Anti-sintering silica-coating CuZnAlZr catalyst for methanol synthesis from CO hydrogenation

- A novel anti-sintering catalyst was synthesized by silica-coating on CuZnAlZr mixed oxides.
- Silica-coating layer can inhibit thermal sintering of active particles and keep larger Cu metal surface area.
- The partial etching lessens the resistance of methanol diffusion.
- As-catalysts have a superior methanol synthesis activity and long-term catalytic stability.

In order to reduce catalytic activity loss induced by irreversible thermal sintering, a novel E-CZAZ-S@SiO2 catalyst was prepared by silica-coating CTAB-assisted co-precipitating CuZnAlZr mixed oxides (CZAZ), followed by a partial etching step. The obtained catalysts were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), N2-adsorption-desorption, H2-temperature programmed reduction (H2-TPR) and CO2-temperature programmed desorption (CO2-TPD). Results showed that co-precipitated CZAZ had a thin plate-shaped crystals, and the BET surface area, pore volume and exposed copper surface area of the catalyst were improved with a CTAB-assisted coprecipitation (CZAZ-S). Round catalyst particles with an average size of 8 nm embedded in silica solid solution were generated after coating silica layer (CZAZ-S@SiO2), and additional strongly basic sites formed in the course of etching with NaOH solution for the result catalyst (E-CZAZ-S@SiO2). The catalytic performance evaluation by CO hydrogenation to methanol showed that larger exposed copper surface area and much more strongly basic sites could boost the catalytic activity, and strengthen Cu-ZnO interaction assured excellent methanol selectivity. Furthermore, as a physical spacer, the silica-coating layer protected fine particles and well dispersed Cu/ZnO from sintering during calcining and high temperature reaction, therefore, the long-term catalytic stability at high temperatures was dramatically improved.

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