Green process for hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate over diatomite supported Cu/Ni bimetallic catalyst

A series of diatomite supported Cu/Ni bimetallic catalysts were prepared using the co-impregnation method to improve the efficiency and selectivity toward methyl 12-hydroxystearate in the hydrogenation of methyl ricinoleate. The catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (H2-TPR). All the characterization results verified the formation of highly dispersed Cu/Ni alloy on support. Moreover, by subtly regulating the Ni/Cu molar ratio as well as the reaction parameters, the hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate proceeded efficiently and selectively, affording 97% yield of methyl 12-hydroxystearate and nearly equivalent conversion of methyl ricinoleate under 2 MPa H2 pressure and at 130 degrees C in 4 h with only 1 wt% of the catalyst Ni7Cu1/diatomite (based on methyl ricinoleate). Besides, the supported Cu-Ni bimetallic catalyst is stable during recycle and reuse. After five cycles of reuse, much catalytic activity is still preserved. Therefore, this low-cost and stable bimetallic catalyst would be promising for the hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate, representing an example of green catalysis for efficiently conversion of biomass to value-added chemicals and materials.

Automated summary

Diatomite supported Cu/Ni bimetallic catalysts prepared using co-impregnation method show high efficiency and selectivity in the hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate. By fine-tuning the Ni/Cu molar ratio and reaction parameters, efficient production with high yield and conversion is achieved, while the catalyst also exhibits stability during recycling.