GM Global Technology Operations, Inc. (Detroit, MI) has patented a two-fuel engine (or hybrid fueled engine) in which hydrogen is produced on board by reacting ammonia with nano-catalysts and is then used to augment the fuel from a gasoline tank.
Hydrogen fuel delivery is managed to supplement gasoline usage with the availability of hydrogen produced from liquid or solid-state ammonia storage. Hydrogen may also be used in an otherwise conventional gasoline fueled internal combustion engine.
GM engineer Nazri Gholam-Abbas created a nano-catalytic method for using ammonia in a condensed and solid-state form as a hydrogen source with little likelihood of a release of ammonia gas in the event of a rupture of storage system. In addition, the storage of ammonia as a hydrogen precursor doesn't require a high-pressure tank. A low cost plastic or composite tank can be used to contain the proposed solid-state ammonia storage materials.
Due to the thermal requirements of this process it is preferred to use the hydrogen during periods of more or less steady state engine operation. The two-fuel engine and hydrogen generation system earned GM U.S. Patent 7,640,896.
One of the requirements of using hydrogen as a fuel is to develop a dense and safe hydrogen storage system. Among various chemical compounds, ammonia with 17.6 wt % hydrogen is a promising candidate as hydrogen carrier.
One of the requirements of using hydrogen as a fuel is to develop a dense and safe hydrogen storage system. Among various chemical compounds, ammonia with 17.6 wt % hydrogen is a promising candidate as hydrogen carrier.
There is interest in reducing consumption of gasoline in vehicles powered by internal combustion engines. To achieve this goal, some vehicle engine systems are adapted to recognize and distinguish between gasoline or a mixture of gasoline and ethanol being pumped from the vehicle fuel tank for injection into the cylinders of the engine. Air is also inducted into the cylinders and the fuel must be injected in an amount for combustion to power the engine and to achieve a suitable exhaust composition for treatment and discharge to the air.
There is also interest in supplementing gasoline with hydrogen but it is difficult to safely store hydrogen gas on-board a vehicle. There remains a need for identifying storable fuels or fuel precursors for conserving gasoline in current passenger and commercial vehicles or in other power plants utilizing hydrogen or a carbon-containing fuel.
Ammonia (NH3) is stored in a solid composition as a hydrogen fuel precursor for a vehicle internal combustion engine that is operated to use hydrogen or a combination of hydrogen and gasoline as fuel. Ammonia is suitably stored as an ligand coordinated with a transition metal compound (or coordination complex) with each coordinated metal compound molecule containing one or more (often several) molecular ammonia ligands.
There is also interest in supplementing gasoline with hydrogen but it is difficult to safely store hydrogen gas on-board a vehicle. There remains a need for identifying storable fuels or fuel precursors for conserving gasoline in current passenger and commercial vehicles or in other power plants utilizing hydrogen or a carbon-containing fuel.
Ammonia (NH3) is stored in a solid composition as a hydrogen fuel precursor for a vehicle internal combustion engine that is operated to use hydrogen or a combination of hydrogen and gasoline as fuel. Ammonia is suitably stored as an ligand coordinated with a transition metal compound (or coordination complex) with each coordinated metal compound molecule containing one or more (often several) molecular ammonia ligands.
Transition metal coordination compounds (suitably compounds of cobalt, iron, or nickel) are preferred because the temperatures and rates of ammonia release (and re-absorption) are particularly suitable for the on-vehicle storage and use of hydrogen precursor. Each ammonia molecule (the ligand or ligands) contributes electrons to a receptive transition metal ion in a coordination compound molecule (e.g., salt molecule) to form a coordinated complex that includes releasable ammonia molecules.
Such ammonia-holding materials may be prepared as a powder for onboard vehicle storage. An ammonia-containing composition is selected for its ammonia content and its suitability for storage at ambient conditions on the vehicle at substantially atmospheric pressure
An ammonia (NH3) dissociation catalyst tube containing a catalyst bed and maintained at 750.degree. C. is used to disassociate ammonia into nitrogen and hydrogen atoms. The ammonia dissociation catalyst is a mixture of nanometer size particles of a Co--NiO--Cu--Zr catalyst deposited in high surface area TiO2 (about 11002/g) and two weight percent platinum deposited on alumina particles
FIG. 1 is a schematic flow diagram illustrating on-vehicle storage of powder of an ammonia-containing transition metal coordination compound in a three-compartment vessel, delivery of ammonia from the storage vessel to a reactor in which ammonia gas is dissociated into hydrogen and nitrogen, and delivery of a gas mixture of hydrogen and nitrogen to an internal combustion engine.
FIG. 2 is a schematic representation of an absorption vessel for receiving a mixture of hydrogen and nitrogen, temporarily absorbing, or separating, nitrogen into a suitable absorbent bed or column, and delivering a hydrogen-enriched gas to the on-vehicle engine.
