fuel various hydrocarbon fuels cxh y or co gas can be utilized to control the reduction reaction oxidation cu moo 2 o 2 u2192 cuo moo 3 u2192 cumoo 4 600 u00b0 c depending on the cu mo ratio of the compositions other phases such as cu 2 moo 5 and their combination with cuo may form according to the binary phase diagram in oxygen cumoo 4 melts incongruently at 835 u00b0 c and at atmosphereic pressure cu 3 mo 2 o 9 exists only between this temperature and 865 u00b0 c where it transforms to cuprous cu 6 moo 4 o 15 which melts congruently at 895 u00b0 c cu 2 moo 5 melts peritectically at 880 u00b0 c the moo 3 u2014 cumoo 4 eutectic occurs near 30 mol cuo at 705 u00b0 c traditional single phase moo 2 anode single cells have been operated at 750 u00b0 c for relatively short time frames there are two reasons that this operating temperature is too high for a practical hydrocarbon fueled sofc stack first though it is possible to test button cells without metallic balance of plant hardware in the fuel flow path practical systems will utilize metal tubing and metal interconnects which will template carbon deposition at lower temperatures than those used in single cell tests secondly molybdenum oxides have.