Reasons for Catalyst Deactivation Analysis
Over time, the activity and selectivity of the catalyst will gradually lose, which is a continuing concern in the field of catalysts. Although catalyst deactivation is inevitable for most processes, some of its direct and drastic consequences can be avoided, delayed or even reversed. The deactivation problem greatly affects the research, development, design and operation of the catalytic process. Therefore, analysis, research and response to catalyst decay are of great significance.
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Alfa Chemistry Catalysts
The catalyst testing experts at Alfa Chemistry Catalysts analyze deactivated catalysts and provide answers to catalysts and process customers in all walks of life.
- Catalyst poisoning test and evaluation
XPS, SIMS, STEM, atomic absorption analyzer and ICP technology can be used as tools for analyzing and studying catalyst poisoning. Among them, STEM can identify the growth of the new structure; the combustion atomic absorption analyzer can directly determine the mercury catalyst poisoning on the catalyst; in the solution, the ICP technology can determine the elements such as lead, arsenic and phosphorus.
- Catalyst fouling analysis
Catalyst fouling usually results in a decrease in porosity and narrowing of pores. These can be studied by nitrogen adsorption methods (BET surface area, pore size and pore size distribution)
- Catalyst thermal degradation analysis
Thermal analysis methods such as thermogravimetric analysis and differential scanning calorimeter can be used to determine the thermal stability and oxidation stability of materials in different atmospheres, as well as quantitative calculations of substances.
- In addition to the above commonly used catalyst deactivation mechanism analysis, Alfa Chemistry Catalysts can also analyze other types of deactivation mechanisms according to customer needs, such as the formation of vapor compounds accompanying transmission, vapor-solid and/or solid-solid reactions, and attrition/fragmentation.
Catalyst Deactivation Mechanism
The mechanism of catalyst deactivation can be briefly summarized as the following categories. 
- The possible effects of carbon (or coke) fouling on the function of supported metal catalysts include: strong chemical adsorption in a single layer or physical adsorption in multiple layers; complete encapsulation of metal particles; blockage of micropores and mesopores, thereby deactivating the catalyst.
Figure 1. Conceptual model of fouling, crystallite encapsulation and pore plugging of a supported metal catalyst due to carbon deposition.
- Supported cobalt catalysts are usually prepared by wet chemical methods, including steps such as impregnation, drying and calcination. A new method to analyze the degradation of the catalyst under thermal stress in the various steps of catalyst preparation has been applied to the support (γ-Al2O3) and the catalyst (10 wt% Co/Al2O3). The researchers analyzed the reduction of Co3O4 and other substances through temperature programmed reduction. The results show that the particles will degrade through cracking and fragmentation. These mechanisms lead to the initial heterostructure of the support (fractures and cracks), which reduces the mechanical resistance of the catalyst and induces particle rupture when the temperature rises.
Figure 2. TPR profiles of samples.
- Calvin H Bartholomew. (2001). "Mechanisms of catalyst deactivation", Applied Catalysis A: General 212(1-2): 17-60.
- Nouria Fatah. (2019). "Analysis of particle breakage during the preparation steps of Co/Al2O3 catalysts", Journal of Materials Science 54: 14275-14286.
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