Catalytic oligomerization of ethylene over Ni-containing dealuminated Y zeolites

New bifunctional Ni–H-Beta catalysts for the heterogeneous oligomerization of ethylene

“…Microporous Ni-zeolite catalysts are, in principle, well suited to this purpose given the large variety of available pore structures and the possibility to fine tune their acidic properties. However, previous studies using Ni loaded on Y [8,10] and MCM-22 [9] zeolites showed that, even initially active, the catalysts experienced a rapid deactivation with time due to heavy (mostly branched) oligomers formed on strong Brønsted acid sites that remained trapped in the micropores. Introducing mesoporosity in the zeolite should facilitate the diffusion of the bulkier oligomers and should, thus, result in an improved activity and stability during the reaction.…”

“…The most commonly studied acid carriers in Ni-based bifunctional ethylene oligomerization catalysts are amorphous SiO 2 -Al 2 O 3 [3,4,12], Al-MCM-41 [5,6], and zeolites [7,8,9,10,11]. Thus, besides Ni sites, these catalysts do also typically bear Brønsted-type acidity due to protons associated to tetrahedral product.…”

“…In this respect, bifunctional solid catalysts comprising isolated nickel ions (thus mimicking the structure of the active site in the homogeneous systems) in ionexchangeable aluminosilicate matrices have been found active in the oligomerization of ethylene at moderate temperatures [3,4,5,6,7,8,9,10,11]. In these catalysts, Ni cations in ion exchanged positions are presumed to be responsible for the activation of ethylene and its oligomerization into linear oddnumbered C 4+ -olefins, typically following a Schulz-Flory distribution, through a coordination-insertion chemistry (so-called true oligomerization mechanism)…”

Theoretical identification of structural heterogeneities of divalent nickel active sites in NiMCM-41 nanoporous catalysts

“…Nickel ions supported on different silica, silica-alumina, natural clay, and zeolite-type porous materials are wellknown catalysts for the selective dimerization [1][2][3][4][5][6][7][8][9] and oligomerization [1,5,[10][11][12][13][14][15][16][17][18][19] of olefins in both gas and liquid phases. The application of silica-supported nickel catalysts for the ethylene dimerization dates back to 1980s [20][21][22].…”

Covalent organic frameworks as supports for a molecular Ni based ethylene oligomerization catalyst for the synthesis of long chain olefins

“…Among those, nickel-exchanged zeolites [15][16][17][18][19][20][21][22][23][24], Ni-MCM and Ni-SBA catalysts [25][26][27][28][29][30][31][32][33], supported NiSO 4 [34][35][36][37][38][39][40][41], supported NiO [42][43][44][45][46][47][48] and nickel-exchanged silica-alumina [49][50][51][52][53]. The most active Niexchanged zeolite [17] and silica-alumina catalysts [51] show the formation of mainly C 4 -C 8 olefins, with high selectivity to butenes (circa 70%). Selectivity to higher olefins can be enhanced by using bigger pore materials such as Ni-MCM catalysts [30,32].…”