Egg-Shell Palladium Catalyst for Pyrolysis Gasoline Hydrogenation
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Solution Overview
Problem
Current catalysts for the first-stage selective hydrogenation of pyrolysis gasoline suffer from low stability and short lifetime due to excessive water and arsenic content, as well as high hydrogenation load, leading to pore blocking and reduced activity.
Innovation Solution
A selective hydrogenation catalyst with an alumina carrier and metal palladium in an egg-shell form, incorporating 0.2-0.5 wt% Pd, 2-8 wt% lanthanum and/or cerium, and 2-8 wt% alkaline earth metal, with a specific surface area of 70-150 m^2/g and pore volume of 0.3-0.6 ml/g, providing improved water-resistance, colloid-resistance, and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional palladium-based catalysts are used for first-stage selective hydrogenation, then high hydrogenation activity and low start temperature are achieved, but catalyst stability and lifetime are reduced due to water and arsenic poisoning
Solution Approach 1:
The patent introduces an egg-shell structured catalyst where the active palladium component is confined to a shell layer on the outer surface of the alumina carrier. This spatial arrangement acts as an intermediary structure that protects the bulk catalyst from water and arsenic poisoning while maintaining high hydrogenation activity at the exposed shell surface.
Solution Approach 2:
The catalyst employs local quality by concentrating the active palladium component specifically in the egg-shell region (0.07-0.15 mm thickness) rather than uniformly distributing it throughout the entire carrier. This localized placement ensures high activity where it is most needed while reducing overall metal loading and improving resistance to deactivation.
2Productivity
If heavy distillate with high hydrogenation load is processed, then feed capacity is increased, but pore blocking occurs leading to reduced catalyst lifetime
Solution Approach 1:
The patent utilizes the porous structure of the alumina carrier with specific pore volume (0.3-0.6 ml/g) and surface area (70-150 m²/g) to manage the hydrogenation load. The egg-shell configuration with controlled porosity allows heavy distillate to access active sites while preventing pore blocking that would otherwise reduce catalyst lifetime.
Solution Approach 2:
The catalyst is segmented into an egg-shell structure where the active component is separated into a distinct shell layer (0.07-0.15 mm) on the carrier surface. This segmentation allows the bulk carrier to provide structural support and porosity while the shell layer handles the hydrogenation reaction, preventing deactivation of the entire catalyst.
3Adaptability or versatility
If water and arsenic content in feed is high, then industrial feed conditions are met, but catalyst stability and lifetime are reduced
Solution Approach 1:
The patent converts the harmful effect of water and arsenic by using the egg-shell structure to protect the bulk catalyst from these contaminants. The shell configuration allows the catalyst to tolerate high water and arsenic content in industrial feeds while maintaining stability, effectively turning the challenging feed conditions into manageable operating parameters.
4Reliability
If egg-shell form with controlled shell thickness is used, then water-resistant and colloid-resistant property is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the egg-shell structure (shell thickness 0.07-0.15 mm, pore volume 0.3-0.6 ml/g, surface area 70-150 m²/g) to optimize the balance between water resistance and manufacturability. These parameter changes define the operational window where the catalyst achieves both improved reliability and feasible manufacturing.
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 enhanced hydrogenation stability and activity, maintaining performance even under conditions with high impurity levels, extending its operational life and ensuring effective hydrogenation of medium or low distillate oils.
Implementation Method 1
The selective hydrogenation catalyst according to the present invention, with alumina as carrier, and metal palladium as active component that supported on the surface of the carrier in an egg-shell form
Implementation Method 2
alumina as carrier, and metal palladium as active component that supported on the surface of the carrier
Data Source
AI summary
A selective hydrogenation catalyst, with alumina as carrier, and palladium as active component that distributed on the surface of the carrier in an egg-shell form, characterized in that: provided that the catalyst is weighed 100%, it comprises 0.2-0.5 wt% active component Pd, 2-8 wt% aids lanthanum and/or cerium, and 2-8 wt% alkaline earth metal. The specific surface area of the catalyst is 70-150 m2/g, the pore volume is 0.3-0.6 ml/g, and the crystal form of the carrier may be θ form or θ, α mixed form mainly composed of θ form. The catalyst is suitable for the selective hydrogenation of medium or low distillate oil, especially for the first stage selective hydrogenation of pyrolysis gasoline. The catalyst has good hydrogenation performance, and can keep good hydrogenation activity and stability especially under the condition that the feed contains a small quantity of water, and the content of colloid, arsenic, and diolefin is higher.