CO2 reforming of methane to synthesis gas over an Ni (1 wt%)/alpha-Al-2 O-3
catalyst was studied in lab-scale fluidized-bed reactors (ID = 3,5 cm). In
the whole range of reaction conditions (p(CH4) = p(CO2) = 25-45kPa, p(N2)
= 10-50 kPa, T-R = 700-800 degrees C, H-mf = 3,4,5 cm, m(eat)/V (over dot)
= 2.8-7.3 g s ml(-1), u/u(mf) = 6.5-11.8) a stable isothermal operation was
achieved. The catalytic performance strongly depended on the oxidation sta
te of the catalyst. When applying a reduced catalyst initial yields of carb
on monoxide and hydrogen near the thermodynamic equilibrium were obtained.
However, a slow decrease of methane conversion and syngas yield caused by c
arbon deposition was observed. The fresh unreduced catalyst exhibited signi
ficantly lower activity. The in situ reduced catalyst was mom active but yi
elded CH4 and CO2 conversions lower than predicted by the thermodynamic equ
ilibrium. The reaction was not influenced by interphase gas exchange. Based
on these results, reaction engineering modeling and simulation yielded a g
lobal kinetic model which described the experimental data with an error of
less than 10% was developed. (C) 2000 Elsevier Science Ltd. All rights rese
rved.