Ammonia-Assisted Nitro Compound Hydrogenation for Catalyst Selectivity

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Solution Overview

Problem

Existing hydrogenation processes for converting nitro compounds to amines face challenges such as high reaction temperatures leading to undesirable side reactions, catalyst deactivation due to local overheating and formation of high-boiling components, and reduced product yield during interruptions or catalyst aging.

Innovation Solution

The process involves adding ammonia to the reaction space during hydrogenation using a supported catalyst containing elements from groups 7 to 12 of the Periodic Table, with specific amounts of ammonia and catalyst compositions to maintain catalyst activity and reduce high-boiling component formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high reaction temperatures are used to maintain catalyst activity and reaction rate, then productivity is improved, but undesirable side reactions increase and catalyst aging accelerates

Engineering Contradiction:

Improvereaction rateVSAvoidside reactions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Ammonia is introduced as an intermediary substance that mediates between the nitro compound and the catalyst. It forms a complex with the nitro compound, facilitating hydrogenation at lower temperatures and reducing the formation of high-boiling side products while maintaining catalyst activity and productivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If extended reaction runtime is used to achieve complete conversion, then product yield increases, but catalyst aging accelerates and selectivity decreases

Engineering Contradiction:

Improveconversion completenessVSAvoidcatalyst activity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Ammonia is added preliminarily to the reaction system before the hydrogenation proceeds to completion. This preliminary action modifies the reaction pathway, allowing complete conversion to be achieved faster while preventing catalyst aging and maintaining high selectivity throughout the reaction runtime.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If mass recirculation is used to achieve complete conversion in loop reactor, then productivity is improved, but high-boiling components accumulate and deactivate catalyst

Engineering Contradiction:

Improveconversion efficiencyVSAvoidhigh-boiling components

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The ammonia converts the potentially harmful formation of high-boiling condensation products into a beneficial pathway by forming ammonium salts instead, which remain in the liquid phase and do not deactivate the catalyst, while still achieving complete conversion through recirculation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Adaptability or versatility

If feedstock supply is interrupted during shutdown, then operational flexibility is improved, but catalyst deactivation occurs due to formation of high-boiling components

Engineering Contradiction:

Improveshutdown capabilityVSAvoidcatalyst activity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Ammonia acts as a cushioning agent during feedstock interruptions. It prevents the formation of high-boiling deactivating components during shutdown periods, protecting the catalyst activity and allowing flexible operational interruptions without permanent catalyst damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances catalyst longevity, increases product yield, and quickly recovers yield after interruptions by minimizing high-boiling component formation and maintaining selectivity.

Implementation Method 1

continuous hydrogenation of a nitro compound to the corresponding amine in a liquid reaction mixture containing the nitro compound in a reaction space in the presence of a supported catalyst which contains as active component at least one element from groups 7 to 12 of the Periodic Table of the Elements

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

continuous hydrogenation of a nitro compound to the corresponding amine

Methodology Applied

Scientific EffectHydrogenation: Hydrogenation

Data Source

PatentEP3697753B1Increase of the catalyst selectivity in the continuous hydrogenation of nitro compounds by addition of ammonia

Publication Date: 2025.10.01 BASF SE

AI summary

The present invention relates to a method for the continuous hydrogenation of a nitro compound to form the corresponding amine in a liquid reaction mixture containing the nitro compound, in a reaction chamber, in the presence of a supported catalyst which contains as the active component at least one element from groups 7 to 12 of the periodic table of the elements, characterised in that ammonia is added to the reaction chamber during hydrogenation.