Methanol-Reformer

A methanol reformer is an apparatus of the chemical industry, used in fuel cell technology in order to produce a methanol -water mixture to release carbon dioxide, pure hydrogen. As the chemical reaction is based on a steam reforming.

Of methanol is reacted with steam over a heterogeneous catalyst by supplying heat energy into hydrogen and carbon dioxide.

Technology

A methanol - water mixture with a molar water-methanol ratio of 1.3 to 1.5 is up to 20 bar compressed, evaporated and superheated to 250 to 280 ° C. The hydrogen produced is separated by a hydrogen permeable membrane made ​​of a palladium -silver alloy ( PdAg ).

For the technical realization there are two basic methods.

• In a heated tubular reactor contains the catalyst. At the reactor inlet the steam - methanol vapor mixture is supplied. The hydrogen separation then takes place in a downstream apparatus. PdAg the membrane is gained from the reformate and hydrogen occurs to a large extent by the membrane.
• The other variant is an integrated membrane reactor. Here, the wall of the reaction zone of a coated PdAg ceramic tube and the hydrogen is separated directly from the reaction zone.

In both variants, the retentate, which contains a significantly depleted proportion of hydrogen combusted in a catalytic burner with air. The released heat energy is used for heating purposes.

Pros and Cons

Methanol reformer are drawn so as not to have to carry hydrogen in compressed gas tanks as a component of hydrogen drive for cars into account. So acceptance may be addressed in the population, where hydrogen is often regarded as too dangerous. The advantage of methanol is in this respect that this liquid is present. However, methanol is toxic as well as gasoline and flammable. The problem is the expensive and error-prone palladium alloy, which has only a moderate thermal shock resistance. The prototype of such a vehicle introduced in 2000 with the NECAR 5 Daimler- Chrysler.