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2023
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What are the causes of catalyst deactivation and what should be paid attention to in industrial use
Classification:
【Summary】The chemical composition of the catalyst does not change before and after the chemical reaction, and the life of the catalyst is theoretically infinite. But in actual use, the catalyst has a certain life, and sometimes, the life is far shorter than imagined. Next, we will tell you the reasons for the deactivation of the catalyst and the matters needing attention during use.
The chemical composition of the catalyst does not change before and after the chemical reaction, and the life of the catalyst is theoretically infinite. But in actual use, the catalyst has a certain life, and sometimes, the life is far shorter than imagined. Next, we will tell you the reasons for the deactivation of the catalyst and the matters needing attention during use.
Analysis of the reasons for the deactivation of the catalyst, there are mainly the following types:
Catalyst poisoning deactivation: there are chemical substances that cause catalyst poisoning in the reactants, such as O, S, P, As, halogen, etc., this deactivation is permanent and irreversible;
Sintering and thermal deactivation of the catalyst: the main manifestations are grain growth, crystallization collapse and reorganization, loss of active components and changes in dispersion structure, which are generally irreversible;
Catalyst plugging deactivation: deposition of impurities or pollutants, catalyst coking, etc., this deactivation mode is partially reversible.
The deactivation process of the actual industrial catalyst is often the result of the above types of deactivation. However, for a certain catalytic reaction process and catalyst, the deactivation process is generally based on a certain type. We need to understand their own process characteristics, analyze the type of inactivation, and then targeted optimization and improvement.
For example: intermittent kettle-type nitro hydrogenation using Raney nickel as catalyst, such as the raw material does not exist in the poisoning substances, it is mainly for blocking deactivation, nitro hydrogenation reaction exothermic intense easy to produce tar by-product, sticking to the surface of the catalyst to cause channel blockage. The intermittent kettle process can be upgraded to a continuous process to reduce the temperature rise and fall process and make the system more stable. At the same time, Raney nickel catalyst with good low temperature activity can effectively reduce tar by-product, thus avoiding blocking and deactivation and improving the service life of the catalyst. Another example is the petrochemical derivative industry, which is often prone to catalyst poisoning and deactivation due to toxic substances such as S in raw materials, which requires strict control of S content in raw materials and gases, before chemical production, the desulfurization adsorbent can be used to desulfurize the raw materials, which can effectively protect the catalyst and greatly improve the service life of the catalyst.
In short, the factors of catalyst deactivation are many and complex, but if we can find out the main factors and take reasonable measures to control them, it will effectively improve the service life and use effect of the catalyst.
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