Ni2P Nanoparticles Embedded in Mesoporous SiO2for Catalytic Hydrogenation of SO2to Elemental S

Xinnan Lu, Mark A. Baker, Dalaver H. Anjum, Georgia Basina, Steven J. Hinder, Wassilios Papawassiliou, Andrew J. Pell, Marina Karagianni, Georgios Papavassiliou, Dinesh Shetty, Dina Gaber, Safa Gaber, Yasser Al Wahedi, Kyriaki Polychronopoulou

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Highly active nickel phosphide (Ni2P) nanoclusters confined in a mesoporous SiO2 catalyst were synthesized by a two-step process targeting tight control over the Ni2P size and phase. The Ni precursor was incorporated into the MCM-41 matrix by one-pot synthesis, followed by the phosphorization step, which was accomplished in oleylamine with trioctylphosphine at 300 °C so to achieve the phase transformation from Ni to Ni2P. For benchmarking, Ni confined by the mesoporous SiO2 (absence of phosphorization) and 11 nm Ni2P nanoparticles (absence of SiO2) was also prepared. From the microstructural analysis, it was found that the growth of Ni2P nanoclusters was restricted by the mesoporous channels, thus forming ultrafine and highly dispersed Ni2P nanoclusters (<2 nm). The above approach led to promising catalytic performance following the order u-Ni2P@m-SiO2 > n-Ni2P > u-Ni@m-SiO2 > c-Ni2P in the selective hydrogenation of SO2 to S. In particular, u-Ni2P@m-SiO2 exhibited SO2 conversions of 94% at 220 °C and ∼99% at 240 °C, which are higher than the 11 nm stand-alone Ni2P particles (43% at 220 °C and 94% at 320 °C), highlighting the importance of the role played by SiO2 in stabilizing ultrafine nanoparticles of Ni2P. The reaction activation energy Ea over u-Ni2P@m-SiO2 is ∼33 kJ/mol, which is lower than those over n-Ni2P (∼36 kJ/mol) and c-Ni2P (∼66 kJ/mol), suggesting that the reaction becomes energetically favored over the ultrafine Ni2P nanoclusters.

Original languageBritish English
Pages (from-to)5665-5676
Number of pages12
JournalACS Applied Nano Materials
Volume4
Issue number6
DOIs
StatePublished - 25 Jun 2021

Keywords

  • MCM-41
  • nickel phosphide (NiP)
  • SOreduction
  • solid-state NMR
  • ultrafine crystals

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