Catalytic activity of HAlBEA and NixHAlBEA zeolites in hydrogen-assisted dehydrochlorination of 1,2-dichloroethane into vinyl chloride monomer

HAlBEA zeolite is prepared by calcination of parent TEABEA zeolite at 823 K for 3 h in air following ionic exchange with NH4NO3 solution. Ni(x)HAlBEA zeolites are prepared by impregnation of HAlBEA with an aqueous solution of Ni(NO3)(2), following a drying at 333 K to obtain Ni(x)HAlBEA. The calcination of HAlBEA and Ni(x)HAlBEA at 773 K for 3 h in air leads to the formation of C-HAIBEA and C-Ni(x)HAlBEA with appeared, for the latter, an octahedral and tetrahedral Ni(II) species incorporated in BEA framework as evidenced by XRD, DR UV-vis and XPS. Red-C-HAlBEA and red-C-Ni(x)HAlBEA are investigated as the catalysts in dehydrochlorination of 1,2-dichloroethane into vinyl chloride monomer in the presence of hydrogen at 503-523 K. Red-C-HAIBEA and red-C-Ni(1.0)HAlBEA show an excellent selectivity toward vinyl chloride (similar to 100%). Activity of HAlBEA and Ni(x)HAlBEA in the catalytic conversion of 1,2-dichloroethane strongly depends on the acidic properties of these materials and for the latter the catalytic activity depend on metal dispersion. The small Ni particles favor the dehydrochlorination of 1,2-dichloroethane to vinyl chloride. With increasing nickel particles size decreases activity of the red-C-Ni(x)HAlBEA catalysts. For these catalysts after kinetic run sintering of nickel phase is observed. Besides of carburization the nickel sintering is the main cause of red-C-Ni(x)HAlBEA deactivation. It is stronger for spent-red-C-Ni(2.0)HAlBEA with larger nickel particles than for red-C-Ni(1.0)HAlBEA containing smaller nickel particles (smaller than 5 nm). (C) 2013 Elsevier Inc. All rights reserved.