Integrated Para-Xylene Production Process
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Solution Overview
Problem
Existing refinery processes fail to effectively utilize C10+ fractions in naphtha streams, leading to underutilization of p-xylene and other xylene isomers, as these fractions are often purged due to catalyst deactivation and building up as unconverted fractions.
Innovation Solution
An integrated process involving catalytic reforming, solvent extraction, dealkylation, transalkylation, and isomerization is employed to convert C10+ fractions into para-xylenes, maximizing xylene and toluene yields by using a combination of de-alkylation and hydro-dearylation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If C10+ fractions are purged from the heavy stream in conventional processes, then catalyst deactivation is prevented, but significant amounts of p-xylene and other xylene isomers are lost
Solution Approach 1:
The patent converts the harmful C10+ fractions (which cause catalyst deactivation) into beneficial xylene products through a series of chemical reactions. The process uses dealkylation to break C10+ molecules into smaller aromatics, transalkylation to redistribute alkyl groups, and disproportionation to convert toluene and C9+ into xylenes. This transforms the problematic heavy fractions into valuable p-xylene and other xylene isomers, simultaneously preventing catalyst deactivation and maximizing xylene yield.
2Ease of operation
If conventional separation processes are used, then simple process operation is maintained, but the entire naphtha stream cannot be converted to xylene isomers
Solution Approach 1:
The patent segments the naphtha feed stream into different carbon ranges (C1-C7 and C8+) and processes each segment through tailored reaction pathways. The C1-C7 stream undergoes solvent extraction to remove aromatics, which are then upgraded through transalkylation and disproportionation. The C8+ stream is separated into C9+ and xylene fractions, with C9+ undergoing dealkylation and transalkylation. This segmentation allows each stream to be optimized for maximum xylene production while maintaining clear, manageable process flows.
3Quantity of substance
If C10+ fractions are recycled in conventional processes, then material utilization is improved, but unconverted fractions build up in the recycling streams
Solution Approach 1:
The patent implements continuous conversion of C10+ fractions through dealkylation, transalkylation, and disproportionation reactions, ensuring that recycled material is constantly transformed into valuable xylene products rather than accumulating. The process maintains steady-state operation where C10+ fractions entering the system are continuously converted, preventing buildup while maximizing material utilization. This continuous action converts the recycling challenge into an opportunity for sustained high-yield xylene production.
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 approach allows for the conversion of the entire heavy fraction of the naphtha feed stream into xylene isomers, particularly increasing para-xylene production and optimizing the use of naphtha streams, thereby enhancing overall yield and efficiency.
Implementation Method 1
a naphtha feed stream is sent to a catalytic reformer. The catalytic reformer reforms the naphtha stream into a reformate stream that is aromatics-rich
Implementation Method 2
exposing the C1-C7 hydrocarbon stream to a first solvent in a solvent extraction unit to form a non-aromatic hydrocarbon stream and an aromatics stream
Implementation Method 3
dealkylating the C9+ hydrocarbon stream in an dealkylation unit with a dealkylation catalyst, thereby forming a dealkylated product stream
Implementation Method 4
upgrading the toluene-rich transalkylation feed stream and the tri-methyl benzene rich stream in a transalkylation unit with a hydrogen stream and a transalkylation catalyst to produce an alkyl-benzene stream and additional amounts of non-aromatic hydrocarbon stream, aromatics stream, and xylene stream
Implementation Method 5
separating the xylene stream into a para-xylene stream and a xylene isomer stream; isomerizing the xylene isomer stream with a isomerization catalyst to produce a para-xylene rich stream
Data Source
AI summary
An integrated process for producing para-xylenes may include catalytically reforming a naphtha feed stream; separating the reformate stream into a C1-C7 hydrocarbon stream and a C8+ hydrocarbon stream; exposing the C1-C7 hydrocarbon stream to a first solvent in a solvent extraction unit to form a non-aromatic hydrocarbon stream and an aromatics stream; upgrading the aromatics stream to form a toluene-rich transalkylation feed stream; separating the C8+ hydrocarbon stream into a C9+ hydrocarbon stream, a para-xylene stream and a xylene isomer stream; dealkylating the C9+ hydrocarbon stream; separating the dealkylation product stream into an additional xylene stream and a tri-methyl benzene rich stream; and upgrading the toluene-rich transalkylation feed stream and the tri-methyl benzene rich stream with a hydrogen stream to produce an alkyl-benzene stream and additional xylene stream, wherein a ratio by weight of the toluene-rich transalkylation feed stream to the tri-methylbenzene rich stream is from 0.3 to 3.