Acidic sites, NiSMM catalysts

Abstraction, a-hydrogen, propylene Acidic sites, NiSMM catalysts, 280... 

FT/IR measurements of adsorbed NH3 on NiSMM catalysts have shown that the number of sites, most probably Bronsted sites, increases due to Ni reduction ( ). This suggests that the newly formed acidic sites are responsible for the increased activity of NiSMM compared with e.g., beidellite, in which no Ni is substituted for Al in the octahedral sites. The newly formed sites should then be highly acidic. In order to verify this statement we have studied the thermal desorption of pyridine from Pd-NiSMM before and after reduction, by means of FT/IR spectroscopy. For comparison, the same study was made with Pd-exchanged synthetic beidellite. 

Since metallic and acidic sites are both created during reduction of NiSMM, it is very difficult to measure exclusively the influence of the metal function on the bifunctional activity of the catalyst. 

The high activity of this catalyst can be ascribed to Br nsted sites of high acidity, vdiich are mainly formed during reduction of lattice nickel. The acidic activity of NiSMM is so strong that, even with 0.7 %w Pd or Pt on the catalyst, effects due to too low a metal activity on the bifunctional activity and selectivity cannot be excluded. 

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See also in sourсe #XX -- [ ]

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