CARBON-DIOXIDE REFORMING WITH METHANE TO CO AND H-2 IN A HOT-WIRE THERMAL-DIFFUSION COLUMN (TDC) REACTOR

In a water-cooled tubular Pyrex reactor of 2.0 cm i.d. and 85 cm long with a tungsten wire of 0.25 mm diameter and 70 cm long, it was possible to obtain 93% conversion with an input ratio CO2/CH4 = 1 at a wire temperature of 1030 degrees C and a linear upward flow rate of 32 cm/min. The reaction is CH4 + CO2 --> 2CO + 2H(2), Delta H degrees = 247 kJ/mol (reaction 1). Lower temperatures required lower flow rates to maintain high conversions. When the flow rates are reduced or the ratio CO2/CH4 > 1 then the reaction CO2 + H-2 --> CO + H2O, Delta H degrees = 41.2 kJ/mol (reaction 2), becomes important resulting in a product ratio of CO/H-2 reaching values as high as 30 with water formation. The thermal electrical efficiency for reaction 1 is, however low, being about 3% based on the electrical energy used. Some formation of oxides of tungsten is observed on the cold walls.