3.3.2 Benzene, toluene and xylene In addition to benzene itself, the catalytic reformer also produces ethylbenzene, toluene and the isomeric xylenes directly. The demand for ethylbenzene is always great as a source of styrene monomer, but toluene does not find great use apart from a relatively small application in polyurethane. This is why most toluene is de-alkylated to increase overall benzene production. A similar problem exists with the xylenes:
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3.3.1 Ethylene, propylene and butadiene Nowadays ethylene is the most important building block for the chemical industry, particularly as a monomer in its own right, as a co-monomer with other vinyls, and as a source of vinyl monomers. It is the prime source for ethylene oxide, which is another major source of polymers, glycols and ethers. They can also be used to build up more complex C4 molecules and aromatics. Some of the ways in which the ethylene molecule is modified to create other chemicals and polymers are
3.3 Petrochemical intermediates and monomers About 80 per cent of all petrochemicals end up in polymers, the most important building blocks being ethylene, propylene, butadiene and benzene. The first three can be polymerized directly but an important slice of their production is used to create more complex monomers. Ethylene is the progenitor of most vinyl monomers (Figure 35), so the pressure on ethylene supply is particularly strong compared for example to propyle
3.2.2 Ethane cracking Although ethane can be cracked thermally, the reaction is slow and does not necessarily yield ethylene at high severity. Careful control of reaction conditions, however, allows the reaction to occur The yield of ethylene is typically nearly 50 wt% with the rest composed of unreacted ethane (40 per cent) and some methane and hydrogen (10 per cent). T
3.2.1 Thermal cracking The bulk of the major monomer and intermediate, ethylene (C2H4), is still produced in the UK by steam cracking without the use of catalysts. Paraffinic feedstocks are best for optimising ethylene yields, and the severity of cracking is specified by the rate of disappearance of a marker compound, usually n-pentane. The severity of the reaction can then be defined as follows: 2.1.1 Memorising 2 1 Different conceptions of learning 1.3 The realities of war – a protest 9.7 Debate 4: representation of Scotland 8.2 Reviews of the first edition Financial Markets Introduction to Political Philosophy 4.1 Natural/social In the previous section we looked at the issue of competing explanations of social problems. Here we want to take a rather different approach by starting from one of the major dividing lines between different types of explanation. These dividing lines are ones that recur in the definition, interpretation and explanation of a range of social issues: for example, patterns of inequality between men and women; crime and juvenile delinquency; the persistence of poverty, and so on. Despite the fact 3.6 Summary Three explanations of poverty developed by social scientists have been considered. The first sees poverty as natural or inevitable, the second focuses on the behaviour of poor people, while the third analyses poverty as the result of economic or political processes. Considering these explanations makes it possible to draw some conclusions about the social science approach to social problems: It relies on arguments making causal claims, rather than ass 3.3 Poverty as the result of poor people The second cluster of common-sense ideas about poverty centre around the theme that the character and behaviour of some types of people causes them to be poor. Such people are in some way ‘flawed’. There may, of course, be different types of flaw, but poor people are distinguished from the rest of ‘us’ by some characteristic that makes ‘them’ poor. This might be their moral character (they are lazy, shiftless, workshy); it might be their abilities or capacities (the IGBP Climate-Change Index How to Write a Check Organic Gardening-How to Plant Bulbs-Tulips Algebra: what are variables, constants, coefficients, terms, and expressions. Pre Algebra - Dividing Mixed Numbers
How do we learn? Understanding ‘how’ is the key to learning more effectively. This unit looks at the three main categories of theories: the acquisitive, constructivist and experiential models of learning. There is no right way to learn but developing an active approach will ensure that you are open to new ideas.
How do we learn? Understanding ‘how’ is the key to learning more effectively. This unit looks at the three main categories of theories: the acquisitive, constructivist and experiential models of learning. There is no right way to learn but developing an active approach will ensure that you are open to new ideas.
In this unit we will consider how language can be used in different ways for different purposes. To do this we will use the theme of memorial and commemoration. In the first section we briefly discuss the life of the poet Siegfried Sassoon before examining both his poetry and prose. Through this we will see how he conveys meaning in different ways for different audiences using different forms. Following this we discuss more generally how different meanings can be conveyed using prose and poetic
Sunset Song was written in the early 1930s and is still one of the best-known and most-debated Scottish novels. In this unit, we discuss whether Sunset Song succeeds as critique of capitalism and whether it has value as a work of literature separate from its propagandistic ambitions.
Sunset Song was written in the early 1930s and is still one of the best-known and most-debated Scottish novels. In this unit, we discuss whether Sunset Song succeeds as critique of capitalism and whether it has value as a work of literature separate from its propagandistic ambitions.
Financial institutions are a pillar of civilized society, supporting people in their productive ventures and managing the economic risks they take on. The workings of these institutions are important to comprehend if we are to predict their actions today and their evolution in the coming information age. The course strives to offer understanding of the theory of finance and its relation to the history, strengths and imperfections of such institutions as banking, insurance, securities, futures, a
This course is intended as an introduction to political philosophy as seen through an examination of some of the major texts and thinkers of the Western political tradition. Three broad themes that are central to understanding political life are focused upon: the polis experience (Plato, Aristotle), the sovereign state (Machiavelli, Hobbes), constitutional government (Locke), and democracy (Rousseau, Tocqueville). The way in which different political philosophies have given expression to various
The IGBP Climate-Change Index brings together key indicators of global change: atmospheric carbon dioxide, temperature, sea level and sea ice. It will be released annually.
The index gives an annual snapshot of how the planet's complex systems - the ice, the oceans, the land surface and the atmosphere - are responding to the changing climate.
The index rises steadily from 1980 - the earliest date the index has been calculated.
The change is unequivocal, it is global, and it is in one directio
Writing a check is a critical skill to finance. This video go through step-by-step describing each part of a check, how to use it, and what it means. The speaker's voice is a little difficult to understand. Run time: 4:07
This video shows the step by step process to planting bulbs. Tulips are among the most reliable and colorful spring-flowering bulbs. This video shows supplies you need and how to correctly plant tulips (Running Time 4:58).
This video is only the first 11 minutes of the full lesson. This lesson consists of providing you with a Self-Tutorial on what is algebra, what are variables, constants, coefficients, terms, and expressions. The tutor explains the use of proper notation, how to combine like terms, find the negation of an algebraic expression, how to evaluate an expression.
In this lesson, students learn to divide mixed numbers by first
rewriting the mixed numbers as improper fractions, then dividing the
improper fractions, then rewriting the resulting improper fraction as a
mixed number, if necessary. For example, to simplify 3 1/3 1 4/7, first
rewrite the mixed numbers as improper fractions, to get 10/3 11/7. Next,
change the division sign to multiplication and flip the second
fraction, to get 10/3 x 7/11. Next, multiply a
