Catalyst particle size distribution

Main physical and chemical properties of catalytic cracking catalysts and their significance I. Chemical properties The chemical composition of a catalyst indicates the contents of its main components and impurities; it usually includes five key parameters: Al2O3, Na2O, Fe2O3, and loss on ignition, with Re2O3 sometimes also being included. 1. Al2O3 content: The Al2O3 content in the catalyst refers to the total amount of Al2O3 present in it, and it is the main chemical component of the catalyst. 2. Na2O content: The Na2O content indicates the level of Na2O impurities present in the catalyst. During the catalytic cracking process, especially when heavy amounts of vanadium are present in the residue fed to the reactor, 3. Fe2O3 content: The Fe2O3 content indicates the amount of Fe2O3 impurities contained in the catalyst. Fe2O3 decomposes at high temperatures and deposits on the catalyst; when it accumulates to a certain extent, it causes catalyst poisoning, which results in a decrease in the catalyst’s activity. 4. SO42- content: The SO42- content indicates the level of SO42- impurities present in the catalyst. SO42- can react with metal oxides that have the ability to capture vanadium (such as alumina) to form stable sulfates, thereby rendering them incapable of capturing vanadium. Therefore, when residue oil is blended in, SO42- poses a greater hazard. 5. Loss on ignition: Loss on ignition refers to the content of volatile components in the catalyst, such as water, ammonium salts, and carbon particles. In production, control its reduction to ≤13%. 6. Re2O3 content: The Re2O3 content is one of the indicators used to represent the performance of a catalyst. Rare earths usually come from the molecular sieves in catalysts; sometimes, rare earth ions are also introduced during the catalyst manufacturing process to improve performance. Generally, the higher the Re2O3 content, the higher the catalyst activity, but the coke yield also increases. For equilibrium catalysts, it is sometimes necessary to know the metal content within them, such as Ni, V, Na, etc., in order to understand the degree of catalyst contamination. II. Physical Properties Physical properties refer to characteristics such as the shape, structure, density, and particle size of a catalyst. It usually includes five main parameters: specific surface area, pore volume, apparent bulk density, wear index, and sieve analysis composition. The following is a brief description of each: 1. Specific surface area: The specific surface area of a catalyst is the sum of its internal and external surface areas. The internal surface area refers to the surface area inside the catalyst’s micropores, while the external surface area refers to the surface area outside those micropores; typically, the internal surface area is much larger than the external surface area. The surface area per unit weight of a catalyst is called specific surface area. Specific surface area is an important indicator for measuring the performance of catalysts. For different products, due to variations in carriers and preparation processes, there is no direct correlation between specific surface area and activity. The method used to determine the specific surface area is the nitrogen adsorption capacity method. 2. Pore volume: Pore volume is a physical quantity that describes the pore structure of a catalyst. The pore structure not only affects the activity and selectivity of catalysts, but also influences their mechanical strength, lifespan, and heat resistance. Pore volume is the total volume of the micropores within porous catalyst particles, measured in milliliters per gram. The size of the pore volume is closely related to the carrier in the catalyst. For the same type of catalyst, the pore volume decreases over time while the pore diameter increases. The method used for measuring pore volume is the water drop method. 3. Wear index: An excellent catalytic cracking catalyst, in addition to having high activity and good selectivity, must also possess a certain level of mechanical strength to resist wear. Catalysts with poor mechanical strength not only suffer from high losses during operation, leading to an increased amount of catalyst required and environmental pollution, but in severe cases they can disrupt the proper distribution of the catalyst between the dilute and dense phases, even rendering the production facility unable to function. The wear resistance of a catalyst is determined by the type of binder used in its preparation; generally, catalysts using aluminum sol as a binder have the best strength and the lowest wear index ； Catalysts using fully synthesized silicoalumina sol as a binder have the lowest strength and a high wear index. Currently, the “wear index” is used to evaluate the wear resistance of microsphere catalysts. The measurement method is as follows: A certain amount of catalyst is placed in the wear index testing apparatus, and it is subjected to abrasion at a constant gas flow rate for 5 hours; what is emitted during the first hour

Main physical and chemical properties of catalytic cracking catalysts and their significance I. Chemical properties The chemical composition of a catalyst indicates the contents of its main components and impurities; it usually includes five key parameters: Al2O3, Na2O, Fe2O3, and loss on ignition, with Re2O3 sometimes also being included. 1. Al2O3 content: The Al2O3 content in the catalyst refers to the total amount of Al2O3 present in it, and it is the main chemical component of the catalyst. 2. Na2O content: The Na2O content indicates the level of Na2O impurities present in the catalyst. During the catalytic cracking process, especially when heavy amounts of vanadium are present in the residue fed to the reactor, 3. Fe2O3 content: The Fe2O3 content indicates the amount of Fe2O3 impurities contained in the catalyst. Fe2O3 decomposes at high temperatures and deposits on the catalyst; when it accumulates to a certain extent, it causes catalyst poisoning, which results in a decrease in the catalyst’s activity. 4. SO42- content: The SO42- content indicates the level of SO42- impurities present in the catalyst. SO42- can react with metal oxides that have the ability to capture vanadium (such as alumina) to form stable sulfates, thereby rendering them incapable of capturing vanadium. Therefore, when residue oil is blended in, SO42- poses a greater hazard. 5. Loss on ignition: Loss on ignition refers to the content of volatile components in the catalyst, such as water, ammonium salts, and carbon particles. In production, control its reduction to ≤13%. 6. Re2O3 content: The Re2O3 content is one of the indicators used to represent the performance of a catalyst. Rare earths usually come from the molecular sieves in catalysts; sometimes, rare earth ions are also introduced during the catalyst manufacturing process to improve performance. Generally, the higher the Re2O3 content, the higher the catalyst activity, but the coke yield also increases. For equilibrium catalysts, it is sometimes necessary to know the metal content within them, such as Ni, V, Na, etc., in order to understand the degree of catalyst contamination. II. Physical Properties Physical properties refer to characteristics such as the shape, structure, density, and particle size of a catalyst. It usually includes five main parameters: specific surface area, pore volume, apparent bulk density, wear index, and sieve analysis composition. The following is a brief description of each: 1. Specific surface area: The specific surface area of a catalyst is the sum of its internal and external surface areas. The internal surface area refers to the surface area inside the catalyst’s micropores, while the external surface area refers to the surface area outside those micropores; typically, the internal surface area is much larger than the external surface area. The surface area per unit weight of a catalyst is called specific surface area. Specific surface area is an important indicator for measuring the performance of catalysts. For different products, due to variations in carriers and preparation processes, there is no direct correlation between specific surface area and activity. The method used to determine the specific surface area is the nitrogen adsorption capacity method. 2. Pore volume: Pore volume is a physical quantity that describes the pore structure of a catalyst. The pore structure not only affects the activity and selectivity of catalysts, but also influences their mechanical strength, lifespan, and heat resistance. Pore volume is the total volume of the micropores within porous catalyst particles, measured in milliliters per gram. The size of the pore volume is closely related to the carrier in the catalyst. For the same type of catalyst, the pore volume decreases over time while the pore diameter increases. The method used for measuring pore volume is the water drop method. 3. Wear index: An excellent catalytic cracking catalyst, in addition to having high activity and good selectivity, must also possess a certain level of mechanical strength to resist wear. Catalysts with poor mechanical strength not only suffer from high losses during operation, leading to an increased amount of catalyst required and environmental pollution, but in severe cases they can disrupt the proper distribution of the catalyst between the dilute and dense phases, even rendering the production facility unable to function. The wear resistance of a catalyst is determined by the type of binder used in its preparation; generally, catalysts using aluminum sol as a binder have the best strength and the lowest wear index ； Catalysts using fully synthesized silicoalumina sol as a binder have the lowest strength and a high wear index. Currently, the “wear index” is used to evaluate the wear resistance of microsphere catalysts. The measurement method is as follows: A certain amount of catalyst is placed in the wear index testing apparatus, and it is subjected to abrasion at a constant gas flow rate for 5 hours; what is emitted during the first hour