Surface characterisation of nickel boride and nickel phosphide catalysts by X-ray photoelectron spectroscopy

Abstract

Der positive Promotor‐Effekt von Bund der negative Effekt von P in NiB‐ bzw. NiP‐Hydrierungskatalysatoren lassen sich durch den Einfluß von B und P auf die Elektronendichte im Ni erklären: B gibt Elektronen an das Ni ab, während P Elektronen aus dem Ni abzieht, was eine Zunahme der Aktivität mit steigendem B‐Gehalt und eine Abnahme der Aktivität mit steigendem P‐Gehalt der Katalysatoroberfläche zur Folge hat.

Effect of Phosphorus Content on Local Structures of NiP Amorphous Alloys

“…White line peak appears only in the near edge of Ni 74 P 26 sample, indicating that the charge transfer from Ni atoms to P atoms occurs when the P concentration is above 25 at.% and for the low-P samples the charge transfers from P atoms to Ni atoms. This accords with XPS results [10,11].…”

“…Such a large disorder confirms that the Ni-P alloys with high P concentration are totally amorphous. The coordination number of Ni-P coordination also increases from 1.8 to 3.0 following the increasing of P concentration form 14 to 26 at.%, different from the small value of Ni 92 P 8 and Ni 90 P 10 . At the same time, the coordination number of Ni-Ni decreases from 10.1 to 9.5 on the contrary.…”

“…Alloying P can modify the catalyst structure, which results in the short range ordering and long range disordering structural characteristics [9]. XPS results show that as the P concentration is lower than 25at.%, charge transfers from P atoms to Ni atoms; and for P concentration higher than 25at.%, charge transfers from Ni atoms to P atoms [10,11]. As the content of P increases, the catalytic activity of Ni-P first increases then decreases, and reaches the maximum when P at.% is about 8～11 wt.% (14 ～ 19at.%) [12].…”

Preparation and catalytic properties of amorphous alloys in hydrogenation of sulfolene

“…Though Ni was the active component, the activity for the hydrogenation of sulfolene increased with metalloid content increases for the same Ni-metalloid amorphous alloy. This is in accordance with the studies of Okamoto et al [24] There exists an obvious correlation between the particle size and the catalytic activity of these samples. With the particle size decreasing (NiB-2 < NiB-1∼NiBP-2 < NiP-2 < NiP-1), the catalytic activity of the samples increased (NiB-2 > NiBP-2∼NiB-1 > NiP-2 > NiP-1).…”

“…The first viewpoint attributed the differences to the differences of the electron densities on the nickel metal among NiP, NiB and NiBP catalysts [17,24,25]. In NiB powder, boron donates electrons to the nickel metal, whereas phosphorus accept electrons from nickel metal in NiP powder.…”