Palladium-based membranes inhibition

Both theoretical and experimental studies have been performed on palladium-based membrane reactors for the water-gas shift reaction. Ma and Lund simulated the performance achievable in a high temperature water-gas shift membrane reactor using both ideal membranes and catalysts [18]. By comparing the results obtained with those related to the existing palladium membrane reactors, they concluded that better membrane materials are not needed, and that higher performances mainly depend on the development of a water-gas shift catalyst not inhibited by CO2. Marigliano et al. pointed out how the equilibrium shift conversion in membrane reactors is an increasing function of the sweep factor (defined as the ratio between the flow rate of the sweep at the permeate side and the flow rate of CO at the reaction side) [19]. The ratio is an index of the extractive capacity of the system. 

Polarization and Inhibition by Carbon Monoxide in Palladium-based Membranes... 

Preparation of Thin Tilms of TiOx on Palladium Foils. Following the procedure reported by Takahashi, an isopropanol based sol of titanium tetra-isopropoxide (TnP) was prepared (10 mL of TUP in 48.4 mL of 2-propanol), to which 6.7 mL of diethanolamine was added to inhibit the formation of oxides. This mixture was stirred for two hours, at which time gel formation was initiated by the addition of 28.1 mL of a dilute water solution (1.42 mL water in 30 mL of 2-propanol). The resulting molar ratio of water to TUP was 2 1, as was recommended by Takahashi and co-workers (22). The palladium substrates were dipped vertically into this solution and then clamped on edge while draining to allow the excess to drip off and to prepare as even a coating as possible. The membranes were then air-dried in a vertical position at 100°C for one hour, followed by a post-treatment with hydrogen (see Figure 2). 

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