Metal particles supported on SiO2-OH nanosphere: New insight into interactions with metals for cellulose conversion to ethylene glycol

The catalytic transformation of cellulose to polyols is one of the significant strategies to overcome the shortage of fossil fuels. Here we report a simple but effective preparation method for Ni-W/SiO2 catalysts by introduction of chelating agents (ammonium hydroxide and ethanediamine) coupled with organic reducing agent (ethylene glycol). The ethylene glycol (EG) yield from microcrystalline cellulose could reach up to 63.3% at 240 °C, 5.0 MPa H2 for 2.0 h over 15%Ni-20%W/SiO2-EEG catalyst. Moreover, some key parameters of process conditions including calcining temperature, reaction temperature and time, H2 pressure and the recycling use of catalysts were investigated. Both theoretical and experimental studies suggested that 15%Ni-20%W/SiO2-EEG catalyst showed the best activity and stability for cascading steps for EG formation at this reaction condition. By the detailed analysis of Ni-W/SiO2 catalysts after calcination via FT-IR, XRD, XPS, thermogravimetry (TG), TEM and element mapping, it could be concluded that on the surface of 15%Ni-20%W/SiO2-EEG catalyst, the particles showed less agglomeration and more homogeneous on the surface of SiO2. Some NixWy alloys (NiW, Ni2W4C) were also formed. Furthermore, it was found that the introduction of ethanediamine could promote the actual loading of nickel and tungsten species slightly according to the analysis of ICP-OES test.