Treatment of trace poisons by sulfur-tolerant shift catalysts
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Raw gas contains certain amounts of fluorine, phosphorus, arsenic, etc., which have a significant impact on the activity of sulfur-resistant shift catalysts. Let’s discuss together what methods are currently being used in coal chemical plants to remove these trace toxins from raw gas. Some plants I’m aware of install pre-conversion reactors in front of the conversion reactors in order to absorb trace amounts of toxic substances and carry out a certain degree of conversion ； What other methods are there?
Adding a pre-conversion furnace in front of the conversion furnace is currently the most common and only method; this pre-conversion furnace is filled with catalyst protectants to absorb trace amounts of toxic substances.
Adding a pre-conversion furnace in front of the conversion furnace is currently the most common and only method; this pre-conversion furnace is filled with catalyst protectants to absorb trace amounts of toxic substances. But based on our usage, it can be considered practically useless, aside from its waterproofing capability.
The pre-transformation catalyst uses magnesium-aluminum spinel as a carrier, with special inorganic pore-forming agents added to increase its porosity while maintaining high strength and strength stability, thereby enhancing its adsorption and detoxification capabilities. It can more effectively adsorb impurities or toxins such as arsenic and dust, protecting the catalyst from poisoning and extending its service life. Sulfur-tolerant shift catalysts are not very sensitive to poisoning by fluorine, phosphorus, and arsenic; however, they are more sensitive to oxygen, tar, and similar substances. It is also sensitive to water, as this catalyst is prepared by an impregnation process and contains K, causing the active components to be easily lost upon contact with water.
I agree with the analyses of those who commented above; the method currently used is generally \"adsorbent + deoxygenation + pre-conversion\", and it has yielded good results: 1. Adsorption – The raw coal gas produced from coal contains impurities and toxins such as coal dust, tar, and arsenic. Furthermore, when the operating conditions fluctuate, it is inevitable that a small amount of condensed water will be carried into the process gas. To protect and extend the service life of the catalyst, a sulfur-resistant shift adsorbent is generally installed above the shift catalyst. This adsorbent boasts advantages such as large pores and high strength, enabling it to effectively adsorb impurities like tar and dust. 2. Deoxygenation: Since a small amount of oxygen can cause sulfation reactions with the active components or carriers in the catalyst, leading to its rapid deactivation, it is necessary to install sulfur-resistant deoxygenation agents above the catalyst bed in order to extend the catalyst’s service life. 3. Pre-transformation: It has been explained above, so no further details are needed.