Environmental Engineering Reference
In-Depth Information
is used as a catalyst (IFQC 2004). The feedstock is also another source of phosphorus in bioethanol
(White Paper 2007). Phosphorus is a powerful catalyst poison and can increase a vehicle's emissions
by deactivating the exhaust catalyst system (IFQC 2004; White Paper 2007). Additionally, phos-
phorus can serve as a nutrient source for microbes (IFQC 2004) and thus it increases bioethanol
impurity, accelerates tank corrosion, and plugs filters and fuel lines.
Because of these effects, international fuel quality standards are becoming more strict concern-
ing the phosphorus content of fuel. However, it is not yet clear whether these specifications should
concern the fuel ethanol or the final fuel product to be more effective (IFQC 2004).
CEN specification includes a 0.50-mg/L maximum (EN 15487) limit for the phosphorus content
of bioethanol. The United States and Brazil doubt the need for this requirement for current bioetha-
nol but acknowledge that this could be an issue for bioethanol derived from nontraditional feedstock
and processes. To achieve this, the United States may consider adding a phosphorus specification
whereas Brazil, which aims to continue deriving bioethanol from its current feedstock, sugarcane,
by fermentation, will not follow (White Paper 2007).
9.3.11 (u
nwaShEd
) g
um
/E
vaporation
r
ESiduE
/n
onvolatilE
m
atErial
Gum, evaporation residue, and nonvolatile (involatile) material are three different procedures that
measure the residue of ethanol evaporation (Costenoble 2006; WWFC 2008). These residues come
principally from additives, carrier oils used with additives, and diesel fuels that contain some heavy
components, such as iron (Fe), copper (Cu), and sulfates (present as SO
3
and SO
4
) (IFQC 2004).
These components form gum and can damage engines by contributing to deposits on the surface
of carburetors, fuel injectors, and intake manifolds as well as ports, valves, and valve guides (Gray
2005; Chevron 2008; WWFC 2008).
The United States currently limits heptane washed gum at 5.3 mg/100 mL (ASTM D381*
method), whereas Brazil limits unwashed gum at 5.0 mg/100 mL (NBR 8644
†
method) and the
EU limits the unwashed residue at 10 mg/100 mL (procedure from Annex II of ECD/2870/2000).
Although the comparison between these processes is not feasible, the difference between the U.S.
and Brazilian methods could determine the presence of nonvolatile materials (RFA 2009). However,
the United States is planning to change its method and to measure the gum concentration without
washing it with heptane (White Paper 2007).
9.3.12 c
hloridE
c
ontEnt
The chloride content of bioethanol varies according to the chloride concentration of the feedstock
from which it is derived as well as according to the quantity of HCl that may be used in the produc-
tion process (IFQC 2004). Chloride ions in water can form HCl that, even in a low concentration,
causes corrosion problems (RFA 2009) in the stainless steel equipment involved in production pro-
cessing or storage or in the vehicle, such as stainless steel exhaust systems and fuel injection equip-
ment (IFQC 2004; WWFC 2008).
Because of this effect on the whole fuel chain, biofuel producers and vehicle manufacturers press
for a low chloride content limit in the fuel quality specification (IFQC 2004; White Paper 2007).
Brazil has currently set its chloride content limit at 1 mg/kg maximum for hydrous ethanol (NBR
10894
‡
method) (White Paper 2007). In any case, Brazilian distilleries have no problem meeting the
chloride specification because they use H
2
SO
4
in place of HCl to avoid corrosion of their equipment
(IFQC 2004).
*
ASTM D381 Standard Test Method for Gum Content in Fuels by Jet Evaporation.
†
ABNT NBR 8644 Fuel Ethylic Alcohol—Determination of Residues by Evaporation.
‡
ABNT NBR 10894 Ethyl Alcohol—Determination of Chloride and Sulphate—Ion Chromatography Method.
