Yttrium-Stabilized Zeolite Catalysts for Fluid Cracking
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Solution Overview
Problem
The degradation of zeolite structure and loss of surface area during the manufacture and use of zeolite-containing catalysts in fluid catalytic cracking processes, leading to reduced cracking activity and frequent catalyst replacement, is exacerbated by the use of peptized aluminas due to lower pH conditions.
Innovation Solution
Incorporating yttrium into the zeolite combined with peptized alumina, either as a water-soluble salt or as a rare earth element, to enhance zeolite surface area retention and attrition resistance, while minimizing the presence of divalent metal cations to stabilize the zeolite structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If peptized alumina is used to manufacture zeolite-containing catalysts, then attrition resistance is improved, but zeolite surface area is lost due to structure degradation
Solution Approach 1:
Yttrium is introduced as an intermediary substance that mediates between the peptized alumina and zeolite structure. The yttrium stabilizes the zeolite framework during the acid treatment process, preventing alumina leaching while maintaining the benefits of peptized alumina for attrition resistance.
Solution Approach 2:
The invention changes the chemical composition parameters by adding yttrium to the catalyst system. This parameter change modifies the chemical environment during catalyst formation, raising the pH stability and preventing zeolite structure degradation while maintaining peptized alumina's attrition resistance properties.
2Duration of action of stationary object
If acid treatment is applied to alumina to improve attrition resistance, then catalyst durability is enhanced, but zeolite structure stability deteriorates
Solution Approach 1:
Yttrium acts as a protective intermediary during acid treatment of alumina. It buffers the acidic environment's effect on the zeolite structure, allowing the alumina to be properly peptized for durability while the zeolite remains stable through yttrium's stabilizing presence.
Solution Approach 2:
The invention creates a composite catalyst system containing alumina, zeolite, and yttrium. This composite structure combines the durability benefits of peptized alumina with the structural stability provided by yttrium-stabilized zeolite, achieving both catalyst durability and zeolite stability simultaneously.
3Productivity
If rare earth metals are added to enhance catalyst performance, then cracking activity is improved, but zeolite structure degradation is accelerated
Solution Approach 1:
The invention extracts or removes harmful rare earth metals from the catalyst system and replaces them with yttrium. This extraction eliminates the zeolite-degrading effect of traditional rare earth metals while maintaining the desired cracking activity through yttrium's catalytic properties.
Solution Approach 2:
The invention changes the rare earth metal composition parameter by substituting harmful rare earth metals with yttrium. This parameter change maintains the catalytic activity needed for cracking while eliminating the structural degradation caused by traditional rare earth metal additions.
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 addition of yttrium significantly improves zeolite surface area retention and attrition resistance, resulting in a more stable and longer-lasting catalyst with improved cracking activity, reducing the need for frequent catalyst replacement.
Implementation Method 1
adding yttrium can improve retention of zeolite surface area when using peptized alumina to manufacture a zeolite-containing catalyst
Implementation Method 2
the lower pH in catalyst preparation slurries containing peptized aluminas lead to leaching of alumina from the silica alumina structures of the zeolite
Implementation Method 3
Incorporating yttrium into the zeolite combined with peptized alumina, either as a water-soluble salt or as a rare earth element, to enhance zeolite surface area retention and attrition resistance
Data Source
AI summary
This invention relates to a process of preparing a catalyst from zeolite and peptized alumina. The invention comprises adding a yttrium compound to the zeolite, either prior to, during, or after its combination with the peptized alumina. The yttrium compound can be added to the zeolite via exchange of yttrium onto the zeolite prior to addition of peptized alumina, or the yttrium can be added as a soluble salt during the combination of the zeolite and peptized alumina. In either embodiment, the zeolite catalyst is then formed from the zeolite, yttrium and peptized alumina, optionally containing other inorganic oxide. This invention is suitable for preparing fluid cracking catalysts.