Oxygenate Conversion Catalyst Carbon Deposition Control
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Solution Overview
Problem
Existing methods for controlling carbon deposition on catalysts in the olefins-to-oxygenates (OTO) process result in inconsistent selectivity to light olefins, adversely affecting ethylene and propylene yield, as neither fully deactivated nor fully regenerated catalysts are favorable for high selectivity.
Innovation Solution
A process utilizing a fluidized bed reactor and a riser reactor system, where the catalyst is a mixture of deactivated and regenerated silicoaluminophosphate molecular sieve, with the regenerated catalyst recycled to adjust carbon deposition levels and utilize heat from the fluidized bed reactor for cracking C4+ hydrocarbons, optimizing the yield of ethylene and propylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is fully regenerated by burning out carbon deposition, then the catalyst activity is improved, but the selectivity to light olefins deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the carbon deposition level on the catalyst as a key parameter. Instead of fully regenerating the catalyst to maximum activity, the process maintains carbon deposition at an optimal level (0.5-5.0 wt%) that balances both catalyst activity and selectivity to light olefins, thereby resolving the contradiction between these two opposing requirements
Solution Approach 2:
The patent implements partial action by performing incomplete regeneration of the catalyst. Rather than completely burning out all carbon deposition, the process intentionally retains a controlled amount of carbon (0.5-5.0 wt%) on the catalyst surface, which acts as a beneficial intermediate that enhances selectivity while maintaining sufficient activity for the reaction
2Manufacturing precision
If the catalyst is left with more carbon deposition, then the selectivity to light olefins is improved, but the catalyst activity deteriorates
Solution Approach 1:
The patent uses parameter changes by precisely controlling the carbon deposition level within the optimal range of 0.5-5.0 wt%. This parameter optimization ensures that enough carbon remains to maintain high selectivity to light olefins, while sufficient catalyst activity is preserved for effective conversion, resolving the trade-off between these two opposing characteristics
3Device complexity
If a single reactor system is used, then the device complexity is reduced, but the productivity deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the reaction system into two distinct reactors: a fluidized bed reactor for oxygenate conversion and a riser reactor for C4+ hydrocarbon cracking. This segmentation allows each reactor to be optimized for its specific function, with the riser reactor providing a short residence time environment that enhances ethylene and propylene yield, thereby resolving the contradiction between system simplicity and productivity
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 process achieves a significant increase in ethylene and propylene yield, up to 83.37 wt%, by precisely controlling carbon deposition and heat management, thereby enhancing the selectivity and efficiency of the OTO process.
Implementation Method 1
SAPO-34 is the most preferred catalyst for OTO process... SAPO-34 catalyst has high selectivity to light olefins and activity
Implementation Method 2
a part of the deactivated catalyst is introduced to the regeneration zone to be regenerated by burning out the carbon deposition
Implementation Method 3
feeding a feedstock comprising oxygenates to the lower reaction zone of the fluidized bed reactor, wherein the feedstock being converted to a reaction product comprising ethylene, propylene and C4+ hydrocarbon
Implementation Method 4
feeding the separated C4+ hydrocarbon stream to the lower reaction zone of the riser reactor, wherein the separated C4+ hydrocarbon stream being cracked to a reaction product comprising ethylene and propylene
Data Source
AI summary
The present invention provides a process for increasing ethylene and/or propylene yield during conversion of oxygenates using a system comprising a reactor and a regenerator, wherein the reactor comprises a fluidized bed reactor and a riser reactor, which process increases ethylene and/or propylene yield by using a mixture of the deactivated catalyst from the fluidized bed reactor and the regenerated catalyst from the regenerator in the riser reactor for further cracking the C4+ hydrocarbon stream separated from the product stream.