You have to use weapons and armor, for example, Torch Pillar.G +5. The 1st job level 180 equipments (Shadowless, Dawn, Holy Son, Safari, Elemental, Hephaestus) and their corresponding weapons (Tianlong, Ultima, Geoheven, Seiryuu, Celestial Stave, Hephaestus Fist) are also good catalysts for G refining. There are some exceptions however, and the ones I know that don't work well are the Holy Son (B) and any of the hunter equips.

If you need better catalysts, use the level 160 XG equipments from the Item Mall.

And yes, acc can't be used as cata.