Ammonia chemisorption procedure

Ammonia chemisorption experiments were carried out at different temperatures ranging from 25 to 400°C to establish conditions for the adsorption studies on the catalysts. The NH chemisorption experiments were performed on an all glass high vacuum system according to the procedure described by Kanta Rao et al. (31). In a typical experiment, about 0.3 g of the catalyst... 

Acidity by Ammonia Chemisorption. Relative catalyst acidity was measured by the quantity of ammonia chemisorbed at the arbitrary conditions of 250°C, 11.2 torr. An Isorpta analyzer (Engelhard model 3A-2) was used the procedure was that described in Ref. 8. 

BET surface area of the catalysts was measured by physical adsorption of nitrogen at 77K. Chemisorption of ammonia was studied on the catalysts at ambient temperature after degassing the catalyst at 150 C for 2 h. O2 chemisorption was carried out at -78°C after reducing the catalysts at 450°C for 2 h in a stream of hydrogen [11]. Determination of oxidation number of vanadium in the V20s/Ti02 catalysts was carried out by titrimetric procedures adopted by Nakamura et al [12]. 

Catalysts preparation - Chemisorption method all catalysts were prepared following a procedure similar to that used by Koritala for the Cu0/Si02 (ref. 10). Ammonia was added to an aqueous solution of Cu(N03)2 3H20 until complete dissolution of the initially precipitated Cu(OH)2 occurred. The oxide support (MxOy) was added to the solution the slurry, under continuous stirring, was then slowly diluted with H2O. The solid was separated by filtration, washed with H2O, dried over night at 110°C and lastly calcined at 350 C for 3 hrs. 

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