2.2.7. Recyclability

The recyclability of the sample is vital for practical industrial applications. The catalytic maintenance of the 20Ni-5Co-5Cu/Al catalyst was also evaluated at 240 ◦C, 4 MPa initial N2 pressure for 4 h. After the reaction, the catalyst was then separated with the assistance of a magnet, washed with methanol several times and dried for the next cycle. Reaction results shown in Figure 10 revealed that the 20Ni-5Co-5Cu/Al catalyst could be used at least 10 times without significant decreases in catalytic conversion and selectivity, which indicated that the 20Ni-5Co-5Cu/Al catalyst exhibited excellent recyclability.

**Figure 10.** The recyclability of the 20Ni-5Co-5Cu/Al sample for in-situ HDO of phenol. Reaction conditions: 30 g deionized water, 15 g methanol, 3 g phenol and 0.5 g catalyst, 240 ◦C, 4 MPa initial N2 pressure, 4 h.
