Preparation of Palladium on Charcoal

[Organikum]

" When attempting a reduction using Pd/C is it necessary to have your precursor in the Sulfate form for this to go?"

This I don´t understand completely - Also it would be helpful if you would specify (link!) WizardX´s writetup and the Adams catalyst .zip file. Damn you have searched - must we all do it again? [/quote]

"Will chloride form cause the catalyst to poison and the reduction fail?"

I have seen many references where a halide is reduced by catalytic hydrogenation, and for example the ROSENMUND is a name reaction doing exactly this. So I say: NO. No fail because of the Cl.

[/quote]"If the reduction goes w/ X.Cl does the Cl reduce the life of the Pd/C catalyst"?

Usually not. The Cl should react with the provided H (or another available compound except the catalyst) to HCl (or else). In the case of HCl this won´t be bad as acidic conditions support the hydrogenation. I would say that the availability of hydrogen is a main factor here (Barium tells this also again and again...). If you run short on available hydrogen the Cl might poison the catalyst - if H is available this won´t happen. (this refers to the magic stirring/shaking/mixing in cat. hydrogenations - or more theoretical: masstransfer problematics).
Hydrogenation with noble metal catalysts is a reaction where it is near impossible to take out isolated factors as it is a complex interdependent system.
But baselines exist:
- Clean reagents. This says here your reagents may be dirty like shit as long as they contain no poisoning and no deactivating compounds. Catalyst poisons - the most hated - are: H2S and CO, deactivators No.1: organic sulphur compounds. Poison is end of prey, deactivators can be beaten sometimes by ultrasound and other tricks.
- Catalyst: The preparation guides on Rhodiums page give you a Pd/C catalyst of low to very low activity. (If somebody does not agree on this he may clear this with Mr. Rylander himself, who is the originator of this. He saw it as necessary to explizitely mention this in his book on hydrogenation methods.  On catalyst preparation he strongly advised not to prepare but to buy them. Period. )
Successful relieable reproducable homepreparation for high activity noble metal catalysts is not to find here nor elsewhere. (but soon will - I hope - and I wish you success Clearlight! The old chemists could make it, you will master it too!).
- Pressure: Maybee with industrial quality catalysts STP reactions are easy but not with homemade catalysts - for sure. 3 to 5 atm are to handle and are titulated as "low" or "elevated pressure" in chemistry. (high pressure is beyond 250atm....)The closed vessel makes also the control of the parameters much easier ´also the uptake of hydrogen can be simply monitored. Last but for sure not least: There is more hydrogen in the reaction mix and the masstransfer is not so problematic then. (you still have to shake the hell out of it or to apply a "stirrer" which has only the name common with what you usually imagine by hearing the word: "stirrer")
- Time: Oh yes the main part of the reaction is often done in 5 to 15 minutes. For superior results - to push yields in reductive alkylations from 80% to near 95%, 5% to 10% gain are usual, it makes sense to let the vessel charged with hydrogen sit for at least 12 hours with slightly reduced temperature and pressure (20%-30% less both) and medium shaking (in difference to the hard shaking at reaction start).

And finally a use for this URUSHIBARA Ni-catalyst! It can be used to clean solvents/reactands from catalyst poison. Boiling URUSHIBARA catalyst with the compounds before hydrogenation degasses (very important! CO!) and absorbes the bad ones (limited - it´s not possible to clean heavy contamination this way). Regarding the ease of preparation of Uru-Cat it might be worth the effort as degassing is necessary anyways (helpful at least).

Somebody with a good library access looking up how Rosenmund prepared his Pd/BaSO4 and Pd/C and the activated charcoal for Pd/C....  This would be a charm. (I can´t do it - seriously, no lazyness)
Freifelder and Rylander already relied on industrial produced catalyst. The literature before WWII hints that there have been big differings in quality - selfmade or not. After what I know by now, it is rather probabel that for reproducable self-preparation of a relieable active catalyst it will be necessary to selfprepare the carrier (activated charcoal or else) too. Animal charcoal, special plant charcoal...   And NO! I am convinced that just using NORIT for example is NOT a wise decision. (In the longer run it should be possible to find one of the uncountable brands of act. charcoal useful for ones purposes - this won´t be one of the very big ones I guess, as they make their products after other specifications than being perfect as catalyst carrier).

Hope that Barium, the big Hydrogenoser, agrees with most I told - I realy would prefer a common line now to popularize catalytic hydrogenations a little bit. Hdrogenations over noble metal won´t ever get a mass movement but to stand so far out this technique has not deserved at all. (I promise to behave too. Yes. I will!   )

Solidarity of those who love it! Common fight against common nonsense! (like: hydrogen -> HINDENBURG; 3atm -> blockbusting explosions; Pd/C -> causing firestorms instantly and always when in contact with air; and more).



some points worth to mention quick I thought.
venceremos!
ORG  

[ClearLight]

Thx Org for the references I've been reviewing them...

  I'm 3/4's of the way through my 2.5" of patents I printed out, however some PM's cleared up the questions:

   1.)precursor  HCL salts do not affect the Pd/C - Pd/BASO4 reactions

   2.) Catalytic activity is dependent upon the surface area of the Pd on the support.  Reduction of your catalyst in H2 is not recommended due to large (>25A) pd crystals being formed. Formaldhyde reduction is preferred.

   3.) Functional groups (aldehydes etc) on the carbon can wack the pd and cause large (reduced surface area) Pd crystals.

   4.) Pd/C in Wizard's write up is 1 shot. Not recommended

   5.) Pd/Barium Sulfate looks very good...experimental to follow.

   The catalytic support carbon is on order and will arrive shortly... Preparation of ones own Activated Carbon has so many variables and requires such extreme temp/pressure gradients that controlling these variables is more complex than most synthesis's here.  And you need a scanning electron microscope for pore size quality control. However I am going to try it anyway. There are several manuf. of Activated Carbon that have rather nice automated selection engines for your catalytic choices.


   Various patent preparations use condensation of the Pd from Sodium salts and use of H2O2 to control crystal formation size.  I will post a complete list of Useful patent refs after i've saved everyone the time by reviewing them.

   I have completed the theoretical analysis for a MW reduction via BASO4 + AcOH + Am.Form.  I'll run a microscale and report TLC results this week.

   To assist in Orgk's request, here are some cites that our eurobee's might be kind enough to look up ( and translate) to assist. I believe they have the original method(s)

Barium Sulfate Catalyst cites:

Houben, Die Methoden der organischen Chemie, 3rd ed., Vol. II, p. 500, Verlag Georg Thieme, Leipzig, 1930; Schmidt, Ber., 52, 409 (1919).

Mozingo, Harris, Wolf, Easton, Hoffhine, and Folkers, J. Am. Chem. Soc., 67, 2092 (1945).

Schmidt, Ber., 52, 409 (1919).

Rosenmund and Langer, Ber., 56, 2262 (1923).

[Vitus_Verdegast]

Maybe using ultrasound for precipitating palladium could make the homemade Pd/C catalyst much more potent?
The much smaller particles created by sonification should provide a much larger surface area for hydrogen absorption, n'est-ce pas?  

Of course only the highest quality of activated carbon should be used.

Preparation of Pd/C catalysts via ultrasound: a study of the metal distribution.

Bianchi, C. L.; Gotti, E.; Toscano, L.; Ragaini, V.   
Department of Physical Chemistry and Electrochemistry,  University of Milan,  Milan,  Italy.  

Ultrasonics Sonochemistry  (1997),  4(4),  317-320.

CAN 128:66888, AN 1998:41122


Abstract

Palladium supported on active carbon catalysts was prepd. using ultrasound during one of the prepn. steps.  An investigation of the metal distribution into the pores of the support was performed both by a deep characterization of the prepd. samples and by a catalytic reaction involving some org. reactants to be reduced. 

Hydrogen spillover within carbon-supported palladium catalyst prepared under ultrasound.

Cheng, Z. X.; Yuan, S. B.; Fan, J. W.; Zhu, Q. M.; Zhen, M. S.   
Department of Chemistry,  Tsinghua University,  Beijing,  Peop. Rep. China.   

Studies in Surface Science and Catalysis  (1997),  112(Spillover and Migration of Surface Species on Catalysts),  261-266.

CAN 128:106832, AN 1998:89933   


Abstract

The Pd/active-carbon catalyst was prepd. in soln. through a redn. of Pd(II) with formaldehyde, and the obtained metallic particles were around 10-30 .ANG. with a mean size about 16 .ANG. either applying ultrasound in catalyst prepn. or varying palladium loading (0.8-5 wt.%). 
H₂ spillover from Pd onto the carbon surface could occur in Pd/C at 200°C, and H/Pd decreased with the increase of Pd loading; the ultrasound in Pd/C prepn. led to a greatly increased amt. of spillover H₂, and H/Pd could reach a high value of 6.8 for 0.8 wt.% sonicated Pd/C catalysts.  The Pd/C activity (mole H₂/min.g.Pd) in nitrobenzene hydrogenation at 30°C increased with the palladium loading. 

[Vitus_Verdegast]

A new method to prepare highly dispersed supported metal catalysts.

Bianchi, C.L.; Carli, R.; Lanzani, S.; Lorenzetti, D.; Vergani, G.; Ragaini, V.    Dep. Phys. Chem. Electrochem.,  Univ. Milan,  Milan,  Italy.   

Catalysis Letters  (1993),  22(4),  319-25.

CAN 120:308377, AN 1994:308377


Abstract

On a solid surface the effects of the implosion of the bubbles, created during a sonication run, are commonly used to clean or to erode the surface itself.  Ultrasound was used in order to obtain a ruthenium on alumina catalyst distinguished by a very high value of the dispersion of the metal.  The samples were characterized with different techniques in order to study the influence of the sonication on both the metal crystallites and the support. 

An optimized route for the preparation of well dispersed supported ruthenium catalysts.

Bedrane, Sumeya; Descorme, Claude; Duprez, Daniel.    Laboratoire de Catalyse en Chimie Organique (LACCO),  UMR 6503 CNRS, University of Poitiers,  Poitiers,  Fr.   

Journal of Materials Chemistry  (2002),  12(5),  1563-1567.

CAN 137:133874, AN 2002:299822


Abstract

The prepn. of ceria and ceria-zirconia supported 1 wt.% ruthenium catalysts was optimized to obtain well-dispersed Ru particles.  The influence of the prepn. method and treatment conditions on the final morphol. of the catalyst was investigated.  Ceria-supported catalysts, prepd. by incipient wetness impregnation under ultrasound and further treated under hydrogen, had an optimum metal dispersion.  In fact, H2 chemisorption results and TEM observations demonstrated a large increase in the metal accessibility when impregnation was carried out with ultrasound assistance.  Ceria-supported ruthenium catalysts with dispersion £60% were prepd. 

Manufacture of supported metal catalysts.

Shibabuchi, Noriko; Suzuki, Toshio; Hirota, Kazuo.  (Unitika Ltd., Japan).
Jpn. Kokai Tokkyo Koho  (1999), 5 pp.

JP  11033412
CAN 130:187675, AN 1999:97246


Abstract

Solns. contg. catalytic metals are controlled to pH 5-9, surfactants are added, and then porous materials are dipped in the solns. and then ultrasonically treated for manuf. of supported metal catalysts.  Large amt. of metal catalysts can be uniformly supported

Manufacture of metal-loading catalysts.

Suzuki, Toshio; Kanbashi, Noriko; Hirota, Kazuo.  (Unitika Ltd., Japan).   
Jpn. Kokai Tokkyo Koho  (1998), 6 pp.

JP  10085614
CAN 128:249108, AN 1998:208703   


Abstract

The title catalysts are manufd. by ultrasound treating porous materials with immersing in active metal-contg. solns.  Large amt. of catalytic metals are loaded with good uniformity.