Phosphorus-Free CHA Zeolite Catalyst for Olefin Selectivity
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Solution Overview
Problem
Current catalysts for converting oxygenates to olefins, such as methanol to olefins (MTO) processes, face challenges in achieving high activity and selectivity, particularly for longer chain light olefins, with SAPO-34 catalysts experiencing rapid deactivation and ZSM-5 catalysts having lower selectivities.
Innovation Solution
A catalyst comprising a zeolitic material with the CHA framework structure, free from phosphorous, and incorporating one or more alkaline earth metals like Mg, Ca, or Sr, which enhances the activity and selectivity of oxygenate conversion to olefins, extending the time on stream and improving selectivity towards longer chain light olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SAPO-34 catalyst is used for MTO reaction, then high selectivity to lower olefins is achieved, but rapid deactivation occurs
Solution Approach 1:
The invention extracts phosphorous from the CHA framework structure to eliminate the rapid deactivation problem while retaining the high selectivity to lower olefins. The patent specifically states that removing phosphorous from the framework eliminates the deactivation issue that plagues SAPO-34 catalysts.
Solution Approach 2:
The invention creates a composite catalyst system combining phosphorous-free CHA zeolite with alkaline earth metals (Mg, Ca, Sr, or Ba). This composite approach enhances catalyst stability and extends lifetime while maintaining the high selectivity characteristics of the CHA structure.
2Duration of action of stationary object
If ZSM-5 catalyst is used for MTO reaction, then slower deactivation is achieved, but lower olefin selectivity results
Solution Approach 1:
The invention modifies the local quality of the CHA framework by incorporating alkaline earth metals at specific sites within the zeolite structure. This local modification enhances the catalyst's ability to produce olefins while maintaining structural stability and extended lifetime.
Solution Approach 2:
The invention changes the chemical composition parameters of the CHA framework by removing phosphorous and incorporating alkaline earth metals. This parameter change transforms the catalyst properties to achieve both high olefin selectivity and extended catalyst lifetime simultaneously.
3Productivity
If phosphorous is included in CHA framework, then catalyst activity is enhanced, but rapid deactivation occurs
Solution Approach 1:
The invention extracts phosphorous from the CHA framework to eliminate the deactivation pathway while preserving catalytic activity through the alkaline earth metal incorporation. The patent explicitly states that phosphorous removal eliminates rapid deactivation.
Solution Approach 2:
The invention changes the compositional parameters by replacing phosphorous with alkaline earth metals in the CHA framework. This parameter substitution maintains catalyst activity while fundamentally improving catalyst lifetime and stability.
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 catalyst demonstrates high activity and selectivity in converting oxygenates to olefins, comparable to SAPO-based materials, with extended catalyst life and improved selectivity, particularly for longer chain light olefins, by using a phosphorous-free CHA framework with alkaline earth metal incorporation.
Implementation Method 1
A catalyst comprising a zeolitic material with the CHA framework structure, free from phosphorous, and incorporating one or more alkaline earth metals like Mg, Ca, or Sr, which enhances the activity and selectivity of oxygenate conversion to olefins
Data Source
AI summary
The present invention relates to catalyst comprising one or more metal oxides and/or metalloid oxides and a zeolitic material having the CHA framework structure comprising YO2 and X2O3, wherein Y is a tetravalent element and X is a trivalent element, wherein the zeolitic material comprises one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba, and combinations of two or more thereof, and wherein the framework of the zeolitic material comprised in the catalyst contains substantially no phosphorous, as well as to a process for the preparation of a catalyst comprising one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba, and combinations of two or more thereof and to a catalyst obtainable therefrom. Furthermore, the present invention relates to a method for the conversion of oxygenates to olefins employing the inventive catalyst, as well as to the use of the inventive catalyst in specific applications.