(286e) Techno-Economical Analysis of Solar Thermochemical Ammonia Production At near Atmospheric Pressure | AIChE

(286e) Techno-Economical Analysis of Solar Thermochemical Ammonia Production At near Atmospheric Pressure


Michalsky, R. - Presenter, Kansas State University
Pfromm, P. - Presenter, Kansas State University
Parman, B. - Presenter, Kansas State University
Amanor-Boadu, V. - Presenter, Kansas State University

Techno-economical analysis of solar thermochemical
ammonia production at near atmospheric pressure

Michalsky 1, Peter H. Pfromm 1, Bryon Parman
, Vincent Amanor-Boadu 2

1 Department of Chemical Engineering, 2
Department of Agricultural Economics,

State University, Manhattan, Kansas, USA


Ammonia is the
basis for modern agriculture and ensures the food supply for a growing world
population. It is used widely as base chemical for the chemical industry. Over
100 million metric tons NH3 are produced world wide per year. NH3
has been proposed recently as sustainable transportation fuel and may enable
efficient H2 storage.

At industrial
scale the Haber-Bosch process synthesizes NH3 catalytically at high pressure and elevated temperature with natural
gas and nitrogen as main inputs. Globally this process consumes up to 5%
of all natural gas produced and 2% of the total world energy production, with
significant fossil-based CO2 emissions. Aiming at reactive NH3
synthesis without natural gas from air and steam at ambient pressure, this work
studies a solar thermochemical cycle employing a molybdenum-based reactant.

Based on Gibbs
free energy computations, a process sequence of Mo2N formation from
its elements, nitride hydrolysis forming NH3 and MoO2 at
ambient pressure, and metal oxide reduction using solar heat and H2
as chemical reducing agent below 1200 °C, is proposed. Experimental data on a
Mo-based transition element reactant utilized for the fixation of N2
and formation of NH3 from the solid nitride hydrolyzed with steam
will point out process limiting steps such as diffusion in the solid state and
ionicity of an interstitial nitride reactant. To assess sustainability and
economic competitiveness compared to the state of the art Haber-Bosch
process, the mass and energy balance for Mo-based solar thermochemical NH3
synthesis including on-site production of H2 used as reducing agent
will be presented along with an economic analysis determining the price of NH3
required for breaking even with plant investment and operational costs.