Industrial Synthesis of N-Methylhydroxylamine Hydrochloride by Electrochemical Reduction of Nitromethane

An industrial electrolytic cell was designed for the electrochemical synthesis of N-methylhydroxyl-amine hydrochloride (N-MHA). Copper was used as the cathode, graphite as the anode, and a cation membrane as the separator. The results show that N-MHA with a high purity of 99% can be electrosynthesized directly from nitromethane in HCl solution. Under a constant current of 1000–2500A·m−2 in the temperature of 30–50°C, the average yield, current efficiency, and reaction selectivity were 65%, 70%, and 99%, respectively. Graphite electrode and membrane material can be used continuously in the preparative electrolysis for 5000h. Moreover, the effects of the electrode and membrane materials, current intensity, electrolyte temperature, and other associated parameters on the electrosynthesis results were investigated. The direct current power consumption was 8151.3kW·h·(1000kg N-MHA)−1. This method is a simple separation process with limited contamination and hence, is a new green synthesis method for the industrial production of N-MHA.