助剂Cu对Ni/γ-Al2O3催化剂低温还原性能影响

A series of CuNi/γ-Al2O3 catalysts with different Cu contents were prepared and evaluated by the gas-phase benzene hydrogenation as a probe reaction. After reduction at 160 ℃, the Cu-promoted CuNi/γ-Al2O3 catalysts exhibited considerably higher activity than Ni/γ-Al2O3 catalysts, and the copper content played an important role in the catalyst reducibility and catalytic activity. The catalyst, CuNi/γ-Al2O3 with copper to nickel atomic ratio 1∶1, exhibited best catalytic activity and stability. XRD(X-ray diffraction) results showed that the addition of copper to the Ni/γ-Al2O3 catalysts significantly improved the dispersion of NiO over γ-Al2O3, the CuNi/γ-Al2O3 with copper to nickel atomic ratio 1∶1 had optimal dispersion, and further addition was accommodated by the decreasing of the dispersion of NiO. TPR(temperature programmed reduction) results suggested the addition of copper promoted the reducibility of supported nickel oxide by enhancing surface segregation of a NiO-like phase, while copper to nickel atomic ratio in excess of 3∶5 had practically no additional promoting effect.