15 replies to this topic

[JayAlchemAPL]

The most common and cheap transition metal oxide for Fischer Tropsch (FT) catalysis is iron oxide. One glance at the floor of a metal shop and sourcing iron oxide catalyst seems like a perfectly reasonable proposition. However, most of the literature indicates there are surface characteristics and other details that matter as much as the raw material type used.  Other important factors are things like: purity, particle size, porosity, pretreatment regimes, addition of promoters and/or supports (such as alumina oxide), and co-catalysts such as cobalt/copper/etc will allow for higher selectivity (meaning less deviation across the possible range of products) higher catalyst activity thus higher efficiency in carbon conversion to liquid fuel.

These considerations for FT catalyst making do not necessarily render DIY catalyst making impossible, but lack of attention to these details will definitely challenge activity of the FT reaction as a whole.

Earlier FT experiments have used magnetite for the catalyst to synthesize anywhere in the range from diesel, methane, and/or wax as a liquid product from wood gas/coal gas.  Magnetite, is naturally magnetic iron ore, the 'black rust', Fe3O4, also iron (II,III) oxide.  I am trying to recreate what these earlier experiments may have achieved. Like many of us that are interested in reading about this technologies we all start at the FT archives here: http://www.fischer-tropsch.org/

I was able order magnetite in a form other than ultra fine sand, Riesse Viking, which typically this company deals with selling quantities of this iron ore in the magnitudes of train cars. So this means that a 50lb order from them is considered a free sample, which they sent to me. Their purity is from 70-80 % mixed with aluminum oxide and silicon oxide -sand around .01-2.5 mm dia. Alumina oxide has been studied as a promoter in FT activity, and silicon oxide is inert.



This is not the only place to obtain magnetite. Another method is to  pack a pipe with steel wool and lighting it on fire while blowing compressed air through the tube. While some iron oxide is successfully produced, often times it was difficult to keep the flame lit, or the air would blow the finer powder out of the tube before being fused into a workable particle range. Some was still successfully made, but it was difficult to achieve any sort control toward sieveable particle range or consistency.



I was also able to find a whole pile of stainless steel lathe chips of a uniform size for this project. They are beautiful, sharp metal chips from a lathe about  1.25 mm in length.  The interest in starting with stainless steel is that it has about 10% chromium in it. Some articles have suggested (ie: Nature http://www.nature.co...s/156506b0.html) that chromium can actually be a promoter of iron FT catalyst because chromium oxide has a very high tendency in its adsorption of hydrogen. To oxidize the stainless steel metal, I used an oxy-acetylene cutting torch down in the shop. It was adjusted for an oxygen rich flame to melt and oxidize the chips and held about 2 inches from the pile of chips. This actually worked quite well. Some clumps were created, so I just chopped them up with a mallet. I was able to fire them evenly and it was common to observe a bubbling effect on the surface creating micro pores. This is only better for catalyst surface area!



It is also fairly cheep to obtain pure magnetite from ceramics suppliers. I was able to get it from Anexer which sells it for about 1.50 a lb. Their site here: http://www.axner.com...?find=magnetite
Most magnetite that you will find at ceramic supply stores will be ultra fine because it is used to mix with glazes, magnetite is used to create a dark black finish. It is fine like sand/powder. Since magnetite melts at about 1540C, the plan is to melt it with the oxy-fuel cutting torch in the shop. Here is a quick article of an account of someone trying the same thing: http://www.oocities....e/homemagn.html
I have currently not used the magnetite sand from Anexer quite yet but will be doing this one soon after running some of the other catalysts.

[Mike LaRosa]

Hi J, Just Mike LaRosa here. We usually try to get to Lake Michigan a couple of times a summer near Two Rivers, WI. Along the western shore there are usually black bands of iron that are along the shoreline.  I have collected a few cans of this stuff when I have seen it as it collects because of it's magnetic properties. Is this something you might be interested in looking at ? I'd be glad to put some in a zip lock in a bubble pack and mail your way. Just e-mail me direct if you'd be interested. Hope all is well on the West Coast. Just ice, snow and cold here right now. Regards, Mike LaRosa

[JayAlchemAPL]

Magnetic sand, how cool it must look pooling up into clumps. I have to ask, does it all face north?
I wouldn't mind tinkering around with some if you wouldn't mind sending it to us.

Particle size is always an important consideration when trying to understand catalyst activity, and I'll tell you- trying to sieve out magnetic sand from slightly larger pieces of magnetic sand is probably one of the more annoying separations I have tried to conduct, and not entirely successful either. But if any does come out in the fuel, then it would be great to simply swipe a magnet through the gasoline to pick up any fine stray particles!

[JayAlchemAPL]

There are two more steps typically considered for the pretreatment of catalysts to induce catalytic activity.

After producing the basic catalyst with desired physical characteristics, there is typically a calcination step. During calcination, the catalyst is heated up to the 400-500C range and held for several hours. This step is to ensure that any volatile components are burned off of the catalyst surface. Any volatile components can gunk up any active sites and disable the activity of the catalyst. Here is an article that describes the preparation and pretreatment of a co-precipitated catalyst. The calcination step here is done in air at 500C for 5 hours. http://wiki.gekgasif...h Catalysts.pdf

A second pretreatment step, reduction with hydrogen can be combined as a start up procedure in the reactor column itself as an in situ operation. Some catalysts require a reduction step before they are catalytically active. Before the reactor column is brought up to temperature, all of the oxygen should be purged out of the system. This is because oxygen will attack active sites and decrease the efficiency of the catalyst. I have been doing this with a tank of nitrogen for this reason, and to prevent any stoichiometric mixtures of oxygen and gas into the reactor column. Hydrogen then is brought into the system and ramped up to 250C. It seems there is quite a range among articles of the amount of time one should reduce an Fe2O3 iron catalyst, anywhere from 2 to 24 hours. There are also some studies being conducted in activating catalysts in situ with carbon monoxide as well, such as the suggestion by this article: "Activation studies with an iron fischer-tropsch catalyst in fixed bed and stirred tank slurry reactors" http://onlinelibrary...740311/abstract

Has anyone attempted to make FT catalysts?

[mikeotter]

Jay,
keep it up!!  I want to add a few things here. I needed Iron Oxide at one point for a few things I was working on so I done some things similar to what you are doing.  I propped a length of stove pipe on the 45 with a 90 elbow at the bottom pointing up..... Use pure Oxygen or mix it with the air you blow in.  Be VERY careful and start slow with the Torch Oxygen. Ramp it up at a rate you feel comfy. The stainless will spew some evil shit so be careful. Your difficulty in keeping it lit will no longer be an issue at all.   I'll go one step further in explaining how effective this is.  If you have a steady hand with a cutting torch ( or a roller guide ) you can start making a cut and turn the combustible gas right off after you press the blow out bar on the torch as long, as you keep moving slow and steady. Keep the bar pressed as the cut starts,keep moving and just turn the gas off.  You'll notice that the cut keeps going as you are not blowing metal out so much as you are just burning it with the OX..  
http://en.wikipedia....essemer_process
http://en.wikipedia....gen_steelmaking
Look here and here for the heat potential .... BE CAREFUL !!!
It don't take a bunch of Oxygen to get the job done so it's fairly cheap.
Tell Payphone thanks for hooking me up again :)
Thanks for all you do out there,
Mike Anthony

[jmonty1750]

If had known you were looking for iron oxide I would have let you have my wood powered Escort after it died. It was generating copious amounts of iron oxide at that point and not much else.  Seriously, though this is one place where you may want to look into the availability of commercial catalysts.  With SASOL in commercial production and others trying to come on line there may be proprietary catalysis available for the purpose.  You have enough of a hill to climb in small scale that you don't need to take on that challenge as well.  I believe SASOL uses oxygen blown gasifiers with steam injection so they are starting with nitrogen free gas.  Tolerance to tar and ash impurites by the catalysis is almost nil so you have to really work the filtration.  US Air Force has qualified its planes to fly on FT fuel.  GE and the Navy flew an F-18 on camelina derived bio fuel last April.  This is going to happen commercially, and from what I've worked with the commercially made stuff is already very good stuff.

Joe - M

[sustainbiofuels]

Do you think the cost of a commercially prepared catalyst doesn't reflect the work involved in making a viable material?

Often times, the price of a material is an indication of the work required to make it to an acceptable level of quality, do you feel that magnetite is not priced this way?  It isn't always so, do you think this is the case with these catalysts?

Don't you think your lack of an explosion proof setup is asking for trouble?  You're working with hydrogen around open electrical contacts, heating tapes etc.  I would strongly advise you to rethink your design and make it entirely explosion proof, don't hurt yourself.

[tonofsteel]

In order to make explosion proof electrical circuits you can use the following intrinsic safety barriers that will reduce the risks (there are other manufacturers that have similar offerings I believe):

http://www.phoenixco...ching/31248.htm

From the site:

Quote

Intrinsic Safety technology prevents explosions in areas where electrical equipment is used and explosive air-gas mixtures exist in their most easily ignited concentrations. This is accomplished by limiting the electric and thermal energy to levels that are incapable of ignition of these concentrations under both normal and abnormal conditions.

Where can you buy catalysts from?  I have looked and found several companies that manufacter them but there is never a way to purchase them easily.

It seems like the catalyst is going to be one of the more difficult things to get right, so if there is a way to purchase small quantities from someplace that did not cost a fortune that may be preferable to trying to get yet another variable right from the start (it looks to involve quite a bit of effort and specialized techniques, and it is difficult to measure your results).  But I guess there may be no alternative in the end.

I did see one place that was selling samples for somewhere around $250 per kg, but it was a zeolite catalyst and I am not sure about the characteristics or if it would be suitable for this application.  As well it indicated it was for educational institution use so I dont know if it would be available to anyone.

If there are going to be several people interested in experimenting maybe there would be a way to group buy some from a manufacturer?

Does anyone out there know where it is possible to get some iron oxide based catalyst?

A more broad question is what would be the best technology to obtain biomass to liquid?  I have found several different approaches and they fall under 3 categories:

- Fast pyrolysis (with or without catalyst)
- Slow pyrolysis (with catalyst)
- Gasification + Fischer–Tropsch Synthesis

Fast pyrolysis looks like it would be relatively hard to achieve since it is complex.  You need to heat sand/catalyst to high temperatures and react it with the biomass trying to heat it at 500 Degrees/sec and then quickly cool it.  It looks like you cannot distill the resulting liquid and need to have complex processes to reform it into a usable product.

The slow pyrolysis looks to get usable diesel or other liquid straight out of the process without having to do much processing, but there are highly guarded proprietary catalysts and process conditions that are used.  It seems like it would be harder to obtain a proper catalyst for this route.

Since the gasifier on here is a well developed and mature product it seems that it makes sense to persue the Gasification + Fischer–Tropsch Synthesis.  The liquids can be distilled so any usable fractions should be fairly easily seperatable, and any waxes or other products can be processed using existing petrochemical processes.

I am wondering though that since catalyst is used in pyrolysis to favor certain hydrocarbon chains forming, would it be possible to utilize a catalyst closer to the gasification process to make the Fischer-Tropsch Synthesis more selective towards the hydrocarbon chains you are trying to synthesize?

[sustainbiofuels]

All my industrial experience is in synthetic organic, and polymer chemistry, but one has to wonder if catalysts like this may be best prepared immediately prior to their use, even under N2 or argon.  Aldrich sells the finely divided magnetite, and the alumina, maybe it's just a simple prep, combined with a promoter, once one has these materials on hand.  Research also indicates they don't tolerate the tars and such that often contaminate syngas prepared from wood gasification.  Will try and find some literature on catalyst preps but have to hit the library.  I'm willing to bet engineers aren't good at preparing catalysts, this is the domain of chemists.

It appears that iron catalysts are always used for distillates in the diesel fuel range, it's temperature and pressure manipulation that select for chain length.  I think the "water gas shift" is used to alter ratio's of CO to H2 in the syngas.  Regardless I think the production of a lot of "wax" is inevitable.  As in all petroleum synthesis, subsequent cracking is necessary to achieve max yields.  The kind of cracking that would not be possible by the do it yourselfer.

[sustainbiofuels]

http://www.rsc.org/e...65546-00001.pdf

[Chemiboy]

sustainbiofuels said:

All my industrial experience is in synthetic organic, and polymer chemistry, but one has to wonder if catalysts like this may be best prepared immediately prior to their use, even under N2 or argon.  Aldrich sells the finely divided magnetite, and the alumina, maybe it's just a simple prep, combined with a promoter, once one has these materials on hand.  Research also indicates they don't tolerate the tars and such that often contaminate syngas prepared from wood gasification.  Will try and find some literature on catalyst preps but have to hit the library.  I'm willing to bet engineers aren't good at preparing catalysts, this is the domain of chemists.

It appears that iron catalysts are always used for distillates in the diesel fuel range, it's temperature and pressure manipulation that select for chain length.  I think the "water gas shift" is used to alter ratio's of CO to H2 in the syngas.  Regardless I think the production of a lot of "wax" is inevitable.  As in all petroleum synthesis, subsequent cracking is necessary to achieve max yields.  The kind of cracking that would not be possible by the do it yourselfer.

I'm a Chemical Engineering graduate,  and I'm currently working on my PhD in Heterogeneous Catalysis.  I work on a daily basis alongside chemists (post-docs & post-grad students), our jobs are virtually identical. I have extensive experience in catalyst synthesis. To say that Chemical Engineers aren't as good at catalyst synthesis as Chemists is non-sense.  Catalyst synthesis is certainly not all in the domain of chemists, especially when it comes to heterogeneous catalysis.

Chemiboy

[minerec]

Hallo!


I have some questions about the FT catalyst.

As I understand, elementery iron catalysis the reaction, not Fe3O4, so the first step is to reducate the Fe3O4 with CO to elementery Fe. In theory, shuldent Fe2O3 work as well?

I do understand that big catalyst surface is wanted, thats why iron oxide is used but wuld iron shavings work as well? I know it might not work as well as Fe3O4, but wuld it catalise the reaction?

I have some werry fine iron povder amd a small amount of Fe2O3, but no magnetite.


Thank you for your help!

[BACel]

A cheap source of stainless thou it may not produce good catalyst is inside of tires. Another possible source that may give a more uniform end product is stainless ball bearings. The price will probably be high ....... It seems like the focus should be the catalyst that produces the highest octane fuel. Because diesels are not that picky unless your trying to fuel newer high pressure diesels .I would not do that unless it was a necessity because it is easy to damage the  IP ,intake /exhaust sensors, and injectors .

on a grass root level its green(er) gasoline substitute that interests me.

[minerec]

I experimented on a small scale FT reactor I built a while ago. I mixed Fe2O3 with a Al(OH)3 gel and baked ti at about 600*C for 2 hours. It expandet and become realy porous. I grindet it by hand to small peases and filled in a 15mm stainless tube. I heated it to about 500*C with a propane torch and started to put hydrogen trugh. First nothing happent, thain after a while watter started to spray out of the exsit tube, meaning that the reduction was suxesful, becouse hydrogen took oxigen out of the Fe2O3, forming watter and living pure Fe.

I sealed the reactor and made a oil bath around it. I heated it to boilingpoint (aboute 300*C i guess)and started flowing dryed and cleaned woodgas trugh. Interastingly, nothinh happend. No hydrocarbons, no watter, nothing. I gave the flask where the exsit products shuld slow to my friend who just came at a visit and he smelled it and said in smells like petrol. Not much, but it is a strart.

The problem might be in temperature (havent got a temperature sonde), catalyst(not promoted, just Fe and Al2O3) or bad qualyti of gas( H2/CO about 1/2 at woodgas and a lot of nitrogen). Anyway, I am planing further planing and a small fuel plant in the future.

Any ideas, sugestions...?

Lep pozdrav!

[minerec]

For a higher reacrtion rate a magnetie catalyst is not the best option. It just havent got enough surface area on witch the gases culd react. I made a batch of aboute 100g of catalyst just a week ago and is curently drying and tomorow it wil go in a caltinateing oven. It is made from iron carbonate on keiselgur support promoted with copper and potasium. This is the cheapest, most efective catalyst if you ask me.

Quite a ambishious plan there i must say:)