Renewable Naphtha Aromatics Route via Toluene Disproportionation
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Solution Overview
Problem
Existing chemical industrial processes are unable to effectively produce benzene or para-xylene, which are crucial monocyclic aromatic hydrocarbons, using bio-naphtha due to its high ethylbenzene content, and lack methods to valorize renewable naphtha as a raw material.
Innovation Solution
A novel process combining pyrolysis, disproportionation, and transalkylation reactions, along with separation steps, to produce benzene, xylene, and para-xylene from renewable naphtha, followed by oxidation to terephthalic acid and condensation to polyethylene terephthalate, while managing the value assignment based on renewable naphtha content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bio-naphtha is used as raw material for production of monocyclic aromatic hydrocarbon, then renewable raw material utilization is improved, but the content ratio of ethylbenzene by-product becomes high making it unsuitable for para-xylene production
Solution Approach 1:
The patent segments the production process into distinct stages: pyrolysis to produce toluene, followed by disproportionation or transalkylation to produce xylene. This segmentation allows each stage to be optimized independently, with the pyrolysis stage handling the renewable naphtha input and the subsequent stages refining the product composition to achieve desired para-xylene content.
Solution Approach 2:
The patent uses toluene as an intermediary substance in the production process. Bio-naphtha is first pyrolyzed to produce toluene, which then serves as the feedstock for disproportionation or transalkylation reactions to produce xylene. This intermediary approach allows the process to transform the high ethylbenzene-content bio-naphtha into a product with suitable composition through controlled chemical reactions.
2Manufacturing precision
If conventional catalytic reforming reaction is used with heavy naphtha, then para-xylene production is achieved, but light naphtha or bio-naphtha cannot be used as raw material
Solution Approach 1:
The patent changes the fundamental reaction parameters and process conditions by replacing catalytic reforming with pyrolysis followed by disproportionation or transalkylation. This parameter change enables the process to accept light naphtha and bio-naphtha as raw materials, which have different compositional characteristics from heavy naphtha, while still producing para-xylene as the final product.
Solution Approach 2:
Instead of using catalytic reforming that requires heavy naphtha, the patent inverts the approach by using pyrolysis to break down naphtha into toluene, then using disproportionation or transalkylation to build up xylene. This inverted pathway allows flexibility in raw material selection, accepting lighter naphtha fractions and bio-naphtha that would be unsuitable for conventional catalytic reforming.
3Productivity
If pyrolysis of bio-naphtha is performed, then xylene is produced, but high ethylbenzene content makes it unsuitable for para-xylene production
Solution Approach 1:
The patent implements a continuous process where pyrolysis produces toluene, which immediately feeds into disproportionation or transalkylation reactions to produce xylene. This continuous transformation eliminates the accumulation of unwanted ethylbenzene by converting it through the reaction sequence, maintaining both productivity and product purity throughout the process.
Solution Approach 2:
The process effectively discards the problematic ethylbenzene intermediate by converting it through disproportionation or transalkylation reactions into desirable xylene products. The ethylbenzene that would normally be a by-product is recovered and transformed into valuable para-xylene, improving both productivity and product purity.
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
Enables the production of benzene, para-xylene, terephthalic acid, and polyethylene terephthalate from renewable naphtha, assigning value based on its content, thus promoting sustainable production and reducing carbon emissions.
Implementation Method 1
step (A-1) of pyrolyzing the naphtha raw material in the presence of water vapor, to produce and separate toluene
Implementation Method 2
step (A-2) of subjecting toluene to disproportionation reaction or transalkylation reaction, to produce and separate at least one monocyclic aromatic hydrocarbon of benzene or xylene
Implementation Method 3
step (A-4) of oxidizing the para-xylene, to obtain terephthalic acid
Implementation Method 4
step (A-5) of obtaining polyethylene terephthalate by condensation reaction of terephthalic acid and ethylene glycol
Data Source
AI summary
The invention provides a method capable of producing a monocyclic aromatic hydrocarbon such as benzene or xylene effective as a base raw material, with a naphtha raw material containing renewable naphtha. The method for producing at least one monocyclic aromatic hydrocarbon of benzene or xylene with a naphtha raw material containing renewable naphtha includes step (A-1) of pyrolyzing the naphtha raw material in the presence of water vapor, to produce and separate toluene, and step (A-2) of subjecting toluene to disproportionation reaction or transalkylation reaction, to produce and separate at least one monocyclic aromatic hydrocarbon of benzene or xylene.