Octane number blending components
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I would like to ask whether refineries currently use MTBE and other chemical ingredients to blend low-octane gasoline in order to increase its octane rating and bring it in line with the 90 or 93 national standards This post was last edited by Shuichangshou on 2009-3-12 15:03]
The United States banned the addition of MTBE to gasoline nationwide in May 2006. To date, Europe is still using MTBE. In China, MTBE remains a good oxygenating additive for automotive gasoline at present. As China’s C4 resources increase, although there are many uncertainties regarding the future use of MTBE in gasoline blending, its consumption for chemical production is expected to rise significantly, leaving a promising market outlook.
Our company is still making extensive use of it, especially for producing high-octane gasoline (97#); it’s impossible to get the product out of the factory without it.
Currently, most refineries across the country use MTBE or manganese additives to increase octane rating. Canada and the United States strongly promoted the use of MTBE over a decade ago (in the early 1990s), but now neither country advocates nor permits its use. The main reason is concern that MTBE leaking into the environment could pose potential risks to human health (although this has not yet been proven). It’s a pity that China is currently actively promoting its use.
Many factories in China still use MTBE as a blending agent to increase the octane rating of gasoline. Although it has been proven that MTBE has a high permeability and causes severe pollution to groundwater, it remains the primary method used for blending gasoline in China. The use of MTBE is no longer allowed abroad. In China as well, new technologies are being researched, such as etherified gasoline; these technologies are still in the process of development. But for now, this type of fuel is still needed. :L
It seems that most small refineries these days raise the octane rating of their products by mixing low-octane oils such as naphtha with synthetic aromatics to produce chemicals like MTBE, before selling them. Do such products have significant quality defects?
As environmental regulations become increasingly stringent, stricter requirements are placed on the content of aromatics, particularly benzene, in gasoline. As a result, some refineries have been forced to install aromatics extraction units, which inevitably leads to a loss in the octane rating of the reformed gasoline. Therefore, it is becoming increasingly difficult to rely solely on reforming to increase the octane rating of gasoline; alternative methods such as alkylation, isomerization, and etherification must also be considered (although the drawback of etherification is that it results in a loss of calorific value when used to increase octane rating).
MTBE and alkylated oils are used
The composition of gasoline sold in China currently is roughly as follows: catalytic cracking gasoline accounts for about 3/4, reformated gasoline about 15%, MTBE about 1%, and other types (including straight-run gasoline, hydrocracked gasoline, alkylated gasoline, etc.) account for about 9%. Reformated gasoline, MTBE, and alkylated gasoline have relatively high octane numbers; generally, 90# and 93# gasoline do not require special blending. However, 95# and especially 97# gasoline need to have a large amount of reformated gasoline added to them in order to increase their octane number.