-5-2004 at 08:45

Axehandle, just be very carefull when pouring molten Al.
I'm not sure if you're experienced in this field, but if there are any volatile substances in the mould things could/will get very ugly when pouring.
Instant vapourising of volatiles by the molten metal can cause bursting and send molten metal flying everywhere.
Common practise would be to heat the mould prior to pouring to as high as you can get it to be (in your case) and keep it there until you pour. Put a metal bin over the mould and shove that propane burner you have there under the bin into the mould if possible. It has to be hot.

It also helps metal flow in the mould and you'll get a better quality casting.
Sorry if you're aware of the risks, but if you're not, molten Al on your flesh can really f'k up your day.

axehandle - 13-5-2004 at 09:02

I'm going to use standard casting sand. The grains are quite big, so the whole mass is very porous.

Btw: I've cast before. But thanks for your concern.

maxke - 24-5-2004 at 09:02

Axehandle,

Have you visited the following page ?

http://www.backyardmetalcasting.com/

There are sections about propane burners and building a refractory. The info inside is compact but might be of use.

The best of luck and mad respect for your work here, and your achievements in general. (your homepage has a large drool factor btw)

axehandle - 24-5-2004 at 09:12

Quote:

Axehandle,

Have you visited the following page ?

http://www.backyardmetalcasting.com/

Many times. But thanks anyway.

Ramiel - 25-5-2004 at 01:03

Document! Document! Document!
um... yea.
-Ramiel

Back in business!

axehandle - 15-6-2004 at 11:07

My newly built electrical melting furnace seems to work: http://www.sciencemadness.org/talk/viewthread.php?tid=1968

... so now I can soon begin casting aluminum again!!!!

axehandle - 19-6-2004 at 10:02

Now I only need to build a cylindrical crucible and clean up my workshop^H^H^H^H^H^H^H^Hkitchen... then the work will FINALLY continue. I have some pretty amazing designs in my head to put down on paper.

The only thing that's still in a "floating" stage is the sulfur burner... I have many dirrerent ideas there, most of which would probably not work.

My most recent idea reminds of a hot glue gun. Pre-cast rods of sulfur are pressed against a hot Al plate with a small hole in it. Sulfur is turned into gas at the plate, the gas is then ignited piezoelectrically. This could go wrong in so may ways, though...

Another idea would be to let molten sulfur drip into a ceramic chamber, the part of the bottom where the droplets land is a constant red-heat by heating coil embedded in it. This could probably be adjusted to remove the need for a gas-stream preheater (before the catalyst chamber). The obvious problem here is coupling ceramics to aluminum tubing... the heat expansion properties are very dissimilar. This one is still my favorite though, since it's very simple to build, now that I can fire ceramics...

Sulfur burner...

axehandle - 11-8-2004 at 06:46

I think I have solved the problem of designing a good small-scale sulfur burner! Drawings will follow...

Edit1: ..if I can get this fscking scanner to work, that is... Ah, mentionable is that the burner must be places in an airtight vessel (I'm thinking glass here, it will look pretty) with air pumped in, and a pipe leading the SO2 + air mix towards a muffle heater that will bring the gas up to 500 degrees C, after which it will pass through a catalyst pipe and then to an SO3 absorption flask... let's see if we can get this scanner to work now..

Edit2: Here we go. The "heater" will probably be a small heating plate made of resistance wire embedded in phosphate bonded cement:

[Edited on 2004-8-11 by axehandle]

[Edited on 2004-8-11 by axehandle]

Hey Axehandle

Eclectic - 14-11-2004 at 13:03

Ok, I found the correct thread for this.
Here is a recipe:
4.5 kg V2O5
13.3 kg KOH
42.8 Kg kieselguhr (diatomaceous earth, pool filter)
14.3 ground spent catalyst residue
6.4 kg sulfur
2 kg ammonia
32.5 kg 16 Be H2SO4

Then I went to some patents and found out about more recent optimized catalysts using Cs instead of K.
I can try to find smaller batch recipes from US patents if you are interested. The optimum temp seems to be aboyt 450 C. Reaction is exothermic, and higher heats increase reaction speed but push the equilibrium the wrong way.

Eclectic - 14-11-2004 at 13:54

So why do you think sulfur will not react with aluminum to make aluminum sulfide?

Can you get stainless steel tubing from a plumbing supply? It should be fairly inert to SO2 adn SO3.

In all the discusion about thermostats, here is one I didn't see: Your heating element has a positive temperature coefficient, so it you can measure the current and voltage across the heating element, you can figgure the resistance. Translating that to an actual temp reading might be tricky, but if you get a circuit to hold the element resistance constant, your temp will be constant also.

Eclectic - 14-11-2004 at 14:57

A good source of fairly cheap and pure scrap aluminum is aluminum electrical cable. About 99.5% pure with a little silicon and magnesium.

Danger! Danger!

Eclectic - 16-11-2004 at 11:49

You should test molten sulfur in hot aluminum in a thermite safe location before scaling up. Al/S powder is used as an ignitor for thermite! See thermite threads. Stainless steel would be MUCH safer.

V2O5 catalyst

tetrahedron - 30-9-2012 at 16:33

in new zealand they also add potassium sulfate:

http://nzic.org.nz/ChemProcesses/production/1B.pdf

(comes with temperature control graph)

Arsole - 13-12-2012 at 23:03

8 years too late man.

Anyone still working on the contact process?

plante1999 - 14-12-2012 at 09:49

I did, you can look in lab scaleindustrial processes volume two.

I used platinum instead of vanadium however, and I got good result.

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