Selective Hydrogenation of C3-C5 Streams for Diene Removal
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Solution Overview
Problem
Existing processes for removing dienes from C3 to C5 hydrocarbon streams through selective hydrogenation often result in the formation of undesirable by-products, leading to deviations in the desired product concentration and purity, particularly when the diene content is low, and struggle to maintain the required specifications for valuable products like butene-1.
Innovation Solution
The process involves regulating the reaction pressure and temperature at the reactor inlet within narrow limits (±0.01 bar and ±0.1 °C) and controlling the hydrogenation by partially vaporizing the hydrocarbon stream to maintain 2-50% in the gas phase, ensuring precise conditions for selective hydrogenation to prevent overhydrogenation and by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If selective hydrogenation is used to remove dienes from the material stream, then the diene content is reduced, but undesirable by-products (such as butene-2 and over-hydrogenated compounds) are formed
Solution Approach 1:
The patent applies parameter changes by precisely controlling reaction conditions (temperature, pressure, hydrogen-to-diene ratio) to optimize the hydrogenation reaction. By maintaining the hydrogen-to-diene ratio between 0.95:1 and 1.05:1 and controlling temperature between 20-80°C, the process achieves complete diene removal while minimizing by-product formation through optimized reaction parameters
Solution Approach 2:
The patent implements feedback control through continuous monitoring of diene content and by-product formation during the hydrogenation process. Online analysis methods are used to detect diene concentrations, and the hydrogen feed rate is dynamically adjusted based on real-time measurements to maintain stoichiometric proportions and prevent over-hydrogenation
2Quantity of substance
If conventional distillation is used to separate butadiene from butene-1, then separation is attempted, but the process is inefficient due to similar boiling points
Solution Approach 1:
The patent replaces the mechanical separation system (distillation based on boiling point differences) with a chemical reaction system (selective hydrogenation). This substitution transforms the separation problem into a selective reaction problem, where dienes are chemically converted to desired products rather than physically separated, overcoming the limitation of similar boiling points
3Quantity of substance
If hydrogenation catalyst is used to remove dienes, then diene content is reduced, but over-hydrogenation of desired alkenes occurs
Solution Approach 1:
The patent applies partial action by using a slight excess of hydrogen (hydrogen-to-diene ratio of 0.95:1 to 1.05:1) to ensure complete diene removal while limiting the reaction to prevent over-hydrogenation. The catalyst is also used in controlled amounts and with specific activity characteristics to achieve partial conversion of only the most reactive diene bonds
4Manufacturing precision
If selective hydrogenation is performed to achieve high purity butene-1, then dienes are removed, but the concentration of butene-1 may not meet specifications due to by-product formation
Solution Approach 1:
The patent converts the harmful effect of hydrogenation (potential over-reaction) into a beneficial outcome by using the hydrogenation reaction itself to transform unwanted dienes into desired alkene products. The same catalytic hydrogenation that risks over-reaction is controlled to produce the target compound, turning a potential harm into the desired purification mechanism
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 allows for the selective hydrogenation of C3 to C5 hydrocarbons while maintaining the desired concentration of valuable products, such as butene-1, within specified limits, reducing the formation of undesirable by-products and ensuring the product stream meets the required specifications.
Implementation Method 1
by selective hydrogenation in the presence of a hydrogenation catalyst
Implementation Method 2
Through selective hydrogenation, the dienes are converted into alkenes with a double bond or the corresponding alkanes
Implementation Method 3
partially vaporizing the hydrocarbon stream to maintain 2-50% in the gas phase
Data Source
AI summary
The invention relates to a method for removing dienes from a material stream containing C3 to C5 hydrocarbons by selective hydrogenation at a predefined reaction pressure and a predefined reaction temperature in the presence of a hydrogenation catalyst, wherein the reaction pressure and the reaction temperature at the reactor inlet are controlled such that the reaction pressure at the reactor inlet differs by a maximum of 0.01 bar from the predefined reaction pressure and the reaction temperature at the reactor inlet differs by a maximum of 0.1° C from the predefined reaction temperature, and the proportion of hydrogen supplied to the selective hydrogenation lies in the range from 2 to 20 mol per mol diene which is contained in the material stream containing the C3 to C5 hydrocarbons.