Carbon deposition in steam methane reforming over a Ni-based catalyst: Experimental and thermodynamic analysis

The experimental investigation of the steam methane reforming process over an industrial Ni-based catalyst was presented. The set of experiments was performed in order to comprehend the effect of the carbon deposition on the methane conversion and pressure drop in a reformer. Various operating conditions such as temperature (600 °C and 800 °C), steam-to-methane ratio (0.5, 1.0, 2.0) and pressure were tested in the experiments. The thermodynamic analysis was accomplished to calculate the equilibrium carbon formation zones for various operating conditions and the experimental results were compared with the results of thermodynamic analysis. The experiments revealed that the methane conversion close to equilibrium is at a residence time of about 5 kgcat·s/ molCH4. The methane conversion as a function of the time on stream was experimentally determined. The maximum decrease in the methane conversion was observed for the steam-to-methane ratio (β) of 0.5. For β=2.0 and β=1.0, the decrease in the methane conversion is minimal. The reforming efficiency and mass of deposited carbon were determined for all investigated operation parameters. When the steam-to-methane ratio is greater than 1, the rate of carbon deposition has an almost linear dependence versus time on stream. For β=2 and T = 800 °C, the carbon deposition rate is approximately 0.12 g/h; for β=2 and T = 600 °C - 0.21 g/h, for β=1 and T = 800 °C - 0.29 g/h, for β=1 and T = 600 °C - 1.02 g/h.