Two-Reactor Pyrolysis Oil Deoxygenation to Prevent Catalyst Plugging
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Solution Overview
Problem
Pyrolysis oil deoxygenation processes result in catalyst plugging and fouling due to the formation of solids, and hydrogenation of aromatics, which lowers the octane rating of resulting naphtha, limiting the utilization of pyrolysis oil as a biofuel.
Innovation Solution
A method involving partial deoxygenation in a first reactor using a deoxygenation catalyst, followed by simultaneous deoxygenation and dehydrogenation in a second reactor with a dehydrogenation catalyst, minimizing plugging and preserving aromatic compounds to enhance the octane rating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If complete deoxygenation is performed in a single reactor, then oxygen removal is maximized, but catalyst plugging and fouling increase due to solid formation
Solution Approach 1:
The deoxygenation process is divided into two separate reactors: a first reactor for initial deoxygenation and a second reactor for complete deoxygenation. This segmentation allows the first reactor to handle the bulk of oxygen removal while preventing excessive solid formation that would plague a single reactor system, thereby maintaining catalyst activity and reducing plugging issues.
Solution Approach 2:
The first reactor performs preliminary deoxygenation to remove a significant portion of oxygen before the feed enters the second reactor. This preliminary action reduces the oxygen load on the second reactor's catalyst, preventing rapid deoxygenation that would generate excessive solids and cause plugging, while still achieving complete deoxygenation overall.
2Productivity
If deoxygenation is performed at high temperature, then deoxygenation efficiency is improved, but hydrogenation of aromatics occurs which lowers octane rating
Solution Approach 1:
The two-reactor system allows different temperature and catalyst conditions in each reactor. The first reactor can operate at conditions optimized for deoxygenation without excessive hydrogenation, while the second reactor completes deoxygenation. This segmentation enables better control over selectivity and reduces unwanted aromatic hydrogenation that would occur in a single high-temperature reactor.
3Quantity of substance
If deoxygenation is performed, then oxygen content is reduced, but reaction duration is limited due to catalyst deactivation from solids
Solution Approach 1:
By dividing the deoxygenation into two reactors, each catalyst bed operates for longer durations without deactivation. The first reactor's catalyst handles the initial oxygen removal with manageable solid formation, while the second reactor's catalyst receives pre-treated feed with less oxygen, reducing its deactivation rate and extending its operational life.
Solution Approach 2:
The first reactor performs preliminary deoxygenation to reduce the oxygen content before feed enters the second reactor. This preliminary action protects the second reactor's catalyst from rapid deactivation by excessive solid formation, thereby extending the overall reaction duration and reducing the frequency of catalyst regeneration or replacement.
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 reduces catalyst plugging, maintains aromatic compounds, and increases the octane rating of the naphtha, while minimizing hydrogenation and polymer formation, thereby improving the efficiency and quality of biofuel production.
Implementation Method 1
contacting a pyrolysis oil with a deoxygenation catalyst in a first reactor at deoxygenation conditions to produce a first reactor effluent
Implementation Method 2
The first reactor effluent is contacted with a dehydrogenation catalyst in a second reactor at conditions that deoxygenate the first reactor effluent while preserving the aromatic compound
Data Source
AI summary
Methods and apparatuses are provided for deoxygenating pyrolysis oil. A method includes contacting a pyrolysis oil with a deoxygenation catalyst in a first reactor at deoxygenation conditions to produce a first reactor effluent. The first reactor effluent has a first oxygen concentration and a first hydrogen concentration, based on hydrocarbons in the first reactor effluent, and the first reactor effluent includes an aromatic compound. The first reactor effluent is contacted with a dehydrogenation catalyst in a second reactor at conditions that deoxygenate the first reactor effluent while preserving the aromatic compound to produce a second reactor effluent. The second reactor effluent has a second oxygen concentration lower than the first oxygen concentration and a second hydrogen concentration that is equal to or lower than the first hydrogen concentration, where the second oxygen concentration and the second hydrogen concentration are based on the hydrocarbons in the second reactor effluent.