Single Step and Non-Catalytic Process for Formaldehyde Production from Methane using Microchannel Reactor: Theoretical Analysis

Conventionally, methane is reformed into syngas, and subsequently converted into C1-oxygenates (methanol and formaldehyde). A novel option is the catalyst-free single-step conversion of methane to C1-oxygenates. This study presents a comprehensive model of methane partial oxidation to formaldehyde as an intermediate chemical species in methane oxidation process using microreactor. The dependency of C1-oxygenates yield on operating parameters is crucial. Therefore a representative mathematical model is constructed and solved in order to investigate the effect of operating temperature, feed flow-rate, and composition on the formaldehyde yield. Fifty-four coupled of differential equations are solved by finite element method. Moreover, to simulate the process, GRI-Mech 3.0 is employed as the reaction kinetics. A good agreement was achieved when the model results were compared with experimental data from the literature in terms of formaldehyde concentration and methane conversion. Finally, results of the study are presented and discussed on the basis of a major reaction pathway proposed in this study for methane oxidation at low temperature, and the important design criteria are presented. With respect to the model results, 5.5% yield for formaldehyde per one pass of microreactor was achieved at the operating condition of T = 1000 K and O2/CH4 ratio = 17.