Direct synthesis of hydrogen peroxide from hydrogen and oxygen over Pd-supported HNb3O8 metal oxide nanosheet catalyst

摘要

A two-dimensional layered niobium oxide and its exfoliated nanosheet were examined as potential solid acid supports for direct synthesis of hydrogen peroxide from hydrogen and oxygen under intrinsically safe and noncorrosive reaction conditions. The catalytic performance strongly depended on the acid strength of the support material. The Pd-supported protonated niobium oxide nanosheet catalyst (Pd/HNb3O8-NS) with remarkably enhanced acidity was superior to layered Pd/KNb3O8 or Pd/HNb3O8 to promote the reaction. Hydrogen peroxide decomposition testing revealed that, although HNb3O8 was comparable to its exfoliated counterpart, HNb3O8-NS, in suppressing hydrogen peroxide decomposition without hydrogen, HNb3O8 was virtually ineffective in preventing hydrogen peroxide hydrogenation in the presence of hydrogen. However, compared with HNb3O8, HNb3O8-NS was found to be still effective at suppressing hydrogen peroxide hydrogenation. The different efficiency observed between HNb3O8 and HNb3O8-NS in the prevention of hydrogen peroxide hydrogenation implies that use of a highly acidic support is advantageous to effectively suppress faster and therefore more unfavorable hydrogen peroxide hydrogenation compared with decomposition. This result clearly demonstrates that the highly acidic HNb3O8 nanosheet can serve as an efficient solid acid support for direct synthesis of hydrogen peroxide from hydrogen and oxygen.