Pygas Upgrading to BTX via Segmented Aromatization
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Solution Overview
Problem
Current processes for producing aromatic compounds from pyrolysis gasoline are limited by the low recovery of higher value aromatics due to the presence of lower value C5 and greater non-aromatics, which reduces the yield of valuable benzene, toluene, and xylenes.
Innovation Solution
A method involving aromatization of pyrolysis gasoline in an aromatization unit to convert C5-C6 non-aromatic hydrocarbons to benzene-toluene-xylenes (BTX), followed by hydrotreatment, hydrodealkylation-transalkylation, and processing in an aromatics recovery complex to enhance the recovery of benzene, toluene, and xylenes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrolysis gasoline is processed using traditional methods, then the process is simple, but the recovery of higher value aromatics is limited
Solution Approach 1:
The patent divides the pyrolysis gasoline processing into multiple distinct units: aromatization unit, selective hydrotreatment unit, hydrodealkylation-transalkylation unit, and aromatics recovery complex. Each unit performs a specific function to convert non-aromatic hydrocarbons into aromatic compounds through sequential chemical transformations, thereby increasing the overall recovery of valuable aromatics while managing process complexity through modular design
Solution Approach 2:
The patent employs multiple chemical reactions that change the molecular structure and composition parameters of the hydrocarbon stream. The aromatization unit converts non-aromatics to aromatics through cyclization and dehydrogenation reactions, the hydrotreatment unit adjusts hydrogen content and removes olefins, and the hydrodealkylation-transalkylation unit modifies the carbon distribution among aromatic products, thereby optimizing the final aromatic composition
2Productivity
If C5-C6 non-aromatic hydrocarbons are converted to BTX, then the yield of aromatic compounds increases, but the process requires multiple treatment steps
Solution Approach 1:
The patent performs preliminary aromatization of the pyrolysis gasoline to convert non-aromatic hydrocarbons into aromatic compounds before the main separation and recovery process. This preliminary chemical transformation creates the necessary aromatic species that can then be selectively recovered in the subsequent aromatics recovery complex, thereby ensuring high yield while organizing the complex process into logical sequential stages
3Productivity
If steam cracking is used to produce ethylene, then ethylene production is efficient, but coking occurs as an unwanted side reaction
Solution Approach 1:
The patent addresses the coking problem by using the aromatic compounds produced during the aromatization process as beneficial products rather than viewing them as unwanted byproducts. The selective hydrotreatment and hydrodealkylation units then process these aromatics into high-value BTX products, converting what could be considered harmful coke-prone conditions into valuable aromatic chemistry opportunities
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 significantly increases the recovery of aromatic compounds, particularly benzene, toluene, and xylenes, improving the overall yield and value of the aromatic products compared to traditional methods.
Implementation Method 1
aromatizing the pyrolysis gasoline in an aromatization unit, thereby converting the C5-C6 non-aromatic hydrocarbons to a first stream comprising benzene-toluene-xylenes (BTX)
Implementation Method 2
hydrotreating the first stream comprising BTX in a selective hydrotreatment unit, thereby producing a de-olefinated stream comprising BTX
Implementation Method 3
hydrodealkylating and transalkylating the de-olefinated stream comprising BTX in a hydrodealkylation-transalkylation unit
Implementation Method 4
hydrodealkylating and transalkylating the de-olefinated stream comprising BTX in a hydrodealkylation-transalkylation unit
Data Source
AI summary
In accordance with one or more embodiments of the present disclosure, a method for producing aromatic compounds from pyrolysis gasoline comprising C5-C6 non-aromatic hydrocarbons includes aromatizing the pyrolysis gasoline in an aromatization unit, thereby converting the C5-C6 non-aromatic hydrocarbons to a first stream comprising benzene-toluene-xylenes (BTX); hydrotreating the first stream comprising BTX in a selective hydrotreatment unit, thereby producing a de-olefinated stream comprising BTX hydrodealkylating and transalkylating the de-olefinated stream comprising BTX in a hydrodealkylation-transalkylation unit, thereby producing a second stream comprising BTX, the second stream comprising BTX having a greater amount of benzene and xylenes than the first stream comprising BTX; and processing the second stream comprising BTX in an aromatics recovery complex, thereby producing the aromatic compounds from the pyrolysis gasoline, the aromatic compounds comprising benzene, toluene, and xylenes.