Molecular Sieve Modification for Catalytic Cracking Stability
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Solution Overview
Problem
Current catalytic cracking catalysts face challenges with activity stability and heavy metal contamination resistance, particularly due to the deposition of nickel and vanadium, which deactivates the molecular sieve structure and reduces catalytic efficiency in heavy oil processing.
Innovation Solution
A method for modifying molecular sieves by mixing metal ions of Group IIIB elements with organic complexing agents and dispersants, followed by spray-drying and calcination, to create a catalyst with improved activity stability and heavy metal contamination resistance, where the Group IIIB elements exist as both ion-exchanged and independent phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earths or phosphorus are used to modify the molecular sieve to improve activity and stability, then the catalytic activity and hydrothermal stability are improved, but the heavy metal contamination resistance is insufficient
Solution Approach 1:
The patent uses a composite modification approach by combining rare earth elements (Group IIIB metal ions) with phosphorus to modify the molecular sieve. This composite modification strategy allows the catalyst to simultaneously achieve improved catalytic activity, hydrothermal stability, and heavy metal contamination resistance, which single-element modification cannot accomplish alone.
Solution Approach 2:
The patent introduces phosphorus specifically into the extra-framework aluminum sites of the molecular sieve, creating localized phosphorus-rich regions that serve as heavy metal traps. This local quality enhancement allows the catalyst to maintain its overall structural stability while providing specific zones for heavy metal capture, thereby improving contamination resistance without compromising activity.
2Object-affected harmful factors
If the molecular sieve is modified to increase heavy metal contamination resistance, then the resistance to vanadium and nickel is improved, but the catalytic activity stability may be compromised
Solution Approach 1:
The patent optimizes the molar ratio of phosphorus to Group IIIB metal ions, controlling the amount and distribution of phosphorus in the modified molecular sieve. By precisely adjusting this parameter, the catalyst achieves optimal balance between heavy metal contamination resistance and catalytic activity stability, preventing excessive phosphorus from blocking active sites while ensuring sufficient heavy metal capture capacity.
3Stability of the object's composition
If the molecular sieve structure is stabilized to improve hydrothermal stability, then the crystal structure stability is improved, but the heavy metal capture capacity is reduced
Solution Approach 1:
The patent separates the functions of hydrothermal stability and heavy metal capture by introducing phosphorus into specific extra-framework sites rather than modifying the entire molecular sieve structure uniformly. This segmentation allows the core molecular sieve framework to maintain its hydrothermal stability while specific localized regions provide heavy metal capture functionality, resolving the contradiction between structural stability and contamination resistance.
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 modified catalyst exhibits enhanced activity stability and resistance to heavy metal contamination, maintaining catalytic performance even after exposure to vanadium and nickel, with improved crystal structure stability and effective heavy metal capture.
Implementation Method 1
mixing a solution containing metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent to form a suspension containing a precipitate of Group IIIB element; and mixing the suspension containing a precipitate of Group IIIB element with a molecular sieve slurry
Implementation Method 2
mixing and stirring a solution containing the metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent to form a suspension containing a precipitate of Group IIIB element
Implementation Method 3
mixing and stirring a solution containing the metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent to form a suspension containing a precipitate of Group IIIB element
Implementation Method 4
followed by spray-drying and optionally calcining, to obtain a molecular sieve modified with the Group IIIB element
Implementation Method 5
followed by spray-drying and optionally calcining, to obtain a molecular sieve modified with the Group IIIB element
Data Source
AI summary
The invention relates to a molecular sieve modification method and a catalytic cracking catalyst containing a molecular sieve. The method comprises: mixing a solution containing an ion of a Group MB metal in the periodic table, an organic complexing agent, and/or a dispersant and a precipitation agent, and stirring the same to form a suspension containing a precipitant of a Group IIIB element; and mixing the resulting precipitant and a molecular sieve slurry, stirring the same to obtain a mixed slurry containing the precipitant of the Group MB element and a molecular sieve, and performing spray drying and optional calcination, to obtain a modified molecular sieve. The catalyst comprises, as calculated based on the catalyst mass being 100%, 10-55% of a modified molecular sieve (on a dry basis), 10-80% of clay (on a dry basis), 0-40% of an inorganic oxide (on an oxide basis), and 5-40% of a binding agent (on an oxide basis). The catalyst has good activity stability and heavy metal contamination resistance.