IZM-2 Zeolite Catalyst Si/Al Ratio Optimization
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Solution Overview
Problem
Current isomerization processes for aromatic C8 cuts face challenges in minimizing net losses due to conflicting requirements for acid site density and strength in zeolite catalysts, leading to suboptimal selectivity and activity.
Innovation Solution
A catalyst comprising an IZM-2 zeolite with a silicon to aluminum molar ratio between 60 and 95, preferably between 60 and 80, is used for isomerization under specific operating conditions, enhancing selectivity and reducing net losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the acid site density of the zeolite catalyst is increased to improve isomerization activity, then the productivity increases, but the selectivity decreases due to increased side reactions
Solution Approach 1:
The patent changes the chemical composition parameter of the zeolite catalyst by optimizing the Si/Al molar ratio to between 60 and 95. This parameter adjustment modifies the acid site density and strength, achieving a balance between isomerization activity and selectivity, thereby resolving the contradiction between productivity and harmful side reactions.
2Productivity
If the acid site strength of the zeolite catalyst is increased to improve isomerization activity, then the productivity increases, but the selectivity decreases due to increased dealkylation reactions
Solution Approach 1:
The patent adjusts the chemical composition parameter of the zeolite catalyst by controlling the Si/Al molar ratio within the range of 60-95. This modification optimizes the acid site strength to promote isomerization reactions while suppressing dealkylation side reactions, thus resolving the contradiction between productivity and substance loss.
3Productivity
If a bifunctional catalyst with noble metal is used to achieve both hydrogenation and isomerization, then the productivity increases, but the complexity of the catalyst formulation increases
Solution Approach 1:
The patent extracts and eliminates the noble metal component from the bifunctional catalyst system, using only the zeolite IZM-2 with optimized Si/Al ratio. This simplifies the catalyst formulation while maintaining both hydrogenation and isomerization capabilities through the zeolite's intrinsic properties, resolving the contradiction between productivity and complexity.
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
The optimized catalyst significantly improves selectivity and reduces net losses in the isomerization of aromatic C8 cuts, achieving better para-xylene production yields while minimizing unwanted byproducts.
Implementation Method 1
Isomerization reactions as well as side reactions are mainly catalyzed by the acid function. The properties of the zeolite (number and strength of Bronsted acid sites, topology of the microporous network, etc.), acting as an acid function, thus have a direct impact on the properties of the bifunctional catalyst, and in particular its selectivity.
Implementation Method 2
Ethylbenzene is first hydrogenated to ethylcyclohexenes on the metal sites, these cycloolefin intermediates are then isomerized to dimethylcyclohexenes on the acid sites of Bronsted.
Data Source
AI summary
A catalyst is described comprising at least one IZM-2 zeolite containing silicon and aluminum atoms, at least one matrix, and at least one metal from Group VIII of the Periodic Table of Elements, the zeolite having a ratio of the number of moles of silicon to the number of moles of aluminum between 60 and 150. Said catalyst is used in a process for the isomerization of an aromatic filler comprising at least one compound with eight carbon atoms per molecule.