The Transmission of Electrolytically Deposited Hydrogen through a Palladium Membrane Electrode

A colorimetric study was made of the kinetics of the reduction of acidic titanium(IV) chloride solutions by hydrogen diffusing through a palladium membrane. The rate of this reaction was found to be first order with respect to the concentration of the titanium and was inhibited by the addition of organic poisons. The inhibition followed an adsorption isotherm leading to the conclusion that the rate of the reaction was controlled either by adsorption of titanium(IV) or by a reaction involving an adsorbed titanium(IV) species.

Section: Results and Discussion Of Resultssupporting

confidence: 91%

mentioning

confidence: 99%

The Reaction of Titanium(IV) with Hydrogen at Palladium Membranes

Franklin¹,

McDaniel²

1969

“…According to the literature (13)(14)(15)(16), dissolved oxidants (including oxygen) also result in inaccurate pH and reference electrode potentials due to depolarization of the palladium hydride electrode. It is shown beIow that electrode lifetimes of the order of 1-2 weeks can be obtained by proper selection of the electrode volume and surface to volume ratio, even in the presence of dissolved oxygen.…”

Section: Electrodesmentioning

confidence: 99%

A Palladium Hydride pH Electrode for Use in Buffered Fluoride Etch Solutions

Jasinski

1974

pH measurements can be made in aerated, concentrated, aqueous NH4F‐HF etch solutions with palladium electrodes cathodically charged to palladium hydride. Electrode life and stability in ammonium fluoride, as well as in NH2SO4 , pH 3.6 sodium citrate and in pH 8 ammonium phosphate are enhanced by maximizing the palladium hydride concentration, electrode volume as well as volume to surface ratio. Electrode lifetimes have been measured in the range of 7–14 days for all solutions, times which are significantly longer than have been reported previously in the literature for palladium hydride electrodes.

“…The investigations reported in Parts I and II, (1,2), show that it is necessary to measure the rate of transmission of hydrogen as a function of the hydrogen pressure on the exit side of the membrane to obtain a more complete characterization of the mechanism. In this paper, the dependence of the rate of transmission on pressure and temperature as well as on membrane thickness is described.…”

mentioning

confidence: 99%

The Transmission of Electrolytically Deposited Hydrogen through a Palladium Membrane Electrode

Damour¹,

Castellan²

1964

Self Cite

An investigation of the pressure and temperature dependence of the maximum rate of transmission of hydrogen through palladium is described. The pressure dependence in the range from 0.329 to 1 atm indicates that the penetration-exit reaction, H(ads) ~ H(bulk), is the slowest surface reaction, but is nonetheless very fast having an exchange current density of about 0.8 amp/ cm 2 at 1 atm pressure. From the temperature dependence it is found that at temperatures slightly below room temperature the diffusion coefficient can be represented by D z 0.0260 exp (--6800/RT)cm2/sec. The investigations reported in Parts I and II, (1, 2), show that it is necessary to measure the rate of transmission of hydrogen as a function of the hydrogen pressure on the exit side of the membrane to obtain a more complete characterization of the mechanism. In this paper, the dependence of the rate of transmission on pressure and temperature as well as on membrane thickness is described. In the experiments described here, the entrance compartment of the cell contains 2N H2804 saturated with hydrogen gas at 1 atm pressure. The exit compartment contains hydrogen gas at arbitrary pressures (below 1 atm). Apparatus and MaterialsThe cell used here was similar to that used in the work described in Part II. The palladium membrane was held in the unit shown in Fig. 1. This unit fits into the position of the cathode unit of the cell described in Part II. In this arrangement the palladium disk is clamped between two pieces of Teflon by a brass fitting. The palladium is cut large enough so that it makes electrical contact with the brass. The lower piece of brass is soldered to a Kovar metal-to-glass seal which is in turn connected to a constant pressure system by a Teflon O-ring connection. This arrangement provides tight enough seals to hold a vacuum of 10 -3 mm over the period of a day or more. The entire cell is immersed in a thermostat controlled to _+0.1~ The constant pressure system on the exit side contained a manometer, a thermostated 12 liter ballast bulb, a thermostated gas buret, appropriate arrangements to change mercury levels to keep the pressure constant, and a dry ice-acetone trap to prevent access of mercury vapor to the palladium. The system could be evacuated. From the measured change of volume of 1 Pre~ent address: St. Anselm's College, Manchester, New Hampshire.~ ~rT"?i eHon Sl eev e Pd Cathode ~Teflon Washer II To Gas Meosur,nq System Fig. 1. Cathode unit hydrogen at the constant pressure in a specified time interval, the rate of transmission can be calculated.The other instruments used were the same as those described in Part II. However, the potential of the membrane was not measured. In addition, a thermocouple well (made of thin-walled Teflon tubing) was placed in the cell with its tip near the palladium disk to permit the measurement of the temperature in the cell near the disk.The materials used and the precautions taken were the same as those described in Part II with the following exceptions. The membrane was flamed in a ...