Butanol Extraction from Hydroalcoholic Solutions
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Solution Overview
Problem
The separation of water and ethanol in hydroalcoholic solutions is hindered by the formation of azeotropes, and the presence of butanol complicates this process further, especially in the Lebedev process where butanol accumulation reduces butadiene yield and increases energy consumption and equipment size.
Innovation Solution
A process involving a water-ethanol separation step with a distillation column, a demixing step using a settling tank, and a butanol separation step, allowing for the partial extraction of butanol to produce effluents rich in ethanol and water, which can be recycled without significant ethanol loss, and a practically pure butanol effluent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate water and ethanol, then ethanol can be recovered, but the formation of water-ethanol azeotrope limits the recovery of pure ethanol
Solution Approach 1:
The separation process is divided into multiple stages: first distillation column for preliminary separation, then liquid-liquid extraction stage, followed by second distillation column for final purification. This segmentation allows each stage to address specific separation challenges, overcoming the azeotrope limitation by combining multiple separation mechanisms
Solution Approach 2:
An organic solvent is introduced as an intermediary substance in the liquid-liquid extraction stage. This solvent selectively extracts ethanol from the water-ethanol mixture, breaking the azeotropic relationship and enabling pure ethanol recovery that cannot be achieved by distillation alone
2Adaptability or versatility
If butanol is present in the water-ethanol mixture, then the mixture can be treated, but separation is complicated by formation of water-butanol azeotrope
Solution Approach 1:
Butanol is selectively removed from the mixture in the liquid-liquid extraction stage using an organic solvent. The solvent preferentially extracts butanol due to its chemical properties, separating it from the water-ethanol system before the final distillation stage, thus simplifying the overall separation process
Solution Approach 2:
The process utilizes differences in chemical parameters (solubility, polarity) rather than just physical parameters (boiling point). By changing the separation mechanism from thermal distillation to chemical extraction, the process can handle complex multi-component mixtures including azeotropes that are difficult to separate by traditional distillation
3Productivity
If butanol is recycled with ethanol in the Lebedev process, then butanol can be reused, but butanol accumulates and reduces catalyst selectivity
Solution Approach 1:
Butanol is selectively extracted and separated from the recycled stream using liquid-liquid extraction. The purified ethanol is recovered for recycling to the reactor, while butanol is removed from the recycle loop. This prevents butanol accumulation that would otherwise poison the catalyst, while still allowing ethanol recycling to maintain productivity
4Use of energy by moving object
If butanol is removed without significant energy consumption, then energy efficiency is improved, but pollution of water effluent may occur
Solution Approach 1:
An organic solvent serves as an intermediary extraction medium that selectively removes butanol from the aqueous stream at low energy cost. The solvent forms a separate organic phase containing butanol, leaving the aqueous phase relatively clean. This avoids high-energy distillation while preventing water pollution through selective phase separation
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 enhances ethanol concentration for recycling, reduces energy consumption, and minimizes butanol accumulation in the Lebedev process, improving catalyst selectivity and overall butadiene yield while reducing equipment size and utility consumption.
Implementation Method 1
a water-ethanol separation step, comprising a water-ethanol separation section comprising a distillation column
Implementation Method 2
a demixing step comprising: a mixing section of said hydroalcoholic solution withdrawn in step a) with the water/butanol/ethanol fraction withdrawn in step c); a settling section of the preceding mixture comprising a settling flask in which the pressure is less than or equal to 6 bar absolute, said settling section producing a heavy phase comprising mainly water and a light phase
Data Source
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AI summary
The invention relates to a method for treating a hydroalcoholic feedstock comprising ethanol and butanol to produce an ethanol-rich effluent, a water-rich effluent and a butanol-rich effluent, comprising a) a water-ethanol separation step comprising a distillation column supplied with said hydroalcoholic feedstock and comprising at least 14 theoretical plates, a molar reflux ratio of less than or equal to 1.2, a side stream in the butanol accumulation region and two injections of recycled flows from steps b) and c); b) a demixing step comprising a section for mixing the flow drawn off in step a) and the fraction drawn off in step c), and a settling section, the heavy phase being recycled to the distillation column of step a); c) a butanol separation step comprising a distillation column supplied by the light phase from step b), comprising a side stream of a water/butanol/ethanol fraction recycled to the mixing section of step b) and producing a butanol-rich effluent and an ethanol-water distillate recycled to the distillation column of step a). Said method appears to be particularly useful for treating hydroalcoholic effluent in the context of the Lebedev method.