Performing Department
(N/A)
Non Technical Summary
Statement of the problem or opportunity:The conventional approach to industrially producing nitrogenous fertilizers helps feed about half of the world's population but is energy inefficient and requires extensive infrastructure. Together, the conventional Haber and Ostwald use about 1 - 2 % of the world's produced energy and produce almost 3 % of anthropogenic carbon dioxide emissions. A relatively simple, efficient, and inexpensive method is needed that can improve the productivity and profitability of farming for all of the world's population while lowering climatic impact. Recent advances in Luna's dual phase membrane technology have developed into an opportunity to directly oxidize nitrogen gas, N2, to nitrates for fertilizers. A catalytic membrane reactor has been designed for producing nitrates with potentially ten times less energy than the conventional processes, is independent of natural gas or other fossil fuel resources, and is amendable to rapid start up and shut down. This means that fertilizer can be locally produced on demand even with intermittent renewable energy sources, such as wind and solar.?Project objectives and description of the efforts:Luna will demonstrate the direct oxidation of nitrogen from air to nitrates with a catalytic membrane reactor. The first objective is to formulate the molten phase chemistry of the dual phase membranes. While all of the relevant chemical processes have been described in the literature, Luna will formulate a molten system that combines all of these processes in the most efficient conditions. The second objective is to fabricate and demonstrate the complete membrane system. The Phase I program will culminate in the design of the scaled up membrane module that will be built in Phase II program. A team will be develop that includes Trimeric Corporation for process engineering and techno-economic analysis, Nooter/Eriksen for integration with power generation infrastructure for pilot scale demonstration in Phase III, and an industrial partner who can process the nitrates into a fully formulated fertilizer product.Anticipated results and potential commercial applications:The catalytic membrane reactor for local, on-demand nitrate production for fertilizers is expected to improve energy efficiency, lower the costs of farming, and foster global food security. Because the Haber process is largely dependent upon fossil fuels as a source of hydrogen, the proposed technology will promote the use of renewable energy by relieving the dependence of fertilizer production on fossil fuels. The reductions in infrastructure requirements can also enable fertilizer production by communities and regions that presently lack this capability.
Animal Health Component
50%
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Goals / Objectives
The proposed research will improve plant production by significantly decreasing the energy and infrastructure cost of producing nitrates for fertilizer. Only about half of the world's population presently benefits from industrially produced nitrogenous fertilizers. Nitrates for fertilizer are conventionally produced by first reducing nitrogen gas, N2, to ammonia through the Haber process and then oxidizing ammonia to nitric acid through the Ostwald process. In practice, the Haber process uses over two times more energy than the ideal minimum and only about 25 % of the energy released in the Ostwald process is usable. The efficiency losses of these two large energy conversions mean the Haber and Ostwald processes together waste over 1,000 kJ/mol HNO3. Worldwide nitrate production by the Haber and Ostwald processes consumes 1 - 2 % of global energy generation and produces about 3 % of the world's anthropogenic CO2 emissions. In contrast, directly oxidizing N2 to nitrates is a small change in energy and an efficiency of only 40 % would waste less than 100 kJ/mol HNO3. Luna is proposing the LuNOX process for direct N2 oxidation that will use 10 times less energy than the conventional processes by avoiding the ammonia intermediate state. In the LuNOX process, a catalytic membrane reactor converts compressed air and steam to concentrated nitric acid using energy generated from renewable or fossil fuel sources. Lower infrastructure costs are also expected primarily because the LuNOX process uses lower temperatures and/or pressures than the Haber and Ostwald processes. Producing nitrates with less energy and fewer infrastructure requirements will lower the overall fertilizer costs, improve crop production and profitability, and increase access to industrial fertilizers to an even greater percentage of the world's population. The Functional Objectives of the overall program are:Functional Objective 1: Decrease the amount of energy required to fix N2 as nitrates. In contrast to the Haber and Ostwald processes, the LuNOX process can potentially use as little as one-tenth the energy in scalable, distributed systems. This increased energy efficiency can be achieved by directly oxidizing N2 to nitrate in comparatively mild operational conditions.Functional Objective 2: Eliminate the dependence of N2 fixation on natural gas or other fossil fuels. The LuNOX process is designed to consume compressed air and steam. Unlike the conventional processes, this means the LuNOX process can be powered by renewable energy sources, such as wind and solar.Functional Objective 3: Enable local fertilizer production on demand with minimal infrastructure. Using a single process (LuNOX) that uses relatively mild temperatures and pressures instead of the conventionally combined, intensive processes (Haber and Ostwald) will decrease infrastructure costs. The LuNOX process will also enable faster startup and shutdown times for better compatibility with renewable energy sourcesThe overall Phase I program technical objective is to demonstrate the direct oxidation of N2 to nitric acid with a catalytic dual phase membrane. The specific Phase I technical objectives are:Technical Objective 1: Develop the molten phase chemistry. The molten phase hydroxide/nitrate/transition metal catalyst chemistry will be developed to achieve high performance conversion of N2 to nitric acid under efficient operational conditions. Development will primarily rely on testing the rate and extent of 1) molten hydroxide conversion to nitrate through oxidation of N2 with O2 as well as 2) the conversion of molten nitrate back to hydroxide and the release of HNO3 upon exposure to steam.Technical Objective 2: Demonstrate and evaluate the catalytic membrane reactor. A catalytic membrane reactor for direct N2 oxidation will be developed and demonstrated with a tubular membrane format. The demonstration will include a parametric evaluation of operational parameters and conditions.
Project Methods
The following section outlines the work plan and performance schedule. The plan is structured to demonstrate technical feasibility and commercial viability of the technology for efficient direct oxidation of N2 to nitrates. The high-level schedule covers the eight month Phase I period broken down by task.Task 1: Define system requirements and specificationsLuna will define the requirements and specifications for handling, developing, and operating the membrane materials and reactor systems. The team of chemists, engineers, and Environmental Safety & Hazards personnel will review the membrane test setups prior to assembly and operation to ensure control, performance, and safety. Personnel will be trained for operating the membrane test setup in accordance with a detailed Standard Operating Procedure. A kick-off meeting will be held with the National Program Leader to establish communication and to learn how to best satisfy the interests of the USDA. An emission control plan will be developed to meet the standards in place for the conventional Ostwald process. A study of fertilizer producer needs will be performed to better understand how to prepare and store the nitric acid product for incorporation into commercial fertilizer formulations.Task 2: Develop molten phase chemistry and establish operational conditionsThe molten phase chemistry will be formulated with a batch-mode test setup. The conversion chemistry is based upon the molten phase hydroxide-nitrate equilibrium. The oxidation of N2 with O2 converts molten hydroxide to nitrate upon exposure to compressed air. The release of nitric acid converts the molten nitrate back to hydroxide upon exposure to steam. A batch-mode test individually studies either the forward or reverse reactions of the hydroxide-nitrate with small molten samples (e.g. 2 - 3 g) without the solid ceramic phase to better understand the effects of molten phase composition and operational conditions on performance. During this initial stage of development, batch-mode testing is advantageous because it is faster, less expensive, and more informative than testing the molten phase in a complete membrane system. This testing accelerates technical development by developing a more thorough and validated understanding of molten phase chemical effects and relevant operational conditions.The batch-mode testing will validate and refine the effects of formulation or conditions that have been already been developed based upon thermodynamic calculations, Lewis acid/base effects, literature review, and experience. This includes the effects of both the molten formula (i.e. LiOH/LiNO3 vs KOH/KNO3) and operational conditions (i.e. temperature and pressures) on the rate and extent of chemical conversion. The chemical potentials of the iron redox transitions are a good match for catalyzing N2 oxidation. Interestingly, FeO2- dissolved in the eutectic mixture molten KOH and LiOH that has been activated with a small fraction of Ca(OH)2 is notably similar to the K2O/CaO-supported Fe3O4 catalyst materials commonly used in the Haber process. Operation of the catalytic membrane reactor at lower temperatures and pressures will result in lower energy and infrastructure costs. The molten phase formulation will therefore be developed to achieve the better performance at lower operational temperature and pressures. The molten phase will be ready for application and testing in the membrane format after development of the formulation and refined expectations regarding the ideal range of operating conditions. Altogether, Luna has expertise for efficiently and effectively formulating and refining the molten phase system.The batch-mode setup tests the molten phase chemistry within a Parr Instruments pressure vessel. The Parr vessel has a 100 ml volume and is rated for pressures up to 3,000 PSI. The molten phase is exposed to a flow of either compressed air or steam. The test setup will be upgraded with a benchtop steam generator for steam at 100 PSI. The rate and extent of the molten phase reactions are determined by monitoring the composition of the gases (i.e. H2O, O2, NO, NO2) exiting the Parr vessel. The reaction progress will be determined by measuring the HNO3 that condenses upon cooling the exiting gas in a distillation column.Task 3: Demonstrate and validate the catalytic membrane reactorThe catalytic membrane reactor will be demonstrated and validated with a complete tube membrane. The membrane is the wall of the tube. At this stage of development, Luna uses a standard sized tubular membrane that is 10 cm long, a 6.4 mm (1/4") outer diameter, and a 4.8 mm (3/16") inner diameter. This standard sized tube membrane is inserted into test membrane holder and operated in a tube furnace for temperature control. The tube membrane holder is presently being assembled, validated, and used for CO2 separation membranes. The tube membrane is fabricated by infiltrating the molten phase into the porous walls of yttria-stabilized zirconium oxide (YZO) tube. The nanoporous YZO tube materials are high strength ceramics produced by CoorsTek Ceramics. The combination of wall thickness and mechanical strength of the nanoporous material can withstand pressure gradients over 20 atm. If the Phase I results indicate that significant changes in YZO tube dimensions are warranted for this application, Luna will develop a custom tube design for CoorsTek Ceramics to produce in Phase II or III. In Phase II, multiple tube membranes will be packed together into a shell to produce and test scaled up membrane modules.The batch-mode setup will be transitioned into the membrane test setup by exchanging the Parr vessel and heater with for the membrane holder and tube furnace. The tube membrane holder is a steel tube that holds and seals the tube membrane so that the gas on the outside of the tube membrane is isolated from the gas on the inside of the tube membrane. The compressed air feed flows over the outside of the tube membrane, supplies the N2 and O2 reactant gases, and exits the setup as the retentate. The steam sweeps the inside of the tube and removes the permeated HNO3 product. The tube membrane test holder is placed inside a wide bore (6"), split tube furnace for temperature control. The membrane test setup will use the same compressed air, steam generator, HNO3 distillation column, product measurement sensor systems that were previously used on the batch-mode setup.Task 4: Develop Phase II and commercialization plansThe Phase II plan will be further detailed and developed to prepare the direct N2 oxidation technology for Phase III and commercialization. The plan will be updated regularly based upon the requirements and specifications developed in Task 1 as well as the performance and operational parameters developed in Tasks 2 and 3. The catalytic membrane reactor will progress to technological readiness level (TRL) 6 by the end of Phase II. A prototype membrane module will be tested in a simulated operational environment with supporting subsystems. These subsystems will include air compression, steam generation, HNO3 condensation, and sensorization for process monitoring and control. The Phase II program will also include partnership with Trimeric Corporation to provide process engineering consultation and a techno-economic analysis. The combination of successful prototype module demonstration and system level analysis of projected operating and infrastructure costs will well-position the technology for Phase III. In Phase III, the direct N2 oxidation technology will evolve to the pilot scale and then commercialized with public and/or private funding sources. Luna will use Foresight Science and Technology for commercialization assistance consultation to prepare the Phase III program. Foresight will assist with developing a fertilizer production partner for the Phase II program.