Importance of industrial processes

Transcription

1 Chapter 50 Importance of industrial processes 50.1 Development of synthetic products for modern ways of living 50.2 Advantages and disadvantages of industrial processes 50.3 Recent progress in industrial processes Key terms Progress check Summary Concept map P. 1 / 36

2 50.1 Development of synthetic products for modern ways of living What are industrial processes? Raw materials Bulk chemicals Synthetic products examples: petroleum minerals air water examples: ammonia sulphuric acid methanol sodium hydroxide chlorine ethene examples: drugs detergents plastics paints fertilizers Figure 50.1 A simplified diagram for the production of synthetic products in the chemical industry. P. 2 / 36

3 Learning tip Bulk chemicals are chemicals that are sold thousands of tonnes a year and used for the production of synthetic products. The industrial processes are usually carried out in chemical reactors of chemical plants Development of synthetic products for modern ways of living Figure 50.2 A chemical plant that manufactures fertilizers. P. 3 / 36

4 raw materials water energy Chemical Reactor desired products by-products wastes unconverted raw materials Figure 50.3 A schematic diagram to illustrate an industrial process carried out in a chemical reactor. Water acts as one of the raw materials, a solvent or a cooling agent in the process. The desired products are separated from the by-products and the unconverted raw materials Development of synthetic products for modern ways of living P. 4 / 36

5 Learning tip A by-product is a substance formed at the same time as the desired product during a chemical reaction. In most cases, by-products are wastes and lower the yield of the desired products. The rate and yield of the chemical reactions can be optimized by controlling the reaction conditions (e.g. temperature, pressure, catalyst, etc.) in the chemical reactor Development of synthetic products for modern ways of living P. 5 / 36

6 Development of synthetic products Food Fertilizers (e.g. ammonium nitrate) Pesticides Petrochemical-based plastics such as polystyrene foam containers and polyethene food wraps (a) (b) (c) Figure 50.4 (a) Ammonium nitrate is manufactured on a large scale. (b) Pesticides are sprayed to kill pests to increase the yield of crops. (c) Food wrap is made from polyethene Development of synthetic products for modern ways of living P. 6 / 36

7 Medical care Drugs like aspirin (a painkiller) and penicillin (an antibiotic) PVC-made disposable syringes and blood transfusion bags (a) (b) (c) (d) Figure 50.5 (a) Aspirin and (b) penicillin are two of the end products of the petrochemical industry. (c) Disposable syringes are made of PVC. (d) PVCmade blood transfusion bags can be used to store blood from donors Development of synthetic products for modern ways of living P. 7 / 36

8 Clothing Synthetic fibres made from polyesters and nylon Figure 50.6 Jacket made of polyester and nylon. Housing Plastics such as urea-formaldehyde and polyurethanes are good heat-insulating materials for building houses Development of synthetic products for modern ways of living P. 8 / 36

9 Transport Some fuel tanks are made of high-density polyethene (HDPE). Methyl tertiary-butyl ether (MTBE) made from methanol is used as a fuel additive in petrol. Figure 50.7 The use of fuel additive like MTBE can reduce the amount of pollutants in the car exhaust Development of synthetic products for modern ways of living P. 9 / 36

10 Key point Chemical industry involves industrial processes which convert raw materials from natural resources into synthetic products. Example 50.1 Class practice Development of synthetic products for modern ways of living P. 10 / 36

11 50.2 Advantages and disadvantages of industrial processes What is petrochemical industry? Petrochemical industry produces chemicals (known as petrochemicals) from petroleum or natural gas. Petroleum or Natural gas Petrochemicals e.g. ethene, propene and benzene Synthetic products e.g. polyethene, PVC Figure 50.8 A simplified flow diagram for the production of synthetic products in the petrochemical industry. P. 11 / 36

12 Learning tip During World War II, there was a great demand for synthetic products to replace the expensive natural products. Think about 50.2 Advantages and disadvantages of industrial processes P. 12 / 36

13 Advantages and disadvantages of using industrial processes such as petrochemical industry for the manufacture of products from social, economic and environmental perspectives Advantages It attracts overseas or local investments to the society. The setting up of chemical plants creates job opportunities for local people. The traffic network related to the chemical plants improves the infrastructure of the community. The taxes collected from the industry generates income for the government Advantages and disadvantages of industrial processes P. 13 / 36

14 Disadvantages Some chemical plants generate solid and liquid wastes coming from the catalysts and chemical reagents used in reactions. Some of them are harmful and some are even toxic. Burning of fuels and some industrial processes like cracking may emit gaseous pollutants. They pollute the air. Figure 50.9 Gaseous pollutants emitted from the chemical plant may pollute the air Advantages and disadvantages of industrial processes P. 14 / 36

15 Disadvantages The cost for pollution control is high. The potential risks of chemicals require safe operation of the chemical plants. The cost for safety control is high. Key point The fundamental challenge for the chemical industry is to manufacture products demanded by the society at an acceptable cost, without causing damage to the environment Advantages and disadvantages of industrial processes P. 15 / 36

16 50.3 Recent progress in industrial processes The industrial processes are developed to become more efficient and environmentally friendly. Production of Vitamin C Vitamin C is found in citrus fruits such as oranges, lemons and grapefruits. Figure Citrus fruits are rich in vitamin C. P. 16 / 36

17 Vitamin C can be extracted from plants, but the supply cannot meet the worldwide demand. There is an inadequate and shrinking supply of natural vitamin C. Pure vitamin C is obtained by large-scale industrial production Recent progress in industrial processes Figure Vitamin C tablets sold in the market are produced on a large scale industrially. P. 17 / 36

18 Two main processes used for production of vitamin C Chemical name of vitamin C: ascorbic acid Chemical structure: Two main processes: 1. The traditional Reichstein process 2. The newer two-stage fermentation process 50.3 Recent progress in industrial processes P. 18 / 36

19 Reichstein process It is a combined chemical and microbial method (fermentation) for producing ascorbic acid from D-glucose. The overall yield of vitamin C produced from this process is about 60%. Learning tip Fermentation is a form of anaerobic respiration occurring in certain micro-organisms. It causes an organic compound to split into simpler substances Recent progress in industrial processes P. 19 / 36

20 Step 1 Reduction Step 2 Fermentation Step 3 Chemical synthesis D-glucose D-sorbitol L-sorbose KGA (2-keto-L-gulonic acid) Step 4 Condensation L-ascorbic acid (vitamin C) Step 5 Purification H 2 O Purified vitamin C 50.3 Recent progress in industrial processes Figure Process of producing vitamin C the Reichstein process. P. 20 / 36

21 Two-stage fermentation process It uses fermentation twice for producing ascorbic acid from D-glucose. The overall production cost of this process is only two-third that of the Reichstein process. The overall yield of vitamin C produced from this process is also about 60%. Example Recent progress in industrial processes P. 21 / 36

22 Step 1 Reduction Step 2 Fermentation Step 3 Fermentation D-glucose D-sorbitol L-sorbose KGA (2-keto-L-gulonic acid) Step 4 Condensation L-ascorbic acid (vitamin C) Step 5 Purification H 2 O Purified vitamin C 50.3 Recent progress in industrial processes Figure Process of producing vitamin C the two-stage fermentation process. P. 22 / 36

23 Recent progress in industrial production of vitamin C Domination of the vitamin C production market by Mainland China Manufacturers in Mainland China still dominate the vitamin C production market. Exploration of new technology for vitamin C production A yeast-based single-step fermentation method was developed for the conversion of L-sorbose to L-ascorbic acid (vitamin C). L-sorbose yeast-based single-step fermentation 50.3 Recent progress in industrial processes L-ascorbic acid P. 23 / 36

24 Key point Vitamin C can be produced by the Reichstein process and the two-stage fermentation process. Besides, research is under way to produce vitamin C in a more efficient and environmentally friendly way. Class practice Recent progress in industrial processes P. 24 / 36

25 Key terms 1. ascorbic acid 抗壞血酸 2. bulk chemical 散裝化學品 3. petrochemical 石油化學產品 4. petrochemical industry 石油化學工業 5. raw material 原材料 6. Reichstein process 賴希斯坦製造法 7. synthetic product 合成產物 8. two-stage fermentation process 二步發酵法 P. 25 / 36

26 Progress check 1. What are industrial processes? 2. Can you suggest some examples of synthetic products? 3. How do the synthetic products benefit the modern ways of living in the following areas? (a) Food (b) Medical care (c) Clothing (d) Housing (e) Transport 4. What is petrochemical industry? P. 26 / 36

27 5. What are the advantages and disadvantages of using petrochemical industry for the manufacture of products? 6. What are the sources of vitamin C? 7. Can you name the process currently used to produce vitamin C on a large scale? 8. What are the similarities and differences between the two main industrial processes of producing vitamin C? 9. What is the recent process in the industrial production of vitamin C? Progress check P. 27 / 36

28 Summary 50.1 Development of synthetic products for modern ways of living 1. Industrial processes involve chemical processes which convert raw materials to bulk chemicals and then to synthetic products. 2. The development of synthetic products meets and satisfies our daily needs in different major areas of modern living such as food, medical care, clothing, housing and transport. P. 28 / 36

29 50.2 Advantages and disadvantages of industrial processes 3. Petrochemical industry produces petrochemicals to make a wide variety of synthetic products. Summary P. 29 / 36

30 4. Advantages of using industrial processes (e.g. in petrochemical industry) for the manufacture of products: (i) It attracts overseas or local investments to the society. (ii) The setting up of chemical plants creates job opportunities for local people. (iii) The traffic network related to the chemical plants improves the infrastructure of the community. (iv)the taxes collected from the industry generates income for the government. Summary P. 30 / 36

31 5. Disadvantages of using industrial processes (e.g. in petrochemical industry) for the manufacture of products: (i) Some chemical plants generate solid and liquid wastes, which are harmful and even toxic. (ii) Burning of fuels and some industrial processes like cracking may emit gaseous pollutants. (iii) The cost for pollution control is high. (iv)the cost for safety control is high. Summary P. 31 / 36

32 50.3 Recent progress in industrial processes 6. Vitamin C (or ascorbic acid) is found in citrus fruits, but there is an inadequate and shrinking supply of natural vitamin C. 7. There are two main processes used for the production of vitamin C on a large scale the Reichstein process and the two-stage fermentation process. 8. The Reichstein process is a combined chemical and microbial method (fermentation) for the production of ascorbic acid from D- glucose. Summary P. 32 / 36

33 9. The two-stage fermentation process uses fermentation twice for the production of ascorbic acid from D-glucose. The process has a lower cost and is more environmentally friendly when compared with the Reichstein process. 10. Scientists are still looking for more environmentally friendly methods to manufacture vitamin C on a large scale. Summary P. 33 / 36

34 Concept map Raw materials to Bulk chemicals then to Synthetic products convert INDUSTRIAL PROCESSES examples Petrochemical industry Industrial production of vitamin C P. 34 / 36

35 Petrochemical industry social, economic and environmental considerations Advantages: attracts overseas or local investments to the society creates job opportunities for local people improves infrastructure of the community generates income for the government Disadvantages: generate solid and liquid wastes, which are harmful and even toxic emit gaseous pollutants from burning of fuels and some industrial processes high cost for pollution control high cost for safety control Concept map P. 35 / 36

36 Industrial production of vitamin C Reichstein process Two-stage fermentation process Fermentation + chemical synthesis Two fermentation stages Concept map P. 36 / 36