Issue 5/2022 - New progress in chemical chain ammonia oxidation to nitric oxide

Recently, the team of Wang Xiaodong, a researcher at the Catalysis and New Materials Research Center of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the research team of North Carolina State University in the United States have made progress in the chemical chain ammonia oxidation to nitric oxide, and proposed a new process
of ammonia oxidation to nitric oxide based on chemical chain technology.

Since the early 20th century, the Ostwald Process for the selection of ammonia oxide gas to nitric oxide using platinum group metal alloys as catalysts has been considered the industry standard
for nitric acid production.
However, the reaction temperature of this process is high (800~950 °C), the catalyst loss is serious, and it is the largest industrial emission
of greenhouse gas_N2O.
Therefore, the development of low-cost and efficient catalysts and green ammonia oxidation processes have attracted extensive attention
.

In this work, the research team used the non-precious metal _V2O5as a catalyst to oxidize ammonia to nitric oxide under relatively mild conditions (650 °C), which showed excellent ammonia selective oxidation performance.

Compared with the traditional Ostwald process, the ammonia oxidation process based on chemical chain technology has the following advantages: chemical chain ammonia oxidation is divided into two steps of reduction oxidation, which is conducive to accurately regulating the residence time of NH₃, the reduction degree of oxide catalyst and the ratio of NHx to lattice oxygen on the surface of the catalyst.
The reduced catalyst can be oxidized and regenerated, which is conducive to inhibiting the inactivation of the catalyst; The use of lattice oxygen instead of non-selective gas-phase oxygen is beneficial to inhibit_N2Oformation.
The traditional ammonia oxidation process uses air as the oxidant, and the gas product contains a large amount of inert gas N2 (accounting for about 3/4 of the total airflow), and the chemical chain ammonia oxidation uses the lattice oxygen of the metal oxide catalyst as the oxidant, eliminating_N2 in the gas flow, and the NH₃ oxidation process can be strengthened
.