The influence of heat treatment on the thermal stability of Pd composite membranes

Glass frit sealing method for macroscopic defects in Pd-based composite membranes with application in catalytic membrane reactors

“…Initially, the as-fabricated film was tested for one week at each temperature to obtain a baseline measurement of potential nitrogen permeance growth, plotted as circles in Figure 3. The nitrogen permeance growth rates for the as-fabricated film were very similar to those observed for un-annealed pure Pd membranes on the same supports in our previous work [27,28], with the growth rate being 1.2 × 10 -12 (mol m -2 s -1 Pa -1 ) h -1 at 520 °C and 8.7 × 10 -12 (mol m -2 s -1 Pa -1 ) h -1 at 600 °C. Guazzone and Ma [29] also observed an increasing leak growth rate with temperature, reporting that the temperature dependence followed an Arrhenius relationship with an activation energy similar to the self-diffusion of Pd.…”

“…The membrane was then re-tested beginning at 520 °C, whereat the initial nitrogen permeance was about equal to the last data point at 600 °C and a nitrogen permeance growth of 8.6 × 10 -13 (mol m -2 s -1 Pa -1 ) h -1 was observed. This slightly lower growth rate compared to before sealing may be attributed to the 600 °C annealing period before sealing, as we found in our previous annealing work [28]. More importantly, upon raising the temperature to 560 °C, the nitrogen permeance began to grow significantly and the frit seal appeared to fail completely within the week of testing.…”

Review of Supported Pd-Based Membranes Preparation by Electroless Plating for Ultra-Pure Hydrogen Production

“…Finally, some researchers propose the improvement of membranes properties, mainly the increase of permeation rate and thermal stability simultaneously to the presence of defects is decreased, by using a further thermal treatment step (>640 °C) after the palladium plating [ 42 ]. Although this alternative is not strictly an improvement of the metal deposition process, it can be used to enhance the previously prepared membrane.…”

“…Palladium is expensive and scarce and the growing demand for its use in large-scale applications is expected to keep driving up its price [ 34 ]. Two of the most studied strategies to reduce the cost of the membranes are: (a) minimizing the amount of palladium required to achieve a fully dense layer [ 35 , 36 , 37 , 38 ] and (b) increasing the use life-span since these membranes can suffer deactivation by poisoning and cracking by thermal or mechanical stress [ 39 , 40 , 41 , 42 , 43 ]. Taking into account the typical equation used to describe the hydrogen permeation flux ( ) through a Pd-based membrane (Richardson equation, Equation (1)) as function of hydrogen permeability ( k ), metal thickness ( t ) and pressure driving force , it is obvious that a decrease in the metal thickness provokes an increase of the permeation capability [ 28 , 44 ].…”

Pt-based structured catalysts on metallic supports synthesized by electroless plating deposition for toluene complete oxidation

“…The electroless coating process has gained wide acceptance in the market due to the coatings' excellent corrosion and wear resistance properties [25,26]. Recently electroless nickel nanosheets on carbonaceous materials as supercapacitor electrode [27,28], and electroless palladium nano-scale layers on porous materials for hydrogen membrane separation [29,30] Ultrasonic vibration test Bending fastness test Tearing fastness test 200 no weight loss no surface cracking no surface peeling 350 no weight loss no surface cracking no surface peeling 450 no weight loss no surface cracking no surface peeling 600 no weight loss no surface cracking slight surface peeling metallic structured substrate was achieved by using this new technique of EPD. The as-obtained structured catalysts were analyzed by several characterization methods and adhesion strength tests to reveal their chemical and physical properties.…”