Tandem Catalyst for Alkane Dehydrogenation Selectivity

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Solution Overview

Problem

The catalytic dehydrogenation of alkanes, such as propane to propylene, faces challenges due to thermodynamic limitations and low selectivity of existing oxidative dehydrogenation (ODHP) catalysts, which result in low per-pass yields of propylene.

Innovation Solution

The development of tandem catalysts comprising a support with catalytically active particles for dehydrogenation and a catalytic porous overcoat for selective hydrogen combustion, which spatially organizes the catalysts at the nanoscale to enhance selectivity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If oxidative dehydrogenation catalysts are used to overcome thermodynamic limitations, then propane conversion is improved, but propylene selectivity deteriorates due to over-oxidation

Engineering Contradiction:

Improvepropane conversionVSAvoidpropylene selectivity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The catalyst is segmented into two distinct functional components: a dehydrogenation catalyst (Pt/Al2O3) and a selective hydrogen combustion catalyst (In2O3). This segmentation allows each component to perform its specific function independently, with the dehydrogenation catalyst converting propane to propylene and the combustion catalyst selectively removing hydrogen, thereby preventing over-oxidation of propylene while maintaining high conversion

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a nested structure where the In2O3 combustion catalyst is deposited as an overcoat on the Pt/Al2O3 dehydrogenation catalyst particles. This nested configuration allows the combustion function to be integrated with the dehydrogenation function, enabling selective hydrogen combustion to occur in proximity to the dehydrogenation sites without direct contact between oxygen and the propylene product, thus resolving the selectivity-conversion trade-off

Inventive Principle:

Principle #7Nested doll (Nesting)

2Productivity

If high temperatures are applied to overcome equilibrium limitations, then dehydrogenation rate is improved, but energy consumption and thermodynamic constraints worsen

Engineering Contradiction:

Improvedehydrogenation rateVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful effect of thermodynamic equilibrium limitations into a benefit by introducing a coupled hydrogen combustion reaction. The endothermic dehydrogenation reaction is thermally coupled with the exothermic hydrogen combustion reaction, allowing the heat generated by combustion to drive dehydrogenation forward, thereby overcoming equilibrium constraints without requiring external high-temperature input

Inventive Principle:

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

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

The tandem catalyst design achieves high per-pass product yields, with up to 76% selectivity at 40% conversion for propylene, significantly exceeding the yields of state-of-the-art ODHP catalysts.

Implementation Method 1

catalyst particles comprising a material that is catalytically active for dehydrogenation of the alkane or an alcohol

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

a catalytic porous overcoat on the catalyst particles, the porous overcoat comprising a material that is catalytically active for selective hydrogen combustion

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

the porous overcoat comprising a material that is catalytically active for selective hydrogen combustion

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS12311343B2Tandem catalysis for alkane and alcohol dehydrogenation coupled to selective hydrogen combustion

Publication Date: 2025.05.27 NORTHWESTERN UNIV

AI summary

Tandem catalysts for the dehydrogenation of alkanes and/or alcohols in tandem with selective hydrogen combustion are provided. Also provided are methods of making the catalysts and methods of using the catalysis for the dehydrogenation of alkanes and/or alcohols. The catalysts include a support having a surface, dehydrogenation catalysts particles dispersed on the surface of the support, and a porous selective hydrogen combustion catalyst overcoat on the dehydration catalyst particles. The catalysts couple dehydrogenation with selective hydrogen combustion in a sequence of reactions occurring in tandem to shift the equilibrium of the dehydrogenation towards higher conversion.