Barney

Acetic Anhydride can be made by passing vaporizing glacial acetic acid and passing it through a small furnace to increase temperature to around 900 deg f. As the vapors pass through the furnace "coils" a catalyst such as Diammonium Phosphate DAP is injected. The output from the furnace will contain Ketene gas, which is very deadly. As the gas leaves the furnace it should be quenched with glacial acetic acid (as pure as possible) - the rest of the ketene gas is passed into another "absorber" phase which should be under vacuum. Here the ketene and more glacial acedic acid and weak anhydride produced earlier are brought into intimate contact basically leaving pretty pure Acetic Anhydride and Acetic Acid which are then seperated using standard distillation - any heavy ends can be taken off the bottom, Acetic acid recycled within the distillation apparatus. The scope and scale of this is more for large scale production - like 3 tank cars a day or whatever. This is off the top of my head from a process I used decades ago. It was all very simple and produced a pure product. Do not quote me on any temperatures mentioned, in fact, I have avoided stating them for various reasons. You will need a fridge unit and a way to pull a vacuum on the system - possibly steam ejectors but that will pollute the air - a liquid ring vacuum pump of some sort would be more suitable. I could get the actual plans for a plant with all the details but it would take some doing - and first I would have to see if it is all legal and legit from a copyrite/etc. point of view; Actually, the availability of complete information on building a permanent facility might not be useful to you due to "scale" and the fact that there are newer processes that are much more efficient (as far as I know, this one is almost 80 years old). Really, I just thought I would add what I knew of this and test my memory - it has been a long time. None of this info is proprietary and should be out there at the back of some larger chemistry department libraries. The actual plans for a plant might still be "owned" by some company - but I imagine all that has expired by now; so the plans might be public domain. Anyone know about this stuff? I believe it is used to make aspirin and cellulose acetate so it might still be available for purchase from your local chemical supplier. Beware. Also Acetic Anhydride itself is wicked stuff that will suck the moisture out of your skin or eyes, then turn into pure acetic acid, causing extreme tissue destruction, that can even persist as it moved down through layers of skin to the tissue below; destroying all as it progresses. Let us know how things end up if you get a chance. Good luck and be safe! Barney