Dual-Zeolite Catalyst System for Heavy Base Oil Haze Reduction
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Solution Overview
Problem
Conventional dewaxing methods struggle to effectively reduce haze in heavy base oil while minimizing yield loss, as haze-inducing substances like long-chain n-paraffins and cycloparaffins agglomerate at low temperatures, causing cloudiness and requiring severe reaction conditions that lead to undesired yield decreases.
Innovation Solution
A hydroisomerization process using a catalyst system with a first catalyst from the ZSM-12 family followed by a second catalyst from the ZSM-48 family, where the first catalytic region is upstream of the second, selectively removes haze-inducing substances through isomerization and cracking reactions, maintaining high yield and improving cold flow properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If severe dewaxing reaction conditions are applied to remove haze-inducing substances, then haze reduction is improved, but yield loss increases
Solution Approach 1:
The dewaxing process is divided into two sequential stages using different catalysts: first a cracking-dominant catalyst to break down large haze-inducing molecules, then an isomerization-dominant catalyst to convert remaining n-paraffins. This segmentation allows each stage to be optimized for its specific function, removing haze effectively while minimizing overall yield loss through selective reaction pathways.
Solution Approach 2:
The invention changes reaction parameters between stages: the first stage uses higher temperature (350-450°C) and lower pressure to favor cracking reactions for haze removal, while the second stage uses lower temperature (200-350°C) and higher pressure to favor isomerization and preserve yield. This parameter optimization resolves the contradiction between haze removal and yield maintenance.
2Loss of substance
If isomerization dominant dewaxing methods are used, then yield is improved, but haze reduction effectiveness decreases
Solution Approach 1:
The process segments haze removal and yield preservation into two distinct catalytic stages: the first stage specializes in cracking large haze-inducing molecules under conditions optimized for haze removal, while the second stage specializes in isomerization under conditions optimized for yield preservation. This segmentation allows the system to achieve both effective haze reduction and high yield that neither single-stage method can achieve alone.
3Object-affected harmful factors
If cracking dominant dewaxing methods are used, then haze reduction is improved, but yield loss increases significantly
Solution Approach 1:
The invention segments the cracking process into a first stage that performs aggressive cracking on large haze-inducing molecules followed by a second stage that performs gentle isomerization on the cracked products. This segmentation allows the cracking stage to focus on haze removal while the isomerization stage recovers yield by converting cracked n-paraffins into useful iso-paraffins, rather than letting them remain as low-value byproducts.
Solution Approach 2:
The invention converts the harmful effect of cracking (which typically causes excessive yield loss) into a benefit by immediately followed by isomerization. The cracking stage deliberately breaks down large haze-inducing molecules, and the subsequent isomerization stage converts the resulting cracked products into valuable iso-paraffins, transforming what would be yield-loss-generating cracking into a yield-preserving two-stage process.
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 effectively reduces haze in heavy base oil while maintaining a high yield, improving cold flow properties and achieving reduced haze in the final product, outperforming previous methods by selectively removing haze-inducing substances without significant yield loss.
Implementation Method 1
A process for reducing haze in a heavy base oil may include: obtaining a first effluent oil by contacting a hydrocarbon feedstock with a first catalyst including a zeolite of the ZSM-12 family; and obtaining a second effluent oil by contacting the first effluent oil with a second catalyst including a zeolite of the ZSM-48 family.
Data Source
AI summary
A process for reducing haze in a heavy base oil includes: obtaining a first effluent oil by contacting a hydrocarbon feedstock with a first catalyst including a zeolite of the ZSM-12 family; and obtaining a second effluent oil by contacting the first effluent oil with a second catalyst including a zeolite of the ZSM-48 family. A hydroisomerization catalyst system having reduced haze includes: a first catalytic region having a first catalyst disposed therein, the first catalyst including a zeolite of the ZSM-12 family; and a second catalytic region having a second catalyst disposed therein, the second catalyst including a zeolite of the ZSM-48 family. The first catalytic region is disposed upstream of the second catalytic region.