refineries

=chemistry =suggestion =energy

 

 

Current refineries use catalytic reformers, which produce benzene and other aromatics. Benzene is bad, and when burned in car engines, the other aromatics produce particulate pollution.

Here is an alternative process.


Send your oil to a fluid catalytic cracker.

Distill the products into 5 fractions:
fraction A: methane -> converted to syngas
fraction B: ethylene -> plastics / ethanol
fraction C: C2 to C4
fraction D: C5 to C6
fraction E: >70 C -> aromatic separator -> distillation


fraction C + D get:
hydroformylation (branched) -> Tishchenko reaction -> distillation

distilled from fraction C:
ethane -> converted to syngas / sold as compressed ethane
propane + butane -> sold as LPG
aldehydes -> returned to Tishchenko reaction reactor
esters -> transesterification reactor

distilled from fraction D:
<60 C -> added to gasoline
60-100 C -> diesel / jet fuel
100-160 C -> returned to Tishchenko reaction reactor
esters -> transesterification reactor

transesterification reactor:
- add ethanol and/or methanol
- do transesterification
- distill out products with (95 C < bp < 190 C) and return the rest


Extra syngas from methane and ethane can be used to produce methanol.
Extra ethylene can be hydrated to ethanol or added to fraction C.

Ethylene can also be used for olefin metathesis: ethylene and C4 can be reacted for propylene, or ethylene and C7 to C10 can be reacted for gasoline production.


aromatic separator:
This uses a selective solvent to separate aromatics, and then the products are distilled.

aliphatics:
<140 C -> diesel / jet fuel
>140 C -> returned to FCC

aromatics:
<100 C -> sold as benzene
100-180 C -> added to gasoline / jet fuel
>180 C -> converted to syngas


The gasoline product then consists of:
- FCC products with (25 C < bp < 60 C)
- esters of C3 to C7 branched carboxylic acids (95 C < bp < 190 C)
- C3 to C7 branched alcohols
- relatively low amounts of toluene, xylenes, and trimethyl benzenes


Oil contains some sulfur, and small amounts of sulfur poison many hydroformylation catalysts, but there are now sulfur-tolerant hydroformylation catalysts. For one example, see this paper. Heterogeneous catalysts for hydroformylation are also practical.

This type of refinery implies greater production of propane and butane, but that might not be a bad thing. LPG has a good octane rating, it's clean-burning, and unlike CNG, converting cars to run on LPG is relatively cheap
.


 

 



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