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I've been reading some old threads about solid catalysts, but they're all long dead and I don't see any of them having been generally adopted.

I'm most interested in acid catalysts good for esterification of FFAs.

So what has anyone found to work? Is anyone using amberlyst or DOW 2037 or the sugar catalyst?

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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I made some acid sugar catalyst a couple of years ago. It works fine with FFAs and WVO which contains >30% FFA.
 
Location: Scotland | Registered: March 19, 2006Reply With QuoteReport This Post
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I think DKenny is considered an expert in acid esterification of FFAs. At least, I think I remember reading something to that effect.

Why don't you invite him to this thread in a PM?
 
Registered: September 26, 2005Reply With QuoteReport This Post
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I had started a thread on Montmorillonite K-10 as a solid-catalyst here .


"Political language... is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind."

George Orwell
 
Registered: June 09, 2006Reply With QuoteReport This Post
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David,
thanks for the invite.

While I do know lots about acid processing I have never use a solid catalyst..sorry.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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DOWEX MONOSPHERE DR-2030 has been mentioned in a few places, and M-31 in a couple more.

M-31 sounds like it might work better in a wet environment. Anybody know what the differences between them would be?

http://www.dow.com/liquidseps/prod/sac.htm has a whole pile of strong acid catalysts, off of them based on styrene and limiting the temperature to 135C. I'd kind of like to process at a higher temperature than that. Anybody know of a solid acid catalyst on some sort of ceramic substrate so I wouldn't have to worry about temperature?

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post



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are you pressurizing your setup? 135C is way over methanol's boiling point. even mixed..

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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dkenny asks:

quote:
are you pressurizing your setup? 135C is way over methanol's boiling point. even mixed..


You could say thatSmile

I'm specifically looking to polish the fuel that comes out of my supercritical reactor. Glycerides are low, processing speed is quick, gylcerin is pure, but the acid number is a little high. I could dry it and run it through the processor again, but would rather heat it that much only once.

After supercritical processing a few hundred PSI doesn't mean much....

The reaction happens much faster at high temperatures and pressures. I've found that FFAs esterify quite nicely - without catalyst - a temperatures of ~220C and 1500 PSI.

I also found you can esterify with glycerin at those temperatures and pressures - again without catalyst. Kind of cool.

Over the next week or so I'll be building a small esterification reactor, good for a couple thousand PSI and temperatures up to the limit of the catalyst.

If anyone has some sugar catalyst, or some kind of commercial catalyst (amberlyst bd20 would be nice to try) just let me know.

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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Scuse me David. Are you saying you have a working supercritical reactor? Could sound that way from the statements "I have found" but looking back through your posts I see no mention of building it and you are mentioning an intention to build something in the next week or so. I am a little confused.


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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Ant asked:

quote:
Scuse me David. Are you saying you have a working supercritical reactor?


Yes, I spent the last six months building one. It works pretty well except for two problems.
1) I built it in carbon steel, and supercritical methanol corrodes it. That's easy to fix.
2) At the end of the cycle it has an excess FFA level.

It's possible that the iron is having negative catalytic impacts, but after talking to Saka and others I'm inclined to believe that it's a natural consequence of the esterification process.

Which brings us back to the purpose of this thread: solid catalysts for esterification. I know I can finish the fuel by drying it, adding dry methanol, and reprocessing, but continuous flow through a solid catalyst would be much more efficient.

What I plan to build in the next week or two is something much simpler - lower temperature, lower pressure, just a test bed for solid catalyst esterification.

So, anybody have any advice on solid acid catalysts? Sugar catalyst? Amberlyst? Something else?

Thanks,

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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quote:
Yes, I spent the last six months building one. It works pretty well


Any reason not to share the details with us?


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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Ant asks:

quote:
Any reason not to share the details with us?


A few. The time spent is one, but mostly it's because we're not talking about something of general interest to the homebrewer community. It's not easily replicated, is not cheap, and in the hands of many would be downright dangerous.

3000 PSI? 650 degree methanol? What could possibly go wrong? Smile

The supercritical process is great for 24x7 operation in a commercial setting. It's hugely expensive overkill for a home setting.


--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post



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Are you sure it's FFA's causing the high acid number after transesterifiction? How high is the acid number?

You could use magnesol to get rid of the acidic parts and clean it with a centrifuge.
 
Registered: August 14, 2006Reply With QuoteReport This Post
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cfunderburg says:
quote:
Are you sure it's FFA's causing the high acid number after transesterifiction? How high is the acid number?


Nothing goes in but oil and methanol. Glycerin and biodiesel comes out, and something that titrates from a low of maybe 2 to a high of 5 or six. I'm not sure what else it could be other than FFAs. If I translated the numbers properly the ASTM spec is around .5.

quote:
You could use magnesol to get rid of the acidic parts and clean it with a centrifuge.


Are you sure about that? I'd never heard of magnesol being used to remove FFA's, just glycerin and soap. I'd love to have a way to remove them and just feed them back into the process, something better than caustic stripping. I'll take a look at the magnesol.

Thanks,

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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Magnesol and other Used Cooking Oil cleaners can remove FFA's.

We sell a Silicate Gel that removes FFA's but I thought the idea was to esterify these so it is 100% Biodiesel.

David, I think our Macroporous resin will esterify the remaining FFA's at temp. >70 deg. C.
The resin's maximum operating temp. is 120 deg. C. or 250 deg. F.

I believe you said your reacting at ~300 deg. C
So you would need to reduce the temp. below 120 deg. C minimum and I would recommend <100 deg. C (perhaps 80 deg. C since at this temp. the mixture would only require about 22 psi in system pressure in order to keep the methanol from vaporizing). If these conditions were maintained then the mixture could be run through a the macro. resin bed and if given 2 hours of contact time the FFA's should be reduced by 90%.

For every one mole of FFA - you will get one mole of water. So given 3% FFA's in the final mixture, during the esterification process you would produce <0.2% water.

Say you have 1000 grams biodiesel - then 30 grams will be FFA's. (assume an avg. molar wt. for FFA's at 280 g/mole) Then the esterification reaction will create (30g/280g) 0.1 mole of water or 1.8 grams of water (<2ml per liter of reacted biodiesel/ffa's)

GCG
 
Location: Michigan | Registered: May 08, 2007Reply With QuoteReport This Post
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Are you sure about that? I'd never heard of magnesol being used to remove FFA's, just glycerin and soap.


Yes that was the original use. It reduces rather than removes if I remember rightly and also was not that cost effective.

I seem to also remember that sodium silicate was good for stripping out FFAs.

Pardon me if you have made it clear but what percentage FFA are you talking in the bio?

Are you sure it is actually a problem fuel wise?

Or just meeting spec?

FFA tends to reduce viscosity and so far no one has shown any problem with FFA attacking steel that I know of.

Solid catalyst estrification would seem the better answer to the problem though. If there is a problem.

Re the reactor. Are you aware someone is building one in another thread? More of a supercritical testube design but very ambitious for homebrew.

Perhaps you would consider joining the thread and helping him to stay safe?

He has cold pressure tested it so far and it passed around 5000psi off the top of my head.

He is planning to add heat next.

I would be personally interested in details of your system, by pm if you prefer. I would be happy to abide to any reasonable conditions you wish to impose on what I do with the info.

You may note in the heating with WVO threads I did not disclose the details of Murphy's burner head even though I thought it was a simple innovation on top of everyone elses work and should rightly be shared with the forum.

The point being that I will respect your wishes on disclosure if you choose to share information with me privately.


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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GCG sez:
quote:
..... I thought the idea was to esterify these so it is 100% Biodiesel.


It certainly is, and the most preferred method would be to esterify during the supercritical state with some high temperature catalyst.

If that doesn't work, then a nice solid catalyst that works fairly quickly at more reasonable temperatures would be acceptable.

And if *that* doesn't work, then some way to trap the FFAs for later processing would get the job done, if not ideally.

I'll contact you offline about getting a sample of your solid catalyst.

Ant sez:
quote:
Pardon me if you have made it clear but what percentage FFA are you talking in the bio?

Are you sure it is actually a problem fuel wise?

Or just meeting spec?


It's just a problem meeting spec. It looks like the resulting fuel is in the 2-5% FFA range.

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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probably harmless in practice but spec is spec if that's what you need.


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post



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Update:

I got 5 pounds of Tulsion T-45 resin from http://arborbiofuelscompany.com/biodiesel_dry_wash_equipment.html

It arrived yesterday. Today I filled an 8 oz canning jar about 2/3 full of the resin beads, then mixed some FFAs from split byproduct in a 2:1 ratio with methanol (1/3 methanol, 2/3 FFA).

The mix titrated at 7 when diluted with the methanol.

I dropped the canning jar in a water bath at ~130F.

After this many minutes it titrated at:

15 5
30 3.2
45 2.4
60 2.0
75 1.6
105 1.5
135 1.5
290 1.3

After that I added 2 more oz methanol to the mix, kept warm in the water bath for an hour, and titration went UP to 1.9.

I'm also testing DOWEX 2030; I'll let everyone know how that comes out in a few days.

I'm not really satisfied yet with the results; I need to take fuel titrating around 4-5 - fuel with a bit of water in it from earlier esterification - and get it below .5. I'm not there yet.

FWIW, which probably isn't much, I'm trying to get some amberlyst bd20 for testing.

--- David
 
Location: Maine, USA | Registered: July 06, 2007Reply With QuoteReport This Post
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David,

Great test and it appears you have stumbled on something we recently discovered while performing a methanol flush of our Lead Resin Column filled with the Thermax' Tulsion T-45 BD Macro ion exchange resin: See the video for methanol flush here: Chads454 photobucket.

Anyway while we were filming this procedure we decided on the fly to show everyone the methanol purity test using an alcoholmeter and then follow it up with a soap test titration.

Well when we began to do the titration by adding the flushed methanol sample to the isopropanol/bromophenol blue mixture; it went yellow immediately and when testing the methanol for acidity it came up fairly acidic.

We believe this is due to the resins ability to interact with the free fatty acids created when the soap molecule is converted to a fatty acid.

We are not sure exactly what is happening but it seems possible that the resin is retaining or adsorbing some amount of the FFA's and it takes quite a bit of flushing to remove them all since they seem to be present all the way up to the 5th bed volume of methanol flushing...

Lastly in your experiment you only heated the sample to 130 deg. F and this equivalent to 55 deg. C and this isn't hot enough for the resin to esterify the FFA's fully. The manufacturer recommends >70 deg. C or ~160 deg. F. and 120-180 minutes of residence time.

I am very interested in your study - once again simply wonderful work your doing.

By-the-way we sent a sample of the flush methanol to Van Gerpen at Idaho University to be analyzed. Hopefully I will hear something on this soon.

GCG

This message has been edited. Last edited by: GCG,
 
Location: Michigan | Registered: May 08, 2007Reply With QuoteReport This Post
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