Catalytic Membrane Reactor for Alkane Dehydroaromatization
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Solution Overview
Problem
The non-oxidative dehydroaromatization of methane to benzene is thermodynamically limited and prone to catalyst deactivation due to carbon deposits, limiting large-scale commercial deployment, as existing methods either fail to shift the equilibrium effectively or promote undesirable side reactions.
Innovation Solution
A process involving a catalytic membrane reactor with a dehydrogenation catalyst and a hydrogen transport membrane, where hydrogen is fed as a reactant and selectively removed within the reactor, combined with controlled oxygen transport to optimize partial pressure gradients and minimize coke formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen selective membrane is used to shift thermodynamic equilibrium, then aromatic product yield is improved, but catalyst deactivation due to coke formation worsens
Solution Approach 1:
The patent extracts and removes hydrogen from the reaction zone using a hydrogen selective membrane, shifting the thermodynamic equilibrium toward aromatic product formation. This extraction of hydrogen prevents coke formation by maintaining lower hydrogen partial pressure, thereby extending catalyst lifetime while improving aromatic yield
Solution Approach 2:
The patent changes the operating parameters by controlling hydrogen partial pressure through membrane-based hydrogen removal. By dynamically adjusting hydrogen concentration in the reaction zone, the process optimizes both aromatic production and catalyst stability, resolving the contradiction between yield and catalyst lifetime
2Productivity
If electrochemical hydrogen removal is used, then thermodynamic equilibrium is shifted, but polyaromatic hydrocarbon formation increases
Solution Approach 1:
The patent introduces a hydrogen selective membrane as an intermediary component that selectively removes hydrogen from the reaction zone. This intermediary mechanism achieves equilibrium shift without the harsh conditions of electrochemical methods, preventing polyaromatic hydrocarbon formation while maintaining catalyst integrity
3Productivity
If external hydrogen separation is implemented, then unreacted alkane recycle is enabled, but process complexity increases
Solution Approach 1:
The patent merges the hydrogen removal function with the reactor system by integrating a hydrogen selective membrane directly into the reaction zone. This combination enables in-situ hydrogen separation and facilitates unreacted alkane recycle without requiring external separation equipment, thereby reducing process complexity while maintaining high productivity
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 dynamically controls the thermodynamic equilibrium, maximizing aromatic hydrocarbon yields while extending catalyst lifetime by reducing coke formation and avoiding the need for external hydrogen separation, thus offering a more efficient and stable conversion process.
Implementation Method 1
a hydrogen transport membrane separating said first zone from a second zone; allowing hydrogen to selectively pass through the hydrogen transport membrane into said second zone
Implementation Method 2
a catalytic membrane reactor comprising a reactor inlet, a dehydrogenation catalyst and a reactor outlet; feeding through said reactor inlet a feed comprising hydrogen and at least one C1-4 alkane so that the alkane and hydrogen contact said dehydrogenation catalyst
Implementation Method 3
operating said reactor at a temperature and pressure sufficient to allow dehydrogenation of said alkane and formation of said aromatic hydrocarbon and hydrogen
Implementation Method 4
in one embodiment, a limited amount of oxygen transport across the membrane into the reaction zone takes place to increase process stability
Data Source
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Figure 3~4A
AI summary
A process for conversion of natural gas to aromatic hydrocarbons in a catalytic membrane reactor is described herein. The catalytic membrane reactor comprises a dehydrogenation catalyst and a membrane that can selectively transport hydrogen under high temperature operating conditions such as 600 °C to 800 °C. Aromatic hydrocarbons are produced stably for a long time by a process characterized by hydrogen co-feed with the reaction gases to the one end of the to the reaction zone while hydrogen is extracted selectively with use of the membrane as the reactive gas mix passes through the reaction zone.