Multiple-Stage Catalyst System for Propylene Production
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Solution Overview
Problem
Current propylene production methods, such as steam cracking and Fluid Catalytic Cracking (FCC) units, cannot keep pace with the rapid increase in propylene demand due to limitations in existing catalyst systems, leading to inadequate supply and inefficient processes.
Innovation Solution
A multiple-stage catalyst system comprising an isomerization catalyst zone with silica-alumina catalyst, a metathesis catalyst zone with mesoporous silica catalyst impregnated with metal oxide, and a cracking catalyst zone with mordenite framework inverted (MFI) structured silica catalyst, which converts 2-butene to propylene through isomerization, metathesis, and cracking reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking or FCC units are used for propylene production, then existing production capacity is maintained, but propylene demand cannot be met due to insufficient responsiveness
Solution Approach 1:
The catalytic system is segmented into multiple functional stages: isomerization catalyst (silica-alumina) to convert 2-butene to 1-butene, metathesis catalyst (mesoporous silica with metal oxide) to perform the core metathesis reaction, and cracking catalyst (MFI structured silica) to crack heavier products. This segmentation allows each catalyst to be optimized for its specific function, enabling high propylene selectivity and rapid response to demand changes
Solution Approach 2:
The invention uses composite catalyst systems combining different material types: silica-alumina for isomerization, mesoporous silica impregnated with metal oxides (W, Mo, Re) for metathesis, and MFI structured silica for cracking. These composite materials provide synergistic effects that enhance overall propylene production efficiency and adaptability
2Productivity
If traditional single-stage catalysts are used, then process simplicity is maintained, but propylene yield and selectivity are insufficient
Solution Approach 1:
The catalytic system is divided into three distinct zones with specific functions: isomerization zone (silica-alumina, Al2O3/SiO2 ratio 1:99 to 20:80) to equilibrate butene isomers, metathesis zone (mesoporous silica with metal oxide) to produce propylene and heavier olefins, and cracking zone (MFI structured silica) to convert C5+ olefins to additional propylene. This segmentation achieves high propylene yield while managing complexity through functional specialization
Solution Approach 2:
The multiple-stage catalyst system performs multiple functions in sequence: isomerization of butenes, metathesis to form propylene and C5-C6 olefins, and cracking of heavier products. This multi-functionality within a single integrated system maximizes propylene yield from the feedstock
3Manufacturing precision
If metathesis reactions are performed without controlled isomerization, then process simplicity is maintained, but propylene selectivity decreases due to uncontrolled side reactions
Solution Approach 1:
The isomerization catalyst zone performs preliminary action by converting 2-butene to 1-butene before the metathesis reaction. This pre-isomerization ensures optimal substrate composition for the metathesis catalyst, enhancing propylene selectivity and preventing unwanted side reactions that would occur with uncontrolled isomerization during metathesis
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 system enhances propylene yield and selectivity, improving the overall efficiency and responsiveness to demand by optimizing the conversion of butene to propylene, while minimizing the production of undesirable byproducts and reducing operating costs.
Implementation Method 1
introducing a hydrocarbon stream comprising 2-butene to an isomerization catalyst zone to isomerize the 2-butene to 1-butene, where the isomerization catalyst zone comprises a silica-alumina catalyst
Implementation Method 2
passing the 2-butene and 1-butene to a metathesis catalyst zone to cross-metathesize the 2-butene and 1-butene into a metathesis product stream comprising propylene, unconverted C 4 , and higher metathesis product C 5 and C 6 olefins, where the metathesis catalyst comprises a mesoporous silica catalyst support impregnated with metal oxide
Implementation Method 3
cracking the metathesis product stream in a catalyst cracking zone to produce propylene, where the catalyst cracking zone comprises a mordenite framework inverted (MFI) structured silica catalyst
Data Source
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AI summary
Embodiments of processes and multiple-stage catalyst systems for producing propylene comprising introducing a hydrocarbon stream comprising 2-butene to an isomerization catalyst zone to isomerize the 2-butene to 1-butene, passing the 2-butene and 1-butene to a metathesis catalyst zone to cross-metathesize the 2-butene and 1-butene into a metathesis product stream comprising propylene and C4-C6 olefins, and cracking the metathesis product stream in a catalyst cracking zone to produce propylene. The isomerization catalyst zone comprises a silica-alumina catalyst with a ratio by weight of alumina to silica from 1:99 to 20:80. The metathesis catalyst comprises a mesoporous silica catalyst support impregnated with metal oxide. The catalyst cracking zone comprises a mordenite framework inverted (MFI) structured silica catalyst.