Microchannel reactor for intensifying oxidation of methanol to formaldehyde over Fe-Mo catalyst

Abstract

Abstract The paper deals with catalytic oxidation of methanol to formaldehyde in a microchannel reactor (MCR) in view of the process intensification. Every channel in the experimental MCR was 1 mm in diameter, 10 mm in height and was filled with an industrial Fe-Mo catalyst ground to a fraction of 0.15–0.25 mm. Methanol concentration in the feed mixture was 6.5 and 12 mol%, oxygen to methanol molar ratio was 1.5, the temperature was in the range 240–360 °C. Safe processing of the reaction in MCR at methanol concentration as high as 12 mol% makes it possible to reach approximately a 10-fold increase in the specific formaldehyde productivity per unit volume of the catalyst even within the explosive range of oxygen-methanol mixtures. Numerical simulation of the process by use of a continuum model revealed its sufficient consistency with the experimental results. It was shown that methanol conversion decreased by ∼12% after operation for 100 h at 300 °C and 12 mol% of methanol. In contrast, at the same conditions but at standard 6.5 mol% of methanol, the decrease in the conversion did not exceed 3%. The use of MCR for highly exothermic reactions has high potential due to extremely high rates of heat and mass transfer, provided that the catalyst used has stable activity of fine particles during on-stream operation.