Catalyst electrophoretic deposition

GP 2] [R 3a] The selectivity-conversion behavior was determined for the commercial Shell Series 800 catalyst, in a fixed bed and electrophoretically deposited in micro channels (20 vol.-% ethylene, 80 vol.-% oxygen 0.3 MPa 230 °C) [101] 54% selectivity at 17% conversion was found at the maximum, when processing without promoters. 

Louh, R. R, Ghang, A. C. C., Chen, V., and Wong, D. Design of electrophoretically deposited microporous layer/catalysts layer composite structure for power generation of fuel cells. International Journal of Hydrogen Energy 2008 33 5199-5204. 

The activities of CNTs have been evaluated by Girishkumar et al. [7] using ex situ EIS. Their study was conducted in a three-compartment electrochemical cell using a GDE electrode (a carbon fibre paper coated with SWCNTs and Pt black as an anode or cathode). Electrophoretic deposition was used to deposit both the commercially available carbon black (CB) for comparison and the SWCNT onto the carbon Toray paper. Commercially available Pt black from Johnson Matthey was used as the catalyst. In both cases, the loading of the electrocatalyst (Pt), the carbon support, and the geometric area of the electrode were kept the same. EIS was conducted in a potentiostatic mode at either an open circuit potential or controlled potentials. 

Similarly, catalyst coatings can be used to produce MSs via thin film gas phase deposition, with chemical (up to 10 pm thickness) and physical vapour deposition methods (< 1 pm) typically used to deposit metals and metal oxide thin-fihns. Other methods such as electrophoretic deposition of alumina, ZnO, Ce02 and Zr02 coating layers inside the microreactors are also used (Cybulski and Moulijn, 2006 Hessel et al., 2005c). 

Fig. 8. Schematic of a catalyst coating apparatus for electrophoretic deposition or anodic oxidation inside assembled microreactors.

Camara EHM, BreuQ P, Briand D, Giullot L, Pijolat C, de Rooij NF (2010) Micro gas preconcentrator in porous silicon flUed with a carbon absorbent. Sens Actuators B 148 610-619 De AngeUs L, Riva R (1995) Selectivity and stability of a tin dioxide sensor for methane. Sens Actuators B 28 25-29 Dhandapani B, Oyama ST (1997) Gas phase ozone decomposition catalysts. Appl Catal 11 129-166 Dougami N, Takada T (2003) Modification of metal oxide semiconductor gas sensor by electrophoretic deposition. Sens Actuators B 93 316-320... 

Electrophoretic deposition is a colloidal process used to coat either aluminium or stainless steel [122]. Either adhesion layers or complete coatings can be achieved. To-date mainly alumina suspensions have been used for electrophoretic deposition. Wunsch et al. coated microchannels with alumina nanopartides dissolved in oxalic add and mixed with alumina gd or glycerol [124] 2-4 pm thick adhesion layers were formed. Fbdisdi et al. applied dectrophoretic predpitation of industrial catalyst powders at 100 V (dc) [140]. After 2 min a uniform deposition of the catalyst powder on the surface was achieved. 

Another possibility of ceramic material application is the use of coatings and foams inside, for example, metallic microstructure devices. Here, well-known technologies such as CVD processes, sputtering, electrophoretic deposition, sol-gel methods in combination with spin coating, dip coating, or wash coating methods, or the use of anodic oxidation for aluminum-based devices will lead to either dense, protective ceramic coatings or porous layers used as catalyst support. 

A well-distributed deposition of Pt/C nanocatalyst and Nafion ionomer on bofh hydrophilic and hydrophobic carbon-based electrodes has been successfully obfained using a Pt/C concentration of 1.0 g/L, an electrical field of 300 V/cm, and a deposition time of 5 minutes [118]. The deposition of Pt/C nanocatalysts and Nafion solution via the electrophoretic process gives rise to higher deposition efficiency and a uniform distribution of catalyst and Nafion ionomer on the PEMFC electrodes. 

Fodisch et al. [156] applied electrophoretic precipitation of industrial catalyst powders at 100 V (DC). After 2 min, uniform deposition of the catalyst powder on the surface was achieved. As an alternative to impregnation methods, palladium was deposited... 

Deposit formation on the electrode occurs via particle coagulation. Electrophoretic migration results in the accumulation of particles and formation of a homogeneous layer at the relevant electrode. The potential of EPD for film formation on various materials and complex shapes is of great interest for the preparation of microstructured catalyst and reactors. A review about electrodeposition of ceramic and organoceramic materials can be found in Ref. [223]. 

Nishimori H., Tatsumisago M., Minami T. Preparation of thick silica films by the electrophoretic sol-gel deposition on a stainless steel sheet. J. Ceram. Soc. Jpn 1995 103 78-80 Schulze-Bergkamen H., Yamane M. Effects of reaction parameters on the preparation of thick silica gel films by an interfacial polymerization I. Effects of pH and type of catalyst. J. Sol-Gel Sci. Technol. 1995 5 185-191... 

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