Zeolite Y Catalyst Basic Treatment for Hydrocracking Selectivity
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Solution Overview
Problem
Conventional hydrocracking catalysts face challenges in achieving high activity and selectivity for middle distillates, with zeolite Y catalysts displaying lower selectivity due to strong acid sites and amorphous silica-alumina catalysts having low activity, while modification methods like alkaline treatment create mesoporosity but compromise catalytic activity.
Innovation Solution
A catalyst comprising a dealuminated zeolite Y modified by basic treatment to introduce extra-lattice aluminium atoms and thermal treatment, creating a sulphide phase with a specific Si/Al ratio and mesopore volume, enhancing both activity and selectivity for middle distillates through improved Brønsted acidity and intercrystalline diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If zeolite Y is used as catalyst support, then catalytic activity is improved, but selectivity for middle distillates deteriorates due to strong acid sites
Solution Approach 1:
The patent applies parameter changes by modifying the Si/Al ratio of zeolite Y from conventional high values (3.5-5.0) to a lower range (2.5-4.0), which increases the density of acid sites and enhances catalytic activity. Simultaneously, the patent introduces mesoporosity through basic treatment to improve selectivity by facilitating product diffusion and reducing secondary cracking reactions.
Solution Approach 2:
The patent creates a composite catalyst structure combining dealuminated zeolite Y with mesoporous characteristics. The composite nature integrates the high activity of zeolite Y with the improved selectivity properties of mesoporous structures, achieving both high conversion and good middle distillate selectivity.
2Manufacturing precision
If amorphous silica-alumina is used as catalyst support, then selectivity for middle distillates is improved, but catalytic activity deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of the support material from amorphous silica-alumina to crystalline zeolite Y with controlled Si/Al ratio and mesoporous structure, thereby achieving both high activity and good selectivity simultaneously rather than trading one for the other.
3Manufacturing precision
If alkaline treatment is applied to create mesoporosity, then selectivity for middle distillates is improved, but catalytic activity deteriorates
Solution Approach 1:
The patent performs preliminary dealumination of zeolite Y before applying basic treatment to create mesoporosity. This preliminary action ensures that the subsequent mesoporosity creation does not excessively damage the crystal structure or remove too many acid sites, thereby preserving catalytic activity while achieving improved selectivity.
Solution Approach 2:
The patent optimizes the parameters of basic treatment (concentration, temperature, time) to create mesoporosity with controlled volume and distribution, ensuring that acid site density is maintained at optimal levels for high catalytic activity while achieving sufficient mesoporosity for improved selectivity.
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 modified catalyst achieves higher conversion and selectivity for middle distillates by balancing mesoporosity and acidity, producing kerosene and diesel fuels effectively.
Implementation Method 1
a stage of basic treatment consisting of mixing said dealuminated zeolite Y with a basic aqueous solution making it possible to withdraw silicon atoms from the structure and insert extra-lattice aluminium atoms in the framework of the zeolite
Implementation Method 2
at least one stage of thermal treatment
Implementation Method 3
The hydrocracking catalysts used in hydrocracking processes are all of the bifunctional type combining an acid function with a hydrogenating function
Implementation Method 4
enhancing both activity and selectivity for middle distillates through improved Brønsted acidity and intercrystalline diffusion
Data Source
AI summary
The present invention describes a hydrocracking and/or hydrotreatment process using a catalyst comprising an active phase containing at least one hydrogenating/dehydrogenating component selected from the group VIB elements and the non-precious elements of group VIII of the periodic table, used alone or in a mixture, and a support comprising at least one dealuminated zeolite Y having an overall initial atomic ratio of silicon to aluminum between 2.5 and 20, an initial weight fraction of extra-lattice aluminum atoms greater than 10%, relative to the total weight of aluminum present in the zeolite, an initial mesopore volume measured by nitrogen porosimetry greater than 0.07 ml·g−1 and an initial crystal lattice parameter a0 between 24.38 Å and 24.30 Å, said zeolite being modified by a) a stage of basic treatment comprising mixing said dealuminated zeolite Y with a basic aqueous solution, and at least one stage c) of thermal treatment.