Exhaust manifold micro ammonia cracker for hydrogen engine

Last crawled date: 1 year, 11 months ago

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 engine powered cars, trucks and marine propulsion. The cracker uses 7% wt Ruthenium and 10% wt Cesium promoted CeO2 supported catalyst in a microchannel configuration. The 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 75 kJ/mol of NH3 with high cesium promoter loadings on ceric oxide support, which translates into only 7.2 KW/kg of H2 reformed per hour, allowing for 92% of the required energy for decomposition is provided by exhaust heat from the diesel engine.
The amount of ruthenium and cesium needed is very minimal, only 0.0017 kg and 0.005 kg respectively is required to reform 1 kg of hydrogen per hour at the desired efficiency and power density, translating into a cost of only $200 for the raw materials of the catalyst and promoter based on current market prices for a 2 kg/hr cracker, sufficient for a medium-sized vehicle. The cost of the cerium oxide support comprising 83% of the catalyst mass is negligible. Cesium reserves are estimated to be 84,000 tons, with Ruthenium reserves around 5000 tons, since 5x more cesium is used than Ruthenium, the reserves allow for the production of billions of medium-sized car crackers.

Most of the cost of the cracker is found in manufacturing, not raw materials.
Forming the tiny stainless steel microchannels from a solid block is performed by wire electrical discharge machining. Washcoating 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 $1000-1500 per kg-hour of capacity at high production volumes, of which 15-20% represents material costs.
The ammonia cracker is located on the exhaust manifold for closed-cycle hydrogen diesel engines, utilizing engine exhaust heat supplying 92% of cracker energy needs, with oxy-hydrogen combustion providing the balance.
The volume of the ammonia cracker for 20 kg/hr, enough for a large class-8 semi-truck at full power, takes up only 20 liters, and weighs less than 10 kg!
The cracker is configured in a modular fashion. The modules consist of a housing, each consisting of multiple microchannels inside. 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 oxygen and hydrogen to provide heat during startup.

Reactor type: Micro-channel stainless steel
Catalyst: 7% wt Ru 10% wt Cs promoted on CeO2
Ru Catalyst required per Kg hour H2 reformed: 0.001 kg
Ce Catalyst promoter per Kg hour H2 reformed: 0.005 kg
Gravimetric density: 0.50 kg/kg H2-hr
Volumetric density: 1 L/kg H2-hr
Energy consumption: 6 kw/kg H2-hr
Percent of reforming energy from exhaust heat: 92%
Conversion rate: 99.8%
Operating temperature: 500 °C
Additional hydrogen consumed for dissociation: 0%, only during startup.
Ammonia equivalent hydrogen density: 113 kg/m3
Ammonia consumption: 6 kg liquid NH3/kg H2-hr
Startup time: 10 minutes
Cracker cost: $1000/kg-hr capacity
Ruthenium cost: $8000/kg
Cesium cost: $30,000/kg