MASSIMO BARBIERI
Politecnico di Milano – Technology Transfer Office, Milano, Italy

Abstract

This paper presents a method for extracting and analyzing patent data specific to the industrial synthesis of ammonia.
The research was performed using Espacenet and Orbit Intelligence applying a combination of keywords and classification symbols.
The main classification codes used are as follows C01C 1/02 (Preparation of ammonia), C01C 1/04 (Preparation of ammonia by gas phase synthesis), C01C 1/0405 (Preparation of ammonia by gas phase synthesis from nitrogen and hydrogen in the presence of a catalyst), and C25B 1/27 (Electrolytic production of ammonia).
Thermocatalytic methods, specifically the Haber-Bosch process, are the most frequently claimed.

Introduction
Ammonia is a crucial synthetic product and ranks as the second-largest chemical compound manufactured globally, with an annual production of 150/160 million tonnes.
Around 80% of ammonia is used in the fertilizer industry to synthesize nitrogen compounds, like urea. Ammonia is converted into nitric acid which, upon being mixed with ammonia, results in ammonium nitrate. (1)
With a hydrogen content of 17.6% by weight and no carbon, ammonia has been recognised as a promising medium for energy storage.
Ammonia is commonly produced via the Haber-Bosch process, reliant on iron-based catalysts, where hydrogen and nitrogen (in a 3:1 ratio) react in the gas phase under elevated temperatures (300-500 °C) and pressures (100-250 bar).
The reaction to consider is the following:

3 H2 + N2 ↔ 2 NH3

Hydrogen is generated in methane steam-reforming plants, whilst nitrogen is obtained from secondary reforming units.
Despite being an exothermic reaction (∆H ° = -91.8 kJ/mol), the dissociation of the triple bond in nitrogen requires high energy (941 kJ / mol).
From a ...