Ni-exchanged Y-zeolite. An efficient heterogeneous catalyst for acetylene hydrocarboxylation

A series of Ni-modified Y-zeolites with varying Ni loading in the presence of cupric salt as promoter were studied for acetylene hydrocarboxylation performed in a batch reactor. The catalysts were characterized by elemental analysis, H-2-TPR, XRD, NH3-TPD, pyridine-FTIR, SEM, TG-DTG and Raman. It was found that the catalytic activity showed a pronounced dependence on the supports, metal introduction method, promoters and reaction conditions. The nickel species present as charge compensation cations in the zeolite framework constitute the active sites, and the acid sites help to promote the performance of carbonylation. Moreover, two types of coke were observed, and the remarkable reusability of NiY is attributable to the location of the coke outside the zeolite crystals. High catalytic performance was obtained over a NiY(7.0) catalyst with 62 g(acrylic acid)/(g(cat). h) of yield at 235 degrees C,3.6 MPa of initial total pressure and 0.8 mM/l of cupric bromide within 40 min of reaction time. This is the most effective heterogeneous system for synthesizing acrylic acid by carbonylation of acetylene to date. (C) 2014 Elsevier B.V. All rights reserved.