Oxidative Dehydrogenation Butadiene Process Solvent Limit
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Solution Overview
Problem
Existing processes for producing butadiene from n-butenes through oxidative dehydrogenation face challenges such as the accumulation of organic peroxides and high-boiling secondary components, which can lead to reactor blockages and increased wastewater contamination, and require excess oxygen that impairs catalyst activity.
Innovation Solution
A process involving an n-butene-containing feed gas stream, an oxygen-containing gas, and an oxygen-containing cycle gas stream is used for oxidative dehydrogenation, with the product gas stream being cooled and partially separated to remove high-boiling components, and aromatic hydrocarbon solvents are employed to absorb C4 hydrocarbons, with the solvent content in the cycle gas stream limited to less than 0.2% by volume to prevent catalyst deactivation and reduce organic solvent traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If excess oxygen is used to maintain catalyst activity, then catalyst stability is improved, but organic peroxide accumulation increases creating safety risks
Solution Approach 1:
The patent extracts and removes organic peroxides from the reaction system through a quenching step using a quench medium. This separates the harmful peroxide byproduct from the main reaction cycle, allowing excess oxygen to be used for catalyst stability without peroxide accumulation risks.
Solution Approach 2:
The patent introduces a quench medium as an intermediary substance that reacts with and neutralizes organic peroxides formed during oxidative dehydrogenation. This mediator allows the main reaction to proceed with excess oxygen while the intermediary handles the harmful byproduct removal.
2Productivity
If aromatic hydrocarbon solvent content in cycle gas is increased to absorb C4 hydrocarbons, then absorption efficiency is improved, but catalyst deactivation increases due to solvent traces
Solution Approach 1:
The patent changes the concentration parameter of aromatic hydrocarbon solvent in the cycle gas from higher levels to specifically less than 0.2 vol%. This parameter optimization maintains sufficient absorption efficiency while reducing catalyst deactivation caused by solvent traces.
3Device complexity
If high-boiling secondary components are not separated, then process complexity is reduced, but reactor blockages occur reducing productivity
Solution Approach 1:
The patent performs preliminary separation of high-boiling secondary components through quenching before they can accumulate and cause reactor blockages. This advance removal prevents operational disruptions while maintaining relatively simple process equipment.
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 effectively minimizes the accumulation of organic peroxides and high-boiling components, reduces wastewater contamination, and maintains catalyst activity by limiting aromatic hydrocarbon solvent content, thereby enhancing process efficiency and safety.
Implementation Method 1
Butadiene can also be obtained by oxidative dehydrogenation of n-butenes (1-butene and/or 2-butene) in the presence of molecular oxygen
Implementation Method 2
ca) cooling of the product gas stream b
Implementation Method 3
Da) absorption of the C 4 hydrocarbons comprising butadiene and n-butenes in an aromatic hydrocarbon solvent as absorbent
Data Source
Figure 1
AI summary
A process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a1 comprising n-butenes; B) feeding the input gas stream a1 comprising n-butenes, an oxygenous gas and an oxygenous cycle gas stream a2 into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, steam, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b and optionally at least partly removing high-boiling secondary components and steam, giving a product gas stream b'; Cb) compressing and cooling the product gas stream b' in at least one compression and cooling stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, steam, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; Da) absorbing the C4 hydrocarbons comprising butadiene and n-butenes in an aromatic hydrocarbon solvent as an absorbent and removing uncondensable and low-boiling gas constituents comprising oxygen, low-boiling hydrocarbons, any carbon oxides, aromatic hydrocarbon solvent and any inert gases as gas stream d2 from the gas stream c2, giving an absorbent stream laden with C4 hydrocarbons and the gas stream d2, and then desorbing the C4 hydrocarbons from the laden absorbent stream, giving a C4 product gas stream d1; Db) at least partly recycling the gas stream d2 as cycle gas stream a2 into the oxidative dehydrogenation zone, wherein the content of aromatic hydrocarbon solvent in the cycle gas stream a2 is limited to less than 1% by volume.