Olefin Production via Segmented XTO-OC Catalyst Circulation
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Solution Overview
Problem
Current processes for converting oxygen-containing organic compounds to olefins, such as methanol to olefins (MTO), face challenges in achieving optimal yields and selectivity for ethylene and propylene due to limitations in catalyst performance and reaction zone optimization.
Innovation Solution
A combined XTO-OC process utilizing a zeolitic molecular sieve catalyst with P-modification and alkaline earth or rare earth metal modification, featuring separate reaction zones for XTO and OC reactions, and a catalyst regeneration zone, where the catalyst circulates between zones to optimize conditions and reduce coke deposition, enhancing catalyst selectivity and overall yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reaction zone is used for both XTO and OC reactions, then device complexity is reduced, but manufacturing precision and selectivity of olefin production deteriorate
Solution Approach 1:
The reaction system is divided into two separate reaction zones: a first reaction zone for XTO reaction and a second reaction zone for OC reaction. This segmentation allows each zone to be optimized for its specific reaction type, improving overall olefin selectivity while maintaining manageable system complexity through modular design.
Solution Approach 2:
The catalyst system is designed to perform multiple functions across different zones. The same catalyst type can be used in both XTO and OC reactions, but with different operational parameters. This multi-functionality approach maintains device simplicity while achieving high selectivity through parameter optimization rather than structural complexity.
2Productivity
If catalyst is continuously regenerated and circulated between zones, then productivity and catalyst selectivity are improved, but device complexity and operational difficulty increase
Solution Approach 1:
The catalyst is continuously regenerated and circulated between reaction zones, ensuring that active catalyst sites are always available. This continuous operation maximizes olefin production yield by preventing catalyst deactivation and maintaining optimal catalytic activity throughout the process.
Solution Approach 2:
The catalyst regeneration system is designed to automatically restore catalyst activity without requiring external intervention. The catalyst self-regenerates through controlled burning of coke deposits, and the circulation system automatically redistributes regenerated catalyst to reaction zones, reducing operational complexity despite the continuous circulation requirement.
3Manufacturing precision
If coke deposition is allowed to occur on catalyst, then catalyst selectivity for certain products improves, but loss of substance and catalyst life are worsened
Solution Approach 1:
Coke deposition, which normally deactivates catalyst, is converted into a beneficial selective deactivation mechanism. By controlling coke formation, non-selective acid sites are deactivated while preserving selective sites, thereby improving product selectivity. The coke is then burned off during regeneration, restoring catalyst activity for the next cycle.
Solution Approach 2:
The catalyst operates in periodic cycles: during reaction phases, controlled coke deposition enhances selectivity; during regeneration phases, coke is burned off to restore activity. This periodic alternation between selectivity-enhancing coke deposition and activity-restoring regeneration maintains both product selectivity and catalyst life throughout operation.
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 results in higher yields of light olefins by selectively deactivating non-selective acid sites, reducing paraffin and aromatic formation, and allowing for better heat integration and catalyst management, leading to improved ethylene and propylene production.
Implementation Method 1
contacting the first portion of said oxygen-containing organic feedstock in the XTO reactor with the catalyst at conditions effective to convert at least a portion of the feedstock to form a XTO reactor effluent comprising ethylene and propylene
Implementation Method 2
contacting said hydrocarbon fraction containing C4-C7 olefins and the second portion of said oxygen-containing organic feedstock in the OC reactor with the catalyst to convert at least a portion of said hydrocarbon fraction containing C4-C7 olefins and oxygen-containing organic feedstock to ethylene and propylene
Implementation Method 3
a catalyst regeneration zone being a fast fluidization bed system, said catalyst circulating in the three zones
Data Source
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AI summary
The present invention relates to a process to make light olefins, in a combined XTO-OC process, from an oxygen-containing, halogenide-containing or sulphur-containing organic feedstock comprising : a0)providing a first portion and a second portion of said oxygen-containing, halogenide-containing or sulphur-containing organic feedstock, a)providing a catalyst comprising zeolitic molecular sieves containing at least 10 membered ring pore openings or larger in their microporous structure, b)providing an XTO reaction zone, an OC reaction zone and a catalyst regeneration zone, said catalyst circulating in the three zones, such that at least a portion of the regenerated catalyst is passed to the OC reaction zone, at least a portion of the catalyst in the OC reaction zone is passed to the XTO reaction zone and at least a portion of the catalyst in the XTO reaction zone is passed to the regeneration zone;c)contacting the first portion of said oxygen-containing, halogenide- containing or sulphur-containing organic feedstock in the XTO reactor with the catalyst at conditions effective to convert at least a portion of the feedstock to form a XTO reactor effluent comprising light olefins and a heavy hydrocarbon fraction; d)separating said light olefins from said heavy hydrocarbon fraction; e)contacting said heavy hydrocarbon fraction and the second portion of said oxygen-containing, halogenide-containing or sulphur-containing organic feedstock in the OC reactor with the catalyst at conditions effective to convert at least a portion of said heavy hydrocarbon fraction and oxygen-containing, halogenide-containing or sulphur-containing organic feedstock to light olefins.