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Production of middle distillate (C 10 -C 20 ) from synthesis gas (CO ? H 2 ) through hydrocracking of wax ([C 21? ) was carried out in a dual-bed reactor. Co/TiO 2 catalyst was used in the first-bed reactor to produce wax from synthesis gas, and a mesoporous Pd-alumina composite catalyst (Pd-Al 2 O 3 ) was used in the second-bed reactor to produce middle distillate through hydrocracking of wax. For comparison, a Pd catalyst supported on mesoporous alumina (Pd/Al 2 O 3 ) was also examined as a second-bed catalyst. The catalytic performance of PdAl 2 O 3 and Pd/Al 2 O 3 for hydrocracking of wax to middle distillate was tested and compared. It was revealed that selectivity for middle distillate in the dual-bed reactor was much higher than that in the first-bed reactor, indicating that both Pd-Al 2 O 3 and Pd/Al 2 O 3 catalysts in the secondbed reactor served as an efficient catalyst for hydrocracking of wax to middle distillate. Furthermore, Pd-Al 2 O 3 catalyst showed a higher selectivity for middle distillate than Pd/ Al 2 O 3 . The enhanced catalytic performance of Pd-Al 2 O 3 for hydrocracking of wax to middle distillate was due to high Pd dispersion and high Pd surface area. Large medium acidity of Pd-Al 2 O 3 catalyst was also responsible for its high catalytic performance in the hydrocracking of wax to middle distillate.

Mesoporous Ni-Al 2 O 3 (XNiAl) catalysts with different Ni/Al atomic ratio (X) were prepared by a coprecipitation method for use in hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of Ni/Al atomic ratio of mesoporous XNiAl catalysts on their physicochemical properties and catalytic activity for steam reforming of LNG was investigated. Physical properties of XNiAl catalysts did not show a consistent trend with respect to Ni/Al atomic ratio, while chemical properties of XNiAl catalysts strongly influenced by Ni/Al atomic ratio. Nickel species were highly dispersed on the surface of XNiAl catalysts through the formation of nickel aluminate phase or solid solution of nickel oxide and nickel aluminate phase. In the steam reforming of LNG, both LNG conversion and hydrogen composition in dry gas showed volcano-shaped curves with respect to Ni/Al atomic ratio. Nickel surface area of XNiAl catalysts was well correlated with LNG conversion and hydrogen composition over the catalysts. Among the catalysts tested, 0.8NiAl (Ni/Al = 0.8) catalyst with the highest nickel surface area showed the best catalytic performance.

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Production of middle distillate (C 10 -C 20 ) from synthesis gas (CO ? H 2 ) through hydrocracking of wax ([C 21? ) was carried out in a dual-bed reactor. Fischer-Tropsch catalyst (Co/TiO 2 ) was used in the first-bed reactor to produce wax from synthesis gas, and a mesoporous Pd-alumina composite catalyst (Pd-Al 2 O 3 ) was used in the second-bed reactor to produce middle distillate through hydrocracking of wax. Both Fischer-Tropsch synthesis function of Co/TiO 2 catalyst and hydrocracking function of Pd-Al 2 O 3 catalyst were deactivated during 100 h-hybrid Fischer-Tropsch synthesis reaction. It was revealed that deactivation behaviors of Co/TiO 2 and Pd-Al 2 O 3 catalysts were governed by different factors. Wax accumulation and Co sintering were responsible for deactivation of Co/TiO 2 catalyst in the Fischer-Tropsch synthesis reaction. Loss of Pd dispersion and Pd surface area of Pd-Al 2 O 3 catalyst was responsible for its decreased catalytic performance in the production of middle distillate through hydrocracking of wax.