Composite Zeolite Catalyst for Simultaneous Heavy Reformate Conversion
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Solution Overview
Problem
Current methods for converting heavy reformate into xylenes have limited efficiency due to the sequential nature of dealkylation and transalkylation reactions, which restricts the production of xylenes at the expense of benzene yield, necessitating a more effective catalyst for simultaneous conversion.
Innovation Solution
A composite zeolite catalyst comprising interwoven ZSM-5 and Mordenite zeolites with an intergrowth region at the nanometer scale, characterized by specific XRD peaks, and impregnated with rhenium, allowing for simultaneous dealkylation and transalkylation reactions in a single reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential dealkylation and transalkylation reactions are used to convert heavy reformate into xylenes, then xylenes can be produced, but the conversion efficiency is limited and benzene yield is reduced
Solution Approach 1:
The patent combines dealkylation and transalkylation functions into a single catalyst composite containing both ZSM-5 and mordenite zeolites. This allows both reactions to occur simultaneously in one reactor, eliminating the sequential process limitation and improving overall conversion efficiency while maintaining product distribution.
Solution Approach 2:
The invention uses a composite catalyst material comprising ZSM-5 and mordenite zeolites with specific Si/Al ratios. The composite structure provides complementary active sites that facilitate both dealkylation and transalkylation reactions concurrently, resolving the efficiency-yield contradiction.
2Productivity
If a single catalyst is used for simultaneous dealkylation and transalkylation, then conversion efficiency improves, but catalyst design complexity increases
Solution Approach 1:
The patent employs a composite zeolite catalyst combining ZSM-5 and mordenite with controlled Si/Al ratios. This composite approach achieves simultaneous dealkylation and transalkylation activity while managing structural complexity through defined compositional parameters and synthesis procedures.
3Ease of manufacture
If heavy reformate is directly added to gasoline pool, then processing is simple, but benzene content restrictions are violated and value is lost
Solution Approach 1:
The patent transforms the heavy reformate composition by converting C9+ alkylaromatics into xylenes and other valuable products through catalytic dealkylation and transalkylation. This parameter change in product distribution achieves compliance with benzene content regulations while maintaining processing efficiency.
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 catalyst enhances the yield and selectivity of xylenes while reducing the formation of undesirable aromatics and coke precursors, leading to improved catalyst performance and extended catalyst life.
Implementation Method 1
transalkylation of these compounds formed by dealkylation with other C9+ alkylaromatics present in the feed
Implementation Method 2
dealkylation of the C9+ alkylaromatics to benzene and toluene
Implementation Method 3
the composite zeolite catalyst further comprises 0.01 wt. % to 20 wt. % rhenium impregnated thereon
Data Source
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AI summary
A method of forming composite zeolite catalyst particles includes combining a silicon source, an aqueous organic structure directing agent having a polyquaternary ammonium compound, water and an aluminum source to form a catalyst gel. The method also includes heating the catalyst gel to form the composite zeolite catalyst particle having an intergrowth region with a mixture of both Mordenite crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst particles, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions.