Cracking Catalyst with Eta-Alumina and Molecular Sieves
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Solution Overview
Problem
Current cracking catalysts fail to produce gasoline with lower olefin content but higher aromatics and isoparaffins, improve diesel oil quality, and increase the content of light olefins and isobutane in liquefied petroleum gas, which are essential for meeting environmental and industrial demands.
Innovation Solution
A cracking catalyst comprising alumina, phosphorus, and molecular sieves, with η-alumina, χ-alumina, or γ-alumina, and optionally clay, where the alumina is formed from β-alumina trihydrate and phosphorus, enhancing cracking ability and product quality by a synergistic effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing cracking catalysts are used to increase light oil production, then cracking ability is improved, but olefin content in gasoline increases and aromatics/isoparaffins content decreases
Solution Approach 1:
The catalyst uses a composite structure combining η-alumina (30-70 wt%) with molecular sieves (zeolite-Y and/or ZSM-5) and silica-alumina matrix. This composite material design allows simultaneous optimization of cracking activity and product selectivity, resolving the contradiction between high light oil production and low olefin content in gasoline.
Solution Approach 2:
The invention specifies precise compositional parameters: η-alumina content of 30-70 wt%, molecular sieve content of 10-50 wt%, and silica-alumina ratio of 2-10. By controlling these parameters, the catalyst achieves both high cracking ability for light oil production and selective cracking that reduces olefin content while increasing aromatics and isoparaffins in gasoline.
2Productivity
If existing cracking catalysts are used to increase cracking ability, then light oil yield is improved, but diesel oil quality deteriorates (lower aniline point, higher density, lower cetane number)
Solution Approach 1:
The composite catalyst system with η-alumina as main component (30-70 wt%) combined with molecular sieves creates synergistic effects that simultaneously enhance cracking activity for higher light oil yield and improve diesel oil quality by controlling cracking depth and selectivity, achieving both high productivity and high manufacturing precision.
Solution Approach 2:
The catalyst exhibits different active sites with distinct functions: η-alumina provides strong acid sites for cracking heavy oil to increase light oil yield, while molecular sieve components provide shape-selective sites that control product distribution to improve diesel oil quality parameters (aniline point, density, cetane number). This local quality differentiation resolves the contradiction.
3Productivity
If existing cracking catalysts are used to produce more light olefins and isobutane, then cracking activity is improved, but content of light olefins and isobutane in liquefied petroleum gas decreases
Solution Approach 1:
The catalyst combines η-alumina with specific molecular sieves (zeolite-Y and/or ZSM-5) in optimized ratios to create a composite material that maintains high cracking activity while enhancing selectivity toward light olefins and isobutane, thereby increasing their content in the liquefied petroleum gas product.
Solution Approach 2:
By optimizing the molecular sieve content (10-50 wt%) and silica-alumina ratio (2-10), the catalyst achieves parameter changes that simultaneously maintain high cracking activity and maximize the production of light olefins and isobutane in the LPG fraction, resolving the contradiction between productivity and product composition.
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 achieves higher cracking activity, reduces olefin content in gasoline, increases aromatics and isoparaffins, lowers diesel oil density, raises cetane number, and enhances light olefin and isobutane content in liquefied petroleum gas, resulting in improved product quality and increased light oil production.
Implementation Method 1
the alumina is formed from β-alumina trihydrate and phosphorus
Implementation Method 2
a process for preparing the catalyst comprises drying a slurry containing an aluminum compound, a molecular sieve and water, wherein the aluminum compound is capable of forming η-alumina, or a mixture of an aluminum compound capable of forming η-alumina and an aluminum compound capable of forming χ-alumina and/or γ-alumina, and then calcining the slurry
Data Source
AI summary
A cracking catalyst, which contains alumina, phosphorus and molecular sieve, with or without clay, wherein said alumina is η-alumina or a mixture of η-alumina and χ-alumina and/or γ-alumina, and wherein the catalyst contains, on the basis of the total amount of the catalyst, 0.5-50 wt % of η-alumina, 0-50 wt % of χ-alumina and/or γ-alumina, 10-70 wt % of molecular sieve, 0-75 wt % of clay, and 0.1-8 wt % of phosphorus, measured as P2O5. The catalyst not only has higher cracking activity and higher cracking ability for cracking heavy oil, but also improves significantly quality and yield of gasoline, LCO and LPG in cracking products.