Dynamic Catalytic Reactors (DCR). The project will be focussed at developing electrically driven ammonia cracking for production of hydrogen in decentralise locations. White paper: Faria_DCR_20230209
Abstract
Ammonia (NH3) is a key chemical vector to reducing the costs of storing and transporting hydrogen. Ammonia (NH3) is considered as the only carbon-free hydrogen storage material that can overarch water, energy, and food value-chains, while allowing long and short-term energy storage at lower costs than that of pure hydrogen. While ammonia Haber-Bosch synthesis is currently operated in large scale (160 million tons per year globally), the conversion of ammonia back to nitrogen and hydrogen is only conducted at small scales using energy inefficient methods. Unfortunately, recovering molecular hydrogen (H2) from NH3 cracking is energy-demanding due to theendothermicity of the reaction and poor activity of conventional catalysts below 700 #C. In fact, the specific energy consumption of the conventional NH3 cracking technology is c.a. 10.1 kWh/KgH2, even at large scales (1000 kgH2/day), limiting widespread application of this process. A crucial component of an NH3 cracking technology is the catalyst promoting the endothermic process. Conventional catalysts are based on metal nanoparticles (e.g. Nickel) with a wide range of sizes and shapes commonly decorating metal oxide supports (e.g. g-Al2O3); however, these materials conform to a theoretical activity limit, i.e., the Sabatier limit that essentially forces the utilization of high temperatures to ensure that all the N-and H- surface intermediates couple to form nitrogen and hydrogen. Clearly, new technologies for efficient ammonia cracking are required.To break this fundamental limitation the DCR project aims at leveraging dynamic operation of the catalytic reactor, by switching the temperature of the reactor from low to high values at fastrates, which can enhance the reaction rate thanks to the activation of the N-N bond formation reaction at high temperatures and theN-H bond dissociation at low temperature. This project will enable (1) operation of the ammonia cracking reactor in an intermittentmanner, which is highly desirable when the system is deployed in remote locations for quick-response to energy demands, and (2) it will improve energy efficiency as the endothermicity of the reaction can be covered by the utilization of electrical heating insteadof convective heating using fuel-powered ovens. The utilization of electrical heating is a major assent when operating in islanded regions as the system could potentially be coupled to a renewable energy resource (e.g. PV or Wind). The utilization of electrical heating will also reduce the footprint of the reactor, which will enable portability and transportability. This is particularly interesting for the US Navy during operation in islanded regions. In the DCR project we will develop a new system capable of cracking ammonia at high rates in a continuous flow reactor using electrical heating. Detailed reaction kinetics and mechanistic studies will enable the development of accurate models that can be applied to estimate the reactor size and thepotential techno-economic feasibility of the process for decentralize production of hydrogen from ammonia. In close collaboration with the group of Dr. Heather Willauerof ONR Code 33 the team at the University of Twente will stablish the foundational research on the utilization of electrically heated reactors for the ammonia cracking. This knowledge will help the US Navy in identifying the potential of this technology for portable hydrogen production units and the future challenges that must be address before field deployment.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 29, 2023
- Source ID
- N629092312047
Entities
People
- Jimmy Faria
Organizations
- Office of Naval Research
- United States Navy
- University of Twente