| Summary: |
Fritz Haber's work on the fixation of nitrogen from the air, for which he was given the Nobel Prize in Chemistry (awarded in 1919), is one of the most important contributions to the development of the world as we know it. Annually, c.a. 200 million tons of ammonia are produced industrially by the Haber-Bosch process, using N2 (from air) and H2 (from natural gas). Most of this ammonia is for the production of fertilisers, which sets one of the bases of modern society upon which relies the capacity to feed a population of 7 000 Million. Yet, the traditional production route depends on methane, being highly intensive in the use of energy and emitting large quantities of CO2.
Heterogeneous photocatalysis is proposed as a sustainable alternative technology for producing ammonia by renewable sources, including nitrogen from air,
water, metal-free catalysts and ideally sunlight for reaction activation. Portugal is one of the European countries with higher insolation levels. The opportunity
for the potentiation of photo-assisted technologies, can constitute a strategic line for the development and differentiation of the country as regards environmental-friendly industrial solutions and energy self-reliance.
Graphite-like carbon nitride (g-C3N4), recently attracted much attention because of its similarity to graphene and its properties as an optical semiconductor.
Compared to TiO2, g-C3N4 presents a smaller bandgap of 2.7 eV, corresponding to an absorption up to 450 nm, which represents a great advantage for solardriven
processes. Modifications on carbon nitride will be carried out for introducing reducing sites for N2 conversion to NH3, including exfoliation, thermal post treatment at controled atmosphere and hard-templating.
The photoreactor configuration is a key feature for the industrial feasibility of the new method for NH3 production. The present project targets the development
of novel multifunctional photoreactor configurations for NH3 production de  |
Summary
Fritz Haber's work on the fixation of nitrogen from the air, for which he was given the Nobel Prize in Chemistry (awarded in 1919), is one of the most important contributions to the development of the world as we know it. Annually, c.a. 200 million tons of ammonia are produced industrially by the Haber-Bosch process, using N2 (from air) and H2 (from natural gas). Most of this ammonia is for the production of fertilisers, which sets one of the bases of modern society upon which relies the capacity to feed a population of 7 000 Million. Yet, the traditional production route depends on methane, being highly intensive in the use of energy and emitting large quantities of CO2.
Heterogeneous photocatalysis is proposed as a sustainable alternative technology for producing ammonia by renewable sources, including nitrogen from air,
water, metal-free catalysts and ideally sunlight for reaction activation. Portugal is one of the European countries with higher insolation levels. The opportunity
for the potentiation of photo-assisted technologies, can constitute a strategic line for the development and differentiation of the country as regards environmental-friendly industrial solutions and energy self-reliance.
Graphite-like carbon nitride (g-C3N4), recently attracted much attention because of its similarity to graphene and its properties as an optical semiconductor.
Compared to TiO2, g-C3N4 presents a smaller bandgap of 2.7 eV, corresponding to an absorption up to 450 nm, which represents a great advantage for solardriven
processes. Modifications on carbon nitride will be carried out for introducing reducing sites for N2 conversion to NH3, including exfoliation, thermal post treatment at controled atmosphere and hard-templating.
The photoreactor configuration is a key feature for the industrial feasibility of the new method for NH3 production. The present project targets the development
of novel multifunctional photoreactor configurations for NH3 production designed with advanced multiphysics tools that combine Computational Fluid
Dynamics (CFD) and simulation of radiation. A unitary element of the reactor, will be simulated using CFD tools in order to optimize the photocatalytic performance of the system and geometric parameters. The unitary element will be repeated in a network to generate a strucutred reactor. Simulations of
hydrodynamics, mass transfer, chemical reaction and radiation will be performed to obtain the best structure configuration.
The structured multifunctional photoreactors designed with CFD will be developed following two strategies: the 3DImmobCat in which carbon nitride materials are deposited as films over 3D micro/meso-structured surfaces; and the 3DStructCat where the catalyst is blended in the resins for the reactor manufacturing as 3D structured scaffolds. Both solutions, 3DImmobCat and 3DStructCat, will be tested using additive manufacturing fabrication technology. Optimized 3DImmobCat structures will be fabricated with a 3D stereolithography (SLA) printer, and coated with carbon nitride photocatalysts. 3DStructCat scaffolds will be produced using carbon nitride photocatalysts as inks in a Direct Ink Writing (DIW) extruder. The NH3 production in the structured photocatalytic reactors will be then tested and optimized in order to assess the maximum conversion and selectivity. The experimental data will enable the validation of the CFD simulations.
Lastly, the industrial process for NH3 production using SuN2Fuel technology will be integrated using process simulators. At the end of the project, an estimate of
the implementation costs of this technology in the industry will be presented. Particular attention will be paid to investment costs for the reactors
manufacturing, considering AM, reactive polymerisation techniques (RIM and RTM) or thermoplastic injection. The usage of sunlight for massive production of
NH3 for fuel is going to be analysed by Plafatorma Solar de Almeria and consulting company Carbon-Neutral Consulting. The SuN2Fuel assesses experimentally the utilization of the NH3 stream in fuel-cells, and uses these results in the integrated process simulation. The existing ammonia stripping technologies to obtain the NH3 stream are also considered in the process simulators.
This is a multidisciplinary project, which benefits from the synergies generated from a team with relevant academic and industrial experience on materials
science, photocatalysis, fuel cells, solar technologies, and process simulation and engineering. The ultimate goal is the development of two prototypes with
different configurations, the 3DImmobCat and the 3DStructCat, that can be easily implemented as industrial reactors for ammonia production using sustainable
resources (water and air), cost-effective catalysts (carbon nitride-based materials) and energy-efficiency light sources (LEDs or sunlight). |