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Developing Fuels > DF10 > Flashcards

DF10 Flashcards

1
Q

What is a primary pollutant?

A

An air pollutant emitted directly from a source.

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2
Q

What are secondary pollutants?

A

When primary pollutants react in the atmosphere.

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3
Q

What are some of the primary pollutants (from vehicles and other sources)?

A
  • particulates
  • volatile organic compounds (VOC)
  • carbon monoxide (CO)
  • carbon dioxide (CO2)
  • nitrogen oxides (NOx)
  • sulfur oxides (SOx)
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4
Q

What are particulates?

A

Particularly small carbon particles smaller than 2.5 x 10^-12 m.

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5
Q

What are the major sources of particulates?

A
  • volcanoes
  • burning fuels
  • burning coal
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6
Q

What are the major polluting effects of particulates?

A

Penetrate deep into the human body - causing heart attacks and lung cancer.

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7
Q

What are the major sources of VOC?

A
  • plants

- unburnt fuel from petrol engines

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8
Q

What are the major polluting effects of VOC?

A

photochemical smog

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9
Q

What are the major sources of CO?

A
  • incomplete combustion of hydrocarbons in fossil fuels

- burning biomass

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10
Q

What are the major polluting effects of CO?

A
  • toxic gas

- photochemical smog

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11
Q

What are the major sources of CO2?

A

combustion of fossil fuels

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12
Q

What are the major polluting effects of CO2?

A

greenhouse effect

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13
Q

What are the major sources of NOx?

A

combustion of fuels in power stations and vehicles

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14
Q

What are the major polluting effects of NOx?

A
  • acid rain

- photochemical smog

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15
Q

What are the major sources of SOx?

A
  • volcanoes

- burning of fuels containing sulfur

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16
Q

What are the major polluting effects of SOx?

A
  • toxic gas

- acid rain

17
Q

What is the equation for complete combustion?

A

hydrocarbon/alcohol + oxygen → carbon dioxide + water

18
Q

What is the equation for incomplete combustion?

A

hydrocarbon/alcohol + oxygen → CO + C + water

19
Q

Why does incomplete combustion occur?

A

Limited supply of oxygen - either CO or C produced (and water).

20
Q

How is SO2 produced from fuels?

A

Burning of sulfur compounds in fuels:

S + O2 → SO2

21
Q

How are NOx produced from fuels?

A

Burning of nitrogen compounds in fuels:

N2 + O2 → 2NO

22
Q

How are NOx produced from vehicles?

A
  • burning in fuels

- nitrogen and oxygen in the air react in very high temperatures of a vehicle engine

23
Q

How is acid rain produced from SOx?

A
  • SO2 + H2O → H2SO3 (atmosphere)
  • then SO2 is oxidised to make SO3 in stratosphere
  • SO3 + H2O → H2SO4
24
Q

How is acid rain produced from NOx?

A

2NO/2NO2 + H2O + 1.5O2 → 2HNO3 (atmosphere)

25
Q

What are the harmful effects of acid rain?

A
  • breathing difficulties
  • corrodes limestone buildings
  • kills forests
  • kills life in lakes
26
Q

How is photochemical smog produced?

A

When primary pollutants absorb sunlight to produce secondary pollutants (e.g. ozone, NO2, nitric acid).

27
Q

What are the harmful effects of photochemical smog?

A
  • haziness
  • reduced visibility in air
  • respiratory problems in humans
28
Q

How are pollutants removed in petrol engines?

A

CO: 2CO + O2 → 2CO2
hydrocarbons: complete combustion
NO: 2NO + CO → N2 + 2CO2

29
Q

Where do the reactions to remove pollutants in petrol engines occur?

A

In a three-way catalytic converter - consisting of platinum/rhodium (on a porous support).

30
Q

How are SOx pollutants best prevented?

A

Removing sulfur impurities from fuels.

31
Q

What are the main pollutants present in diesel engines?

A
  • CO
  • hydrocarbons
  • particulates
  • NOx compounds
32
Q

How are CO and hydrocarbons removed in diesel engines?

A

CO: 2CO + O2 → 2CO2
hydrocarbons: complete combustion

33
Q

How are particulates removed in diesel engines?

A
  • diesel particulate filters

- regeneration (burning it off)

34
Q

How are NOx compounds removed in diesel engines?

A
  • Recycle some of the exhaust gases through the cylinder, lowering the temperature and amount of NOx formed.
  • Reagent (e.g. ammonia) is used rather than a catalyst
35
Q

How are is SO2 best prevented?

A

Using ultra low-sulfur fuels

Developing Fuels (11 decks)

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