Ethene oligomerization on nickel microporous and mesoporous-supported catalysts: Investigation of the active sites

Abstract

Complete body of DFT-MD results, results of Monte Carlo simulations, setup and results of microkinetic modeling, additional experimental details and results (PDF) CatMAP files (ZIP) ■ AUTHOR INFORMATION

Nature of Active Nickel Sites and Initiation Mechanism for Ethylene Oligomerization on Heterogeneous Ni-beta Catalysts

“…Focusing on the nickel-carbonyl region of interest, the most intense IR bands are clearly those peaking at 2214 and 2205 cm -1 of CO adsorbed on isolated Ni 2+ ions counterbalancing the negative charge of the zeolite framework (i.e. at ion exchange positions) 33,[42][43][44] , that is, the nickel species generally considered as the active sites in Ni-aluminosilicate catalysts 2,13,15,19,25,26 . The different CO vibration frequency for these two ion-exchanged Ni 2+ cations signs for a distinct electron accepting capability (i.e.…”

“…In this regard, dual-functional materials comprised of nickel ions dispersed on acidic porous aluminosilicates such as mesoporous amorphous silica-alumina [10][11][12][13][14] , Al-doped ordered mesoporous silicas (e.g. Al-MCM-41, Al-SBA-15, and related materials) [15][16][17][18][19][20] , and zeolites [21][22][23][24][25] are the most prospective solid catalysts so far investigated for this reaction. However, catalysts based on Ni dispersed on purely microporous zeolites such as X 21 , Y 22 , and MCM-22 23 typically experience a fast deactivation due to the accumulation of heavy oligomers within the channels and cages.…”

“…those replacing H + in bridged Si-OH-Al groups of the acidic aluminosilicate carrier, are widely assumed to be the active species 2,13,15,19,[24][25][26] , although their oxidation state has been extensively debated. Thus, even though in most previous studies monovalent nickel ions were postulated as the most likely active sites 16,21,[27][28][29][30][31][32] , more recent spectroscopic 24,25,33,34 and computational 26 works advocate for divalent nickel as the active nickel species. Moreover, for Ni-aluminosilicates with low density of framework Al sites (i.e.…”

Ethene Dimerization on Zeolite-Hosted Ni Ions: Reversible Mobilization of the Active Site

“…7 Nevertheless, there is accumulating evidence provided by us and others that the reaction follows the Cossee–Arlman mechanism (Scheme 1) 8−11 known from homogeneous catalysis. The three-dimensional structure of the Ni-aluminosilicates plays a central role in alkene oligomerization: experimental results show that dimer formation is first order in alkene pressure on Ni-silicaalumina 10,12 but second order in Ni-zeolites. 12,13 1-Butene formation is also second order in mesoporous Ni-silicaalumina at low temperatures, where it was demonstrated that condensation of ethene in the pores stabilized catalytic activity.…”

Interaction of Ethylene with Irn (n = 1–10): From Bare Clusters to γ-Al2O3-Supported Nanoparticles

“…Interaction of light alkenes with metal clusters has been widely studied in the past due to its important applications in the fields of fine chemistry and petroleum refining. As the smallest alkene and one of the most common probe molecules, the adsorption of ethylene on supported metal catalysts has been widely investigated [1,2,3,4,5]. Keppeler et al [3] studied ethylene hydrogenation on the NaY and KL zeolite-supported Pt 13 cluster and found ethane was the only product.…”