Hydrotreating Catalyst Arsenic Poisoning Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydrotreating catalysts used in petroleum refining are poisoned by arsenic present in hydrocarbon feedstocks, leading to deactivation, as arsenic irreversibly binds with active nickel components, and existing catalysts are not effective in removing high concentrations of arsenic from hydrocarbon feedstocks.
Innovation Solution
A catalyst composition comprising an alumina support with an underbedded molybdenum and phosphorus component and an overlaid nickel component, with a surface nickel-to-molybdenum atomic ratio greater than 1.8, is developed to enhance arsenic absorption and storage, thereby protecting hydrotreating catalysts from arsenic poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydrotreating catalysts are used, then hydrodesulfurization activity is maintained, but arsenic poisons the catalyst by irreversibly binding with active nickel, leading to deactivation
Solution Approach 1:
The patent introduces an intermediary arsenic removal catalyst layer positioned between the feedstock and the hydrotreating catalyst. This intermediary layer selectively absorbs and retains arsenic compounds before they can reach and poison the hydrotreating catalyst, thereby protecting the main catalyst while maintaining hydrodesulfurization activity.
Solution Approach 2:
The patent extracts the arsenic removal function from the hydrotreating catalyst system by creating a separate, dedicated arsenic removal catalyst composition. This separate catalyst layer selectively removes arsenic from the feedstock, preventing it from interfering with the hydrotreating catalyst's nickel active sites.
2Productivity
If existing catalysts are used, then hydrodesulfurization function is provided, but they are not effective in removing high concentrations of arsenic from hydrocarbon feedstocks
Solution Approach 1:
The patent applies local quality by creating a catalyst composition with non-uniform metal distribution, specifically an overlaid nickel component on an underbedded molybdenum and phosphorus component. This localized concentration of nickel on the surface enhances arsenic absorption capacity while the underlying molybdenum and phosphorus provide structural stability and prevent sintering under high-temperature conditions.
Solution Approach 2:
The patent employs composite materials by combining multiple metal components (nickel, molybdenum, phosphorus) with alumina support in a layered structure. The composite catalyst composition integrates the arsenic-absorption capability of nickel with the thermal stability and structural support of molybdenum, phosphorus, and alumina, achieving both high arsenic removal efficiency and catalyst durability.
3Productivity
If nickel concentration is increased to enhance arsenic absorption, then arsenic removal capability improves, but catalyst complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies preliminary action by first depositing the molybdenum and phosphorus components onto the alumina support, then subsequently overlaying the nickel component. This sequential deposition approach allows for controlled nickel distribution on the surface while the underlying molybdenum-phosphorus layer provides a stable foundation, simplifying the manufacturing process compared to attempting to create uniform high-nickel catalysts.
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 effectively removes over 98% of arsenic from hydrocarbon feedstocks, reducing arsenic concentration to less than 0.005 ppmw, and maintains enhanced hydrodesulfurization activity, making it suitable for processing feedstocks with high arsenic concentrations.
Implementation Method 1
the catalyst effectively removes over 98% of arsenic from hydrocarbon feedstocks, reducing arsenic concentration to less than 0.005 ppmw
Implementation Method 2
maintains enhanced hydrodesulfurization activity
Data Source
AI summary
A catalyst that is useful for the removal of arsenic from hydrocarbon feedstocks. The catalyst comprises an alumina support, underbedded molybdenum and phosphorus components, and an overlayer of a nickel component. The catalyst further has the unique property of having a surface nickel-to-molybdenum atomic ratio of greater than 1.8 with a bulk nickel-to-molybdenum atomic ratio of less than 2.2. The nickel accessibility factor of the catalyst is greater than 1.2. The catalyst is prepared by the application of two metals impregnation steps with associated calcination steps that in combination provide for the underbedded metals and overlayer of nickel.