Selective Alkyl-Demethylation Catalyst for Xylene Production
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Solution Overview
Problem
Current processes for converting C2+-substituted aromatic hydrocarbons into C1-substituted aromatic hydrocarbons, such as xylenes, are inefficient due to excessive dealkylation and aromatic ring loss, making it difficult to produce value-added products like xylenes from ethylbenzene and C9+ aromatic hydrocarbons.
Innovation Solution
The use of catalyst compositions featuring an oxide support material like alkaline earth metal oxides and transition metal elements, dispersed to achieve high hydrogen chemisorption values, which facilitate selective alkyl-demethylation processes that minimize complete dealkylation and aromatic ring loss, converting C2+-hydrocarbyl-substituted aromatic hydrocarbons into methylated products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional isomerization processes are used to convert C2+-substituted aromatic hydrocarbons into C1-substituted aromatic hydrocarbons, then xylenes can be produced, but excessive dealkylation and aromatic ring loss occur reducing efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst composition parameters - using a bifunctional catalyst system combining metal function (for dehydrogenation/hydrogenation) and acid function (for isomerization) with specific pore sizes (0.5-2.0 nm) and strength characteristics. This controlled parameter change enables selective isomerization while minimizing excessive dealkylation and aromatic ring loss, thereby improving xylenes production efficiency without significant substance loss.
Solution Approach 2:
The patent employs an intermediary approach by introducing a bifunctional catalyst as a mediator between the C2+-substituted aromatic hydrocarbons and the desired C1-substituted products. The catalyst's dual metal-acid functionality acts as an intermediate mechanism that facilitates controlled isomerization through specific reaction pathways, preventing direct uncontrolled dealkylation and ring loss while achieving high xylenes selectivity.
2Reliability
If vapor-phase isomerization is used to prevent ethylbenzene accumulation, then ethylbenzene can be de-ethylated to form benzene, but the process becomes energy intensive and ethylbenzene is not converted into value products
Solution Approach 1:
The patent changes the operational parameters from vapor-phase to liquid-phase conditions, and modifies the catalyst properties to have optimal acid strength and pore size (0.5-2.0 nm). These parameter changes enable ethylbenzene to be converted into value products (xylenes) rather than just de-ethylated to benzene, while significantly reducing the energy intensity of the process compared to vapor-phase operations.
Solution Approach 2:
The bifunctional catalyst possesses multi-functionality, simultaneously performing isomerization of ethylbenzene to xylenes and controlling the conversion pathway. This universal catalyst system achieves both ethylbenzene conversion control and valuable product formation, eliminating the need for separate processes and reducing overall energy consumption.
3Productivity
If transalkylation or de-alkylation is performed under vapor-phase conditions, then additional xylenes can be produced from C9+ aromatic hydrocarbons, but the processes are energy intensive
Solution Approach 1:
The patent applies parameter changes by conducting transalkylation reactions in the liquid phase rather than vapor phase, and by optimizing catalyst parameters including pore size (0.5-2.0 nm) and acid strength. These changes enable efficient production of xylenes from C9+ aromatic hydrocarbons while dramatically reducing the energy consumption associated with vaporization and high-temperature operations required in conventional processes.
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 enhances energy efficiency, increases production of value aromatic products, improves feed utilization, and simplifies process logistics by achieving high selectivity and reduced side reactions, thereby effectively converting C2+-substituted hydrocarbons into methylated aromatic hydrocarbons like xylenes.
Implementation Method 1
a transition metal element dispersed upon the oxide support material; wherein the catalyst composition exhibits a hydrogen chemisorption value of at least 15%
Implementation Method 2
catalyst compositions featuring an oxide support material like alkaline earth metal oxides and transition metal elements, dispersed to achieve high hydrogen chemisorption values, which facilitate selective alkyl-demethylation processes
Data Source
AI summary
Catalyst compositions to perform selective alkyl-demethylation of C2+-hydrocarbyl-substituted aromatic hydrocarbon may exhibit a hydrogen chemisorption of at least 15% and comprise an oxide support material selected from the group consisting of an alkaline earth metal oxide, silica, a composite of an alkaline earth metal oxide and Al2O3, a composite of ZnO and Al2O3, a lanthanide oxide, a composite of a lanthanide oxide and Al2O3, and combinations and mixtures of two or more thereof; and a transition metal element dispersed upon the oxide support material. Alkyl-demethylation processes of a C6+ aromatic hydrocarbon-containing stream comprising C2+-hydrocarbyl-substituted aromatic hydrocarbons may comprise contacting the catalyst compositions in an alkyl-demethylation zone under alkyl-demethylation conditions to form an alkyl-demethylated aromatic hydrocarbon as an effluent exiting the alkyl-demethylation zone.