Transient behaviour of an adiabatic fixed-bed methanator

Abstract The transient behaviour of an adiabatic fixed-bed catalytic reactor has been studied experimentally as well as theoretically using the hydrogenation of small amounts of CO and CO 2 to methane as the test reactions. The axial temperature profile in a 0·5-litre reactor containing a Ni/Al 2 O 3 catalyst was measured as a function of time after applying changes of the carbon oxide concentration in the feed and of the feed temperature. Besides, a quasi-homogeneous model was developed to simulate the transient behaviour of the reactor; its partial differential equations were solved numerically using the Crank-Nicholson algorithm. The agreement between measured and calculated reactor responses was quite good at carbon oxide concentrations up to 2·2 vol %, an inlet temperatures below 250°C and in the space velocity range of 5000–25000 h −1 , under which conditions the reaction is so slow that mass and heat transfer limitations do not occur.