Two-Step C2+ Olefin Oligomerization for Higher-Carbon Olefins
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Solution Overview
Problem
Existing methods for upgrading light olefins to higher carbon olefins have limited efficiency and yield, particularly in producing specialty chemicals and fuels like jet fuel and diesel.
Innovation Solution
A two-step oligomerization process involving a first oligomerization in a serial reactor with a lights removal column and a second oligomerization using a fractionation column, followed by hydroprocessing, to convert ethylene and propylene to higher molecular weight olefins, optimizing catalysts and conditions for each step to enhance yield and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oligomerization methods are used to convert light olefins to higher carbon olefins, then the process is simple, but the yield and efficiency are limited
Solution Approach 1:
The oligomerization process is divided into multiple sequential reaction zones within a single reactor. The first reaction zone converts C2-C4 olefins to C6-C10 olefins, while the second reaction zone further converts these to C10-C20 olefins. This segmentation allows each zone to be optimized for specific conversion requirements, achieving high yield of higher carbon olefins while maintaining a relatively simple overall process structure.
2Productivity
If a single oligomerization step is used, then the process is simple, but the conversion efficiency of ethylene is insufficient
Solution Approach 1:
The reactor is divided into two distinct reaction zones with different catalyst systems and operating conditions. The first zone uses a catalyst optimized for C2-C4 to C6-C10 conversion, while the second zone uses a different catalyst optimized for C6-C10 to C10-C20 conversion. This segmentation enables high conversion efficiency of ethylene to higher carbon olefins in a single continuous process.
Solution Approach 2:
Two oligomerization reactions that would traditionally require separate units are merged into a single reactor with multiple zones. The effluent from the first reaction zone is directly fed into the second reaction zone without intermediate separation, combining the functionality of two process units into one while achieving high overall conversion efficiency.
3Manufacturing precision
If traditional separation methods are used after oligomerization, then the process is simple, but the purity of the isoolefinic stream is insufficient for specialty chemical production
Solution Approach 1:
A lights removal column is introduced as an intermediary separation unit between the reaction zone and the final product stream. This column selectively removes light components (unreacted C2-C4 olefins and gaseous byproducts) from the effluent, providing a purified intermediate stream that can be further processed or directly used as high-purity isoolefinic product for specialty chemical applications.
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 conversion of ethylene to C4+ olefins and produces an isoolefinic stream with enhanced yields of C6+ olefins, suitable for jet fuel and diesel production, with improved energy and cost efficiency.
Implementation Method 1
oligomerizing at least a portion of the ethylene stream to convert at least 90% of the ethylene contained in the ethylene stream to a C4+ olefin stream
Implementation Method 2
oligomerizing the C4+ olefin stream and a propylene/C4+ olefin stream in a second oligomerization unit to produce the isoolefinic stream
Data Source
AI summary
A method for producing an isoolefinic stream may include: oligomerizing an ethylene stream to a C4+ olefin stream in a first olefin oligomerization unit comprising a serial reactor and a lights removal column, wherein the C4+ olefin stream contains no greater than 10 wt % of methane, ethylene, and ethane combined; and wherein the ethylene stream contains at least 50 wt % ethylene, at least 2000 wppm ethane, no greater than 1000 wppm of methane, and no greater than 20 wppm each of carbon monoxide and hydrogen; and oligomerizing the C4+ olefin stream and a propylene/C4+ olefin stream in a second oligomerization unit to produce the isoolefinic stream.