Correlation between acidic properties of nickel sulfate supported on TiO2-ZrO2 and catalytic activity for ethylene dimerization

Abstract

A series of catalysts, NiSO 4 /TiO 2 -ZrO 2 , for ethylene dimerization was prepared by the impregnation method using an aqueous solution of nickel sulfate. For NiSO 4 /TiO 2 -ZrO 2 sample, no diffraction line of nickel sulfate was observed up to 30 wt%, indicating good dispersion of nickel sulfate on the surface of TiO 2 -ZrO 2 . The addition of nickel sulfate to TiO 2 -ZrO 2 shifted the phase transition of TiZrO 4 from amorphous to orthorhombic to a higher temperature because of the interaction between nickel sulfate and TiO 2 -ZrO 2 . The number of acid sites of NiSO 4 /TiO 2 -ZrO 2 increased in proportion to the nickel sulfate content up to 20 wt% of NiSO 4 . Nickel sulfate supported on TiO 2 -ZrO 2 was found to be very active even at room temperature, giving a maximum in both activity and acidity, when the catalyst containing 20% NiSO 4 was calcined and evacuated at 500°C. The asymmetric stretching frequency of the S @ O bonds for NiSO 4 /TiO 2 -ZrO 2 samples was related to the acidic properties and catalytic activity. That is, the higher the frequency, the higher both the number of acid sites and the catalytic activity for ethylene dimerization.

Characterization of NiSO4Supported on Fe2O3and Catalytic Properties for Ethylene Dimerization

“…A considerable number of papers have dealt with the problem of nickel-containing catalysts for ethylene dimerization. [1][2][3][4][5][6][7][8][9][10][11] One of the remarkable features of this catalyst system is its activity in relation to a series of n-olefins. In contrast to usual acid-type catalysts, nickel oxide on silica or silica-alumina shows a higher activity for a lower olefin dimerization, particularly for ethylene.…”

“…In contrast to usual acid-type catalysts, nickel oxide on silica or silica-alumina shows a higher activity for a lower olefin dimerization, particularly for ethylene. [1][2][3][4][5][6]12 It has been suggested that the active site for dimerization is formed by an interaction of a low-valent nickel ion with an acid site. 9,13 It has been reported that the dimerization activities of such catalysts are related to the acidic properties of surface and low valent nickel ions.…”

“…28 So far, however, supported nickel sulfate catalysts have been used mainly on alumina, zirconia, and titania-zirconia. 1 Procedure. FTIR spectra were obtained in a heatable gas cell at room temperature using a Mattson Model GL6030E spectrophotometer.…”

Effect of Al2O3Addition and WO3Modification on Catalytic Activity of NiO/Al2O3-TiO2/WO3for Ethylene Dimerization

“…A considerable number of papers have dealt with the problem of nickel-containing catalysts for ethylene dimerization. [1][2][3][4][5][6][7][8][9][10][11] One of the remarkable features of this catalyst system is its activity in relation to a series of n-olefins. In contrast to usual acid-type catalysts, nickel oxide on silica or silicaalumina shows a higher activity for a lower olefin dimerization, particularly for ethylene.…”

“…In contrast to usual acid-type catalysts, nickel oxide on silica or silicaalumina shows a higher activity for a lower olefin dimerization, particularly for ethylene. [1][2][3][4][5][6]12 It has been suggested that the active site for dimerization is formed by an interaction of a low-valent nickel ion with an acid site. 9,13 In fact, nickel oxide, which is active for C 2 H 4 -C 2 D 4 equilibration, acquires an activity for ethylene dimerization upon addition of nickel sulfate, which is known to be an acid.…”