Acetic Acid Purification via Crotonaldehyde Concentration Control
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Solution Overview
Problem
Current methods for producing acetic acid through methanol carbonylation face challenges in achieving high-quality acetic acid with good potassium permanganate test results due to the presence of by-products like acetaldehyde, crotonaldehyde, and 2-ethylcrotonaldehyde, which require expensive facilities and high energy consumption for separation and treatment.
Innovation Solution
Control the crotonaldehyde concentration in the acetic acid stream to a specific level or lower and operate the light ends column with a higher reflux ratio to concentrate crotonaldehyde, allowing it to react and form less harmful by-products, thereby improving the quality of acetic acid without the need for large-scale ozone treatment or expensive facilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques (acetaldehyde separation facilities or ozone treatment) are employed to decrease acetaldehyde and crotonaldehyde, then the potassium permanganate test result is improved, but the installation cost and facility expense increase significantly
Solution Approach 1:
The invention extracts and removes crotonaldehyde specifically from the acetic acid product through a dedicated removal step, separating this harmful by-product from the main product stream. This targeted extraction approach eliminates the need for complex ozone treatment facilities or expensive acetaldehyde separation systems, thereby improving the potassium permanganate test result while avoiding significant installation costs
Solution Approach 2:
The invention changes the operational parameters of the existing light ends column by adjusting the reflux ratio to a specific range (0.05 to 0.50) to optimize crotonaldehyde concentration in the overhead stream. This parameter adjustment enables effective crotonaldehyde removal through subsequent simple distillation or extraction steps, rather than requiring complex treatment facilities, thus improving product quality while minimizing capital investment
2Quantity of substance
If aqueous phase is subjected to distillation in acetaldehyde-removing column to remove acetaldehyde, then acetaldehyde concentration is decreased, but the treatment energy increases due to high latent heat of vaporization of water
Solution Approach 1:
Instead of distilling the aqueous phase to remove acetaldehyde, the invention extracts acetaldehyde from the overhead stream using water or other solvents. This liquid-liquid extraction method removes acetaldehyde without requiring vaporization of large amounts of water, thereby achieving the same purification goal with significantly lower treatment energy consumption
Solution Approach 2:
The invention introduces water or other solvents as intermediary substances to facilitate acetaldehyde removal through liquid-liquid extraction. These intermediaries selectively dissolve acetaldehyde from the overhead stream, enabling efficient separation without the need for energy-intensive distillation of the aqueous phase, thus reducing treatment energy while maintaining effective acetaldehyde concentration control
3Quantity of substance
If light ends column operates with higher reflux ratio to concentrate crotonaldehyde, then crotonaldehyde concentration in overhead stream increases, but the energy consumption for distillation increases
Solution Approach 1:
The invention optimizes the reflux ratio parameter within a specific range (0.05 to 0.50) to achieve the desired crotonaldehyde concentration in the overhead stream. By operating within this optimized parameter range, the system achieves effective crotonaldehyde concentration and subsequent removal with minimized distillation energy consumption, avoiding both excessive energy use and insufficient 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 approach enables the efficient production of high-quality acetic acid with improved potassium permanganate test results while reducing energy costs and eliminating the need for costly ozone treatment facilities, by effectively managing by-product concentrations and recycling processes.
Implementation Method 1
A methanol carbonylation process is known as a process for industrially producing acetic acid. According to this process, for example, methanol is allowed to react with carbon monoxide in the presence of a catalyst in a reactor to form acetic acid
Implementation Method 2
the resulting reaction mixture is separated, using an evaporator, into a vapor phase including acetic acid and light ends, and a residual liquid phase (residue phase) including acetic acid and the catalyst, the vapor phase is subjected to distillation in a distillation column (light ends column)
Implementation Method 3
The acetaldehyde is converted into crotonaldehyde by aldol condensation
Implementation Method 4
the resulting reaction mixture is separated, using an evaporator, into a vapor phase including acetic acid and light ends, and a residual liquid phase
Data Source
AI summary
Provided is a method capable of industrially efficiently producing acetic acid yielding a good potassium permanganate test result, without costing much. In the acetic acid production method, (1) by-produced acetaldehyde is industrially advantageously removed from a process stream, and (2) a crotonaldehyde concentration in an acetic acid stream from a light ends column is controlled to a specific level or lower, and/or a reflux ratio at a second distillation column is controlled to 0.1 or more. In addition, (3) the method includes the step of subjecting at least one of an aqueous phase and an organic phase of a light ends column overhead condensate to distillation in a crotonaldehyde-removing column; the light ends column is operated at a reflux ratio of 2 or more (when the aqueous phase is refluxed); and the crotonaldehyde-removing column is operated so as to meet a specific condition(s).