Xylene Isomerization Catalyst with Controlled Acid Sites
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Solution Overview
Problem
Conventional xylene isomerization catalysts experience significant xylene loss during the isomerization process, leading to economic losses for petrochemical companies, due to uncontrolled acid sites in zeolites and high lead content, which affects ethylbenzene conversion rates.
Innovation Solution
A catalyst is developed by impregnating or mixing zeolites with specific metal salts, such as beryllium or calcium acetylacetonate, to control the acid sites and minimize xylene loss, using a zeolite with a silica-to-alumina molar ratio of 20-100, supported with VIII group metals like platinum, tin, or bismuth, and an inorganic binder, optimizing the structural characteristics and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional zeolite catalysts supported with VIII group metal and lead are used for xylene isomerization, then ethylbenzene conversion is achieved, but xylene loss is large (0.8-1.5 wt% or higher) and lead content is very high
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by replacing lead with alternative metals (Sn, Bi, Pd, Pt, Au, Ag, Cu, Zn) and optimizing the zeolite composition (silica-to-alumina ratio of 10-100). This parameter change reduces xylene loss to 0.1-0.5 wt% while maintaining ethylbenzene conversion, resolving the contradiction between productivity and substance loss.
Solution Approach 2:
The patent creates a composite catalyst material combining zeolite (ZSM-5, ZSM-11, ZSM-23, or ZSM-35) with VIII group metal and alternative metal components. This composite structure achieves both high ethylbenzene conversion and low xylene loss by synergistically combining the functions of different materials, eliminating the need for high lead content.
2Productivity
If conventional zeolite catalysts with uncontrolled acid sites are used, then isomerization reaction proceeds, but disproportionation reaction occurs causing xylene loss
Solution Approach 1:
The patent controls the acid site strength and distribution by optimizing the zeolite silica-to-alumina ratio (10-100) and introducing alternative metal components. This parameter control suppresses the disproportionation reaction (harmful side reaction) while maintaining the desired isomerization reaction rate, resolving the contradiction between productivity and harmful factors generation.
3Productivity
If high lead content is used in the catalyst to enhance activity, then ethylbenzene conversion improves, but environmental and safety concerns increase
Solution Approach 1:
The patent extracts and removes the harmful lead component from the catalyst system while retaining the essential catalytic function. By replacing lead with environmentally friendly alternative metals (Sn, Bi, Pd, Pt, Au, Ag, Cu, Zn), the patent eliminates lead toxicity concerns while maintaining or improving ethylbenzene conversion activity.
Solution Approach 2:
The patent uses alternative metals that can be used in smaller, more controlled amounts compared to lead, creating a more sustainable and environmentally friendly catalyst system that does not rely on toxic heavy metals.
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 high ethylbenzene conversion with low xylene loss, outperforming conventional methods, as demonstrated by the graphs showing improved catalytic performance in xylene isomerization reactions.
Implementation Method 1
a catalyst for xylene isomerisation, comprising a carrier including a zeolite, having a molar ratio of silica to alumina of 20 ∼100, impregnated with or mixed with a metal salt (I)
Implementation Method 2
isomerization catalysts generally serve to facilitate the isomerization reaction between xylene isomers
Implementation Method 3
serve to convert ethylbenzene into benzene through a dealkylation reaction
Implementation Method 4
convert the ethylbenzene into a xylene isomer through the isomerization reaction
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed herein is a catalyst for xylene isomerization, including: a carrier including a zeolite, having a molar ratio of silica to alumina of 20 ~ 100, impregnated with or mixed with a metal salt (I) having an amount of a metal component of 0.05 ~ 5.0 wt% relative to a zeolite, and an inorganic binder, in which an amount of the zeolite is 10 - 90 wt% based on the total amount of the carrier, wherein the carrier is supported with a VIII group metal such that an amount of the VIII group metal is 0.001 ~ 3.0 wt% based on a total amount of the catalyst, or is supported with the VII group metal additionally supported with tin, bismuth or lead such that an amount of the tin, bismuth or lead is 0.01-5.0 wt% based on the total amount of the catalyst, and a method of producing the catalyst. The catalyst for xylene isomerization is advantageous in that, when xylene or C8 aromatic compounds are isomerized using the catalyst, the ethylbenzene conversion is increased while the xylene loss is decreased, compared to conventional technologies.