Search

Production of polyols and other chemicals from cellulose was important for sustainable society, and it had long relied on the design of suitable catalysts to achieve high yield of lower polyols. Herein, we reported a new preparing strategy for nickel-tungsten catalyst to fabricate Ni-W/SiO2@C catalysts coated by thin carbon. The crystal carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2. The prepared composites were characterized by means of XRD, N2 physisorption, thermogravimetry, XPS, TEM, element mapping and atomic force microscope. These characterizations confirmed that more phases including WO3, Ni, NiW alloys and NiC were formed by incorporation of porous crystal carbon. Moreover, the metallic particles were dispersed in size range of 2-8 nm influenced by coating carbon and ethanediamine (dispersant). The activities of catalysts were evaluated in hydrogenolysis of cellulose to lower polyols at 240 °C under 5.0 MPa H2 pressure in the presence of water. Results showed that catalyst Ni-W/SiO2@C-12 was more favorable for EG production, with the highest EG yield of 60.7% and 100% cellulose conversion after reaction for 60 min.Graphical Abstract: The series of high efficient nickel-tungsten catalysts Ni-W/SiO2@C were fabricated and coated by thin carbon. The thin coating carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2. [ABSTRACT FROM AUTHOR]

The superficial chemical environment of the catalyst supports played an important role in heterometallic catalysts preparation. The functions of hydroxy groups on the surface of SiO 2 nanosphere was investigated in catalyst preparing and cellulosic biomass conversion to ethylene glycol (EG). The results demonstrated that 15%Ni-20%W/SiO 2 -OH catalyst was favorable for EG production, with the highest yield of 63.1 and 42.1% from microcrystalline cellulose and hardwood pulp, respectively. The characterization and activity tests suggested that the existence of hydroxy groups could promote the formation of more Ni-W alloys (e.g. NiW, Ni 4 W) under the same preparing condition, which supplemented and enhanced the incorporation of intrinsic nickel and tungsten catalytic activity, especially for enhancement of retro-aldol condensation reaction. Moreover, the metallic Ni 0 was generated in higher amount when supported on hydroxy-rich SiO 2 , boosting hydrogenation of the unsaturated intermediates. Finally, the reusability investigation of the catalyst implied that embedded Ni and W in alloys could inhibit leaching of metals in pressurized hot water. [ABSTRACT FROM AUTHOR]