Multi-Step Scrubbing for Iodine Recovery in Carbonylation
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Solution Overview
Problem
Current methods for recovering iodine-containing compounds from gaseous streams in carbonylation processes are inefficient, leading to raw material loss and environmental concerns due to the presence of regulated pollutants like methyl acetate.
Innovation Solution
A multi-step scrubbing process using methyl acetate, acetic acid, and water to recover iodine-containing compounds, with the option to recycle used scrubbants back into carbonylation reactions, enhancing material recovery and process integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-step scrubbing method is used to recover iodine-containing compounds, then the process is simple, but the recovery efficiency is insufficient and raw materials are lost
Solution Approach 1:
The single-step scrubbing process is divided into multiple sequential scrubbing zones, each using different scrubbants (methyl acetate, acetic acid, water) to progressively remove different components from the gaseous stream. This segmentation allows each zone to specialize in removing specific compounds, thereby improving overall recovery efficiency while maintaining operational simplicity through a modular design approach.
2Ease of operation
If iodine-containing compounds are not recovered from gaseous streams, then the process operation is straightforward, but raw material loss increases and environmental harm occurs
Solution Approach 1:
The scrubbed gaseous streams containing recovered iodine-containing compounds and other valuable materials are fed back into the carbonylation process as reactants. This feedback loop ensures that materials that would otherwise be lost are returned to the production process, reducing raw material loss and minimizing environmental harm while integrating smoothly into the existing operational framework.
3Productivity
If multiple scrubbing steps are implemented to improve recovery, then recovery efficiency increases, but device complexity increases
Solution Approach 1:
The multi-step scrubbing system uses scrubbants that serve multiple functions: methyl acetate removes iodine-containing compounds, acetic acid removes additional contaminants, and water removes remaining impurities. Each scrubbant is selected to perform multiple roles including solvent extraction, purification, and preparation of streams for recycling back into the carbonylation process, thereby achieving high recovery efficiency without proportionally increasing system complexity.
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 recovers iodine-containing compounds and acetic acid, reducing raw material losses and environmental impact by integrating scrubbed streams into various chemical processes, thereby improving process efficiency and reducing the need for additional iodine-containing compounds.
Implementation Method 1
scrubbing the stream with methyl acetate containing liquid to produce a used scrubbant containing methyl acetate and iodine-containing compounds
Implementation Method 2
contacting at least some of the methyl acetate-scrubbed gaseous stream with a liquid containing acetic acid in a second scrubbing zone to produce a second used scrubbant containing acetic acid and methyl acetate
Implementation Method 3
contacting at least some of the acetic acid-scrubbed gaseous stream with a liquid containing water in a third scrubbing zone to produce a water-scrubbed gaseous stream and a third used scrubbant, the third used scrubbant containing water and acetic acid
Data Source
Figure 1
AI summary
The invention provides methods for recovering iodine-containing compounds from a gaseous stream that contain at least one iodine-containing compound. The method includes: (a) contacting the gaseous stream with liquid methyl acetate in a first scrubbing zone to produce a methyl acetate- scrubbed gaseous stream and a first used scrubbant, the first used scrubbant containing methyl acetate, acetic acid, and the iodide compound; and (b) contacting at least some of the methyl acetate-scrubbed gaseous stream with liquid acetic acid in a second scrubbing zone to produce an acetic acid- scrubbed gaseous stream and a second used scrubbant, the second used scrubbant containing methyl acetate and acetic acid. The method may further include a third scrubber step that includes contacting at least some of the acetic acid-scrubbed gaseous stream with water in a third scrubbing zone to produce a water-scrubbed gaseous stream and a third used scrubbant, the third used scrubbant containing water and acetic acid. The gaseous stream may also contain other components, for example hydrogen, carbon monoxide, methyl acetate, acetic acid, acetic anhydride, nitrogen, ethylidene diacetate, methane, argon or a combination of two or more of the foregoing. Optionally, at least some of the third used scrubbant with reactants may be combined in a chemical process that uses mixtures of acetic acid and water.