Novel method for metallic zinc and synthesis gas production in alkali molten carbonates

This paper addresses the exploration of an unconventional route for potentially cost effective and cleanly technology by partial oxidation of methane with zinc oxide to co-producing metallic Zn and synthesis gas. The results of thermodynamic analysis indicate that the direct gas–solid reaction is possible theoretically. The experimental investigates have been carried out in a molten salt reactor at the temperature range of 850–950 °C. The GC analysis results of exhaust revealed that the gases compositions were H2, CO and CH4, in which the CO2 could not be detected. Both the CH4 conversion and the ratio of H2/CO increased with the increasing of reaction temperature, the ratio of H2/CO was 2 at around temperatures 925 °C. After the reaction completed the product of metallic zinc was successfully collected in the reactor and was characterized by X-ray diffraction (XRD) and electron probe microanalysis (EPMA). The results showed that the eutectic mixture of K2CO3 and Na2CO3 (weight ratio is 1:1) acts as the reaction medium and the thermal storage in this process was feasible. Furthermore the XRD analysis results of molten salt after reacting with CH4 + ZnO indicated that there were other complicated chemistry reactions in this reaction system, in which alkali molten carbonates maybe also act as the catalyst.