Selective hydrodechlorination of 1,2-dichloroethane on NiSiBEA zeolite catalyst: Influence of the preparation procedure on a high dispersion of Ni centers

Abstract

NixSiBEA zeolites (x=1–2 Niwt.%) were prepared by a two-steps postsynthesis method which consists of (1) creation of vacant T-sites by dealumination of tetraethylammonium BEA zeolite with nitric acid and then (2) impregnation of resulting SiBEA zeolite with an aqueous solution of Ni(NO3)2, following a drying (333K) of as prepared NixSiBEA. The calcination of NixSiBEA at 773K for 3h in air leads to formation of C-NixSiBEA with an isolated pseudo-tetrahedral Ni(II) species incorporated in BEA framework as evidenced by combined use of XRD, DR UV–vis, XPS and TPR. The reduction of C-NixSiBEA (873K, 3h in flowing 10% H2/Ar) leads to formation of red-C-NixSiBEA with a very high dispersion of nickel (>65%) measured by oxygen chemisorption. The red-C-NixSiBEA catalysts were active in hydrodechlorination of chlorinated volatile organic compound (1,2-dichloroethane) at relatively low reaction temperatures (523–543K) with a very high selectivity (90%) into desired product, ethylene. TPH experiments have shown that after hydrodechlorination of 1,2-dichloroethane a very little amount of carbonaceous and chlorine-containing species are present on spent NixSiBEA zeolite catalysts.