Hydrotreating Catalyst Metal Ratio for Deactivation Resistance
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Solution Overview
Problem
Fixed-bed catalytic hydrotreating processes for heavy petroleum fractions face rapid deactivation and clogging due to the deposition of metal impurities and coke, leading to reduced catalyst lifespan and increased costs, necessitating the development of catalysts with improved demetallization and desulfurization capabilities.
Innovation Solution
A catalytic system comprising a unique mixed formulation using molybdenum as the Group VIB metal and nickel or cobalt as Group VIII metals, with specific atomic ratios and optionally phosphorus or boron, applied in both hydrodemetallization (HDM) and hydrodesulphurization (HDS) stages to enhance performance and extend catalyst life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalysts are used in fixed-bed hydrotreating processes, then initial demetallization and desulfurization performance is achieved, but catalyst deactivates rapidly due to metal deposition and clogging
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst's metal composition ratios. Specifically, it uses a Group VIII metal to Group VIB metal atomic ratio between 0.3:1 and 0.7:1, with Group VIB metal content between 2-9% and Group VIII metal content between 0.3-2%. This optimized composition reduces deactivation rates and extends catalyst operational life in fixed-bed hydrotreating processes.
Solution Approach 2:
The patent employs composite materials by combining multiple metals from different periodic table groups (Group VIB: Mo, W; Group VIII: Ni, Co, Fe, Pt, Pd, Rh, Ir) with a porous refractory oxide support. This composite structure creates synergistic effects that enhance both demetallization activity and resistance to deactivation, allowing the catalyst to maintain performance longer under severe operating conditions.
2Productivity
If molybdenum content in catalyst is increased to improve demetallization performance, then catalytic activity increases, but catalyst cost increases
Solution Approach 1:
The patent optimizes the molybdenum content parameter to a specific range (2-9% by weight of MoO3) rather than using excessive amounts. This controlled parameter change, combined with the optimized metal ratio (0.3:1 to 0.7:1 for Group VIII to Group VIB), maintains high demetallization efficiency while minimizing molybdenum consumption and associated costs.
Solution Approach 2:
The patent applies local quality by creating an optimized distribution and ratio of different metal components within the catalyst. The specific atomic ratio between Group VIII and Group VIB metals (0.3:1 to 0.7:1) ensures that each metal contributes maximally to its function, reducing the need for excessive molybdenum while maintaining high demetallization activity.
3Productivity
If temperature is increased to compensate for catalyst deactivation, then demetallization activity is maintained, but coke deposition increases accelerating clogging
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst (metal ratios and content) to maintain high activity at lower temperatures. By using optimized Group VIII to Group VIB metal ratios (0.3:1 to 0.7:1) and specific content ranges, the catalyst achieves sustained demetallization efficiency without requiring temperature increases that would accelerate coke formation and clogging.
4Duration of action of stationary object
If guard zones are used to protect main catalyst beds, then catalyst lifespan is extended, but process complexity and number of catalyst zones increase
Solution Approach 1:
The patent creates a universal catalyst formulation that performs both guard zone protection and main catalytic function effectively. By optimizing the metal composition (Group VIII to Group VIB ratio of 0.3:1 to 0.7:1, with controlled content ranges), a single catalyst type can serve multiple functions, reducing the need for complex multi-zone configurations while maintaining extended operational duration.
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 catalytic system significantly reduces metal content, improves overall process performance, and extends catalyst lifespan by maintaining high demetallization and desulfurization efficiency, while minimizing molybdenum usage and associated costs.
Implementation Method 1
catalytic hydrotreating makes it possible, by bringing a hydrocarbon charge into contact with a catalyst whose properties, in terms of metals and porosity, are well defined beforehand, to substantially reduce its content of asphaltenes, metals, sulfur and other impurities
Implementation Method 2
The subsequent second stage, called hydrodesulphurization, consists in passing the product of the first stage and the hydrogen over a hydrodesulphurization catalyst
Implementation Method 3
The support is generally based on alumina, its role consists in dispersing the active phase and presenting a texture and a porosity adapted to good capture of the metallic impurities
Data Source
AI summary
Catalyst comprising at least one metal of group VIB; at least two metals of group VIII, of which one is the promoter of VIII-1 group metal and the other is co-promoter of VIII-i group metal, where i is 2-5; and at least one support comprising a porous refractory oxide, where the elements of the group VIII ([VIII-1/(VIII-1+...+ VIII-i)]) are present in the atomic ratio of 0.5-0.85, is new. Independent claims are included for: (1) catalytic system comprising at least two catalysts, where: the first catalyst comprises a metal or group VIB metal content of 2-9 wt.% of the metal trioxide or group VIB metals, and the sum of contents of metals of group VIII comprises 0.3-2 wt.% of the metal oxide of the group VIII; the second catalyst comprises a metal or group VIB metal content of strictly 9-17 wt.% of the metal trioxide or metals of the VIB group, and the sum of the contents of Group VIII metals, comprises 2-5 wt.% of the metal oxide of group VIII; and first and second catalysts have an identical atomic ratio; and (2) a process of hydrotreating of heavy hydrocarbon charges comprising at least a step of hydrodemetallation and hydrodesulfurization, and implementing at least one catalyst with respect to the same atomic ratio in each of the of hydrodemetallation and hydrodesulfurization step.