Volume 229, 2021

The effect of H2 : N2 ratio on the NH3 synthesis rate and on process economics over the Co3Mo3N catalyst

Abstract

In this study, the process economics of ammonia synthesis over Co3Mo3N was investigated by searching for an optimum feed stoichiometry. From ammonia synthesis rate measurements at atmospheric pressure and 400 °C over Co3Mo3N, it was found that the rate was independent of H2 : N2 stoichiometry for stoichiometries above 0.5 : 1. For H2 : N2 stoichiometries below 0.5 : 1, there was a linear dependency of ammonia synthesis rate on the H2 : N2 stoichiometry. Static measurements of hydrogen adsorption isotherms at 25, 50, and 100 °C revealed that the adsorbed amounts of strongly bound hydrogen over the Co3Mo3N surface were saturated at around 100 Torr hydrogen pressure. This pressure corresponds to the partial pressure of hydrogen when the H2 : N2 stoichiometry is around 0.5 : 1, confirming the role of strongly bound hydrogen in ammonia synthesis. These results were used to modify an existing kinetic expression to be used in a conceptual design, based on a late mixing strategy for the hydrogen stream. This conceptual design and its economic analysis revealed that using low hydrogen stoichiometries can cut the investment and operating costs by a factor of 2.

Graphical abstract: The effect of H2 : N2 ratio on the NH3 synthesis rate and on process economics over the Co3Mo3N catalyst

Associated articles

Article information

Article type
Paper
Submitted
11 des 2019
Accepted
31 jan 2020
First published
06 feb 2020

Faraday Discuss., 2021,229, 475-488

The effect of H2 : N2 ratio on the NH3 synthesis rate and on process economics over the Co3Mo3N catalyst

M. Y. Aslan, J. S. J. Hargreaves and D. Uner, Faraday Discuss., 2021, 229, 475 DOI: 10.1039/C9FD00136K

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements