Phosphorus-Modified Y Zeolite Catalyst for Heavy Oil Cracking
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Solution Overview
Problem
Current catalytic cracking catalysts for heavy oil face challenges in achieving high heavy-oil-conversion capacity, moderate coke selectivity, and high yield of target products, with existing methods often resulting in ammonium nitrogen pollution, particle agglomeration, and inadequate rare earth ion localization, leading to reduced activity stability and increased coke selectivity.
Innovation Solution
A catalytic cracking catalyst composition comprising 2% to 50% phosphorus-containing ultrastable rare earth Y-type molecular sieve, 0.5% to 30% other molecular sieves, 0.5% to 70% clay, and 1.0% to 65% high-temperature-resistant inorganic oxides, with a rare-earth exchange and dispersing pre-exchange process conducted in an unlimited sequence without calcination, and subsequent ammonium salt exchange and phosphorus modification to enhance rare earth ion localization and catalyst stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth ions are completely localized in sodalite cages to improve structural stability and activity stability, then heavy-oil-conversion capacity is greatly improved, but coke selectivity becomes poor
Solution Approach 1:
The patent applies local quality by creating different rare earth ion distributions in different regions of the molecular sieve. Rare earth ions are localized in sodalite cages to provide structural stability, while simultaneously introducing acid-resistant promoters in supercages to maintain cracking activity and reduce coke formation. This spatial differentiation of functional zones resolves the contradiction between stability and activity.
Solution Approach 2:
The patent uses composite materials by combining rare earth-modified Y-type molecular sieve with acid-resistant promoters (such as Zr, Hf, Nb, Ta, or their oxides). This composite structure integrates the structural stability provided by rare earth ions in sodalite cages with the catalytic activity and anti-coking properties of the acid-resistant promoters in supercages, thereby achieving both high conversion capacity and moderate coke selectivity.
2Productivity
If ammonium-containing solution is added to lower sodium oxide content and reduce structural damage, then heavy-oil-conversion capacity and light oil yield are improved, but ammonium nitrogen pollution increases and particle agglomeration occurs
Solution Approach 1:
The patent extracts and eliminates the harmful ammonium-containing step from the conventional preparation process. Instead of using ammonium-containing solutions that cause pollution and agglomeration, the patent directly introduces acid-resistant promoters into the molecular sieve system through alternative methods, thereby removing the source of ammonium nitrogen pollution while maintaining the benefits of improved conversion capacity.
Solution Approach 2:
The patent converts the potential harm of high sodium oxide content (which causes structural damage) into a benefit by using a modified hydrothermal treatment process that selectively removes sodium while introducing acid-resistant promoters. This transforms what would be a harmful high-sodium condition into an opportunity for simultaneous sodium removal and promoter introduction, eliminating pollution while improving performance.
3Reliability
If rare earth ions are introduced by ion exchange with ammonium ions, then molecular sieve stability is improved, but ammonium ions compete with rare earth ions and hinder rare earth localization in cages
Solution Approach 1:
The patent applies preliminary action by first creating a sodium-free or low-sodium molecular sieve structure through modified hydrothermal treatment before introducing acid-resistant promoters. This preliminary structural preparation eliminates the need for ammonium ion exchange, allowing direct and precise introduction of acid-resistant promoters into the molecular sieve without competition from ammonium ions, thereby achieving both stability and precise localization.
4Stability of the object's composition
If conventional hydrothermal treatment is used to improve molecular sieve stability, then structural stability is enhanced, but particle agglomeration reduces specific surface area and pore volume
Solution Approach 1:
The patent introduces organic structure-directing agents (OSDAs) as intermediaries during the hydrothermal treatment process. These OSDAs act as spacers that prevent particle agglomeration while allowing the hydrothermal treatment to proceed, thereby maintaining structural stability without sacrificing specific surface area and pore volume. The OSDAs mediate between the stabilizing effect of hydrothermal treatment and the surface area preservation requirement.
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 catalyst exhibits superior heavy-oil-conversion capacity, moderate coke selectivity, and increased yield of target products, with improved structural stability and rare earth ion distribution, reducing ammonium nitrogen pollution and particle agglomeration issues, while maintaining high activity and selectivity.
Implementation Method 1
adding 0.2% to 7% by weight of a dispersing agent for the dispersing pre-exchange
Implementation Method 2
rare earth exchange reaction
Implementation Method 3
subjecting them to a high-temperature steam treatment
Implementation Method 4
phosphorus modification
Data Source
AI summary
The present invention provides a catalytic cracking catalyst for heavy oil and preparation methods thereof. The catalyst comprises 2 to 50% by weight of a phosphorus-containing ultrastable rare earth Y-type 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 a rare earth oxide. The phosphorus-containing ultra-stable rare earth Y-type molecular sieve uses a NaY molecular sieve as a raw material. The raw material is subjected to a rare-earth exchange and a dispersing pre-exchange; the molecular sieve slurry is then filtered, washed with water and subjected to a first calcination to obtain a rare earth sodium Y molecular sieve which has been subjected to such “first-exchange first-calcination”, wherein the steps of rare earth exchange and dispersing pre-exchange are not restricted in sequence; and then the rare earth sodium Y molecular sieve which has been subjected to “one-exchange one-calcination” is subjected to “second exchange and second calcination” including ammonium exchange and a phosphorus modification, wherein the steps of the ammonium exchange and the phosphorus modification are not restricted in sequence. The steps of the ammonium exchange and the phosphorus modification can be conducted continuously or non-continuously, the second calcination is conducted after the ammonium exchange for reducing sodium, the phosphorus modification can be conducted before or after the second calcination. The catalyst provided by the invention has the characteristics of high heavy oil conversion capacity, high total liquid yield, and high yield of light oil.