Sulfur Injection in Fluidized Bed Dehydrogenation
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Solution Overview
Problem
Current alkane dehydrogenation processes face challenges such as short catalyst life, high coke formation, and heat exchanger malfunctions due to sulfur content in hydrocarbon streams, leading to reduced production efficiency and increased costs.
Innovation Solution
Incorporating a sulfur-containing hydrocarbon stream into a fluidized bed dehydrogenation reactor, where it mixes with a heated sulfur-free stream to reduce coke formation on the catalyst, thereby extending the catalyst's on-stream time and avoiding heat exchanger malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a noble metal catalyst is used for dehydrogenation at high temperature, then the dehydrogenation reaction is efficient, but coke forms rapidly on the catalyst surface, reducing catalyst activity and requiring frequent regeneration
Solution Approach 1:
The patent introduces sulfur-containing compounds into the dehydrogenation process, converting the harmful effect of sulfur (which typically poisons catalysts) into a beneficial effect. The sulfur compounds modify the catalyst surface in a controlled manner, reducing coke formation and extending catalyst life, thereby transforming a normally harmful substance into a useful additive for maintaining catalyst performance
Solution Approach 2:
The patent changes the chemical composition parameter of the feed stream by adding sulfur-containing compounds at specific concentrations. This parameter change modifies the catalyst surface properties and reaction conditions, leading to reduced coke formation and improved catalyst stability while maintaining dehydrogenation efficiency
2Productivity
If the catalyst is regenerated frequently to maintain production rate, then catalyst activity is maintained, but catalyst life is greatly shortened and production cost increases
Solution Approach 1:
The sulfur-containing compounds convert the harmful coke deposition into a beneficial surface modification effect. By controlling sulfur concentration in the feed, the catalyst surface is protected from rapid coke formation, extending catalyst life and reducing the frequency of regeneration operations
Solution Approach 2:
The sulfur-containing compounds are introduced into the feed stream before the dehydrogenation reaction, performing a preliminary protective action on the catalyst surface. This preliminary sulfur treatment prevents subsequent rapid coke formation, extending catalyst life before regeneration is needed
3Reliability
If a high-sulfur containing stream is used in the dehydrogenation process, then coke formation is reduced, but heat exchangers may malfunction due to sulfur content
Solution Approach 1:
The patent segments the process into distinct zones: a first dehydrogenation zone where sulfur-containing compounds are introduced and reacted, and a second zone where the stream is processed further. This segmentation allows the sulfur to be managed in a controlled manner, protecting the catalyst while minimizing exposure to heat exchangers that could be damaged by sulfur
Solution Approach 2:
The patent uses an intermediary approach by introducing sulfur-containing compounds in a controlled manner into the dehydrogenation zone, where they serve as a mediator to protect the catalyst from coke formation. The sulfur is introduced at a point where it can be effectively utilized by the catalyst without directly contacting and damaging the heat exchangers
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 increases the on-stream factor of the dehydrogenation unit by 5 to 10% and reduces production costs by maintaining higher catalyst activity and preventing heat exchanger failures.
Implementation Method 1
a sulfur-containing hydrocarbon stream that includes a sulfur-containing compound and hydrocarbons to form a reactant feed stream
Implementation Method 2
contacting the reactant feed stream with a dehydrogenation catalyst under conditions sufficient to produce a first product stream comprising iso-alkenes
Implementation Method 3
As dehydrogenation of isobutane is highly endothermic, the catalyst is periodically heated to a high reaction temperature to provide reaction heat for the dehydrogenation of isobutane
Data Source
AI summary
Systems and processes for producing isomerized alkenes are disclosed. The systems mainly include an isomerization unit, a dehydrogenation unit, and a MTBE synthesis unit. A hydrocarbon stream is fed into the isomerization unit to form iso-alkanes in a sulfur free hydrocarbon stream. The sulfur free hydrocarbon stream is heated and then combined with a sulfur-containing hydrocarbon stream comprising sulfur containing compounds to form a reactant feed stream to the dehydrogenation unit. The iso-alkanes is dehydrogenated to form iso-alkenes. The formed iso-alkenes comprising isobutylene can be used as a feed stock for the MTBE synthesis unit.