Two-Stage Hydrofinishing for Low-Aromatic Base Oils
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Solution Overview
Problem
Modern refining processes for producing lubricating oils often result in base oils with undesirable levels of aromatics, residual organic sulfur, and/or nitrogen, despite using hydrogen processes to improve lubricating properties and low temperature performance.
Innovation Solution
A two-stage hydrofinishing process using a crystalline molecular sieve SSZ-91 and noble metal catalysts under varying temperature conditions to produce a low aromatic base oil, with the second stage operating at a lower temperature than the first.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage hydrofinishing process is used, then the process complexity is low, but the aromatic content in the base oil remains high
Solution Approach 1:
The hydrofinishing process is divided into two distinct stages: first hydrofinishing at higher temperature (350-450°C) to remove sulfur and nitrogen, followed by second hydrofinishing at lower temperature (250-350°C) to saturate aromatic molecules. This segmentation allows each stage to target specific contaminants optimally, achieving low aromatic content (≤5 wt%) that cannot be attained in a single stage.
Solution Approach 2:
The invention changes the temperature parameter between stages - the first stage operates at higher temperature (350-450°C) for efficient removal of heteroatoms, while the second stage operates at lower temperature (250-350°C) to selectively saturate aromatic rings without excessive cracking. This parameter variation optimizes the removal of different harmful components at appropriate conditions.
2Productivity
If hydrofinishing is performed at high temperature to remove sulfur and nitrogen, then heteroatom removal efficiency is high, but aromatic saturation is incomplete
Solution Approach 1:
The process segments heteroatom removal and aromatic saturation into two sequential stages with different temperature conditions. The first high-temperature stage efficiently removes sulfur and nitrogen, while the second low-temperature stage focuses on aromatic saturation, ensuring both functions are optimally performed.
Solution Approach 2:
Temperature is changed between stages to match the optimal conditions for different reactions. High temperature (350-450°C) in the first stage maximizes heteroatom removal kinetics, while lower temperature (250-350°C) in the second stage favors aromatic hydrogenation without promoting unwanted side reactions.
3Object-generated harmful factors
If hydrofinishing is performed at low temperature to saturate aromatics, then aromatic content is reduced, but heteroatom removal is insufficient
Solution Approach 1:
The invention segments the treatment objectives into two stages: the first stage at high temperature handles heteroatom removal, while the second stage at lower temperature handles aromatic saturation. This segmentation ensures each function is performed under optimal conditions without compromise.
Solution Approach 2:
The temperature parameter is varied between stages to optimize different reaction pathways. The first stage uses high temperature (350-450°C) to accelerate heteroatom removal reactions, while the second stage uses lower temperature (250-350°C) to selectively saturate aromatics with minimal cracking.
4Object-generated harmful factors
If a two-stage hydrofinishing process is used, then aromatic content is significantly reduced, but the process complexity increases
Solution Approach 1:
The process is segmented into two hydrofinishing stages with different temperature conditions and catalyst requirements. This segmentation achieves superior aromatic reduction (≤5 wt%) that cannot be obtained in a single stage, justifying the increased complexity through significant performance improvement.
Solution Approach 2:
By changing temperature parameters between stages and using appropriate catalysts for each stage, the process achieves optimal aromatic saturation while maintaining reasonable operational complexity. The first stage (350-450°C) removes heteroatoms, and the second stage (250-350°C) saturates aromatics.
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 significantly reduces aromatics in the base oil by up to 50% compared to single-stage processes, resulting in a high-quality base oil with improved properties such as lower aromatics, pour point, and cloud point spread.
Implementation Method 1
contacting an isomerized stream with a noble metal hydrofinishing catalyst under 1st hydrofinishing conditions to provide a 1st hydrofinished stream
Implementation Method 2
Hydrodewaxing is typically a process for improving the low temperature properties by isomerizing the long chain waxy molecules
Implementation Method 3
Hydrofinishing typically describes a process to further upgrade the lubricating base oil quality including color and oxidation stability often by saturating the aromatic molecules
Data Source
AI summary
Described are processes to produce base oils with one more improved properties, e.g., lower aromatics, economically and/or efficiently. In some embodiments, the processes relate to two stage (or more) hydrofinishing which advantageously provides base oils with lower aromatics than comparable one stage processes.