Experimental study on operating condition optimization and carbon deposition in methane dry reforming with low steam-to-carbon ratio

Low steam-to-carbon ratio dry reforming of methane is a potential route for simultaneously achieving emission reduction and syngas production. However, the strong coupling among the reactions and the high risk of carbon deposition in this system make it difficult to simultaneously optimize methane conversion, syngas composition, and carbon deposition. To optimize the operating conditions of low steam-to-carbon ratio methane dry reforming , a fixed-bed experimental setup was used to investigate the effects of key factors such as reforming temperature （T）, n（CO₂）∶n（CH₄）, n（H₂O）∶n（CH₄）, and total inlet flow rate （Q_V） on methane conversion （X_CH4） and the n（H₂）∶n（CO） . Based on single-factor screening , Q_V was fixed at 3 L·min⁻¹, and a Box–Behnken design was employed to establish a response surface model for multi-factor coupling analysis and operating-condition optimization. The catalyst under the optimal conditions was further characterized by temperature-programmed oxidation coupled with mass spectrometry （O₂-TPO-MS）. The results show that increasing T, n（CO₂）∶n（CH₄）, and n（H₂O）∶n（CH₄） enhance X_CH4, while increasing Q_V reduce X_CH4. At T=1000 °C, CH₄ =1 L·min⁻¹、H₂O =1 L·min⁻¹、CO₂ =1 L·min⁻¹, X_CH4reach a maximum of 96%,while the n（H₂）∶n（CO） is approximately 1. Under the optimal conditions, the carbon deposition amount is determined to be 1.59 mg·g⁻¹, and the deposited carbon is dominated by relatively easy-to-oxidize carbon species. These results provide a reference for subsequent reactor development and carbon suppression strategies in low steam-to-carbon ratio methane dry reforming.