DAO Hydroprocessing for Haze-Free Heavy Base Oil at 0°C
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Solution Overview
Problem
Existing processes for producing heavy base oils from deasphalted oil (DAO) result in products with undesirable high pour and cloud points due to wax compounds, which can form haze at low temperatures, affecting visual quality and filterability, and reduce yield when additional dewaxing steps are applied.
Innovation Solution
A process involving hydrotreating, hydrocracking, catalytic dewaxing, and hydrofinishing of DAO using noble metal and metal-based catalysts to produce a haze-free at 0°C heavy base oil with improved cold-flow properties, maintaining stability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional dewaxing steps are applied to remove wax compounds, then cold flow properties are improved, but product yield is reduced
Solution Approach 1:
The invention changes the processing parameters by conducting hydrocracking at specific temperatures (350-500°C) and pressures (50-200 bar) with controlled hydrogen-to-oil ratios (300-1000 NL/kg) to achieve optimal dewaxing while maintaining high yield. The hydrofinishing step further refines the product at lower temperatures (200-400°C) to remove remaining haze precursors without excessive yield loss.
Solution Approach 2:
The invention uses composite catalyst systems combining hydrocracking catalysts (containing metal functions like Ni, Co, Mo, W on supports like alumina or silica-alumina) with hydrofinishing catalysts (containing noble metals like Pt or Pd on supports). This composite catalytic approach enables simultaneous dewaxing and haze precursor removal with improved selectivity and yield.
2Manufacturing precision
If severe process steps are applied to remove haze precursors, then visual quality is improved, but heavy base oil yield is reduced
Solution Approach 1:
The invention performs preliminary hydrocracking to break down large aromatic molecules and haze precursors before the final hydrofinishing step. This preliminary action reduces the burden on subsequent processing and enables better yield retention while achieving haze-free product quality.
Solution Approach 2:
The invention implements a continuous multi-stage process where hydrocracking feeds into hydrofinishing without interruption, maintaining continuous removal of haze precursors throughout the processing sequence. This continuous action ensures consistent visual quality while optimizing yield through integrated process design.
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 a haze-free heavy base oil with low pour and cloud points, maintaining stability at 0°C without agitation, and higher yields compared to conventional methods.
Implementation Method 1
hydrotreatment to remove nitrogen, sulfur, metals, and other contaminants
Implementation Method 2
hydrocracking to reduce the molecular weight of aromatic compounds
Implementation Method 3
catalytic dewaxing and hydrofinishing of the DAO can improve cold flow properties
Implementation Method 4
catalytic dewaxing and hydrofinishing of the DAO can improve cold flow properties
Data Source
AI summary
A process for producing a base oil composition from a deasphalted oil (DAO) feed, where the DAO feed undergoes hydrotreating, hydrocracking, catalytically dewaxing, hydrofinishing, and fractionating to generate the base oil composition. The base oil composition includes a hazy-free at 0°C heavy base oil comprising (a) a kinetic viscosity ranging from 15 to 21 cSt at 100°C, (b) a 5 viscosity index of at least 95, (c) a pour point of less than -12°C, (d) a cloud point of less than -18°C, and (e) a total aromatics content of 2 wt% or less, where the hazy-free at 0°C heavy base oil maintains a hazy-free appearance when stored undisturbed at 0°C during a test period.