Two-Stage Pyrolysis Oil Upgrading for Higher BTEX Yield
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Solution Overview
Problem
Conventional single-step processes for upgrading pyrolysis oil to light aromatic compounds, such as benzene, toluene, and xylenes, are complex and insufficient to meet demand, often requiring severe conditions.
Innovation Solution
A two-stage catalytic process using a mixed metal oxide catalyst in a first slurry reactor to convert multi-ring aromatic compounds to intermediate compounds, followed by a mesoporous zeolite supported metal catalyst in a second slurry reactor to produce light aromatic compounds with six to eight carbon atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-step process is used to convert multi-ring aromatic compounds to light aromatic compounds, then the process complexity is reduced, but the yield of BTEX is insufficient and severe conditions are required
Solution Approach 1:
The conversion process is divided into two distinct stages: first, multi-ring aromatic compounds are converted to intermediate aromatic compounds (naphthalene, anthracene, phenanthrene) in a first slurry reactor; second, these intermediates are converted to light aromatic compounds (BTEX) in a second slurry reactor. This segmentation allows each stage to be optimized independently, achieving high BTEX yield without requiring severe conditions throughout the entire process.
2Ease of operation
If conventional single-step processes are used, then the processing conditions can be simplified, but the demand for BTEX cannot be met
Solution Approach 1:
The two slurry reactors operate in continuous series, with the effluent from the first reactor feeding directly into the second reactor. This continuous operation ensures that multi-ring aromatic compounds are systematically converted through intermediates to final BTEX products without interruption, maintaining steady production levels that meet market demand while operating under manageable conditions.
3Productivity
If severe conditions are applied in single-step processes, then conversion can be achieved, but the processing conditions become difficult to accomplish
Solution Approach 1:
The process utilizes different catalysts optimized for specific reaction conditions in each stage. The first slurry reactor employs a catalyst system suitable for converting multi-ring aromatics to intermediates, while the second slurry reactor uses a different catalyst optimized for converting intermediates to BTEX. This parameter optimization allows each stage to operate under milder, more controllable conditions while maintaining high overall conversion efficiency.
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
Increases the yield of light aromatic compounds under mild conditions, overcoming the limitations of conventional single-step processes by achieving higher yields of BTEX through a two-stage catalytic process.
Implementation Method 1
contacting a pyrolysis oil feed with hydrogen in the presence of a mixed metal oxide catalyst in a first slurry reactor to convert at least a portion of the multi-ring aromatic compounds in the pyrolysis oil feed to intermediate aromatic compounds
Implementation Method 2
contacting the intermediate stream with hydrogen in the presence of a mesoporous zeolite supported metal catalyst in a second slurry reactor to convert at least a portion of the intermediate aromatic compounds in the intermediate stream to light aromatic compounds
Data Source
AI summary
A method for upgrading pyrolysis oil includes contacting a pyrolysis oil feed with hydrogen in the presence of a mixed metal oxide catalyst in a first slurry reactor, where: the pyrolysis oil feed comprises multi-ring aromatic compounds comprising greater than or equal to sixteen carbon atoms, and contacting the pyrolysis oil feed with hydrogen in the presence of the mixed metal oxide catalyst in the first slurry reactor to convert at least a portion of the multi-ring aromatic compounds in the pyrolysis oil feed to light aromatic compounds comprising di-aromatic compounds, tri-aromatic compounds, or both, passing an intermediate stream comprising the light aromatic compounds to a second slurry reactor downstream of the first slurry reactor; and contacting the intermediate stream with hydrogen in the presence of a mesoporous zeolite supported metal catalyst in a second slurry reactor.