Environmental Engineering Reference
In-Depth Information
i.
Structural Chemistry of DMF
Dimethylformamide is a colorless, polar, high boiling point liquid with a distinc-
tive odor having a molecular formula of C
3
H
7
NO. It is immune to decomposition
upon distillation procedures and even at elevated temperatures. It is freely mis-
cible in water, ketones, esters, alcohols and ethers. However its rate of hydroly-
sis increases in the vicinity of acids and alkalis. DMF is one of the rare liquids
that has a high dielectric constant and low volatility which qualifies DMF as an
excellent universal solvent, particularly for chemical reactions that require a high
solvency power.
Physical Properties:
Density − 0.949 g/cm
3
; Distillation Range- 760 mmHg;
Temperature—347
°
C; Boiling Point- 153
°
C
a.
Production of DMF from Biomass: Carbohydrates
Previously, DMF was widely employed in a number of industries but at a high
cost and low production yield. In 2007, biochemists from University of Wis-
consin (USA) developed a new technique for the convenient conversion of car-
bohydrates to DMF. Earlier, carbohydrates were enzymatically broken down to
fructose which was then deoxygenated to DMF. It was proposed that the produc-
tion of bio-fuel with high yield and low energy consumption from biomass is
possible if 5 oxygen atoms are removed from hexose for the production of DMF.
This step can be carried out in two steps. The first step maneuvers the removal
of 3 oxygen atoms via the process of acid catalyzed dehydration reaction with a
solvent having low boiling point to produce 5-hydroxymethylfuran, following it
butanol solvent is used for quick extraction of DMF, the quicker the extraction,
the bigger the yield. The second step includes removal of two oxygen atoms via
copper catalyzed hydrogenolysis involving the production of two intermediates:
2 methyl furan and 2-methyl,5-hydroxymethylfuran (Leshkov et al.
2007
). These
methods were modified later on by rendering the need of acid based catalysts as
non-imperative. This led to an augmented interest towards DMF as a prospective
gasoline alternative biofuel. Engineers from the automotive community began
paying attention to DMF as an alternate automotive fuel. The first study on the
capability of DMF as a fuel, focusing on its emission and combustion perfor-
mance commenced in Birmingham University of UK. The factors under observa-
tion viable for required performance of a fuel were spray characteristics, laminar
burning velocity and unregulated engine emission (Leshkov et al.
2007
).
b.
Fuel Spray Characteristics
A desired engine performance fuel spray characteristics tremendously influence
the fuel-air mixture generation and combustion manner. A number of compara-
tive studies between spray characteristics of ethanol, gasoline and DMF have
been conducted through use of Optical methods such as Phase Doppler Particle
Analyzer. Results of the studies have shown that spray characteristics of DMF
are preferably favorable over those of ethanol and gasoline. The spray pattern of
DMF was not very different from that of gasoline. DMF spray velocity turned
out to be greater than that of ethanol and DMF spray droplet size very small than
the large ones of ethanol. These findings rendered DMF a considerably suitable
engine fuel given its extreme similarity to gasoline behavior.
