China Nonferrous Metallurgy

Iron-molybdenum catalyst materials are widely used in the chemical industry field, and have different catalytic properties and catalytic effects in different catalytic reactions because of different molybdenum contents. So the accurate analysis of molybdenum content has a guiding role in the production of iron molybdenum catalyst. At present, the determination and analysis of molybdenum content in national standards and industry standards are mainly molybdenum iron (molybdenum content 50%-75%) and molybdenum concentrate (molybdenum≥40%), while the molybdenum content in iron molybdenum catalyst is usually between 20%-50%, and contains other elements. The sample pretreatment method is different from the national standards and industry standards, and it is necessary to establish new analysis parameters to meet the production needs. In this study, the effects of sample dissolution conditions, precipitation formation parameters and calcination temperature on the determination results were investigated, and the condition parameters were optimized. The optimum conditions were determined as follows : the sample was dissolved by four acid (HCl+HNO₃+HF+HClO₄) , the dropping speed of lead acetate precipitant was 3~5 drops/s, the precipitation aging time was 45min, the aging temperature was 70℃, the precipitation washing times was 15 times, and the precipitation burning temperature was 550℃. Under these conditions, the content of molybdenum in iron-molybdenum catalyst can be effectively analyzed. The relative standard deviation is below 0.20%, and the recovery rate of the sample is 98.0%-101.4%, which can meet the requirements of molybdenum content determination in iron-molybdenum catalyst. However, due to the interference of tungsten on the measurement of molybdenum content, this test method is not suitable for iron-molybdenum catalyst samples containing tungsten.