Hydroprocessing Catalyst Modification Using Gaseous Active Agents
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Solution Overview
Problem
Conventional hydroprocessing catalyst modification processes result in contamination due to direct contact of liquid precursor agents, leading to premature deactivation and safety issues, especially with contaminants like sodium, potassium, carbon, nitrogen, water, iron, mercury, phosphorus, and vanadium.
Innovation Solution
A process that converts liquid precursor agents to gaseous active agents in a conversion reactor, then contacts the hydroprocessing catalysts with these agents in a separate production reactor, minimizing contamination by separating the direct contact and using less pure, less expensive precursors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid sulfide precursors are used directly in hydroprocessing catalyst modification, then the catalyst can be modified (sulfided or passivated), but contaminants in the liquid precursor are deposited on the catalyst surface causing premature deactivation
Solution Approach 1:
The process is divided into two separate reactors: a first reactor where the liquid precursor is converted to gaseous form, and a second reactor where the gas contacts the catalyst. This segmentation prevents direct contact between the contaminating liquid precursor and the catalyst, while still achieving the desired modification.
Solution Approach 2:
A gaseous intermediate species is introduced as a mediator between the liquid precursor and the catalyst. The liquid precursor first converts to a gaseous form in the first reactor, which then serves as the active agent in the second reactor. This intermediary gas phase prevents direct deposition of contaminants from the liquid precursor onto the catalyst.
2Reliability
If pure gaseous H2S is used for catalyst sulfiding, then the catalyst modification is effective, but it is not readily available at required purity and concentration in refineries
Solution Approach 1:
The process uses inexpensive liquid sulfide precursors (such as dimethyl disulfide or disulfide oil) that are readily available in refineries, rather than requiring expensive pure H2S. These cheaper precursors are converted to gaseous H2S in the first reactor, providing an economical source of sulfiding agent.
Solution Approach 2:
The process changes the physical state of the sulfide precursor from liquid to gas phase during the conversion step. By converting the liquid precursor to gaseous H2S in the first reactor, the system achieves the desired gaseous sulfiding agent while using more available and economical liquid precursors.
3Ease of manufacture
If disulfide oil is used as sulfide precursor, then it is inexpensive, but it contains relatively high levels of contaminants including sodium, potassium, carbon, nitrogen, water, iron, mercury, phosphorus, and vanadium
Solution Approach 1:
The process separates the contaminant removal step from the catalyst modification step. In the first reactor, the liquid disulfide oil precursor is converted to gaseous H2S, and contaminants are removed in the gas phase. In the second reactor, only the gaseous H2S contacts the catalyst, preventing contaminant deposition while maintaining the economic advantage of using cheap disulfide oil.
Solution Approach 2:
The gaseous H2S serves as an intermediary that separates the contaminating liquid precursor from the catalyst. The liquid disulfide oil converts to gaseous H2S in the first reactor, and this gas phase intermediary carries the sulfur to the catalyst in the second reactor without depositing contaminants.
4Reliability
If ammonia passivation is performed to control catalyst activity, then temperature excursions are prevented, but ammonia leaks and spills cause health and safety issues
Solution Approach 1:
The process uses nitrogen-containing organic compounds as safe alternatives to ammonia. These organic compounds (such as alkylamines or aniline derivatives) are non-hazardous liquids that can be handled without the safety issues associated with ammonia. They serve as temporary precursors that convert to gaseous ammonia only at the catalyst bed, eliminating leakage and spill hazards.
Solution Approach 2:
The process changes the physical state and form of the passivation agent. Instead of using gaseous or liquid ammonia directly, nitrogen-containing organic compounds are used as liquid precursors that convert to gaseous ammonia only at the catalyst bed. This parameter change from ammonia to nitrogen-containing organics eliminates safety hazards while maintaining the temperature control function.
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
Reduces catalyst contamination, enhances catalyst activity, and prevents safety hazards by using gaseous agents, allowing the use of less pure precursors and maintaining catalyst effectiveness.
Implementation Method 1
contacting the precursor agent with a conversion catalyst in the conversion reactor, thereby producing an active agent
Implementation Method 2
The ammonia adsorbs onto the acidic sites of the catalyst and poisons these sites
Implementation Method 3
These organic compounds react with hydrogen over the hydroprocessing catalyst to form the ammonia needed to passivate the catalyst
Implementation Method 4
These organic compounds react with hydrogen over the hydroprocessing catalyst to form the ammonia needed to passivate the catalyst
Data Source
AI summary
Embodiments of the present disclosure are directed to a process for modifying catalysts comprising introducing a precursor agent and hydrogen gas to a conversion reactor; contacting the precursor agent with a conversion catalyst in the conversion reactor, thereby producing an active agent; introducing the active agent to a production reactor; and contacting the active agent with a hydroprocessing catalyst in the production reactor, thereby producing a modified hydroprocessing catalyst.