Hydrodechlorination of 1,2-dichloroethane on nickel loaded Beta zeolite modified by copper: Influence of nickel and copper state on product selectivity

Influence of copper addition to nickel containing zeolite on activity and product selectivity in the hydrodechlorination of 1,2-dichloroethane was investigated. Ni2.0SiBEA and Cu2.0Ni2.0SiBEA zeolites were prepared by a two-steps postsynthesis method which consist of (1) creation of vacant T-atom sites by dealumination of calcined BEA zeolite with nitric acid and then (2) impregnation of as resulting SiBEA with aqueous nickel nitrate solution or co-impregnation with aqueous nickel and copper nitrate solution, respectively. Calcination at 773 K for 3 h in air and then reduction at 873 K over 3 h in flowing 10% H2/Ar of Ni2.0SiBEA and Cu2.0Ni2.0SiBEA, with an isolated pseudo-tetrahedral Ni(II) and Cu(II) species incorporated into BEA framework, leads to formation of red-C-Ni2.0SiBEA and red-C-Cu2.0Ni2.0SiBEA catalysts with very well dispersed metal nanoparticles. The state of nickel and copper in catalysts after calcination, reduction and reaction was characterized by XRD, low-temperature N2 sorption, TPR and XPS. The red-C-Ni2.0SiBEA and red-C-Cu2.0Ni2.0SiBEA catalysts were active in hydrodechlorination of 1,2-dichloroethane with very high selectivity into ethylene (90 and 96% respectively), desired product of this reaction. Thus, the simultaneous introduction of copper and nickel ions in SiBEA in the second step of postsynthesis procedure allows obtaining bimetallic red-C-Cu2.0Ni2.0SiBEA catalyst with well dispersed, separated Cu and Ni particles with higher selectivity toward ethylene than red-C-Ni2.0SiBEA catalyst. TEM experiments have shown that after catalytic run a very small agglomeration of metal particles took place. According to TPH and XPS measurements chlorine containing species are present in spent zeolite catalysts.