Alternating Hydrotreating and Dewaxing Catalyst Bed
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Solution Overview
Problem
The existing hydrotreating and dewaxing processes for hydrocarbon feedstocks face challenges in temperature control due to the exothermic nature of hydrotreating steps and endothermic dewaxing steps, often requiring complex and costly catalyst configurations.
Innovation Solution
A process involving alternating dewaxing and hydrotreating steps using a catalyst with a Group VIII metal, dealuminated aluminosilicate zeolite, and a low acidity refractory oxide binder, primarily free of alumina, is employed to improve temperature control and reduce the amount of dewaxing catalyst required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional hydrotreating and dewaxing processes are used with separate catalyst beds, then dewaxing effectiveness is achieved, but temperature control becomes challenging due to exothermic hydrotreating and endothermic dewaxing reactions
Solution Approach 1:
The patent combines hydrotreating and dewaxing functions into a single catalyst bed containing both metal function (for hydrotreating) and acid function (for dewaxing). This integration eliminates the need for separate catalyst beds, simplifying the reactor configuration and improving temperature control by allowing the exothermic and endothermic reactions to occur simultaneously within the same bed, thereby balancing heat generation and consumption.
Solution Approach 2:
The catalyst system is designed to perform multiple functions simultaneously: the metal component (e.g., nickel, cobalt, platinum, or palladium) provides hydrotreating activity for sulfur removal and aromatic saturation, while the acid component (e.g., zeolite or heteropolyacid) provides dewaxing activity through hydrocracking of wax molecules. This multi-functional catalyst eliminates the need for sequential processing steps with separate catalysts.
2Reliability
If multiple separate catalyst beds are used for hydrotreating and dewaxing, then reaction effectiveness is improved, but the volume of catalyst required increases
Solution Approach 1:
The patent merges hydrotreating and dewaxing catalysts into a single integrated catalyst bed, reducing the total catalyst volume required. By combining the metal function and acid function in one bed, the patent eliminates the need for multiple separate catalyst beds while maintaining both hydrotreating and dewaxing effectiveness.
Solution Approach 2:
The catalyst is designed as a composite material containing both metal components (for hydrotreating) and acid components (for dewaxing) in a single catalyst structure. This composite catalyst system achieves both functions simultaneously, reducing the overall catalyst volume compared to using separate catalyst beds for each function.
3Productivity
If conventional dewaxing catalysts are used, then dewaxing activity is achieved, but the amount of catalyst required is large
Solution Approach 1:
The patent combines dewaxing function with hydrotreating function in a single catalyst bed, reducing the quantity of dewaxing catalyst required. The integrated catalyst system performs both functions simultaneously, eliminating the need for large quantities of dedicated dewaxing catalyst in separate beds.
Solution Approach 2:
The catalyst system is designed to perform multiple functions with a single catalyst formulation, including both hydrotreating (sulfur removal, aromatic saturation) and dewaxing (hydrocracking of waxy molecules). This multi-functionality reduces the total catalyst quantity needed compared to conventional separate catalyst systems.
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
This approach enhances temperature control across reaction stages, reduces the volume of dewaxing catalyst needed, and effectively lowers the cloud and pour points of the hydrocarbon feedstock, making it suitable for ultra-low sulfur diesel fuel production.
Implementation Method 1
hydrotreating the feedstock under hydrotreating conditions in a first reaction zone to obtain a first stage hydrotreated effluent
Implementation Method 2
The dewaxing steps are carried out with a dewaxing catalyst which comprises a Group VIII metal of the Periodic Table
Implementation Method 3
catalytically dewaxing the desulphurised distillate stream
Implementation Method 4
the dewaxing steps are carried out under catalytically dewaxing conditions
Implementation Method 5
the hydrotreating steps are exothermic, whereas quite often the dewaxing step is endothermic
Implementation Method 6
the hydrotreating steps are exothermic, whereas quite often the dewaxing step is endothermic
Data Source
AI summary
The invention provides a process for hydrotreating and dewaxing a hydrocarbon feedstock, comprising the steps of:(a) hydrotreating the feedstock under hydrotreating conditions in a first reaction zone to obtain a first stage hydrotreated effluent; and(b) introducing at least part of the first stage hydrotreated effluent into a second reaction zone in which the first stage hydrotreated effluent is subjected to a series of alternating dewaxing steps and hydrotreating steps.