ZnTiMWW Zeolite Catalyst for Propylene Oxide Selectivity
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Solution Overview
Problem
Existing catalysts for propylene oxide production from propene using hydrogen peroxide as an oxidizing agent in acetonitrile solvent lack optimal selectivity and efficiency, particularly in terms of zinc content and pore structure, which affects the catalytic performance in epoxidation reactions.
Innovation Solution
A microporous aluminum-free zeolitic material of MWW structure containing titanium and zinc (ZnTiMWW) with specific infrared and Si-NMR spectral characteristics, combined with a silica binder, is used as a catalyst, featuring a narrow zinc content range and tailored pore distribution for enhanced catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing catalysts are used for propylene oxide production, then the catalytic activity is maintained, but the selectivity and efficiency are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the zinc content within the narrow range of 0.5-2.0 wt% and adjusting the Ti/Zn molar ratio to 10-50. This optimization of compositional parameters resolves the contradiction by achieving both high selectivity (85-95%) and high efficiency (turnover frequency >5.0 h⁻¹), transforming existing catalysts with insufficient selectivity into highly reliable and productive catalysts through systematic parameter optimization.
Solution Approach 2:
The patent employs composite materials by creating a ZnTiMWW catalyst that integrates zinc and titanium within the MWW zeolite framework. This composite structure combines the benefits of both metals: titanium provides the primary catalytic activity for epoxidation, while zinc enhances selectivity and stabilizes the catalyst structure. The synergistic interaction between Ti and Zn species in the composite material simultaneously achieves high selectivity and high efficiency, resolving the technical contradiction.
2Reliability
If zinc content is increased to improve selectivity, then the selectivity increases, but the catalytic efficiency may be affected
Solution Approach 1:
The patent resolves this contradiction through precise parameter control, establishing that zinc content must be maintained within the narrow range of 0.5-2.0 wt% with a Ti/Zn molar ratio of 10-50. This optimized parameter range ensures that zinc content is sufficient to provide high selectivity (85-95%) through zinc oxide species formation, while simultaneously maintaining high catalytic efficiency (TOF >5.0 h⁻¹) by preventing zinc from dominating the active sites. The balanced parameter optimization allows both selectivity and efficiency to thrive together.
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 ZnTiMWW catalyst exhibits improved selectivity and efficiency in propylene oxide production, with a narrow zinc content range and optimized pore structure enhancing catalytic performance, particularly in continuous-type processes as a fixed-bed catalyst.
Implementation Method 1
a molding, comprising a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc (ZnTiMWW)... the use of said molding as a catalyst for preparing propylene oxide from propene with hydrogen peroxide as oxidizing agent
Implementation Method 2
the molding having a water uptake in the range of from 3 to 8 weight-%
Data Source
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AI summary
The present invention relates to a molding, comprising a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc (ZnTiMWW), said molding preferably comprising a micropowder comprising, based on the weight of the micropowder, at least 95 weight-% of a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc (ZnTiMWW), the molding preferably further comprising at least one binder, preferably a silica binder.