Palladium dichloride catalyst with hydrochloric acid

Method A. Cool a solution of the nitrate-free dichloride, prepared from or equivalent to 5 0 g. of palladium or platinum, in 50 ml. of water and 5 ml. of concentrated hydrochloric acid in a freezing mixture, and treat it with 50 ml. of formahn (40 per cent, formaldehyde) and 11 g. of the carrier (charcoal or asbestos). Stir the mixture mechanically and add a solution of 50 g. of potassium hydroxide in 50 ml. of water, keeping the temperature below 5°. When the addition is complete, raise the temperature to 60° for 15 minutes. Wash the catalyst thoroughly by decantation with water and finally with dilute acetic acid, collect on a suction filter, and wash with hot water until free from chloride or alkali. Dry at 100° and store in a desiccator. 

Two standard ways of catalyst preparation are considered. The first one proceeds through the precipitation of palladium hydroxide from palladium dichloride according to a simple method described in [8]. The support (1 g) is stirred with 15 ml of water. Palladium chloride (0.08 g) in 10% hydrochloric acid solution (5 ml) is added and the suspension is kept stirred during 15 minutes (pH is between 0 and 3). Then soda 20% (around 2.5 ml) is slowly added until pH reaches 12. Formaldehyde (2 ml) is added to reduce palladium hydroxide under stirring at constant pH value (pH = 12) for 1 h. The slurry is then heated to 90°C during 1 minute. pH is adjusted at 5, mbcture is rapidly cooled down, filtered and washed with water. ICP analysis of the filtrate is performed to ensure that the palladium is well on the support and to obtain an accurate value of metal loading of the catalyst. Catalysts prepared according to this method are called P catalysts. 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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