11-01-03 18:29
No 468144
At the bottom of:
../rhodium /tmp2np-
reads:
Catalyst prep
To a solution of 1ml 31% HCl, 40g NiCl2.6(H20) in 350ml EtOH in a 500ml beaker at 50°C is added 35g of...
Activation
10g of the above catalyst was placed in a beaker containing 385 ml 40% aqueous AcOH and 89g NaCl at 70°C for 7 minutes, then the solution is decanted and the Nickel rinsed with 60°C dH2O, then rinsed with EtOH then placed in a 500ml erlenmeyer flask containing 250ml EtOH and charged with...
1. Would 95% food-grade EtOH be sufficient for these procedures?
2. If one were to use .25mm plate Al for the catalyst substrate, would it be required to recalculate for surface area?
Thank you, kind soul, who would expend his energy to satiate the curiosity of another.
over and under, then back to the start
this sidewalk's bottom is the same as its top
(Hive Bee)
11-11-03 05:33
No 470104
Is this in the wrong forum?
I do that all the time...
over and under, then back to the start
this sidewalk's bottom is the same as its top
(Chief Bee)
11-11-03 10:01
No 470140
1. Yes.
2. No (only weight matters as long as it's foil).
Correct forum.
(Hive Bee)
11-11-03 19:45
No 470251
Is there some technique of preparing plate aluminum
for depositing Ni on it? Washing with HCl or somesuch?
[edit]
Doh.. nevermind me...
Post 428336 (Cept: "Precipitated Nickel", Newbee Forum)
over and under, then back to the start
this sidewalk's bottom is the same as its top
(Hive Bee)
11-18-03 02:47
No 471485
Well, just for kicks this weekend I put 350ml of 95% etoh in a 500ml erlenmeyer, put in 1ml 31.45% HCl, then added 40g anhydrous NiCl2 (which I realize is incorrect, I only realized my blunder after addition... damned cannabis!:p). I took a 6"x24" aluminum sheet with a thickness described as "0.025" with no unit and cut many 6" strips about .5-.75" thick, which were then cut into squares and bent into caltrops (opposing edges bent at right angles, two up, two down), washed them in 6N HCl for a few mments before hydrogen evolved, rinsed in dh2o once then began adding them to the erlenmeyer one at a time, 35g total.
Since then it's been about 14 hours, initially the first few caltrops turned completely black almost immediately. Now, I look at it, they are all still evolving H, but the ones that were black lost much of the coating, while no precipitated nickel was observed on the bottom of the flask or in suspension. I can only assume that it redistributed itself. The etoh remains green. I added twice the correct amount of NiCl2, I was just going to pour it off and perform the reaction a second time on new caltrops with the mother liquor. but it hasn't stopped with the bubbling and the thing.
Upon closer inspection, the deposited nickel appears to be a dull, rough, silvery metal coating and not crusty and black like the initial caltrops.
1. Is the dull silvery coating worthy of use? I can't remember which thread I saw it in, but one successful batch was the result of the black and crusty type.
[edit]
chromic - the urushibara nickel cholride solution is green before it has precipitated, but the final catalyst is gray-black, the darker being the prefered as the gray indicates crystalization from too vigourous a precipitation.
Post 251157 (Antibody2: "Re: Preparing Urushibara catalysts", Chemistry Discourse)
Damn!
over and under, then back to the start
this sidewalk's bottom is the same as its top
(Hive Addict)
11-20-03 00:37
No 471831
in theory the thickness of the Al shouldn't matter a whole lot, but in practice i'm not convinced. Because using the a thicker foil is going to affect the rate at which the Ni precipitates from solution.
In Hata's book he talks about retarding the Ni precipiation by cooling the rxn (not on Al mind you, Zn i think). This is reported to reduce the particle size of the resulting catalyst. Ab2 experimented with this variable using Al foil a few years ago. Retatrding the ion exchange some times overnight. It didn't improve yeilds, it resulted in an inactive catalyst. The best yeilds were acheived preparing the catalyst exactly as in my write-up, the whole catalyst prep done in couple hours. The whole rxn just one big dirty slurry, no green colour apparent. Doing it as it is written up you will have difficulty getting all the Al in to the amount of solvent specified, requiring several additions at increasing intervals
I don't want to discourage you, but i suspect you may have acheived the same end with the thicker Al that Ab2 did with the low temperature.
let us know how your rxn turns out
We are all just witnesses.