METHANOL REFORMING IN SUPERCRITICAL WATER FOR HYDROGEN PRODUCTION

ABSTRACT

The production of hydrogen by reforming of methanol in supercritical water was studied in continuous flow apparatus made of nickel base alloys. Experiments were performed at pressures from 25 to 45 MPa, temperatures in the range of 400 to above 600°C and residence times from few seconds up to few minutes. The feed concentration varied from 5 to 64 wt.% methanol. The main component of the product gas is H₂, carbon is converted to CO₂, CO, and CH₄. Methanol conversion is up to 99.9% without addition of a catalyst. Oxidation of the reactor inner surface before gasification turned out to enhance the reaction rate and to lower the carbon monoxide concentration. Obviously, the heavy metals of the inner surface of the reactors catalyze the reaction. Pilot-plant tests (with a flow rate of 100 kg/h) confirm the laboratory experiments and give data for the energy balance of the process.

Keywords:

• methanol
• hydrogen
• supercritical water
• water gas shift reaction
• methanol reforming
• pilot-plant scale

Authors appreciate the contribution of Ms. E. Hauer, Mr. G. Franz, and Mr. K. Weiss who performed the laboratory experiments of the present work and DI. W. Habicht for surface analysis. DI. H. Müller, Mr. R. Drexler and S. Henecka contributed to the pilot-plant experiments. The idea to study methanol reforming in supercritical water and the rough draft of experimental design evolved from discussions with Dr. H. Schmieder.