Due to the advantages of converting tar into useful gases and adjusting the compositions of product gases, catalyst cracking has been of interest since the middle 1980s. The simplified mechanism for catalyst tar reforming can be described as follows [7-9]. First, methane or other hydrocarbons are dissociatively adsorbed onto a metal site where metal catalyzed dehydrogenation occurs. Water is also dissociatively adsorbed onto the ceramic support, hydroxylating the surface. At the appropriate temperature, the OH radicals migrate to the metal sites, leading to oxidation of the intermediate hydrocarbon fragments and surface carbon to CO + H2. David [9,10] summarized the criteria for catalyst as follows:

1. the catalysts must be effective in removing tar;

2. if the desired product was syngas, the catalysts must be capable of reforming methane;

3. The catalysts should provide a suitable syngas ratio for the intended process;

4. the catalysts should be resistant to deactivation as a result of carbon fouling and sintering;

5. the catalysts should be easily regenerated.

6. The catalysts should be strong; and

7. the catalysts should be inexpensive.

Moulijn J. A. [11] has classified main causes of the deactivation into five reasons that are poisoning, fouling, thermal degradation (sintering, evaporation) initiated by the often high temperature, mechanical damage and corrosion/leaching by the reaction mixture. The deactivation phenomenon inside a catalyst particle is described on Figure 2 [11]. Among them, thermal degradation reason often occurs during catalyst reforming tar at relative high temperature (Figure 3).