Titanium-MWW Zeolite Two-Stage Crystallization
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Solution Overview
Problem
Current methods for producing titanium-MWW zeolites are lengthy and inefficient, requiring high-temperature crystallization processes that take several days, which limits the production of high activity catalysts.
Innovation Solution
A process involving the heating of a gel formed from a titanium compound, silicon source, boron source, and MWW templating agent at lower temperatures (35°C to 75°C) for 8 to 30 hours, followed by higher temperature heating (160°C to 190°C) for 5 or more days to form a titanium-MWW zeolite, which is then activated with an acid to enhance its catalytic properties for olefin epoxidation with hydrogen peroxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature crystallization processes are used to produce titanium-MWW zeolites, then the catalyst formation is complete, but the production time is excessively long (several days)
Solution Approach 1:
The crystallization process is divided into two distinct stages: a first crystallization stage at a first temperature (e.g., 100-200°C) and a second crystallization stage at a second temperature (e.g., 200-350°C). This segmentation allows each stage to optimize for different aspects of crystal formation, reducing the total time required while ensuring complete catalyst formation.
Solution Approach 2:
The patent employs temperature parameter changes by conducting crystallization at different temperatures in sequence. The first stage uses a lower temperature to initiate crystal formation, and the second stage uses a higher temperature to complete the process, thereby reducing overall production time while maintaining catalyst quality.
2Reliability
If prolonged heating at high temperatures is applied, then titanium-MWW zeolite synthesis is completed, but the process efficiency is low
Solution Approach 1:
The synthesis process is segmented into multiple crystallization stages with different temperature parameters. This segmentation enables the process to achieve complete synthesis without requiring prolonged single-stage heating, thereby improving overall process efficiency while ensuring synthesis completion.
Solution Approach 2:
The multi-stage crystallization process maintains continuous useful action by transitioning from one crystallization stage to the next without significant interruption. Each stage builds upon the previous stage's results, ensuring continuous progress toward complete synthesis while reducing total time required.
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 process significantly reduces the time required to produce active titanium-MWW zeolites, resulting in a more efficient catalyst formation that is effective in olefin epoxidation reactions, particularly for converting propylene to propylene oxide.
Implementation Method 1
heating a gel formed from a titanium compound, a silicon source, a boron source, an MWW templating agent selected from piperidine and hexamethyleneimine, and water at a temperature in the range of 35°C to 75°C for a period of 8 to 30 hours to form a pre-crystallized gel
Implementation Method 2
heating the pre-crystallized gel to a temperature in the range of 160°C to 190°C for a period of 5 or more days to form the titanium-MWW zeolite
Implementation Method 3
The MWW-templating agent is piperidine or hexamethyleneimine. The zeolite, after it is contacted with an acid, is active in olefin epoxidations with hydrogen peroxide
Data Source
AI summary
Titanium-MWW zeolite is prepared by heating a gel formed from a titanium compound, a silicon source, a boron source, an MWW-tem plating agent, and water at a temperature in the range of 35°C to 75°C for a period of 8 to 30 hours to form a pre-crystallized gel, and heating the p re-crystallized gel to a temperature in the range of 160°C to 190°C for a period of 5 or more days to form the titanium-MWW zeolite. The zeolite, after it is contacted with an acid, is useful in olefin epoxidation with hydrogen peroxide.