Mesoporous Y Zeolite Catalyst for FCC Bottoms Cracking
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Solution Overview
Problem
Existing FCC catalysts face challenges in effectively cracking large hydrocarbon molecules due to pore size limitations, leading to over-cracking and coke formation, as zeolite pores are too small for heavy hydrocarbons, resulting in inefficient conversion and product yield imbalance.
Innovation Solution
A process involving the preparation of mesoporous Y zeolite enhanced with acidity using phosphoric acid and combined with alumina or silica binder, along with colloidal silica and boric acid, to create a bottoms cracking catalyst that accommodates larger hydrocarbon molecules, reducing over-cracking and enhancing conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional zeolite with small pore size is used for cracking, then cracking activity is improved, but large hydrocarbon molecules cannot access the pores leading to over-cracking and coke formation
Solution Approach 1:
The patent employs mesoporous zeolite with larger pore sizes (3-10 nm) compared to conventional microporous zeolite, enabling large hydrocarbon molecules to access the internal pores for cracking. This resolves the contradiction by providing both high cracking activity and access to large molecules, preventing over-cracking and coke formation on external surfaces.
Solution Approach 2:
The catalyst comprises a composite of mesoporous zeolite combined with matrix material (such as alumina or silica-alumina), creating a hierarchical structure that combines the high activity of zeolite with the accessibility of mesopores, allowing simultaneous cracking of various hydrocarbon sizes while maintaining selectivity.
2Adaptability or versatility
If zeolite pore size is increased to accommodate large hydrocarbons, then access to heavy fuel oil molecules is improved, but cracking selectivity and efficiency may be reduced
Solution Approach 1:
Mesoporous zeolite provides controlled porosity with pore sizes of 3-10 nm, which is large enough to accommodate heavy fuel oil molecules (C14-C60) while maintaining sufficient confinement for effective cracking reactions, thus preserving cracking efficiency while improving molecule access.
Solution Approach 2:
The catalyst structure exhibits local quality variations with mesoporous regions for molecule access and zeolite crystalline regions for cracking activity, creating different functional zones within the catalyst particle that optimize both accessibility and reaction efficiency locally.
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 process improves hydrocarbon conversion by reducing bottoms yield and increasing yields of gasoline and light cycle oil, optimizing the FCC unit's product distribution.
Implementation Method 1
acidity of the alumina is also enhanced by peptizing with phosphoric acid
Implementation Method 2
In the presence of an FCC catalyst heavy hydrocarbons are subjected to cracking in the FCC unit
Implementation Method 3
heavy hydrocarbons are subjected to cracking in the FCC unit
Implementation Method 4
acidity of the alumina is also enhanced by peptizing with phosphoric acid
Data Source
AI summary
The present disclosure generally relates to the processing of petroleum-based materials. The present invention disclosure specifically relates to a process for preparing bottoms cracking catalyst for fluid catalytic cracking unit, wherein the process comprises treating Y zeolite with an organic acid, followed by treating with an alkali to obtain Meso Y zeolite; preparing an aqueous solution of pseudoboehmite alumina and phosphororic acid and mixing with Meso Y zeolite to obtain a solution A; mixing a dispersion of colloidal silica and aqueous solution of boric acid to obtain a solution B; mixing the solution A and the solution B to obtain the bottom cracking catalyst.