Magnesium-Modified Y Zeolite for Heavy Oil Cracking
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Solution Overview
Problem
Current methods for modifying type Y molecular sieves, such as those described in prior art, fail to achieve precise localization of rare earth ions, leading to inadequate activity and structural stability, especially when dealing with heavier and poorer quality crude oils, and often result in ammonium nitrogen pollution and particle agglomeration issues.
Innovation Solution
A magnesium-modified ultra-stable rare earth type Y molecular sieve is prepared through a process involving rare-earth exchange, dispersing pre-exchange, and magnesium salt exchange modification, without the use of ammonium salts, to achieve precise localization of rare earth ions and improve acidity, stability, and light oil yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth ions are introduced via conventional ion exchange methods, then the molecular sieve gains improved stability, but the rare earth ions cannot be precisely localized leading to inadequate activity stability
Solution Approach 1:
The patent applies preliminary action by first performing dispersing pre-exchange to separate aggregated particles and create uniform exchange sites before introducing rare earth ions. This preparatory step ensures that rare earth ions can be precisely localized in sodalite cages during the subsequent rare earth exchange, resolving the contradiction between improving stability and achieving precise localization.
2Reliability
If conventional modification methods are used to improve stability, then the molecular sieve structure is enhanced, but ammonium nitrogen pollution is generated
Solution Approach 1:
The patent extracts and eliminates the harmful ammonium salt component from the modification process. By replacing ammonium salts with dispersing agents and directly using rare earth salts for ion exchange, the method achieves structural stability enhancement without generating ammonium nitrogen pollution, thus resolving the contradiction between improving stability and eliminating harmful factors.
3Ease of manufacture
If conventional exchange procedures are used, then the molecular sieve can be modified, but particle agglomeration occurs reducing effectiveness
Solution Approach 1:
The patent applies preliminary action by implementing dispersing pre-exchange before the rare earth exchange. This preliminary step uses dispersing agents to prevent particle aggregation and ensure uniform distribution of exchange sites, thereby maintaining both ease of manufacture and particle dispersion uniformity during the modification process.
4Productivity
If magnesium salt exchange modification is performed without dispersing pre-exchange, then the process is simpler, but the light oil yield and reaction selectivity are insufficient
Solution Approach 1:
The patent applies preliminary action by adding a dispersing pre-exchange step before magnesium salt exchange modification. Although this increases process complexity slightly, it ensures uniform particle dispersion and effective magnesium ion incorporation, which significantly improves light oil yield and reaction selectivity, thereby resolving the contradiction between productivity and process complexity.
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 method results in a molecular sieve with high activity stability, structural stability, low coke yield, strong resistance to heavy metals, and reduced ammonium nitrogen pollution, effectively controlling reaction ratios and enhancing light oil production.
Implementation Method 1
type Y molecular sieves are modified with rare earth via ion exchange
Implementation Method 2
elements such as magnesium and phosphorous are used both domestically and abroad to modify and adjust the molecular sieve to have suitable acidity
Implementation Method 3
subjecting it to a hydrothermal treatment to afford an ultra-stable rare earth type Y molecular sieve having high stability
Data Source
AI summary
The present invention provides a magnesium-modified ultra-stable rare earth type Y molecular sieve and the preparation method thereof, which method is carried out by subjecting a NaY molecular sieve as the raw material to a rare earth exchange and a dispersing pre-exchange, then to an ultra-stabilization calcination treatment, and finally to a magnesium modification. The molecular sieve comprises 0.2 to 5% by weight of magnesium oxide, 1 to 20% by weight of rare earth oxide, and not more than 1.2% by weight of sodium oxide, and has a crystallinity of 46 to 63%, and a lattice parameter of 2.454 nm to 2.471 nm. In contrast to the prior art, in the molecular sieve prepared by this method, rare earth ions are located in sodalite cages, which is demonstrated by the fact that no rare earth ion is lost during the reverse exchange process. Moreover, the molecular sieve prepared by such a method has a molecular particle size D(v,0.5) of not more than 3.0 µm and a D(v,0.9) of not more than 20 µm. Such a molecular sieve has both high stability and high selectivity for the target product, while cracking catalysts using the molecular sieve as an active component is characterized by a high heavy-oil-conversion capacity and a high yield of valuable target products.