Steam Cracking Integrated with Dual Catalyst Metathesis
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Solution Overview
Problem
Current steam cracking processes for producing olefins like ethylene and propene suffer from reduced selectivity and yield due to the production of C4+ compounds, and they are limited to specific hydrocarbon feedstocks such as naphtha and gas condensates, necessitating the development of more efficient systems for producing these valuable chemicals from a broader range of feedstocks.
Innovation Solution
Integration of a steam cracking system with a dual catalyst metathesis system, where the steam cracking effluent undergoes selective hydrogenation and isobutene removal to produce a metathesis feed, which is then processed with a metathesis catalyst and a cracking catalyst to enhance the yield and selectivity of ethylene and propene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is used to produce light olefins, then ethylene and propene can be obtained, but substantial amounts of C4+ compounds are produced which reduce the selectivity and yield of propene and ethylene
Solution Approach 1:
The patent converts the harmful byproduct C4+ compounds into beneficial products by integrating a metathesis system that transforms normal butenes into additional propene and ethylene. The metathesis catalyst and cracking catalyst work together to convert C4 compounds into light olefins, turning the waste stream into a valuable product stream and increasing overall yield.
Solution Approach 2:
The patent changes the chemical parameters of the C4+ compounds through metathesis reactions. By controlling the metathesis process conditions and catalyst selection, normal butenes are converted into different molecular weight distributions that favor propene and ethylene production, thereby changing the product composition from heavy to light olefins.
2Productivity
If steam cracking processes are used, then light olefins can be produced, but the process is limited to specific hydrocarbon feedstocks such as naphtha and gas condensates
Solution Approach 1:
The integrated metathesis-cracking system provides multi-functionality by being able to process various hydrocarbon feedstocks including but not limited to naphtha and gas condensates. The metathesis catalyst can handle different carbon chain lengths and structures, making the overall process versatile and adaptable to different feedstock types while maintaining high light olefin production.
3Quantity of substance
If C4+ compounds are produced in steam cracking, then the overall hydrocarbon conversion is maintained, but the selectivity to propene and ethylene decreases
Solution Approach 1:
The metathesis catalyst acts as an intermediary between the steam cracking process and the final product separation. It mediates the conversion of C4+ compounds by first performing metathesis reactions to create a mixture that includes normal butenes, which are then further converted by the cracking catalyst into propene and ethylene, thereby improving selectivity while maintaining overall conversion.
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 integrated system increases the yield and selectivity of propene and ethylene by converting C4+ compounds into additional ethylene and propene, thereby improving the overall efficiency of olefin production from a variety of hydrocarbon feedstocks.
Implementation Method 1
A metathesis system comprising a metathesis catalyst and a cracking catalyst downstream of the metathesis catalyst
Implementation Method 2
contacting with the cracking catalyst may cause at least a portion of the C5+ olefins produced through metathesis to undergo cracking reactions to produce propene, ethylene, or both
Implementation Method 3
Steam cracking units can be used to convert hydrocarbon feed streams to light olefins, such as ethylene and propene
Data Source
AI summary
Processes for producing olefins include integration of steam cracking with a dual catalyst metathesis process. The processes include steam cracking a hydrocarbon feed to form a cracking reaction effluent containing butenes, separating the cracking reaction effluent to produce a cracking C4 effluent including normal butenes, isobutene, and 1,3-butadiene, subjecting the cracking C4 effluent to selective hydrogenation to convert 1,3-butadiene in the cracking C4 effluent to normal butenes, removing isobutene from a hydrogenation effluent to produce a metathesis feed containing normal butenes, and contacting the metathesis feed with a metathesis catalyst and a cracking catalyst directly downstream of the metathesis catalyst to produce a metathesis reaction effluent. Contacting with the metathesis catalyst causes metathesis of normal butenes to produce ethylene, propene, and C5+ olefins, and contacting with the cracking catalyst causes C5+ olefins produced through metathesis to undergo cracking reactions to produce additional propene, ethylene, or both.