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New Test Cell, RGA data, and Platinum Catalysis

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H2 Splitting Tests

The last week has been extremely interesting around HUG.  Last Monday, we saw our first hint that Platinum is preferentially recombining something.  We were finishing up our last couple calibration runs with a commercial oxide coated constantan wire in H2 when we saw that the first run looked way different than the second run.  Note how the pressure (green line) drops during the first step up cycle, but not the second one.  And then, the resistance drops at higher temperatures - more so in the first one than the second.

 

When I looked closely at the difference between the runs, I saw something very cool in the Platinum temperature and the Silver temperature. (Note:  T_Cu is actually a silver wrapped thermocouple, now, because we are told that silver is less catalytic than the copper.)

While the Wire temps and the Silver temps were extremely similar between the runs, the Platinum temperature was different between the first and second runs.  How different?

 

About this different!  It's not many degrees, but the temperature where it varies the most is also the temperature at which the pressure in the cell was dropping!  

 

 

So, what would cause the platinum to be hotter and the pressure to drop?  Was this commercial constantan splitting H2?  Was it making water that was interacting mildly, but preferentially with the platinum?  (See lab notebook here for full details)

Well, it just so happens that our new RGA (on loan from Nikita Alexandrov), was just about ready to test, so we slowly vacuumed down the cell through the RGA.  

Here is the compiled video made from the scan data (a 2 day effort to write scripts to process data files).

 

The basic conclusion that we can come to is that there was quite a bit of water.  We are newbies, though, and would welcome second opinions and observations.

Our current hypothesis is that H2 was reducing the MgO coating on the wire and making water.  Some of the H and O flew loose and combined on the platinum.  There should be no pressure drop from  H2 + O (in MgO coating) => H20, at least till the H20 started condensing on the cold part of the cell.  We believe it is likely we saw this water coming out of the cell in the RGA scans.

(See lab notebook here for full details)

New Test Cell for Gamma Detection

We have a new cell optimized for getting test wires close to our NaI gamma detector. 

In practice, it looks like this when mounted along with the gamma detector just above it.

 

 

Next Steps:  Combine Gamma Detection with H2 Splitting test

 

Our immediate plan is to test the new cell with a control wire and then install our last remaining Celani wire.  We will load it with Hydrogen while watching the pressure and watching for gamma rays.  Then, we will transfer it to the other cell with the platinum and the silver wrapped thermocouples and test for H2 splitting.  Stay tuned!

 

 

 

 

Comments   

 
+1 #18 john king 2013-12-22 23:24
The rga data is interesting. It certtainly shows how the chemical composition varies during an experiment. My experience with rga is somewhat limited, but.. In my experience, the rga was hooked up in a chamber pumped with a turbo molecular device. The adjoining experimental chamber was connected with a "precision leak" valve. Thus the pressure in the chamber of interest could be varied without overloading the rga equipment. Removing water was done with heat. Usually as part of the preliminary cleaning, the experimental chamber was heated to about 250-300C for 6 to 8 hours. During this "bakeout", hydrogen at about 1 torr was admitted to the test chamber. Then a DC (600V) discharge was ignited in the low vacuum hydrogen atmosphere. It is assumed that the process generates copius atomic hyrfogen and abundant UV emission which chemically atacks almost everything. This combination of heat, plasma discharge, and atomic hydrogen seems to remove most of the virtual water sources, the metallic oxides, and all of the organics. The chamber is obviouly pumped continuously during this procedure and the reaction by-products are removed. Attention to detail is important.
If you want to know chemically wjhat is inside of the reactiion chamber, be prepared ro discover a complex mixture of junk. Taking control of the experiment implies control and removal of the non-essential junk

jdk 22dec2013
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+2 #17 Malachi Heder 2013-12-10 15:45
@ Gerrit

We just received a newer version of our gamma software, we are currently trying to set that up. It should allow for new ways to analyze the data. We also had a broken usb port on the gamma detector, that was just fixed this morning. We are going to play with loading the cell from 1 bar to 3 bar once the gamma analyzer works fully again.

@ All

We will be doing some server maintenance all day today. Data will be slow or non existent for the day. We will work hard to get it back up asap.
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+1 #16 Gerrit 2013-12-10 13:00
Long time without news. How is the gamma measurements going ? A rough time schedule. Any Xmas presents ?
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+1 #15 Malachi Heder 2013-12-05 16:15
@ All

Our network drives dropped off the network last night. We are working to fix this ASAP. Data should start catching up in about 30 min.
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+1 #14 charlie tapp 2013-12-03 16:08
been gone for a while my dad had a rotten kiddney removed he is ok now. anyways was thinking about all the fancy equipment he was hooked up to and was wondering if one of those heart monitors they use would give any usefull info if strapped down to one of the cells ? mabee this thing has a heartbeat we could see. then mabee we could save it before the reaction dies.
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+1 #13 Ecco 2013-11-29 17:13
The Hydrogen Splitting notebook from the Evernote app stopped updating again, even though it still was getting updated on the web interface !!
I was starting to wonder if experiments were still going on, but it was just the app's fault.
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+1 #12 Ryan Hunt 2013-11-25 21:58
@ Ecco - I wish I could combine the best of the blog and comments with the ease and richness of being able to drop everything into Evernote.

Oh, you should be able to see an image much like the one you describe for the RGA, but done for the gamma readings. I should be able to make one with the RGA data, now.
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+2 #11 Ecco 2013-11-25 17:03
@MFMP: as for newly home-processed constantan wires, I see from your experimental logbook on Evernote that your latest ones seem to perform relatively well in terms of minimum R/R0 values reached. But are these reversible? I think it would be a good idea to make sure that the heating process is actually making the wires absorb hydrogen and not just making them decrease resistance due to permanent structural changes.
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+1 #10 Ecco 2013-11-22 23:02
@MFMP: for RGA scans over time what about making spectrogram views of them? With:

X: time
Y: weight/charge
color: partial pressure

They would make for very compact and data-rich graphs. They could also more or less easily converted to audio waveforms that way, which might turn out to be interesting not only for fun but also analysis purposes.
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+2 #9 dak 2013-11-22 13:50
The RGA spectrum is a typical water spectrum.
m/z 3 is H3+ and m/z 19 if H3O+
Some of these cluster ions depend on source pressure so a plot of say m/z 2 vs. m/z 3 will not be entirely linear
You may wish to look at m/z 17 which is water but could also be ammonia. Passing the gases though a drying agent before the RGA can help in this distinction.
Water is almost impossible to remove from vacuum systems without heating the system. Yours is not designed for this.

Ni and Cu have distinct isotopic patterns. Those are not evident in the spectra. Also, you are unlikely to see bare metallic ions unless you purposely make volatile derivatives such as M-(HFAcAc)2.
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