Modified Y-Type Molecular Sieve for Hydrogenated LCO Cracking
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Solution Overview
Problem
Conventional catalytic cracking catalysts are inadequate for processing hydrogenated light cycle oil (LCO) due to poor cracking ability and high hydrogen transfer capacity, leading to inefficient production of light aromatics such as benzene, toluene, and xylene (BTX).
Innovation Solution
A modified Y-type molecular sieve with a rare earth content of 4-11% and phosphorus content of 0.05-10% is developed, featuring a lattice constant of 2.440-2.455 nm, a lattice collapse temperature above 1060°C, and a B acid to L acid ratio of at least 3.5, which is prepared through ion-exchange, mild hydrothermal ultra-stabilization, gas phase ultra-stabilization, acid treatment, and phosphorus modification, enhancing its stability and cracking efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalytic cracking catalysts are used to process hydrogenated LCO, then the catalyst structure is simple and easy to manufacture, but the cracking ability is poor and hydrogen transfer capacity is too high, leading to low BTX yield
Solution Approach 1:
The patent uses composite materials by combining Y-type molecular sieve with multiple modifiers (rare earth elements, phosphorus, gallium, boron) to create a catalyst with enhanced cracking ability and reduced hydrogen transfer capacity, directly resolving the contradiction between simple structure and high productivity
Solution Approach 2:
The patent applies local quality by introducing specific active elements (gallium, boron) and rare earth elements at specific sites within the molecular sieve structure to enhance cracking activity in critical regions while maintaining overall structural simplicity, achieving high BTX yield without excessive complexity
2Productivity
If Y-type molecular sieve with small pore size (0.74 nm) is used, then the catalyst is easy to manufacture, but the accessibility of active centers to polycyclic compounds is poor, reducing cracking efficiency
Solution Approach 1:
The patent changes physical and chemical parameters of the molecular sieve including pore size expansion through secondary pore formation, acid site density adjustment, and metal element incorporation to improve accessibility to polycyclic compounds while maintaining manufacturability through controlled synthesis parameters
3Reliability
If multiple modification steps (ion-exchange, hydrothermal treatment, gas phase treatment, acid treatment, phosphorus modification) are applied, then the catalyst stability and cracking efficiency are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges multiple modification steps into an integrated preparation process where ion-exchange, hydrothermal treatment, and metal impregnation are combined in sequence to achieve cumulative stabilization and activation effects, improving reliability while managing process complexity through systematic integration
Solution Approach 2:
The patent applies preliminary action by performing ion-exchange and hydrothermal stabilization before final metal impregnation and activation, ensuring the molecular sieve structure is pre-stabilized to withstand subsequent processing steps, thereby achieving high reliability without requiring rework
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 Y-type molecular sieve catalyst exhibits improved BTX-rich gasoline yield and reduced coke selectivity, achieving higher conversion efficiency and stability in catalytic cracking of hydrogenated LCO.
Implementation Method 1
The modified Y-type molecular sieve is prepared through ion-exchange, mild hydrothermal ultra-stabilization, gas phase ultra-stabilization, acid treatment, and phosphorus modification
Implementation Method 2
mild hydrothermal ultra-stabilization
Implementation Method 3
gas phase ultra-stabilization
Implementation Method 4
acid treatment
Implementation Method 5
phosphorus modification
Data Source
AI summary
A modified Y-type molecular sieve has a rare earth content of about 4% to about 11% by weight on the basis of the oxide, a phosphorus content of about 0.05% to about 10% by weight on the basis of P2O5, a sodium content of no more than about 0.5% by weight on the basis of sodium oxide, and an active element content of about 0.1% to about 5% by weight on the basis of the oxide, with the active element being gallium and/or boron. The modified Y-type molecular sieve has a total pore volume of about 0.36 mL/g to about 0.48 mL/g, a percentage of the pore volume of secondary pores having a pore size of 2-100 nm of about 20% to about 40%; a lattice constant of about 2.440 nm to about 2.455 nm, and a lattice collapse temperature of not lower than about 1060° C.