CHEMISTRY 30 ORGANIC CHEMISTRY Refining Review and Combustion

CHEMISTRY 30 ORGANIC CHEMISTRY Refining Review and Combustion Reactions

Physical Refining Fractional Distillation � What is it? � Figure 2 Page 386 Solvent Extraction �A solvent is added to selectively dissolve and remove an impurity or separate useful products Dewaxing � Cooling a mixture to precipitate a larger wax fraction

Chemical Processes Purpose � Necessary because distillation produces too much of the heavier fractions of hydrocarbons � Consumers demand the lighter ones (fuel for heating and transportation) (95%) � Only 5% of crude oil is used for things other than fuel (solvents, greases, plastics, synthetic fibres, pharmaceuticals)

Chemical Refining Cracking � Breaking down large molecules with heat and catalysts � Heat = thermal cracking, messy, inefficient � Catalysts = catalytic Cracking much better � Page 389 Figure 5 � Hydrogen = hydrocracking a variation of catalytic cracking with almost no carbon byproducts

Chemical Refining Catalytic Reforming � Forming larger molecules from smaller ones � Forming aliphatic gas fractions into aromatic ones (better burning) � Eg. Heptane to methyl-benzene Alkylation � Increases branching of molecules � Aka isomerization � Again burns better in an engine

Case Studies Octant Number (Page 392) � Read and take a look at questions The Athabasca Oil Sands (Page 395) � Read and take a look at questions � VERY INTERESTING!!!

Combustion Reactions Important reaction for organic compounds � Main use is to burn for transportation and heating Two Types � Complete combustion (any yellow flame burning) � Incomplete combustion

Complete Combustion as we know it! Only products are � Carbon dioxide � Water � Energy Quantitative Show burning of octane

Incomplete Combustion Occurs because there is not sufficient amounts of O 2 Produce carbon monoxide and carbon (soot) in addition to carbon dioxide and water Show three reactions that occur simultaneously in the combustion of octane Look at the oxygen in these three reactions � Which one required the most � So if there s no a ready supply what happens? � Increasing the amount of oxygen increases the efficiency

Addition of Alcohol is an Oxygenator � Provide oxygen to the reaction so requires less � Therefore less carbon monoxide emissions Hence, Ethanol blended fuels � Legislated by many governments now Show burning of ethane vs. Ethanol � Difference in oxygen required � Small but imagine over millions of mols!

Assignment Reading � Nelson Pages 386 -400 Questions � Nelson Page 397 #’s 2, 3, 4, 6, 7, 9 � Nelson Page 400 #’s 1, 3, 4, 5, 6