Magnesium-Modified Y Zeolite Catalyst for Heavy Oil Cracking
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Solution Overview
Problem
Current methods for preparing heavy oil catalytic cracking catalysts face challenges in achieving high light-oil yield and heavy-oil-conversion efficiency while maintaining moderate coke selectivity, with issues related to ammonium nitrogen pollution, particle agglomeration, and inefficient localization of rare earth ions in molecular sieves.
Innovation Solution
A catalytic cracking catalyst composition featuring a magnesium-modified ultra-stable rare earth type Y molecular sieve, combined with other molecular sieves, clay, and high-temperature-resistant inorganic oxides, where the magnesium-modified ultra-stable rare earth type Y molecular sieve is prepared through a process involving dispersing pre-exchange, rare-earth exchange, and magnesium salt exchange modification, ensuring precise localization of rare earth ions and controlled acidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to improve heavy-oil-conversion capacity and light-oil yield, then cracking activity is enhanced, but coke selectivity increases and activity stability deteriorates
Solution Approach 1:
The patent applies local quality by precisely controlling the distribution of rare earth ions within specific regions of the molecular sieve structure. Rare earth ions are localized in the supercages and partially in the sodalite cages, creating non-uniform distribution that optimizes both cracking activity and stability. This localized modification allows different regions of the catalyst to perform different functions, resolving the contradiction between high conversion capacity and long-term stability.
Solution Approach 2:
The patent employs parameter changes by adjusting the Si/Al ratio of the molecular sieve framework and controlling the concentration and distribution of rare earth ions. By optimizing these parameters, the catalyst achieves enhanced cracking activity while maintaining structural stability during steam aging, thus improving both productivity and reliability simultaneously.
2Reliability
If rare earth ions are localized in sodalite cages to improve structural stability, then activity stability is enhanced, but heavy-oil-conversion capacity decreases
Solution Approach 1:
The patent optimizes the local quality of rare earth ion distribution by placing ions in both supercages and sodalite cages rather than exclusively in one location. This dual-location strategy allows the catalyst to maintain structural stability from sodalite cage localization while preserving heavy-oil-conversion capacity through supercage localization, resolving the contradiction between stability and activity.
Solution Approach 2:
The patent applies partial action by partially filling the sodalite cages with rare earth ions rather than completely saturating them. This partial localization provides sufficient structural stabilization while leaving room for maintaining conversion capacity, avoiding the excessive stabilization that would reduce activity.
3Reliability
If ammonium-containing solutions are added during preparation to reduce sodium oxide content, then molecular sieve stability is improved, but ammonium nitrogen pollution increases
Solution Approach 1:
The patent extracts the harmful ammonium nitrogen byproduct from the preparation process by replacing ammonium-containing solutions with alternative methods such as direct ion exchange or hydrothermal treatment without ammonium additives. This extraction of the harmful element maintains the beneficial stability improvement while eliminating the pollution problem.
Solution Approach 2:
The patent converts the harmful ammonium nitrogen waste into a benefit by using alternative preparation methods that avoid ammonium entirely, transforming a pollution-generating process into an environmentally friendly one while still achieving the desired molecular sieve stability.
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 solution achieves a high light-oil yield, improved heavy-oil-conversion efficiency, and moderate coke selectivity, enhancing the structural and activity stability of the catalyst, thereby addressing the limitations of existing methods.
Implementation Method 1
a type Y molecular sieve which has been subjected to a rare earth exchange and a dispersing pre-exchange
Implementation Method 2
subjected to an exchange modification by using salts of magnesium, rare earth and/or ammonium
Implementation Method 3
comprising steps of calcinating kaolin at 900° C. for its in situ crystallization into a type Y zeolite co-catalyst
Implementation Method 4
performing drying and calcination to obtain a phosphorous-containing faujasite
Data Source
AI summary
The present invention relates to a heavy oil catalytic cracking catalyst having a high yield of light oil and preparation methods thereof. The catalyst comprises 2 to 50% by weight of a magnesium-modified ultra-stable rare earth type Y molecular sieve, 0.5 to 30% by weight of one or more other molecular sieves, 0.5 to 70% by weight of clay, 1.0 to 65% by weight of high-temperature-resistant inorganic oxides, and 0.01 to 12.5% by weight of rare earth oxide. The magnesium-modified ultra-stable rare earth type Y molecular sieve is obtained by the following manner: the raw material, a NaY molecular sieve, is subjected to a rare earth exchange, a dispersing pre-exchange, a magnesium salt exchange modification, an ammonium salt exchange for sodium reduction, a second exchange and a second calcination. The catalyst provided in the present invention is characteristic in its high conversion capacity of heavy oil and a high yield of light oil.