Titanium-Doped Silica Catalyst with Pentahedral Ti Coordination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods fail to produce amorphous silica materials with pentahedrally coordinated titanium species effective as catalysts for propylene oxide production, and there is a lack of robust processes for their manufacture.
Innovation Solution
A sol-gel process is used to create amorphous silica catalysts with pentahedrally coordinated titanium species by controlling water content, impurity removal, and titanium doping, followed by aging, drying, and calcination to achieve specific textural properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional titanium doping methods are used on dry silica, then titanium can be incorporated into the silica structure, but pentahedrally coordinated titanium species cannot be formed
Solution Approach 1:
The patent applies preliminary action by performing titanium doping on wet silica gel before drying, rather than on dry silica. The titanium salt solution is impregnated into the wet gel structure, allowing titanium to be incorporated into the silica network while maintaining the coordination structure. Only after this preliminary doping step is the material dried, preserving the pentahedral titanium coordination that would otherwise be lost.
2Productivity
If water glass with low viscosity is used, then the sol-gel process proceeds quickly, but the residual water content is too low to form pentahedral titanium coordination
Solution Approach 1:
The patent applies parameter changes by carefully controlling the viscosity of water glass within the specific range of 400-600 mPa·s. This parameter optimization balances two competing requirements: sufficient water content (20-40 wt%) to enable pentahedral titanium coordination formation, and adequate gelation speed for practical production. The viscosity parameter directly influences both water content and gelation kinetics.
3Manufacturing precision
If multiple impurity removal steps are added, then catalyst purity increases, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges multiple functions into a single washing step using acidic aqueous solution. This combined step simultaneously removes metal ion impurities from the silica gel and maintains the gel structure integrity. The acidic wash solution serves dual purposes: purification and structural preservation, eliminating the need for separate treatment steps and simplifying the overall manufacturing process.
4Manufacturing precision
If aging time is extended, then titanium coordination structure develops better, but production time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the aging temperature within the range of 60-90°C. This temperature optimization accelerates the formation of pentahedral titanium coordination structures, achieving sufficient structural development in 4-6 hours rather than requiring extended aging times at lower temperatures. The temperature parameter is carefully controlled to balance reaction kinetics with energy consumption.
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 resulting catalysts exhibit high activity and selectivity for transforming propylene into propylene oxide, suitable for large-scale industrial production.
Implementation Method 1
adding water glass exhibiting a viscosity in the range of 400 to 600 mPa*s into an acid, thereby yielding silica gel exhibiting residual water content Xwa in the range between Xw1 and Xw2
Implementation Method 2
doping said purified silica gel by contacting the purified silica gel with an acidic aqueous solution of a titanium salt, thereby yielding titanium-doped silica gel
Implementation Method 3
aging said titanium-doped silica gel by suspending the titanium-doped silica gel in an aging-solution for a time span in the range between 4 h and 6 h at a temperature in the range between 60° C. and 90° C.
Implementation Method 4
c. calcining of dried catalyst hydrogel-precursor
Data Source
AI summary
The present invention relates to processes for preparing propylene oxide, comprising reaction of propene with ethylbenzene hydroperoxide in the presence of a catalyst, as well as to catalysts employed in such processes and to methods for their manufacture. The catalysts of the invention are prepared in a process comprising sol-gel-synthesis of catalyst hydrogel-precursor, drying of catalyst hydrogel precursor, calcining of dried catalyst hydrogel-precursor, and optionally hydrophobizing the calcined catalyst hydrogel-precursor. The catalysts of the invention comprise amorphous titanium doped silica comprising pentahedrally coordinated titanium species.