Pyrolysis Oil BTX Upgrading with Sequential Fixed-Bed Catalysts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for upgrading pyrolysis oil to light aromatic compounds, such as benzene, toluene, and xylenes, face challenges in achieving sufficient yield and efficiency under mild conditions, often requiring complex and severe reaction conditions.
Innovation Solution
A two-stage fixed-bed catalytic process using a mixed metal oxide catalyst in the first reactor and a mesoporous supported metal catalyst in the second reactor, converting multi-ring aromatic compounds to di-aromatic and then to light aromatic compounds, respectively, with nickel and tungsten impregnated onto a mesoporous support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple reactions are accomplished in a single processing step, then the process complexity is reduced, but the yield is insufficient to meet demand
Solution Approach 1:
The single processing step is segmented into two sequential fixed-bed reactor stages, each performing specific reactions. The first reactor handles hydrogenation and ring-opening, while the second reactor performs disproportionation and dealkylation, thereby maintaining process simplicity while achieving high BTEX yield through specialized reaction zones.
Solution Approach 2:
Different catalysts with specific properties are placed in different reactor zones to optimize local reaction conditions. The first reactor uses a catalyst suited for hydrogenation, while the second uses a catalyst optimized for disproportionation, allowing each stage to perform its function efficiently without interfering with the other.
2Productivity
If combinations of reactions are accomplished, then the conversion efficiency is improved, but severe conditions are required
Solution Approach 1:
The reaction conditions are optimized by adjusting temperature, pressure, and catalyst composition parameters across the two reactor stages. The first reactor operates under conditions favorable for hydrogenation, while the second reactor uses conditions optimized for disproportionation, achieving high conversion efficiency without requiring uniformly severe conditions throughout the process.
Solution Approach 2:
Composite catalyst systems are used in each reactor, combining multiple metal components and support materials with specific properties. This allows the catalysts to facilitate multiple reactions simultaneously under milder conditions by providing active sites with different functionalities and electronic properties.
3Device complexity
If conventional methods are used, then the process is simpler, but the yield of BTEX is lower
Solution Approach 1:
The process is segmented into two specialized reactor stages instead of using a single conventional reactor, allowing each stage to optimize for specific reaction types and thereby achieve higher overall BTEX yield while maintaining operational simplicity.
Solution Approach 2:
Each reactor stage is equipped with catalysts having locally optimized properties for their specific function, creating zones of enhanced reaction efficiency that collectively produce higher BTEX yields compared to conventional uniform processing methods.
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 higher yields of light aromatic compounds with improved efficiency and stability under mild conditions, eliminating the need for catalyst separation and recycle steps.
Implementation Method 1
contacting the pyrolysis oil feed with hydrogen in the presence of a mixed metal oxide catalyst in a first fixed-bed reactor may cause at least a portion of the multi-ring aromatic compounds in the pyrolysis oil feed to react to produce an intermediate stream comprising di-aromatic compounds
Implementation Method 2
contacting the intermediate stream with hydrogen in the presence of a mesoporous supported metal catalyst in a second fixed-bed reactor may cause at least a portion of the di-aromatic compounds and/or tri-aromatic compounds in the intermediate stream to react to produce a second reactor effluent comprising aromatic compounds having six to eight carbon atoms
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 fixed-bed 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 fixed-bed reactor to convert at least a portion of the multi-ring aromatic compounds in the pyrolysis oil feed to di-aromatic compounds, tri-aromatic compounds, or both, passing an intermediate stream comprising the di-aromatic compounds, tri-aromatic compounds, or both to a second fixed-bed reactor downstream of the first fixed-bed reactor; and contacting the intermediate stream with hydrogen in the presence of a mesoporous supported metal catalyst in a second fixed-bed reactor.