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Keywords:

  • acidity;
  • active sites;
  • Beckmann rearrangement;
  • zeolites

Abstract

The catalytic behavior of isomorphously substituted B-, Al-, Ga-, and Fe-containing extra-large-pore UTL zeolites was investigated in the acylation of p-xylene with benzoyl chloride and Beckmann rearrangement of 1-indanone oxime. The clear synergism between the Brønsted acidity (i.e., the concentration and the strength of protonic acid sites) of UTL catalysts and their activity in benzoylation was established. (Ga)UTL zeolite containing the Brønsted acid sites of medium strength is characterized by the optimum activity and selectivity in the benzoylation of p-xylene. Because of a higher accessibility of active centers, (Al)UTL zeolite appears to be a more active and selective catalyst than (Al)BEA in the benzoylation of p-xylene. In contrast to (B), (Ga), and (Al)UTL, the leaching of active sites occurs in the benzoylation over (Fe)UTL. All UTL zeolites showed 100 % selectivity in the Beckmann rearrangement of 1-indanone oxime, which provides the target 3,4-dihydroquinolin-2(1H)-one. (B) and (Fe)UTL zeolites containing the weakest acid centers were found to be more active in the Beckmann rearrangement of 1-indanone oxime than (Ga) and (Al)UTL: 100 % yield of the target amide was achieved in 240 min of the reaction time over (B) and (Fe)UTL.