Selective Alkylation Catalyst for Mixed Olefins
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Solution Overview
Problem
Conventional processes for producing cumene and sec-butylbenzene require expensive and energy-intensive separation of ethylene from propylene and butylene, as ethylene reacts undesirably with benzene to form ethylbenzene, limiting their use as alkylation agents.
Innovation Solution
A process involving a mixed olefins stream with ethylene and propylene or butylene, using a selective alkylation catalyst with a 12-ring structure zeolite under specific conditions (weight hourly space velocity ≥10 h−1, pressure 1000-5000 kPa, and temperature 100-250°C) to selectively produce cumene and sec-butylbenzene with minimal ethylbenzene formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ethylene is separated from propylene and butylene before alkylation, then ethylbenzene formation is prevented, but separation cost and energy consumption increase
Solution Approach 1:
The harmful ethylene component is selectively removed from the mixed olefins stream by the zeolite catalyst, which extracts only ethylene for alkylation while allowing propylene and butylene to pass through to the cumene production reactor. This selective extraction eliminates ethylbenzene formation without requiring energy-intensive complete separation of all olefins.
Solution Approach 2:
A zeolite-based catalyst bed acts as an intermediary component between the mixed olefins stream and the alkylation reactor. This intermediary selectively interacts with ethylene through adsorption and catalytic conversion, transforming it into desired products while preventing its harmful reaction with benzene downstream.
2Ease of manufacture
If a mixed olefins stream containing ethylene is used directly for alkylation, then separation cost is reduced, but ethylbenzene yield increases
Solution Approach 1:
The process discards the harmful ethylene component from the mixed olefins stream through selective catalytic conversion in the zeolite bed, while recovering valuable propylene and butylene for cumene production. This selective discarding maintains process simplicity by avoiding complete separation while eliminating the harmful effect.
Solution Approach 2:
The zeolite catalyst converts the potentially harmful ethylene component into beneficial products (ethyl groups that can be transferred to propylene/butylene or light hydrocarbons), transforming what would be a harmful side reaction into a useful process that eliminates the harmful effect while maintaining process simplicity.
3Manufacturing precision
If conventional alkylation catalysts are used with mixed olefins, then ethylbenzene selectivity increases, but cumene and sec-butylbenzene selectivity decreases
Solution Approach 1:
The zeolite catalyst utilizes its porous structure with specific pore sizes and channel geometries to selectively adsorb and activate ethylene molecules while excluding or less strongly interacting with propylene and butylene. This molecular sieve effect provides high selectivity for ethylene conversion, improving cumene and sec-butylbenzene production while minimizing ethylbenzene formation.
Solution Approach 2:
The invention employs a composite catalytic system combining zeolite materials with specific framework structures (such as ZSM-5, beta-zeolite, or Y-zeolite) that possess both acidic catalytic sites and size-selective pore structures. This composite functionality enables simultaneous ethylene selectivity and propylene/butylene passage, achieving high manufacturing precision for desired products.
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 approach achieves high selectivity for cumene and sec-butylbenzene production with ethylbenzene yield less than 0.2%, eliminating the need for costly ethylene separation and optimizing energy usage.
Implementation Method 1
contacting benzene with a mixed olefins stream comprising ethylene and an alkylation agent in the presence of a selective alkylation catalyst
Implementation Method 2
a selective alkylation catalyst comprises a zeolite of the 12-ring structure type having a 3D cage structure
Data Source
AI summary
The present invention relates to a process for producing cumene and/or sec-butylbenzene comprising contacting benzene with a mixed olefins stream comprising ethylene and an alkylation agent in the presence of a selective alkylation catalyst under selective alkylation conditions.