Tungsten Hydride Alumina Catalyst Olefin Metathesis

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Solution Overview

Problem

Current propylene production methods, such as steam cracking and paraffin dehydrogenation, fail to meet the growing demand for propylene due to inefficiencies and high capital costs, leading to a supply-demand imbalance and economic challenges in the petrochemical industry.

Innovation Solution

The use of a tungsten hydride catalyst bonded to alumina in olefin metathesis processes, where the molar ratio of olefin reactants is shifted to a stoichiometric deficit of ethylene relative to butylene, enhances conversion and selectivity of propylene production without compromising catalyst stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional steam cracking or paraffin dehydrogenation is used for propylene production, then propylene can be produced, but the process fails to meet growing demand due to inefficiencies and high capital costs

Engineering Contradiction:

Improvepropylene production capacityVSAvoidcapital cost and process efficiency

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent changes the reactant ratio parameter from conventional stoichiometric or ethylene-excess conditions to a butylene-excess condition (ethylene:butylene molar ratio of 0.5:1 to 1:2). This parameter change enables the tungsten hydride catalyst to achieve high propylene selectivity and conversion, improving productivity while avoiding the high capital costs of conventional processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite catalyst system consisting of tungsten hydride species supported on alumina. This composite material combines the catalytic activity of tungsten hydride with the structural stability and surface area of alumina, enabling efficient propylene production from ethylene and butylene metathesis with lower capital investment compared to conventional steam cracking or dehydrogenation units.

Inventive Principle:

Principle #40Composite materials

2Productivity

If olefin metathesis is carried out at stoichiometric ratio or with ethylene excess, then conventional catalytic systems operate, but conversion and selectivity are compromised

Engineering Contradiction:

Improvepropylene conversion and selectivityVSAvoidcatalyst performance consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent inverts the conventional approach by using a butylene-excess feed composition instead of ethylene-excess or stoichiometric ratios. This inversion, combined with the tungsten hydride/alumina catalyst, achieves superior conversion and selectivity for propylene production, resolving the performance limitations of conventional metathesis conditions.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces conventional metathesis catalyst systems (which require specific stoichiometric conditions for optimal performance) with a tungsten hydride/alumina catalyst system that is insensitive to feed composition variations. This substitution provides more reliable and consistent catalyst performance across different operating conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If metathesis reaction proceeds to high conversion, then propylene yield increases, but catalyst stability may be compromised

Engineering Contradiction:

Improvepropylene yieldVSAvoidcatalyst stability and lifetime

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The alumina support in the composite catalyst system provides structural stability and thermal resistance, allowing the tungsten hydride species to maintain high catalytic activity and selectivity even at high conversion levels. The composite structure protects the active tungsten sites from deactivation, extending catalyst lifetime while achieving high propylene yields.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent operates the metathesis reaction at optimized temperature and pressure parameters that balance conversion rate with catalyst stability. By controlling reaction conditions within specific ranges and using the butylene-excess feed composition, the system achieves high propylene yield while maintaining catalyst stability and extending catalyst operational life.

Inventive Principle:

Principle #35Parameter changes

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 increases propylene yield and catalyst stability, reducing energy requirements and downstream separation complexities, resulting in significant economic benefits and prolonged catalyst life.

Implementation Method 1

A representative catalyst comprises a tungsten hydride bonded to alumina that is present in the support

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8389788B2Olefin metathesis reactant ratios used with tungsten hydride catalysts

Publication Date: 2013.03.05 UOP LLC

AI summary

Processes for olefin metathesis, for example for the production of propylene, utilize a catalyst comprising a solid support and a tungsten hydride bonded to alumina present in the support. Conversion, selectivity, and/or catalyst stability advantages may be realized when a first olefin reactant (e.g., ethylene) is present in the hydrocarbon feedstock at a stoichiometric deficit relative to a second, higher carbon number olefin reactant (e.g., butylene).