Hydrocarbon Dehydrocyclization with CO2 Methanation

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Solution Overview

Problem

Current processes for aromatizing non-aromatic hydrocarbons in the presence of CO2 face limitations due to molecular hydrogen production, leading to reduced aromatic hydrocarbon yield and catalyst deactivation, along with inefficiencies in energy use and reactor complexity.

Innovation Solution

The process involves catalytically converting CO2 to methane and water (CO2 methanation) using a combination of dehydrogenation and molecular sieve catalysts, which increases hydrogen consumption and provides heat for the endothermic aromatization reaction, enhancing aromatic hydrocarbon yield while minimizing catalyst coking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If molecular hydrogen is produced during hydrocarbon dehydrogenation, then aromatic hydrocarbon can be formed, but aromatic hydrocarbon yield is limited and catalyst deactivation increases

Engineering Contradiction:
Improvearomatic hydrocarbon yieldVSAvoidcatalyst activity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent converts the harmful effect of molecular hydrogen (which causes hydrogenolysis and coking) into a beneficial resource by introducing CO2 to react with H2 and form methane. This methanation reaction consumes the excess hydrogen that would otherwise cause catalyst deactivation, thereby extending catalyst life and maintaining activity while preserving aromatic hydrocarbon yield.

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

2Quantity of substance

If CO2 is separated from feed upstream of aromatization, then CO2 can be removed, but refrigeration equipment complexity and energy consumption increase

Engineering Contradiction:
ImproveCO2 removalVSAvoidrefrigeration equipment
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent merges the CO2 separation function with the aromatization reaction itself. Instead of using separate refrigeration equipment to remove CO2 upstream, the process allows CO2 to be present in the feed and reacts it in-situ during the aromatization step. This integration eliminates complex refrigeration equipment while achieving CO2 conversion and aromatic hydrocarbon production simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If CO2 is separated downstream of aromatization, then aromatic hydrocarbon recovery can be improved, but the aromatics recovery system becomes bottlenecked

Engineering Contradiction:
Improvearomatic hydrocarbon recoveryVSAvoidaromatics recovery system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent converts CO2, which would otherwise be an inert gas interfering with the recovery system, into methane through the methanation reaction. This transformation removes CO2 from the recovery stream, eliminating the bottleneck effect and simplifying the aromatics recovery system while maintaining high aromatic hydrocarbon recovery efficiency.

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

4Productivity

If hydrogenolysis increases during simultaneous aromatization and RWGS, then aromatic hydrocarbon yield improves, but light saturated hydrocarbon byproduct increases and catalyst coking accelerates

Engineering Contradiction:
Improvearomatic hydrocarbon yieldVSAvoidlight saturated hydrocarbon byproduct
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the system by introducing CO2 as a reactant that shifts the hydrogen utilization pathway. Instead of hydrogen reacting with hydrocarbons to form light saturated byproducts (hydrogenolysis), the CO2 reacts with H2 to form methane. This parameter change redirects the hydrogen consumption pathway, reducing light saturated hydrocarbon byproduct formation while maintaining aromatic hydrocarbon yield.

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 results in a more efficient and stable aromatization process with increased aromatic hydrocarbon yield and reduced catalyst deactivation, as the exothermic CO2 methanation reaction supports the endothermic aromatization process, maintaining reactor efficiency.

Implementation Method 1

catalytically converting CO2 to methane and water (CO2 methanation)

Methodology Applied
Scientific EffectCO2 methanation: Chemical Bonding

Implementation Method 2

the exothermic CO2 methanation reaction supports the endothermic aromatization process

Methodology Applied
Scientific EffectExothermic reaction: Exothermic Reaction

Implementation Method 3

the endothermic aromatization reaction

Methodology Applied
Scientific EffectEndothermic reaction: Endothermic Reaction

Implementation Method 4

catalytically converting CO2 to methane and water

Methodology Applied
Scientific EffectCatalysis: Catalysis

Data Source

PatentUS9796643B2Hydrocarbon dehydrocyclization in the presence of carbon dioxide
Publication Date: 2017.10.24 EXXONMOBIL CHEMICAL PATENTS INC

AI summary

The invention relates to converting non-aromatic hydrocarbon in the presence of CO2 to produce aromatic hydrocarbon. CO2 methanation using molecular hydrogen produced during the aromatization increases aromatic hydrocarbon yield. The invention also relates to equipment and materials useful in such upgrading, to processes for carrying out such upgrading, and to the use of such processes for, e.g., natural gas upgrading.