Low-Alkali IZM-2 Zeolite Catalyst for Aromatic C8 Isomerization
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Solution Overview
Problem
Existing catalysts for the isomerization of aromatic C8 cuts, particularly those using IZM-2 zeolite, suffer from reduced activity due to high alkali metal and alkaline-earth metal content, leading to increased production of net losses through side reactions.
Innovation Solution
A catalyst comprising IZM-2 zeolite with a limited total weight ratio of alkali metal and/or alkaline-earth metal content of less than 200 ppm, combined with a matrix and a Group VIII metal, maintains or enhances activity without reducing selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If catalysts use high content of alkali metal and alkaline-earth metal, then selectivity for isomerization is improved, but activity is reduced and side reactions increase
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by precisely controlling the alkali metal and alkaline-earth metal content to be within 200 ppm, thereby optimizing the balance between selectivity and activity. This parameter optimization resolves the contradiction by finding the optimal concentration range that maintains high selectivity while preventing activity loss and excessive side reactions.
2Reliability
If catalysts use high content of alkali metal and alkaline-earth metal, then selectivity for isomerization is improved, but production of net losses increases
Solution Approach 1:
By changing the compositional parameter of alkali metal and alkaline-earth metal content to below 200 ppm, the patent reduces unwanted side reactions that produce net losses while preserving the selective isomerization function. This parameter control directly addresses the contradiction between selectivity and substance loss.
3Productivity
If catalysts use limited content of alkali metal and alkaline-earth metal, then activity is maintained or enhanced, but selectivity may be compromised
Solution Approach 1:
The patent identifies 200 ppm as the optimal threshold parameter for alkali metal and alkaline-earth metal content. By setting this specific parameter limit, the patent achieves both high activity and maintained selectivity, resolving the contradiction between productivity and reliability through precise parameter definition.
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 catalyst achieves improved catalytic performance with reduced side reactions, enhancing the isomerization of aromatic C8 cuts and minimizing the production of less valuable molecules.
Implementation Method 1
catalyst comprising at least one IZM-2 zeolite, at least one matrix and at least one metal from group VIII of the Periodic Table of the Elements
Implementation Method 2
isomerization of aromatic C8 cuts into xylenes
Implementation Method 3
Ethylbenzene is first hydrogenated to ethylcyclohexenes on the metallic sites
Implementation Method 4
the isomerization of ethylbenzene to xylenes involves a mechanism of difunctional type. Ethylbenzene is first hydrogenated to ethylcyclohexenes on the metallic sites, and these cycloolefin intermediates are then isomerized to dimethylcyclohexenes on the Brønsted acid sites
Implementation Method 5
a hydro-dehydrogenating function borne by a noble metal (generally platinum)
Implementation Method 6
the dimethylcyclohexenes are dehydrogenated to xylenes on the metallic sites
Data Source
AI summary
A catalyst containing a IZM-2 zeolite and a specific content of alkali metal or alkaline-earth metal compounds, and a process for the isomerization of an aromatic C8 cut using the catalyst.