1.1. Ni/BCC catalyst

The procedure of ion exchange is shown in Figure 5 and Figure 6. Yallourn (YL) coal char was used as catalyst support. YL coal (Australian brown coal) received in the form of briquettes. The coal was crushed, sieved to a particle size range of 1 — 2 mm in diameter, and then dried at 380 K for 12 h. The nickel addition to the coal matrix was achieved by ion — exchange with a solution of basic hexa ammine nickel carbonate (NH3)6NiCO3 (Figure 5, 6). The coal was mixed with the (NH3)6NiCO3 solution for 24 h and then recovered by filtration. The recovered solid was washed with distilled water and filtered again. Then, the washed solid was dried under N2 flow at 380 K for 24 h. Last, raw catalysts were produced.

Catalysts was characterized by powder X-ray diffraction on XRD; M03XHF22, Mac Science Co., Ltd, using CuKa radiation(40 kV, 30 mA) in order to identify the potential evolution of the crystalline phases during catalyst pyrolysis tests. The diffractograms were recorded a step time of 10 sec. SEM analysis was applied to study the surface structure of Ni/BCC catalyst (FE-SEM; JSM-6700F, JEOL Datum Ltd.). An atomic absorption flame emission spectrophotometer (AA-6400F, Shimadzu Corp.) was used to examine the amount of Ni on raw Ni/BCC (Ni 9 + 1%-dry). After pyrolyzing with nitrogen gas at 923 K for 90, its weigh loss is approximately 54 %, and therefore, nickel loaded in coal char could be estimated 19.6 + 2%-char base. The intimacy of the contact between coal char and catalyst was so effective that the reactivity was considerably higher than those prepared by a conventional impregnation method [21-24]. Nitrogen adsorption characterization of catalysts was performed on equipment for automatic gas and vapor adsorption measurement (BELSORP-max, BEL Japan Co. Ltd.). Prior to adsorption measurement, the catalysts were degassed at 573 K for 3 h under a dynamic vacuum. The surface areas of fresh catalysts (Ni/BCC), which were obtained after pyrolysis of raw Ni/BCC at 923 K for 90 min is 350 m2/g [28,29].

1.2. Ni/АЬОз catalyst

A conventional nickel catalyst (No. C13-4, Ni 20±2 wt % SUD-CHEMIE CATALYSTS JAPAN, Inc.) that was supported with alumina was also used to compare with Ni/BCC catalyst. It was crushed and sieved to the fraction of 0.5 — 1 mm.