绿色化学与化工导论Chapter-1-introduction.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,PPT,文档演模板,Office,PPT,04 十一月 2026,绿色化学与化工导论Chapter 1 introduction,1.1 ChemistryPast,Present and Future,Chemical products make an invaluable contribution to the quality of our lives and play a fundamental role in almost every aspect of modern society.,Pharmaceuticals products,In twentieth century,World population:,from 1.6 to 6 billion,Life expectancy:,almost 60%,Crop protection and growth enhancement chemicals,The enormous populations demand western levels,The public image of the chemical industry has badly deteriorated in the last ten years.,In some of the major centres of chemicals manufacturing more people gave,positive than negative views,but for many European countries,the ratio of unfavourable to favourable views,was alarmingly high.,1.1 ChemistryPast,Present and Future,Figure 1.1,Trends in the favourability to the chemical industry of the general public(smoothed plots)(based on MORI Opinion Poll figures in the period 19802000).,In the UK,a steady decline in public perception,of the chemicals industries over many years is clearly evident.It is especially disturbing to analyse the survey data more closely and to note that,the 1624 year age group,has the lowest opinion of the chemicals industries.,1.1 ChemistryPast,Present and Future,Figure 1.2,Trend in the number of applications to study chemistry in UK universities(source:UCAS,Universities and Colleges Admissions Services,).,At present,the poor image of chemistry is adversely affecting demand.In the UK,the number of applicants to read chemistry at university has been falling steadily for several years,The number of applicants to read chemical engineering is even more alarming(1000 in the year 2000 in the UK),View of twentieth century chemical manufacturing,(1)Start with a petroleum-based feedstock.,(2)Dissolve it in a solvent.,(3)Add a reagent.,(4)React to form an intermediate chemical.,(5)Repeat(2)(4)several times until the final product is obtained;discard all waste and spent reagent;recycle solvent where economically viable.,(6)Transport the product worldwide,often for long-term storage.,(7)Release the product into the ecosystem without proper evaluation of its long-term effects.,The recipe for the twenty-first century,(1)Design the molecule to have minimal impact on the environment(short residence time,biodegradable).,(2)Manufacture from a renewable feedstock(,e.g.,carbohydrate).,(3)Use a long-life catalyst.,(4)Use no solvent or a totally recyclable benign solvent.,(5)Use the smallest possible number of steps in the synthesis.,(6)Manufacture the product as required and as close as possible to where it is required.,We must train the new generation of chemists to think of the,environmental,social and economic factors,in chemicals manufacturing.,1.2 The Costs of Waste,In the mid-1990s in the USA,for example,only about 300 or so of the 75000 commercial substances in use were classified as hazardous.,Compliance with existing environmental laws will cost new EU member states well over 10 billion;a similar amount is spent each year in the USA to treat and dispose of waste.,Cost of waste can easily amount to 40%of the overall production costs for a typical speciality chemical product.,Production costs,Figure 1.3,Production costs for speciality chemicals.,The Costs of Waste,Figure 1.4,The costs of waste.,1.3 The Greening of Chemistry,Figure 1.5,Options for waste management within a chemical manufacturing process.,Hierarchy of waste management techniques,Prevention,by far the most desirable option,Recycling,the next most favourable option,Disposal,the least desirable option,Cleaner production:,The continuous application of an integrated preventative environmental strategy to processes and products to reduce risks to humans and the environment.For production processes,cleaner production includes conserving raw materials,and reducing the quality and toxicity of all emissions and wastes before they leave a process.,Atom economy,Table 1.1,Atom accounts for a typical partial oxidation reaction using chromate,Element,Fate,Atom utilisation,C,Product(s),Up to 100%,H,Product(s)+waste acid,100%,Cr,Chromium waste,0%,Na,Salt waste,0%,S,Salt waste(after acid neutralisation),0%,O,Product(s)+waste,100%,Atom economy:,how many atoms of the starting material are converted to useful products and how many to waste,.,A typical oxidation reaction:an alcohol a carboxylic acid,chromium(VI)as the stoichiometric oxidant,Environmental factor,It is used to,quantify,the effects of production process to the environment,Idea:,All other compounds formed other than the target product are considered to be,WASTE,.,Atom Economy and environmental effects,Where does the waste come from?,Environmental,factor,E=,The amount of waste,The amount of,target product,The more waste formed,The more serious the pollution,If the atom,Utilization=100%,E,=0,Environmental factor,Environmental factor,Table 1.2,Relative efficiencies of different chemicals manufacturing sectors,Areas traditionally thought of as being dirty(oil refining&bulk chemical production)are relatively clean-they need to be since margins per Kg are low.,Newer industries with higher profit margins and employing more complex chemistry produce much more waste relatively.,Industry sector,Product tonnage,By-product weight/product weight,Oil Refining,10,6,-10,8,0.1,Bulk Chemicals,10,4,-10,6,1-5,Fine Chemicals,10,2,-10,4,5 50+,Pharmaceuticals,10-10,3,25-100+,Environmental quotient,(EQ),E-,Environmental factor,Q-,The extent of hazardousness of the waste to the environment obtained from the performance of the waste in the environment,.,EQ,E,Q,The,E,factor just gives the ratio of the waste and the target product.,But the environmental pollution is strongly associated with the harmful performance of the waste.,Energy Efficiency,Table 1.3,Global lost work in major chemical processes,Process,Theoretical work potential(kJmol,-1,final product),Raw materials,Final product,a,Thermodynamic efficiency(%),Natural gas+air methanol,1136,717,63,Natural gas+air hydrogen,409,236,58,Ammonia(from natural gas+air)nitric acid,995,43,4,Copper ore copper,1537,130,9,Bauxite aluminium,4703,888,19,a,Excludes any steam credit.,Energy efficiency via lost work,Biomass utilisation,Figure 1.6,Biomass utilisation in 2040.,Biomass utilisation,Table 1.4,From fossil to green,Energy source,Percentage of energy sources,1990,a,2040,b,Oil,38,17,Coal,20,18,Gas,16,14,Biomass,16,19,Hydro,5,5,Nuclear,5,6,Solar,14,Wind,7,Based on an energy consumption of,a,3.510,20,J;,b,110,21,J.,We seek to satisfy our need and not our greed,life-cycle assessment,The life-cycle of a product can be considered as:,Pre-manufacturing(materials acquisition),Manufacturing(processing and formulation),Product delivery(packaging and distribution),Product use,End of(first)life,We can no longer afford single-use products.,life-cycle assessment,Figure 1.7,Life-cycle assessment for chemical products(E=energy input;C=consumables input;W=waste).,Pollution prevention options,Figure 1.8,Pollution prevention options in the life-cycle of a chemical product.,