MTW Zeolite Catalyst Pore Optimization for C8 Isomerization
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Solution Overview
Problem
Catalysts for C8 aromatic isomerization processes face challenges in minimizing C8 ring loss while maximizing para-xylene yield, as existing catalysts often result in high cyclic C8 loss due to side reactions and high utility costs, with unpredictable performance due to varying alumina sources and processing steps.
Innovation Solution
A catalyst comprising 1-90% MTW zeolite, 10-99% gamma-alumina binder derived from Boehmite alumina, 0.1-2% noble metal, and at least 100 ppm alkali metal, with a pore volume distribution where 70% of pores are greater than 100 Å, designed to minimize C8 ring loss by optimizing alkali metal content and pore size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the isomerization process is run close to equilibrium to maximize para-xylene yield, then para-xylene yield is improved, but C8 cyclic loss increases due to side reactions
Solution Approach 1:
The patent applies parameter changes by optimizing the pore size distribution of the catalyst (with at least 70% of pore volume having diameter greater than 100 Å) and controlling alkali metal content (at least 100 ppm). These parameter modifications enable the catalyst to achieve high para-xylene yield while minimizing C8 cyclic loss by reducing side reactions through improved selectivity.
2Loss of substance
If a catalyst with ODS alumina binder is used to minimize C8 ring loss, then C8 ring loss is reduced, but catalyst cost increases compared to extruded gamma-alumina catalysts
Solution Approach 1:
The patent changes the pore size distribution parameter of extruded gamma-alumina catalysts to have at least 70% of pore volume with diameter greater than 100 Å. This parameter modification enables extruded gamma-alumina catalysts to achieve C8 ring loss levels comparable to or better than ODS alumina catalysts, while maintaining lower manufacturing cost and easier production scalability.
3Productivity
If alkali metal content is increased to improve isomerization activity, then isomerization activity is improved, but C8 ring loss may increase due to reduced selectivity
Solution Approach 1:
The patent optimizes the alkali metal content parameter to be at least 100 ppm, which provides sufficient isomerization activity while maintaining selectivity. Combined with the optimized pore size distribution, this parameter control ensures that the catalyst achieves high conversion rates without excessive C8 ring loss from side reactions.
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 lower C8 ring loss compared to those using ODS alumina binders, with exemplary embodiments showing C8 ring loss at or below 3%, enhancing para-xylene yield and reducing operational costs by maintaining a favorable balance of activity, selectivity, and stability.
Implementation Method 1
A catalyst for a C8 aromatic isomerization process. The catalyst can include: 1 - 90%, by weight, of a zeolite including an MTW zeolite
Implementation Method 2
10 - 99%, by weight, of a binder including a gamma-alumina, the gamma-alumina being derived from a Boehmite alumina
Implementation Method 3
Generally, the catalyst has a pore volume distribution and at least 70% of a pore volume of the catalyst is defined by pores having a diameter greater than 100 Å
Data Source
AI summary
One exemplary embodiment can be a catalyst for a C8 aromatic isomerization process. The catalyst can include: 1 - 90%, by weight, of a zeolite including an MTW zeolite; 10 - 99%, by weight, of a binder including a gamma-alumina, the gamma-alumina being derived from a Boehmite alumina; 0.1 - 2%, by weight, of a noble metal, calculated on an elemental basis; and at least one alkali metal wherein a total alkali metal content of the catalyst is at least 100 ppm, by weight, calculated on an elemental basis. Generally, the catalyst has a pore volume distribution and at least 70% of a pore volume of the catalyst is defined by pores having a diameter greater than 100 A.