Fe2(BDP)3 Metal-Organic Framework Alkane Isomer Separation

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Solution Overview

Problem

Current separation methods for alkane isomers, such as zeolites and activated carbons, are energy-intensive and inefficient, particularly for separating chemically similar molecules like C5-C7 alkanes, which are crucial for producing high-octane gasoline, as they rely on cryogenic or distillation steps and molecular sieving, making it challenging to selectively isolate valuable di-branched isomers while recycling less valuable mono-branched and linear isomers.

Innovation Solution

A metal-organic framework with the formula Fe2(BDP)3 is used, featuring sharply-angled pore walls that allow for shape-based separation of alkane isomers according to their degree of branching, enabling efficient separation of C5-C7 alkanes at industrially relevant temperatures and pressures without the need for distillation or extreme temperatures, thereby selectively isolating di-branched isomers like 2,3-dimethylbutane and 2,2-dimethylbutane while recycling mono-branched and linear isomers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional separation methods using zeolites and activated carbons are employed, then separation of alkane isomers can be achieved, but energy consumption increases significantly due to reliance on cryogenic or distillation steps

Engineering Contradiction:

Improveenergy consumptionVSAvoidseparation efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The invention changes the operational parameters from cryogenic temperatures and high-energy distillation to ambient or near-ambient temperature adsorption processes using metal-organic frameworks, significantly reducing energy consumption while maintaining separation efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces mechanical separation methods (distillation, cryogenic separation) with adsorption-based separation using metal-organic frameworks, substituting a energy-intensive mechanical process with a selective chemical adsorption process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If molecular sieving using LTA-5A zeolite is used to separate n-hexane from branched isomers, then linear nC6 can be isolated, but the process cannot selectively separate di-branched isomers with different RON values

Engineering Contradiction:

Improveseparation selectivityVSAvoidseparation capability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention applies local quality by designing metal-organic frameworks with specific local pore environments and functional groups that provide different interaction strengths with various alkane isomers, enabling selective separation based on molecular structure and RON value

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention uses composite metal-organic framework materials that combine specific metal centers with organic linkers to create tailored pore structures and chemical environments that can differentiate between subtle structural differences in alkane isomers

Inventive Principle:

Principle #40Composite materials

3Reliability

If distillation is used to separate mono-branched isomers from di-branched isomers to achieve higher octane fuel, then fuel quality improves, but the process becomes more costly and energy-intensive

Engineering Contradiction:

Improvefuel qualityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The invention replaces energy-intensive distillation processes with selective adsorption using metal-organic frameworks, achieving the same fuel quality improvement without the high energy costs associated with thermal separation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces energy consumption in gasoline production by performing separations at or near isomerization temperatures, potentially eliminating the need for toxic aromatic additives and improving the octane number of gasoline, while enhancing the separation efficiency and selectivity of alkane isomers.

Implementation Method 1

The efficient separation of alkane isomers by adsorption is especially challenging, because the molecules are chemically inert and have similar polarizabilities, leaving shape as the main handle available for their differentiation

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

Metal-organic frameworks can offer pore geometries that are unavailable in zeolites or other porous media, facilitating distinct types of shape-based molecular separations

Methodology Applied

Scientific EffectShape-based separation: Molecular Sieve

Data Source

PatentUS9540294B2Metal-organic framework for the separation of alkane isomers

Publication Date: 2017.01.10 RGT UNIV OF CALIFORNIA

AI summary

A metal organic framework Fe2(bdp)3 (BDP2−=1,4-benzenedipyrazolate) with triangular channels is particularly suited for C5-C7 separations of alkanes according to the number of branches in the molecule rather than by carbon number. The metal-organic framework can offer pore geometries that is unavailable in zeolites or other porous media, facilitating distinct types of shape-based molecular separations.