Core-Shell ZSM-5 Beta Molecular Sieve for Propylene Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ZSM-5 and β molecular sieves do not achieve desired catalytic cracking effects, particularly in providing better selectivity to propylene, and there is a need for improved hydrothermal stability and product yield in hydrocarbon conversion reactions.
Innovation Solution
A phosphorus- and metal-containing core-shell molecular sieve is developed, comprising a ZSM-5 core and a β shell, with specific phosphorus and metal content, and a method for synthesizing this sieve by loading phosphorus and metal onto a hydrogen-type core-shell molecular sieve, followed by calcination, to enhance catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ZSM-5 and β molecular sieves are used directly for catalytic cracking, then the molecular sieves provide basic catalytic activity, but they do not achieve desired propylene selectivity and catalytic cracking effects
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the ZSM-5 core provides specific catalytic functions while the β shell provides structural stability and selectivity. This spatial differentiation of functions allows each region to optimize for its specific role, achieving both high propylene selectivity and reliable catalytic cracking performance that neither component could achieve alone.
Solution Approach 2:
The patent uses composite materials by combining ZSM-5 and β molecular sieves into a core-shell structure. This composite approach leverages the complementary properties of both molecular sieves: ZSM-5's catalytic activity and β's structural stability, creating a synergistic effect that improves both propylene selectivity and overall catalytic cracking performance.
2Productivity
If metal ions are introduced into ZSM-5 molecular sieves to improve propylene selectivity, then catalytic cracking performance improves, but hydrothermal stability decreases
Solution Approach 1:
The patent applies local quality by confining metal ions primarily in the ZSM-5 core region rather than distributing them throughout the entire molecular sieve structure. This localized metal ion placement maintains catalytic cracking performance while preserving the hydrothermal stability of the overall structure, as the β shell acts as a protective barrier.
Solution Approach 2:
The patent uses segmentation by dividing the molecular sieve into distinct core and shell regions with different functional characteristics. The core contains metal ions for catalysis, while the shell provides structural stability, effectively separating the functions of catalytic activity and hydrothermal stability to resolve the contradiction between them.
3Productivity
If the molecular sieve structure is modified to improve selectivity, then propylene yield increases, but the structural integrity and service life decrease
Solution Approach 1:
The patent employs composite materials by integrating ZSM-5 and β molecular sieves in a core-shell configuration. This composite structure allows the ZSM-5 core to be modified for high propylene yield while the β shell maintains structural integrity and long service life, achieving both improved productivity and sustained durability.
Solution Approach 2:
The patent applies beforehand cushioning by using the β shell as a protective barrier that anticipates and prevents structural degradation before it occurs. This outer shell cushions the inner ZSM-5 core against hydrothermal stress and structural collapse, ensuring long service life while allowing the core to be optimized for high propylene yield.
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 phosphorus- and metal-containing core-shell molecular sieve exhibits higher hydrothermal stability, propylene yield, and reduced coke selectivity, improving catalytic cracking and conversion of hydrocarbon oils, with enhanced performance in catalytic cracking, alkylation, and isomerization reactions.
Implementation Method 1
the phosphorus- and metal-containing core-shell molecular sieve shows an 27Al MAS NMR with a ratio of the area of a resonance signal peak at a chemical shift of 39±3 ppm to the area of a resonance signal peak at a chemical shift of 54±3 ppm of 0.01-∞:1
Implementation Method 2
ZSM-5 belongs to the orthorhombic system, and has unit cell parameters a=20.07 Å, b=19.92 Å, c=13.42 Å, of which the number of Al atoms in the unit cell can be varied within a range from 0 to 27
Implementation Method 3
a method for synthesizing a phosphorus- and metal-containing core-shell molecular sieve, comprising a step of loading phosphorus and metal on a hydrogen-type core-shell molecular sieve and calcining
Data Source
AI summary
A phosphorus- and metal-containing core-shell molecular sieve has a core composed of a ZSM-5 molecular sieve, and a shell composed of a β molecular sieve. The phosphorus- and metal-containing core-shell molecular sieve has a phosphorus content, calculated as P2O5, of 1-10 wt %, and a metal content, calculated as metal oxide, of 0.1-10 wt %, based on the dry weight of the phosphorus- and metal-containing core-shell molecular sieve. It shows an 27Al MAS NMR with a ratio of the area of a resonance signal peak at a chemical shift of 39±3 ppm to the area of a resonance signal peak at a chemical shift of 54±3 ppm of 0.01-∞:1.