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The catalyst particles used in fluid catalytic cracking (FCC) can undergo attrition, resulting in the production of fine powder. There are many factors that control particle wear. From the point of view of material properties, factors such as particle size, shape, surface roughness, porosity, hardness and the existence of cracks, and from the point of view of process, factors such as time, speed, pressure, shear and temperature are all important. Therefore, in order to ensure that the catalyst has sufficient abrasion resistance, it is necessary to conduct a systematic test on the wear performance and mechanism of the FCC catalyst.
- The professional chemists of Alfa Chemistry Catalysts combined with rich professional knowledge can recommend suitable test methods for customers to analyze the wear performance of FCC catalysts.
- Alfa Chemistry Catalysts uses special equipment to determine the attrition performance of the powdered catalyst in the fluidized bed according to ASTM D5757. This technology is particularly suitable for FCC catalysts (fresh or steam) in the size range of 10 to 180 microns. Abrasion is measured by spraying fluidized samples with moist air, and the percentage of fines after testing is given by Air Jet Abrasion (AJI).
- If necessary, Alfa Chemistry Catalysts can also provide particle size distribution (PSD) analysis, scanning electron microscopy (SEM), nanoindentation, etc. to assist in the study of factors affecting wear characteristics, including hardness, mechanical strength and surface properties and particle strength testing.
Characteristics of Attrition Test Equipment
- Allows to monitor, control and record operating pressure (upstream and downstream fluidized bed reactors), temperature, flow rate and humidity, sample and fine particle weights and other parameters through external weighing scales and experimental time.
- The abrasion separation part is composed of abrasion tube (made of sapphire to increase rigidity and allow air flow) and a separation tube that allows separation of catalyst and fine powder.
- A fine powder collection section includes a specific filter collector and a hygrometer.
- Wu et al. studied the abrasion resistance and mechanism of three catalytic cracking catalysts. The combination of wear test, SEM image and PSD analysis shows that surface characteristics such as shape and surface roughness have little effect on wear resistance, but they can affect the wear mechanism. It is found that particles with irregular shapes will fragment, and wear usually occurs when the surface is rough. These findings are important for the manufacture of some solid catalysts.
Figure 1. Non-linear fitting of specific attrition rate (Ra,m) data for three catalyst samples.
- The air jet method has proved to be an important tool for laboratory evaluation of fluidized bed catalyst wear tendency, but the influence of test temperature and test time is rarely considered. Hao et al. focused on the impact of test temperature and test time on the wear mechanism of methanol-to-olefin (MTO) catalysts in high-velocity air jets. The results show that the test temperature significantly affects the wear mechanism. At room temperature wear and debris coexist, while wear at 500 °C dominates.
Figure 2. Attrition of MTO catalyst in high-speed air jet.
- Fanghua Wu. (2017). "Attrition resistances and mechanisms of three types of FCC catalysts", Powder Technology 305: 289–296.
- Jingai Hao. (2015). "Attrition of methanol to olefins catalyst with high-velocity air jets at elevated temperature", Advanced Powder Technology 26(3): 734-741.
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