ZSM-48 Catalyst Morphology Control for Lubricant Base Stock
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Solution Overview
Problem
Current methods for synthesizing ZSM-48 zeolite crystals often result in irregular shapes and mixed morphologies, which can affect catalytic activity and yield in lubricant base stock production, and existing catalysts may not achieve optimal dewaxing and aromatic saturation during petroleum processing.
Innovation Solution
A method involving a synthesis mixture with a dominant diquaternary ammonium structure directing agent and a secondary tetraalkyl ammonium hydroxide agent to form ZSM-48 crystals, which are then used as a catalyst for dewaxing and aromatic saturation in lubricant base stock production, optimizing crystal morphology and catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-ZSM-48 seed crystals are used in the synthesis mixture, then ZSM-48 crystals can be formed, but the resulting crystals have irregular shapes and mixed morphologies which reduce catalytic activity
Solution Approach 1:
The patent removes non-ZSM-48 seed crystals from the synthesis mixture, extracting the source of morphological defects. This allows the formation of ZSM-48 crystals with uniform morphology and improved catalytic activity, while still achieving successful crystal formation through the optimized synthesis conditions.
Solution Approach 2:
The patent modifies synthesis parameters including the silica-to-alumina ratio (70:1 to 150:1), structure directing agent composition and concentration, pH, and temperature to optimize crystal formation. These parameter changes enable the formation of uniform ZSM-48 crystals without requiring non-ZSM-48 seeds, thereby improving both ease of manufacture and manufacturing precision.
2Shape
If the silica to alumina ratio is increased to 70:1 to 150:1, then fibrous morphology is eliminated, but crystal formation becomes more difficult without non-ZSM-48 seeds
Solution Approach 1:
The patent introduces a specific structure directing agent (SDA) system as an intermediary to facilitate crystal formation under the optimized silica-to-alumina ratio. The SDA mediates between the reactants and the desired crystal structure, enabling uniform ZSM-48 crystal formation without fibrous morphology and without requiring non-ZSM-48 seeds.
Solution Approach 2:
The patent optimizes multiple synthesis parameters simultaneously, including the silica-to-alumina ratio (70:1 to 150:1), structure directing agent type and concentration, pH, and temperature. These coordinated parameter changes enable the formation of uniform crystals while maintaining ease of manufacture by eliminating the need for non-ZSM-48 seeds.
3Productivity
If conventional catalysts are used for dewaxing, then the process can proceed, but optimal dewaxing and aromatic saturation are not achieved
Solution Approach 1:
The patent optimizes catalyst parameters including the silica-to-alumina ratio (70:1 to 150:1), crystal morphology, and structure directing agent composition to achieve optimal dewaxing and aromatic saturation. These parameter changes improve both productivity by enhancing dewaxing efficiency and reliability by ensuring consistent product quality.
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 approach results in ZSM-48 crystals with improved activity and yield in lubricant base stock production, enhancing the dewaxing process and aromatic saturation, leading to higher quality petroleum products.
Implementation Method 1
ZSM-48 crystals having a molar ratio of SiO2 to Al2O3 of 70 to 1 to 150 to 1
Implementation Method 2
exposing a feedstock having a T5 boiling point of at least 400°F (204°C) to a catalyst comprising ZSM-48 crystals under effective dewaxing conditions to form a dewaxed effluent
Data Source
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AI summary
Methods are provided for using a dewaxing catalyst formed using at least two structure directing agents for production of a lubricant base stock. For example, ZSM-48 crystals formed using multiple directing agents (and/or formulated catalysts made using such crystals) can have an increased activity and/or can provide an improved yield during catalytic production of lubricant base stocks. Additionally or alternately, ZSM-48 crystals formed using multiple directing agents (and/or formulated catalysts made using such crystals) can provide improved aromatic saturation during processing of a feed for lubricant base stock production.