Hydrotreating Process with Intermediate Hydrogen Separation
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Solution Overview
Problem
Existing hydrotreating and aromatic saturation processes face challenges in efficiently processing high sulfur and aromatic hydrocarbon feedstocks, leading to increased hydrogen sulfide inhibition and the need for complex multi-stage systems with high recycle gas requirements.
Innovation Solution
An integrated process combining hydrotreating and aromatic saturation with an intermediate hydrogen separation and purification system, which separates and purifies hydrogen to remove ammonia and hydrogen sulfide, allowing for single-stage processing with noble metal catalysts and reduced recycle gas usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional multi-stage hydrotreating and aromatic saturation processes are used to process high sulfur and aromatic hydrocarbon feedstocks, then the desired ultra low sulfur distillate specifications are met, but the system requires complex plant design with multiple stages, high recycle gas requirements, and increased capital costs
Solution Approach 1:
The patent combines hydrotreating and aromatic saturation into a single integrated reaction zone, eliminating the need for separate multi-stage processes. The mixed metal catalyst (containing Group VIII, Group VIB, and Group VI metals) performs both hydrotreating and aromatic saturation functions simultaneously, reducing plant complexity while maintaining ultra low sulfur distillate specifications.
Solution Approach 2:
The mixed metal catalyst system performs multiple functions within a single reaction zone: it conducts hydrotreating to remove sulfur compounds, saturates aromatic hydrocarbons, and operates effectively without requiring intermediate separation stages. This multi-functional catalyst approach eliminates the need for complex multi-stage configurations and high recycle gas requirements.
2Manufacturing precision
If noble metal catalysts are used in the aromatic saturation zone to achieve high cetane number and smoke point, then the distillate quality is improved, but the catalyst is poisoned by hydrogen sulfide requiring intermediate fractionation sections and increased system complexity
Solution Approach 1:
The patent replaces expensive noble metal catalysts with a mixed metal catalyst system containing Group VIII, Group VIB, and Group VI metals that is resistant to hydrogen sulfide poisoning. This mixed metal catalyst maintains high activity throughout the reaction zone without requiring intermediate fractionation sections to protect the catalyst, eliminating the need for complex additional equipment while achieving high cetane number and smoke point.
Solution Approach 2:
The patent uses a composite mixed metal catalyst containing multiple metal types (Group VIII, Group VIB, and Group VI metals) that combines the benefits of high aromatic saturation activity with resistance to hydrogen sulfide poisoning. This composite catalyst material eliminates the need for noble metals and intermediate fractionation sections, simplifying the overall process design.
3Manufacturing precision
If higher hydrogenation function is implemented in the second stage aromatic saturation zone to meet high cetane number requirements, then the distillate quality is improved, but the hydrogen sulfide inhibition from the first stage requires further processing and increases the amount of recycle gas required
Solution Approach 1:
The patent combines hydrotreating and aromatic saturation into a single reaction zone, eliminating the sequential two-stage process that generates hydrogen sulfide inhibition issues. By performing both functions simultaneously with a mixed metal catalyst, the system achieves high cetane number without requiring large amounts of recycle gas to manage hydrogen sulfide inhibition.
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 integrated process enhances catalytic activity and hydrogenation capability, producing superior distillate products with reduced sulfur and aromatic content, and decreases system pressure, thereby simplifying plant design and reducing capital costs.
Implementation Method 1
purifying at least a portion of the vapor stream in an absorption zone in the presence of at least a portion of relatively heavier components of vapor stream from step (b) to produce a high purity hydrogen gas stream and a fuel gas stream
Implementation Method 2
hydrotreating the feedstock with a hydrotreating catalyst in the presence of hydrogen to produce a hydrotreated effluent containing a reduced amount of sulfur-containing hydrocarbon compounds
Implementation Method 3
saturating the aromatic compounds contained in a portion of the hydrocarbon liquid stream with an aromatic saturation catalyst in the presence of hydrogen gas to produce an aromatic saturated effluent
Data Source
AI summary
An intermediate hydrogen separation and purification system is integrated with a hydrotreating and an aromatic saturation process for the production of relatively lower molecular weight products from a relatively heavy feedstock including sulfur-containing and aromatic-containing hydrocarbon compounds. The integrated process allows the processing of heavy hydrocarbon feedstock having high aromatic and high sulfur contents in a single-stage configuration and the using of noble metal catalyst in the aromatic saturation zone. The integrated process increases the overall catalytic activity and hydrogenation capability to produce superior distillate products.