Tungsten Bulk Catalyst Composition for Low-Pressure Diesel Hydroprocessing
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Solution Overview
Problem
Existing hydroprocessing facilities face challenges in efficiently removing sulfur and nitrogen from hydrocarbon feeds due to limited pressure capability and catalyst poisoning, particularly when processing feeds with high levels of multi-ring aromatics, necessitating the development of catalysts that can operate at lower pressures and maintain high desulfurization and denitrogenation efficiency.
Innovation Solution
The use of tungsten-containing bulk catalyst compositions, specifically those with a formula Co\_{1-x}M\_{x}O\_{4} (where M is Mo, V, or Nb) that exhibit a hexagonal crystalline phase, prepared by reacting tungstic acid with cobalt carbonate under hydrothermal conditions, which are effective in hydrodesulfurization and hydrodenitrogenation processes even at reduced pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If direct desulfurization mechanism is used at low pressure, then hydrogen partial pressure requirement is reduced, but catalyst is prone to H2S poisoning
Solution Approach 1:
The patent uses composite catalyst materials containing cobalt, tungsten, and molybdenum in specific ratios (Co:W:Mo = 1:1:1 to 1:4:4) to create a catalyst that resists H2S poisoning while maintaining low-pressure operation capability. The composite structure allows the catalyst to perform direct desulfurization at low hydrogen partial pressure without being poisoned by H2S.
Solution Approach 2:
The patent changes the chemical composition parameters of the catalyst by controlling the ratios of cobalt, tungsten, and molybdenum, as well as the sulfur content (0.1-5 wt%). This parameter optimization enables the catalyst to operate effectively at low hydrogen partial pressure while resisting H2S poisoning through the specific compositional characteristics.
2Productivity
If large amounts of catalyst are used to meet sulfur reduction requirements, then sulfur removal efficiency is improved, but process capacity is limited by temperature and pressure
Solution Approach 1:
The patent optimizes catalyst composition parameters (Co:W:Mo ratios and sulfur content) to enhance catalytic activity per unit mass. This allows achieving high sulfur removal efficiency without requiring excessive catalyst quantities, thereby maintaining process capacity and avoiding temperature and pressure limitations.
Solution Approach 2:
The composite catalyst structure with specific metal ratios provides high catalytic activity that reduces the total catalyst amount needed in the process. This maintains the reactor's process capacity while achieving the required sulfur removal efficiency.
3Stress or pressure
If existing hydroprocessing facilities operate at low pressure, then infrastructure constraints are maintained, but sulfur and nitrogen removal efficiency is reduced
Solution Approach 1:
The patent modifies catalyst composition parameters to enable low-pressure operation with high desulfurization and denitrogenation efficiency. The specific Co-W-Mo composition and sulfur content allow the catalyst to maintain high productivity at reduced hydrogen partial pressure, overcoming the limitation of existing low-pressure facilities.
Solution Approach 2:
The composite catalyst material is designed to provide high catalytic activity at low pressures, allowing existing hydroprocessing facilities to achieve improved sulfur and nitrogen removal efficiency without increasing operating pressure or replacing infrastructure.
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
These catalysts demonstrate high catalytic activity and efficiency in reducing sulfur and nitrogen levels in hydrocarbon products to very low levels, preventing catalyst poisoning and maintaining process effectiveness under low-pressure conditions.
Implementation Method 1
contacting a feed with hydrogen in the presence of a catalyst composition comprising a compound having a formula CoyW1-xMxO4
Implementation Method 2
reacting the tungstic acid and cobalt carbonate to form a catalyst composition
Data Source
AI summary
Compositions can include compounds having a formula: CoyW1-xMx04 (I), wherein M is Mo, V, or Nb; 0.5≥x≥0; and 1<y≤4; and wherein the compound has an X-ray powder diffraction pattern including characteristic diffraction peaks having d-spacing values of about 2.90 Å, 2.56 Å, and 1.73 Å. Methods can include making a bulk catalyst composition including (i) combining tungstic acid and cobalt carbonate and (ii) reacting the tungstic acid and cobalt carbonate to form a catalyst composition, wherein the cobalt carbonate has an X-ray powder diffraction pattern including characteristic diffraction peaks having d-spacing values of about 10.03 Å, 5.91 Å, 4.35 Å, and 4.21 Å.