Which type of catalyst to use? Homemade vs. bought
(Rated as: excellent)
Some bees seems to have failed miserably trying to follow some of my writeups. I donīt know which reactions has failed or who theese bees are since none of them has asked me directly. The issue seems to be the catalyst. It also seems like I am the one to blame for this since I havenīt described which catalyst I have used. For this I am sorry!
The catalysts I use, 5% Pd/C in 99% of the cases, is never homemade. I tried to make my own 5% Pt/C and 5% Pd/C on two occasions, and failed terribly. Then I bought the catalyst from Sigma-Aldrich and it worked great. I used this supply-house bought catalyst for about one year until I relized I was spending a fortune buying catalysts from them. Actually one is spending a fortune buying anything from them. So I decided to buy the catalysts from the manufacutrer instead. The price I payed to buy 100 g 5% Pd/C from Si-Al got me 1 kg top quality 5% Pd/C from the manufacturer.
I know most bees will never be able to buy from the manufacturers, and this is a pity since this is the secret to get really good yields IMHO.
Which catalysts am I using then?
From Johnson Matthey:
Type 38H and 87L 5% Pd/C, equally good for most CTH reductions.
Type 325 5% Pd/Al2O3, very good for low-pressure hydrogenation of nitropropenes to ketoximes.
Type 18 5% Pt/C, very good for schiffīs base reductions.
E 105 O/W 5% Pd/C, very good for most types of CTH reductions
Raney nickel can be made if one can get the Ni/Al alloy Post 361199 (Barium: "Preparation of Raney-nickel", Methods Discourse).
Remember that the activity of all catalysts decreases with time. Some faster than others. If you have made the 5% Pd/C yourself, which seems to give a catalyst of very low activity for most bees, and store it for months and months there is no wonder why the yields are crappy.
Catalytic hydrogenation freak
Iff you use clean startingmaterials homemade cat. works nice.
1 Kg Pd/C wow that's a lot. Sure I could hydrogenate some 100kg with so much cat.
|These catlips(catalyst) are very expensive when ..||Bookmark|
These catlips(catalyst) are very expensive when bought from chem supplier
I have Aldrich and some other catalogs @ hand,i'll take a look.5% Palladium on carbon is 450$ bucks 100 grams.Adams catlips is 700$ for 5 grams.
For those about to synth,we salute you
|no catalytic hydrogenations for bees ?||Bookmark|
What Barium tells would exclude many bees from this wonderful technique. If HEST would disclose how he prepares active catalyst there might bee hope.
Perhaps there is a way to do this at home, the chemists at begin of the century also made their catalyst themself and this was not a bad one I guess.
Please all who are in the know: HOW IS THIS DONE?
- how is poisoning avoided?
- whats the right charcoal?
- how is the carbon activated?
- how can disposition be prejudiced?
My experience tells me that the used hydrogen is important. Hydrogen for fuel cells is ok, welding hydrogen the catalysts dead. I believe that the advantages of CTH result mostly on the fact that the in vitro generated hydrogen is clean.
but thats a guess
I know this has been discussed before. But obviously not in the right way.
The writup's at rhodium's is fine. One of the biggest problems is lead and sulfur, two catalyst poisons, so the starting material must bee pure. Ordinarry hi grade activ carbon made for lab use is greath, the agro-grade is not pure enough. The methal chloride must also bee pure, use only stuff made for annalytical chemistry.
(Stoni's sexual toy)
|> Ordinarry hi grade activ carbon made for lab ...||Bookmark|
> Ordinarry hi grade activ carbon made for lab use is
> greath. The methal chloride must also bee pure, use only
> stuff made for annalytical chemistry.
Doesn't sound like you are saving a lot of money when you still have to buy everything from the supplier thieves.
> I decided to buy the catalysts from the manufacutrer
> instead. The price I payed to buy 100 g 5% Pd/C from Si-
> Al got me 1 kg top quality 5% Pd/C from the manufacturer.
Yes, that's how Si-Al and all their fellow conspirators earn their money. This 900% price increase seems to be the minimum they can survive on, some chemicals are even more overpriced, especially in small quantities.
Remember, 95% of the chems sold by these gangsters are NOT manufactured by them, even when they tell you otherwise. All they do is pay smaller companies to fill the chems into tiny bottles for cut-throat prices, doing some batch quality analysis and documentation and shipping the stuff around. Don't get fooled by the purity grades either, the regular grades and different analytical grades often come from the same railroad tanker car delivered once per week.
I'm really wondering why these obviously rigged prices (which tend to all climb the same each year for most suppliers) aren't investigated.
I'm not fat just horizontally disproportionate.
|Preliminary Catalyst info||Bookmark|
I'm in the middle of research on prep of pd/c catalysts, and i'll post some preliminary results on what i've
found so far searching the patent literature:
Pore size should be small.. and surface area large..
Penetration of Pd complex's into the Carbon does not facilitate H2 contact or reduction
Use of MeOH will reduce PdCl2 surface tension and allow more full penetration when used in Zeolite Y
type Substrate supports
Reduction via H2 instead of Formaldehyde results in larger Pd Crystal growth, hence reduced Pd surface area. Small crystals of Pd are key.
Most of the reaction occurs due to Pd on the surface of the carbon
Pd Surface area is the key to the reduction.
Use of a percentage of non-porous carbon in the Activated carbon will increase the Pd surface area due to "packing" of more pd surface in the mix (same thing w/ rocket fuels using 400 and 200 mesh NH4ClO4 to increase solids loadings)
Addition of .2-5% of SiO2 by Pd weight (use waterglass in the mix) doubles or quadruples catalyst lifetime ( can also buy Activated Charcoal w/ SiO2 loading)
Catalyst reactivation from O2 reduction of ketones and clogging w/ reaction by-products etc can be regenerated by boiling in Formic Acid.
Sulfur or Copper in the Carbon will poison the catalyst.
Activating Carbon requires two treatments, 1 at 200 C and a further at 900 C ( clay pot and barbecue time) in an inert atmosphere ( otherwise 35% C loss due to CO/CO2 oxidation)
Pyrex melts at 821 deg C
Use of H202 in the PdCl2 process doubles (or more) the catalytic reactivy (us pat: 3138560)
------ More to follow --------
Infinite Radiant Light - THKRA
|This is very good information.||Bookmark|
Can you post references? I can go to big university library and scan them for you.
|Get involved too...||Bookmark|
There is a remarkable wealth of information on prep of both activated charcoal and Metal supported catalysts in the uspto. What is really good is reading all the critiques of prior methods which really tells you where things go bad. Given just my preliminary scan of all of this, i can say with some certainty that without the info in the patents, NO homemade Pd/c catalyst has a prayer of performing up to chemhouse supplied. The variables are rather huge, even seen in the fact that norit has 150 different flavors!
So go to advanced search at uspto and search class 502-180 with keywords of either palladium, catalyst etc. etc..
the correct term to load into the query window is:
ccl/502/180 and spec/Palladium
pat num: 4476242 seems to be a good root starting point.
Thx! for the help in getting them up...
Infinite Radiant Light - THKRA