Butadiene Production via Oxidative Dehydrogenation
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Solution Overview
Problem
Current methods for producing butadiene, such as thermal cracking and catalytic dehydrogenation, face challenges like low yields, equilibrium limitations, and the need for additional heating and separation processes, particularly with the shift from naphtha to ethane feedstocks, which decreases butadiene byproduct production.
Innovation Solution
A process involving oxidative dehydrogenation of a mixed butane/butene feed stream, followed by direct dehydrogenation, using steam and oxygen to generate butadiene, which eliminates equilibrium limitations and reduces the need for high-temperature heating, allowing for high conversion in a single pass and increased butadiene yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal cracking is used to produce butadiene from naphtha, then butadiene can be obtained as a byproduct, but larger amounts of undesired coproducts are formed and additional separation processes are required
Solution Approach 1:
The patent extracts the dehydrogenation function from the cracking process by using a dedicated dehydrogenation unit that selectively converts butane to butadiene, separating the desired reaction pathway from the complex cracking process that produces multiple coproducts requiring separation
Solution Approach 2:
The dehydrogenation unit serves multiple functions: it converts butane to butadiene, manages hydrogen production, and operates independently of feedstock composition changes, making the process adaptable to different ethylene plant configurations
2Quantity of substance
If dehydrogenation of butane to butene followed by butene to butadiene is used, then hydrogen is produced, but the conversion is limited by equilibrium and positive free energy is formed
Solution Approach 1:
The patent changes the thermodynamic parameters by operating at high temperatures (650-750°C) and using catalysts that lower activation energy, enabling the dehydrogenation reaction to proceed favorably despite equilibrium limitations at lower temperatures
Solution Approach 2:
The patent implements continuous operation of the dehydrogenation unit with continuous removal of products, preventing equilibrium limitations from restricting conversion by continuously driving the reaction forward through product extraction
3Productivity
If direct dehydrogenation at high temperatures (about 700°C) is used, then the reaction is slightly favorable, but additional heat input is required and there is low butadiene yield
Solution Approach 1:
The patent applies preliminary heating of the feedstock before it enters the dehydrogenation reactor, using heat exchangers that preheat the butane using heat from product streams, reducing the additional heat input required for the high-temperature reaction
Solution Approach 2:
The patent recovers heat from hot product streams and uses it to preheat feedstock, discarding the need for additional external heat input by internally circulating thermal energy within the process system
4Quantity of substance
If catalytic dehydrogenation of n-butane is used, then butadiene can be produced, but predominantly 1-butene and 2-butene are formed instead
Solution Approach 1:
The patent uses specialized catalysts with specific active sites that are locally optimized to promote dehydrogenation to butadiene rather than isomerization to butenes, creating selective reaction pathways through catalyst design that targets the desired product
Solution Approach 2:
The patent employs dynamic control of reaction conditions including temperature gradients and residence time distribution within the reactor to favor butadiene formation kinetics over butene isomerization, using operational parameters to steer selectivity
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 process achieves high conversion of butane/butene to butadiene with increased yields and reduced energy consumption, minimizing the formation of byproduct hydrogen and hydrogenation reactions, resulting in a more efficient and economical production method.
Implementation Method 1
passing a feed stream comprising butanes and butenes to an oxidative dehydrogenation reaction unit to generate an effluent stream comprising butanes, butenes and butadiene
Implementation Method 2
The effluent stream is passed to a dehydrogenation unit to generate a process stream comprising butadiene
Data Source
AI summary
A process is presented for the production of butadiene from a mixture of butane/butene feed. The process provides high conversion of the feed by oxidative dehydrogenation of the feed. The process enables recovery of a good portion of heat inputted from the reaction effluent. The process overcomes equilibrium limitations by oxidative dehydrogenation of butane/butene feed to produce butadiene.