Gas: heating and illuminating – Methane -containing product – or treatment or recovery process – Process including chemical reaction
Patent
1996-12-23
1998-06-09
Marschel, Ardin H.
Gas: heating and illuminating
Methane -containing product, or treatment or recovery process
Process including chemical reaction
48 61, 4236481, 252373, B01J 700, C10L 300, C07C 102, C01B 400
Patent
active
057626588
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/GB95/01500, filed Jun. 26, 1995 which designated the U.S.
This invention concerns improvements in reformers, more especially it concerns improvements in self-sustaining reformers that start-up from ambient temperature. The volume-specific hydrogen output of these improved reformers makes them suitable for application in fuel-cell powered vehicles.
We have disclosed in EP 0 217 532, a self-igniting partial oxidation reformer or catalytic hydrogen generator which has become known as the "Hot Spot" reactor. The basic concept is that methanol and air are co-fed into a reactor containing a packed bed of copper on refractory support catalyst, with a down-stream zone containing platinum or palladium catalyst mixed with copper catalyst The down-stream zone provides self-ignition to raise the reactor temperature to a point a hot spot formed around the point of injection of feedstock into the bed of catalyst. This concept was further developed in the invention of EP 0 262 947, which uses this reactor design to produce hydrogen from hydrocarbons, but using a catalyst composed of platinum and chromium oxide on a support. Further details have been given in a paper in Platinum Metals Review, 1989, 33, (3) 118-127.
As predicted in the above-mentioned prior art, the use of liquid fuels as hydrogen sources for fuel-cell powered vehicles, or even static systems, is attracting considerable interest. The best established conversion system is steam reforming, but this is an endothermic reaction, requiring continuous input of energy. Whilst self-sustaining reforming is clearly an interesting concept, in further studies of the Hot-Spot system, we have found that the reactor as described did not permit scale-up, and therefore there was a need to find alternative and improved reactor and/or system designs.
The present invention provides a self-igniting and self-sustaining hydrogen generation reactor for a feedstock fluid comprising an organic fuel in liquid, atomised (spray), vapour or gas form and a source of oxygen, such as air, said reactor comprising a bed of a permeable fixed bed of copper-supported catalyst and a PGM-supported catalyst, said reactor further comprising an inlet for the feedstock which comprises a multiplicity of restricted entries causing high velocity feedstock injection into the bed together with a significant pressure drop and gas expansion, for example an extended surface area of porous ceramic. Preferably, the inlet is in the form of a porous ceramic tube having a closed end, but other inlet designs may give advantages in particular circumstances.
The invention also provides a method for the production of hydrogen from a feedstock comprising passing an organic fuel and a source of oxygen, such as air, over a bed which is a mass of catalyst comprising copper and palladium or other PGM moieties, characterised in that the fuel is in spray, vapour or gas form and further characterised in that the feedstock enters the mass of catalyst through a multiplicity of entries which cause a significant pressure drop at least sufficient to prevent back-flow of products and results in high velocity injection of feedstock into the bed and feedstock expansion. For example, the entries may be in the form of an inlet having an extended surface area of porous ceramic.
The porous ceramic used in initial tests was a commercial ceramic of pore size 100 .mu.m, purchased from Fairey, England, and this material is therefore recommended, but we expect that alternative porous ceramic materials will provide substantially similar results. It appears that porous metal inlets, whilst having similar gas flow characteristics to porous ceramics, are unsuitable because beat conduction interferes with the reactions being carried out, and could even cause premature ignition of the methanol/air mixture, for example within the feed tube. However, it is possible that further material developments, and/or further reactor design improvements, may permit composite metal/ceramic
REFERENCES:
patent: 4789540 (1988-12-01), Jenkins
patent: 4981676 (1991-01-01), Minet et al.
Edwards Neil
Frost Jonathon C.
Jones Ann-Marie
Pignon John F.
Johnson Matthey Public Limited Company
Marschel Ardin H.
Riley Jezia
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