Pochari Systems is designing, manufacturing and commercializing the world’s first highly compact ammonia cracker to produce hydrogen on demand from liquid ammonia for hydrogen internal combustion engine vehicles.
The cracker uses 4% wt Ruthenium and 20% wt Cesium promoted carbon nanotube supported catalysts in a microchannel configuration.
cracker specifications are based on Engelbrecht and Chiuta 2018,
Chiuta and Everson 2015 and 2016, Di Carlo and Vecchione 2014, and
Hill and Murciano 2014.
The activation energy is as low as 49 kJ/mol of NH3 with high cesium promoter loadings on CNT support, which translates into only 5 KW of heat energy per kg of H2 reformed per hour, allowing for over 100% of the required energy for decomposition being provided by exhaust heat from the engine.
The amount of ruthenium and cesium needed is very minimal, only 1 gram 5 grams respectively is required to reform 1 kg of hydrogen per hour at the desired efficiency and power density.
Cesium is critical in the cracking process as it allowes high conversion of ammonia at lower exhaust temperatures, minimzing unburned ammonia emissions.
Cesium reserves are estimated to be 84,000 tons, with Ruthenium reserves 11,300 tons, since 5x more cesium is used than Ruthenium, the reserves allow for the production of billions of medium-sized car crackers.
half of the cost of the cracker is found in manufacturing, with the
balance comprising raw materials.
Forming the microchannels from a solid metal block is performed by wire electrical discharge machining.
and packing of the catalyst inside these tiny grooves completes the
manufacturing process of a microreactor. Microreactor technology can
be thought of as relatively simple compared to battery manufacturing
as an example. The only complexities and difficulties arise from the
very small dimensions
These small dimensions found in microreactors (as little as 0.15 mm x 0.25 mm) requires elaborate and costly machinery to fabricate, but nonetheless, the cost of the cracker will be approximately $1000-2000 per kg-hour of capacity at high production volumes, of which 50% represents material costs at current raw material market prices.
The ammonia cracker is located on the exhaust manifold for hydrogen combustion engines, utilizing engine exhaust heat supplying 100% of cracker energy needs, with hydrogen combustion providing the balance.
The volume of the ammonia cracker for 12 kg/hr, sufficient for the average fuel flow used by a class-8 semi-truck fully loaded at highway speed, takes up only 6 liters, and weighs less than 10 kg!
The cracker is configured in a modular fashion. The modules consist of a housing, each consisting of a stack of microchannel plates. The module is placed directly outside of each exhaust outlet on the cylinder head, allowing the very hot exhaust gas to pass directly into the microchannels before cooling down. This allows heating the catalyst bed to provide the necessary activation energy. Each module is connect to four rails, supplying both gaseous ammonia to the cracker, and passing reform gas to the purifier. The two smaller rails provide air and hydrogen to provide heat during startup.
Reactor type: Micro-channel
Catalyst: 4% Wt Ru, 20% Wt Cs promoted on CNT
Total catalyst mass per kg hour H2 reformed: 25 grams
Ru Catalyst required per Kg hour H2 reformed: 1 grams
Ce Catalyst promoter per Kg hour H2 reformed: 5 grams
Gravimetric density: 0.50 kg/kg H2-hr
Volumetric density: 0.5 L/kg H2-hr
Energy consumption: 5.5-6 kw/kg H2-hr
Percent of reforming energy from exhaust heat: 100%
Additional hydrogen consumed for dissociation: 0% of fuel flow
Ammonia hydrogen density: 103 kg/m3
Ammonia consumption: 6 kg liquid NH3/kg H2-hr
Startup time: 10 minutes
Cost per kg hr capacity: $2000
Ruthenium price: $8000/kg
Cesium price: $30,000/kg
Carbon nanotube price per kg: $10,000