Cogeneration of HCN in a Solid Oxide Fuel Cell

HCN synthesis from methanol ammonia steam mixtures was studied with the cogeneration of electrical energy in a solid oxide fuel cell (SOFC). The SOFC was electrolyte-supported using a gadolinia-doped ceria (CGO) electrolyte and operated in the temperature range 500-650 degrees C. The anode was a mixture of Ni/CGO composite and an iron antimony oxide catalyst, which is known to catalyze the ammoxidation of methanol to HCN. The catalytic activity of the anode, and its constituent materials, for ammoxidation and ammonolysis reactions was studied in microreactor experiments to optimize the composition of the anode. The anode off-gas from the SOFC was analyzed by gas chromatography as a function of operating temperature and the electrical power drawn from the cell. The anode off-gas contained HCN, with a maximum yield of 40% (with respect to methanol input) and selectivity for conversion of methanol to HCN of 47.5%. CO(2), N(2), H(2), and CH(4) were the other significant reaction products. There was no evidence for electrochemical ammoxidation taking place in the SOFC. Rather, HCN was produced by ammonolysis of methanol, and the H(2) produced by side reactions was oxidized electrochemically in the SOFC.