(561b) Computational Study of a MOF-Supported Single Site Ni Catalyst for Ethylene Dimerization

Metal-organic frameworks (MOFs) with ultrahigh porosity and large surface area have recently emerged as excellent heterogeneous supports for transition metal catalysts, either through functionalization of the linker or direct modification of the nodes. The mesoporous MOF, NU-1000, is of particular interest due to its chemical and thermal stability as well as its large pore size (~30 Å), which facilitates the diffusion of gaseous molecules. More importantly, the coordinatively unsaturated metal sites at the inorganic nodes provide specific sites for metal oxide species to anchor, enabling the synthesis of a highly dispersed and isolated single-site metal catalysts on the internal surface of NU-1000. Through atomic layer deposition, a highly dispersed Ni catalyst (Ni-NU-1000) was successfully synthesized; it shows good activity and stability for ethylene hydrogenation and was predicted to be a potential catalyst for ethylene oligomerization.(1,2)

In this work, we aim to study the structure of the Ni-NU-1000 catalyst and from there to identify the catalytic active sites for ethylene dimerization. In addition, the effect of the pore size on the selectity for 1-butene production have been studied. Furthermore, we have screened the first-row transition metals for their activity toward the ethylene dimerization. The goal is to provide physical insight into properties controlling the activity and selectivity for ethylene dimerization and then guide experimentalists to design a better catalyst for ethylene dimerization.

The current study provides physical insight into the properties of MOF supported metal clusters in controlling the activity and selectivity for dimerization of ethylene to produce 1-butene, which is a basic petrochemical building block and largely used as a co-monomer for the production of light weight polyethylene. As compared to homogeneous catalysts, the novel heterogeneous catalyst has many industrial advantages such as ease of product separation and catalyst recycling.

References
1. Li, Z.; Schweitzer, N. M.; League, A. B.; Bernales, V.; Peters, A. W.; Getsoian, A. B.; Wang, T. C.; Miller, J. T.; Vjunov, A.; Fulton, J. L. J. Am. Chem. Soc., 138, 1977 (2016).
2. Mondloch, J. E.; Bury, W.; Fairen-Jimenez, D.; Kwon, S.; DeMarco, E. J.; Weston, M. H.; Sarjeant, A. A.; Nguyen, S. T.; Stair, P. C.; Snurr, R. Q. J. Am. Chem. Soc., 135, 10294 (2013).