One-Pot Catalytic Conversion of Cellobiose to Sorbitol over Nickel Phosphides Supported on MCM-41 and Al-MCM-41

MCM-41- and Al-MCM-41-supported nickel phosphide nanomaterials were synthesized at two different initial molar ratios of Ni/P: 10:2 and 10:3 and were tested as heterogeneous catalysts for the one-pot conversion of cellobiose to sorbitol. The catalysts were characterized by X-ray diffractometer (XRD), N2 adsorption-desorption, scanning electron microscope (SEM), transmission electron microscope (TEM), 27Al-magnetic angle spinning-nuclear magnetic resonance spectrometer (27Al MAS-NMR), temperature programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction (H2-TPR), and inductively coupled plasma optical emission spectrophotometer (ICP-OES). The characterization indicated that nickel phosphide nanoparticles were successfully incorporated into both supports without destroying their hexagonal framework structures, that the catalysts contained some or all of the following Ni-containing phases: Ni0, Ni3P, and Ni12P5, and that the types and relative amounts of Ni-containing phases present in each catalyst were largely determined by the initial molar ratio of Ni/P as well as the type of support used. For cellobiose conversion at 150 °C for 3 h under 4 MPa of H2, all catalysts showed similarly high conversion of cellobiose (89.5–95.0%). Nevertheless, sorbitol yield was highly correlated to the relative amount of phases with higher content of phosphorus present in the catalysts, giving the following order of catalytic performance of the Ni-containing phases: Ni12P5 > Ni3P > Ni. Increasing the reaction temperature from 150 °C to 180 °C also led to an improvement in sorbitol yield (from 43.5% to 87.8%).