Outline for a Basic Textbook on Catalysis

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Outline of the Basic Textbook on Catalysis for Self-study Exams I. Basic requirements and explanations for the course Catalysts are increasingly being used in a wide range of processes within the petroleum refining industry, chemical industry, polymer materials industry, biochemistry industry, food industry, pharmaceutical industry, and the environmental protection sector, playing a crucial role in these processes. Industrial chemical reactions usually take place in reactors, and the vast majority of these reactors must be equipped with industrial catalysts. In fact, catalytic technology has now become a key technique for controlling the rate and direction of chemical reactions. 　　Catalyst engineering is a science that focuses on engineering issues related to the manufacturing, evaluation and testing, design and development, as well as operation of industrial catalysts. It has every reason to become one of the essential basic knowledge skills for specialists in the chemical industry in the 21st century. 　　This course covers the essential aspects of industrial catalysts, and is divided into five main sections: 1. Overview ； 2. Adsorption in catalysis ； 3. Preparation of the catalyst ； 　　4. Characterization, testing, and performance evaluation of catalysts ； 　　5. Deactivation of the catalyst. 　　 　　Students rely mainly on self-study, aiming to broaden their knowledge while also being able to apply what they have learned to new situations. Through their studies, students not only learn how to produce and manufacture catalysts, but more importantly, how to make better use of various catalysts. 　　II. Key Assessment Points Chapter 1: Overview of Catalysts 1. The role of catalysts in national economy and people’s livelihood 2. Some terms and basic concepts related to catalysis (1) Definitions of catalysts and catalytic action; IUPAC definitions from 1976: activity (reaction rate, rate constant, TOF, conversion rate, STY SV); selectivity; lifetime (stability); price. (2) Basic characteristics of catalysts: ① They can only accelerate reactions that are thermodynamically feasible. ② They only speed up the approach to equilibrium without changing the equilibrium position (they do not affect the equilibrium constant). ③ Catalysts participate in the reaction and accelerate it by altering the reaction pathway. ④ They reduce the activation energy of the reaction. ⑤ Catalysts exhibit selectivity toward certain reactions. (3) Composition and functions of catalysts: main catalyst (active component), carrier, promoters (structural promoters, electronic promoters), and others. (4) Classification of catalysts ① According to the aggregation state. 　② Based on the mechanism of action. (38 Redox, acid-base, coordination, etc.) ③ Based on the category of catalytic materials (170 metals, oxides, etc.) and their functional roles (hydrogenation/dehydrogenation, isomerization, cracking, polymerization). 　 　 Chapter 2: Adsorption in Heterogeneous Catalysis (The 44-step process: Diffusion → Adsorption → Reaction → Desorption → Diffusion) 1. Solid surfaces (54: Asymmetric force distribution), 56: Uneven energy distribution. 2. Two types of adsorption on solid surfaces, 62. 3. Adsorption strength and catalytic activity – the volcanic shape, 131. Chapter 3: Preparation of Catalysts (18, 190: Activation is generally required before actual use.) 1. Carrier-free catalysts – the common solution precipitation method; general process (172: Precipitation/coagulation → Washing/separation → Drying → Shaping → Calcination). (1) Classification of precipitation methods: Single-component simple precipitation, homogeneous precipitation, 184–185; multi-component coprecipitation, homogeneous coprecipitation. 　　(2) Principles and key technical points of precipitation operations ① Selection of metal salts and precipitants. 173 　　② Factors affecting precipitation formation: concentration, temperature, pH value, feeding method, and stirring intensity. 173-174 　　③ Aging and washing of the precipitate. 177 　　④ Drying, roasting, and activation. 179 2. Catalysts with supports – deposition of active components: precipitation, adsorption, ion exchange, impregnation. 3. Leaching method (removal of unwanted substances). 4. Catalyst shaping. Chapter 4: Characterization, testing, and evaluation of catalyst performance. 1. Overview: composition and structure; texture structure (texture) and physical properties; catalytic performance. 2. Composition and structure: composition (265); XRF, AAS; structure (266): XRD, Raman. 3. Texture structure and physical properties: surface area and porosity (212–250); BET method (physical adsorption: 0.05–0.3) and mercury pressure method; particle size and dispersion (251): sieving, sedimentation, XRD-LD; physical properties: density, strength, thermal conductivity. 4. Surface characteristics: composition (271): XPS, AES (surface); structure (276): TEM-SEM (280); dispersion (288); heterogeneity. * Relationship between activity and dispersion – two types of reactions (281): structure-sensitive/reactivity-insensitive. 5. Evaluation of activity and kinetic studies: conversion rate; under identical conditions: (1) practical activity; reaction temperature, SV space velocity; (2) multiphase catalytic reaction process: diffusion → adsorption → reaction → desorption → (6,7) diffusion; *299 L-H mechanism and R-E mechanism; (3) laboratory reactors (batch, continuous, pulsed). Chapter 5: Deactivation of catalysts. 1. Causes of deactivation (315 table). 2. Regeneration (332). III. Key points for study and discussion questions. Chapter 1: Introduction to catalysts. 1. Provide examples illustrating the role of catalysts in national economy and people’s livelihood. 　　2. What is the definition of catalysis as published by the International Union of Pure and Applied Chemistry in 1976? It is necessary to have a profound understanding of its meaning. 　　3. What are the basic characteristics of a catalyst? 　　4. Why can a catalyst only change the rate of a chemical reaction, but not the position of the chemical equilibrium? 　　5. Why is a catalyst that is effective in the forward direction also effective for the reverse reaction? 　　6. How can catalysts be classified based on their aggregation state? 　　7. How can catalysts be classified according to their reaction mechanism? 　　8. What is the definition of a main catalyst? What is the definition of a cocatalyst? 　　9. What is the definition of a carrier? What roles do they play? 10. What is the definition of a catalyst aid? Into which categories can it be divided? 　　11. What are the advantages and disadvantages of heterogeneous catalysis and homogeneous catalysis? 　　12. What are the characteristics of enzyme catalysis? Chapter 2: Adsorption in Catalysis 1. In multiphase catalytic reactions, into how many steps can the process of reactants being converted into products under the action of a catalyst be divided? 　　2. Briefly describe the differences between physical adsorption and chemical adsorption ； 62 　　3. Why is the catalytic performance poor when the adsorption is either too strong or too weak? 131 134 　　 Chapter 3 Preparation of Catalysts 　　1. Write down the general steps for the simple precipitation method. 　　2. What is the use of the coprecipitation method? Preparation of multi-component systems 3. What are the characteristics of the homogeneous precipitation method? 185 　　4. What are the principles for selecting a precipitant? 　　5. How do concentration (pH) and temperature affect precipitation formation? 　　6. How to reduce or avoid the introduction of impurities? 　　7. What is the purpose of drying? 　　8. What is the purpose of calcination? 　　9. What is the difference between adsorption and ion exchange? 188 　　10. Give an example of extraction-based preparation ； 193 　　11. Why are heterogeneous catalysts generally subjected to activation treatment before use? 12. Briefly describe the common molding methods. Chapter 3 Characterization, Testing, and Performance Evaluation of Catalysts 1. What are the indicators used to determine the performance of catalysts? 　　2. Write the definition formula for conversion rate. 　　3. What is airspeed? 16 　　4. What is the yield STY when it is empty? 16 　　5. What is selectivity? 　　8. Briefly describe the mechanism of gas-solid phase catalytic reactions. 　　9. What are the commonly used reactors in experiments? Advantages and Disadvantages 10. What should be the ratio of the reaction tube diameter to the catalyst particle diameter? Why? 25 　　13. How to determine the size of catalyst particles? 　　14. How is the particle size distribution of catalyst particles represented? 15. How to determine the specific surface area of a catalyst? What is the scope of application of the BET method? 16. How are the characteristics of a catalyst’s pore structure typically described? 232 Adsorption Loop 　　17. How are skeleton density (including pores), particle density (including inter-particle gaps), and bulk density defined? What is the size relationship? 256 　　18. What types of mechanical damage can occur to catalysts? 257 19. What methods are available to characterize the bulk and surface composition of catalysts? ； 　　20. What methods are available to characterize the bulk and surface structures of catalysts? ； 21. What information can an electron microscope provide? 22. Briefly describe how catalytic activity is actually characterized? Chapter 5 Deactivation of Catalysts 1. What is catalyst deactivation? 2. What are the categories of reasons for catalyst deactivation? 3. What is catalyst poisoning? 318 4. How is coking caused? How to carry out regeneration? 　　 Brief answer example: What are the main applications of X-ray photoelectron spectroscopy (XPS) in catalysis research? Identification of elements and their concentrations, page 271: What is the physical role in the calcination process of catalysts? Pages 179-180, Section 5: Calculation example: In an industrial process for producing cyclohexane via benzene hydrogenation with an annual output of 50,000 tons, the reactor is filled with Pt/Al2O3 catalysts, and the measured space-time yield is 2500 kg/(m3 of catalyst·h). Calculate the amount of catalyst filled in the reactor in tons (the bulk density of the catalyst is 0.66 g/cm3; one year is considered to consist of 300 days). Page 16: Annual production of 50,000 tons → hourly production = 50,000/300/24 = 6.944 tons → Volume of catalyst required = 6.944*1000/2500 = 2.778 m3 → Mass of catalyst required = 0.66*2.778 = 1.83 tons. 0.66 g/cm3 = 0.66 tons/m3. Page 42: Question 5) k = A*e^(-Ea/R/T). Ea = 8.3145×400×ln(10^3/10^-12) = 1.225×10^5 J/mol = 122.5 kJ/mol. “Catalytic Chemistry” Exam Paper. I. True or False Questions (20 points) (×) 1. The theoretical basis for determining the total surface area of solids is physical adsorption. (  ) 2. X-ray diffraction analysis can provide information on the composition of the catalyst. (  ) 3. Under normal circumstances, the selectivity of a catalyst is more important than its activity. (  ) 4. Enzyme catalysis is superior to homogeneous catalysis, which in turn is better than heterogeneous catalysis. (  ) 5. Catalysts can increase the equilibrium conversion rate of a reaction. (  ) 6. Since a catalyst does not change the equilibrium constant of a chemical reaction, a catalyst that is effective for the forward reaction is generally also effective for the reverse reaction. ( ) 7. For structure-sensitive catalytic reactions, the higher the dispersion of the active components, the greater its catalytic activity. (  ) 8. For supported catalysts, the higher the loading amount of the active component, the better its activity. (  ) 9. When the same adsorbate is adsorbed in a single layer on the same adsorbent, whether it is physical adsorption or chemical adsorption, the amount of adsorption remains the same. (  ) 10. To make full use of the catalyst, the length of the tubular reactor should be at least 50–100 times the diameter of the catalyst particles. II. Short Answer Questions (30 points) 1. Briefly describe the definition of catalysis and its characteristics (list at least four characteristics). (5 points) 2. What are the ways in which catalyst activity is expressed, and explain briefly. (4 points) 3. What are the basic assumptions of the BET theory? Also, explain the pressure range for which the BET equation is applicable and why. (6 points) 4. Write down the various steps of a heterogeneous catalytic reaction. (5 points) 5. In the ethylene hydrogenation reaction carried out on Ni catalysts, ethylene adsorbs more strongly on the crystal surfaces of Ni than on other surfaces. When ethylene adsorption is the rate-determining step (i.e., the adsorption process is slow), the reaction activity on those crystal surfaces is lower than that on other surfaces. Explain this phenomenon using the volcano model. (5 points) Refer to page 130, question 6. The nitrogen saturation adsorption capacity of 1 gram of a certain catalyst, as determined by the BET method using physical adsorption of nitrogen, is 75 cm3 (under standard conditions). Given that the molecular cross-sectional area of nitrogen is 16.210-20 m2, and the volume of 1 mol of nitrogen under standard conditions is 22.4 dm3, determine the specific surface area of this catalyst. (5 points) Refer to page 213: 326.5 m2/g. III. How to distinguish between chemical adsorption and physical adsorption, and explain it. (8 points) IV. Briefly describe the composition of a catalyst and the function of each component. (10 points) 26 V. The supported catalyst Ni/Al2O3 used in hydrogenation and methanation reactions is obtained by using a base as a precipitant to convert nickel nitrate into a hydrated oxide; this oxide is then dried and calcined to yield NiO/Al2O3, which is finally reduced using hydrogen gas. To improve the activity of the catalyst, it is necessary to increase the specific surface area of Ni. This paper analyzes aspects such as the selection of precipitants, the drying process, the calcination process, and the reduction process, to explore how the preparation process can be adjusted in order to enhance the specific surface area of the active components (12 points) VI. In the petrochemical process, naphtha (the fraction with a boiling point range of 60–180°C) is commonly used as a raw material, and acidic molecular sieves are used as catalysts to produce high-octane gasoline through catalytic reforming. When a molecular sieve catalyst of this type was used in this catalytic reaction process, after the reaction proceeded for 10 hours at a certain temperature, both the conversion rate of the reactants and the selectivity of the products decreased significantly. Upon removing the catalyst, it was found that its color had changed from light gray when it was new to light black. Please design a plan: (1) Determine the possible reasons for the decline in catalyst performance using modern analytical testing methods ； XPS, TG-DTA coking (2) Propose methods for catalyst regeneration. (20 points) Burning in an oxygen atmosphere