Difference between revisions 487433 and 507949 on enwiki

'''Alkylation''' is the transfer of an [[alkyl]] group from one molecule to another.

In a standard [[oil refinery]] [[process]], alkylation combines low-molecular-weight [[olefin]]s (primarily a mixture of [[propylene]] and [[butylene]]) with [[isobutane]] in the presence of a [[catalyst]], either [[sulfuric acid]] or [[hydrofluoric acid]]. The product is called alkylate  and is composed of a mixture of high-[[octane]], branched-chain [[paraffin]]ic [[hydrocarbon]]s.  Alkylate is a premium [[gasoline]] blending stock because it has exceptional antiknock properties and is clean burning. The octane number of the alkylate depends mainly upon the kind of olefins used and upon operating conditions.  For example, [[isooctane]] results from combining butylene with isobutane and has an octane rating of 100 by definition.  There are other products in the alkylate, so the octane rating will vary accordingly.

Most [[crude oil]]s contain only 10 to 40 percent of their hydrocarbon constituents in the gasoline range, so refineries use [[cracking (chemistry)|cracking]] processes, which convert high molecular weight hydrocarbons into smaller and more volatile compounds. [[Polymerization]] converts small gaseous olefins into liquid gasoline-size hydrocarbons. Alkylation processes transform small olefin and iso-paraffin molecules into larger iso-paraffins with a high octane number.

Combining cracking, polymerization, and alkylation can result in a gasoline yield representing 70 percent of the starting crude oil. More advanced processes, such as cyclization of paraffins and dehydrogenation of naphthenes to form aromatic hydrocarbons in a [[catalytic reformer]], have also been developed to increase the octane rating of gasoline.  Modern refinery operation can be shifted to produce almost any fuel type with specified performance criteria from a single crude feedstock.

In the whole range of Refinery processes "Alkylation" is a very important process to enhance the yield by regruoping of molecules as desired.
[[Category:Chemistry]]The March of the Volunteers''' (in simplified Chinese 义勇军进行曲) is the [[national anthem]] of [[China]], written in the midst of the [[Sino-Japanese War (1937-1945)]] by the noted poet [[Tian Han]] (田汉) with music composed by [[Nie Er]] (聂耳).  This composition is a [[March_(music)|musical march]].  

It was originally the theme song of the film ''Sons and Daughters in a Time of Storm'' (风云儿女, 1935), a story about nameless heroes and heroines of the Sino-Japanese War.

The song was chosen to be the provisional national anthem on September 27,1949. It became the official national anthem for China on December 4,1982.


==Lyrics==

《义勇军进行曲》

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==Translation==

'''The March of the Volunteers'''

Arise, people who refuse to be slaves!<BR>
Using our flesh and blood, let us build our new Great Wall!<BR>
The Chinese nation arrives at its most dangerous moment,<BR>
Everybody is forced to cry the last roar.<BR>
Arise! Arise! Arise!<BR>
We unite as one,<BR>
Brave enemy’s gunfire, march on!<BR>
Brave enemy’s gunfire, march on!<BR>
March on! March on! On!<BR>