Catalytic elimination of nitrogen organic compounds from the coal-liquid and structural properties of NiMo catalysts supported on NaX and NaY zeolites modified with transition metal cations

Changes in the crystal structure of faujasite (X and Y) type zeolites occurring as a results of sodium ions exchange into transition metal cations (TMC) and impregnation with Mo(VI) and NI(II) ions are described. The catalysts obtained were studied in hydrodenitrogenation reaction (HDN) of coal-liquid. Both ion exchange and surface impregnation were found to cause a destruction of the crystal structure of zeolites. The degree of destruction was proved to depend on the kind of TMC. The NiMo catalysts supported on X type zeolites were less active than those supported on Y type zeolites. which means that the molar ratio SiO2/Al2O3 plays an important for the catalysts performance. The catalysts with Y type zeolite containing a divalent cations show a similar activity in HDN, while this activity for the catalysts with trivalent TMC decreases in the sequence NiMo/NaFeY > NiMo/NaLaY > NiMo/NaCrY > NiMo/NaY. The greatest catalytic activity revealed the NiMo catalysts supported on Y type zeolite in which sodium ions were in 44% exchanged for Fe(III). Moreover, as follows from the results obtained, in the preparation conditions applied Mo(VI) ions are built into the zeolite structure. (C) 2001 Elsevier Science B.V. All rights reserved.