Molecular Sieve Catalyst for C3-C6 Olefin Conversion
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Solution Overview
Problem
Existing catalyst systems for converting methyl halides to C3-C6 olefins suffer from fast deactivation, high selectivity to ethylene, and coke formation, limiting their efficiency and stability, especially when using small-pore zeolites.
Innovation Solution
A process utilizing molecular sieves with a Si/Al atomic ratio ranging from 2 to 18 and pore sizes of 8-membered rings or less, operated at temperatures below 400°C, which stabilizes the catalyst and selectively produces acyclic C3-C6 olefins with reduced ethylene and coke formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small-pore zeolite catalysts (e.g., SSZ-13, SAPO-34) are used to convert methyl halides to light olefins, then high conversion rates are achieved, but catalyst deactivation occurs rapidly and selectivity to ethylene and coke increases
Solution Approach 1:
The patent applies parameter changes by modifying the Si/Al atomic ratio of the molecular sieve catalyst from the conventional low values (e.g., <100 for SSZ-13) to a specific range of 2-18. This parameter optimization balances the acidity required for high conversion with the structural stability needed to prevent rapid deactivation. The patent also optimizes the pore size parameter by selecting molecular sieves with 8-membered ring pores (e.g., CHA, AEI, DDR structures) that selectively promote C3-C6 olefin formation while reducing ethylene and coke production, thereby resolving the contradiction between productivity and reliability.
2Manufacturing precision
If small-pore zeolite catalysts are used, then high selectivity to ethylene is achieved, but selectivity to desired C3-C6 olefins decreases and coke formation increases
Solution Approach 1:
The patent applies local quality by selecting molecular sieves with specific pore structures (8-membered ring pores) that create localized reaction environments favorable for C3-C6 olefin formation. The patent also applies parameter changes by optimizing the Si/Al ratio to modulate the distribution and strength of acid sites within the catalyst, thereby directing the reaction pathway toward desired products while minimizing harmful coke formation. This selective control of local catalytic properties resolves the contradiction between ethylene selectivity and harmful byproduct formation.
3Productivity
If reaction temperature is increased to improve conversion, then productivity increases, but selectivity to ethylene and coke increases and catalyst deactivation accelerates
Solution Approach 1:
The patent applies parameter changes by optimizing the reaction temperature parameter to a specific range (200-400°C) that balances conversion rate with selectivity. Within this temperature window, the patent achieves high conversion to desired C3-C6 olefins while minimizing ethylene and coke formation. The optimized Si/Al ratio and pore structure parameters work synergistically with the temperature parameter to maintain catalyst stability and prevent deactivation, thereby resolving the contradiction between productivity and harmful byproduct formation.
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
The process achieves high selectivity to C3-C6 olefins (>75%) with low ethylene and coke production, maintaining catalyst stability for extended periods, contrary to previous systems that inhibited higher olefin production and suffered from rapid deactivation.
Implementation Method 1
providing a catalyst composition; and contacting said feedstream with the said catalyst composition under reaction conditions
Data Source
Figure 1~2
Figure 3
AI summary
The present disclosure relates to a process for converting one or more methyl halides to acyclic C3-C6 olefins, said process comprising the steps of (a) providing a feedstream comprising one or more methyl halides; (b) providing a catalyst composition; and (c) contacting said feedstream with said catalyst composition under reaction conditions. The process is remarkable in that said reaction conditions include a reaction temperature below 400°C, and in that said catalyst composition comprises one or more molecular sieves with a Si/Al atomic ratio ranging from 2 to 18 and wherein said one or more molecular sieves comprise a plurality of pores, wherein said pores have a shape of an 8-membered ring or less.