Style D 36 by 48

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By-product Formation in Respect of Operating
Conditions on Conversion of Glycerol to Propylene
Glycol Mona-Lisa Banks, Dr. Galen Suppes, Dr.
Rusty Sutterlin, Ali Tekeei, Chuang-Wei (Roger)
Chiu Missouri Soybean Merchandizing Council ,
Department of Chemical Engineering, University of
Missouri Columbia, Lincoln University Louis
Stokes Missouri Alliance for Minority
Participation
ABSTRACT
RESULTS AND DISCUSSIONS
RESULTS AND DISCUSSIONS contd
Reaction Glycerol to Propylene Glycol
Reaction Propylene Glycol to Acetol
The conversion reaction of glycerol to propylene
glycol (PG) results in the yield of different
products namely acetol, water, PG and it has also
shown little selectivity toward ethylene glycol
and other unknown by-products. These
unidentified compounds are consequently called
unknowns. In order to maximize the production
of propylene glycol these unknown by-products
have to be reduced. To properly assess the
unknowns, Gas Chromatograph (GC) testing is done
on the finish product in order to create new
methods to eradicate the unknowns. PG and seven
of the most prominent unknowns were chosen to
carry out the study where the trends are studied
in relation to propylene glycol and reaction
conditions. The seven unknowns are named as the
retention time shown in the gas chromatogram
8.74, 8.78, 9.11 (Ethylene Glycol), 9.15, 9.28,
9.32, and 9.405. The impact of two independent
reaction parameters were investigatedreferred to
as Parameter A (PA) and Parameter B (PB). At
higher PA less unknown are produced during the
reaction. The value of PB applied in this
reaction is very critical as the higher values
result in the production of more unknowns and
less PG in the end product. Based on this
analysis, the reaction should be conducted at
higher value of PA and low PB.


Values of PA
Values of PA
INTRODUCTION
PB
PB
Glycerol is a colorless odorless viscous
by-product of biodiesel. Biodiesel is derived
form vegetable oil and animal fat. For every 9
kilograms of biodiesel produced, about 1 kilogram
of glycerol by-product is formed. Over the years
biodiesel production has increased dramatically
thus the production of the crude glycerol
byproduct has also increased. This has resulted
in decreased glycerol prices, causing the
byproduct to be sometimes discarded as waste as
it is costly to purify. Upgrading this crude
glycerol could increase the profitability of
biodiesel production thus reducing the cost of
producing biodiesel. Propylene glycol is a
product with a 4 growth in the market annually.
Propylene glycol can be used in the
manufacturing of antifreeze for cars, airplanes
and boats. It is used to absorb extra water and
maintain moisture in certain foods, cosmetics,
and medicines. Other uses include the production
of detergents, fragrances, and paints among
others. The main focus of this research is to
convert glycerol into propylene glycol. The
processing of converting glycerol to propylene
glycol uses metallic catalysts and hydrogen and
is called hydrogenolysis. The chemical reaction
of glycerol to propylene glycol is achieved by
removing one molecule of water and then
hydrogenating the process to make propylene
glycol. Fig. 1 Reaction mechanism for
conversion of glycerol to propylene glycol. The
conversion reaction of glycerol to propylene
glycol (PG) results in the yield of different
products namely acetol, water, PG and it has also
shown little selectivity toward ethylene glycol
and other unknown by-products. In order to
optimize the reaction process achieving maximum
production PG seven of the most prominent
unknowns have been chosen to carry out the study
where the trends are studied in relation to
propylene glycol and reaction conditions.

Values of PA

Values of PA
PB
PB

• Reaction PG to acetol
• The conversion indicated that acetol increased
  with increased PB and decreased with
• increased PA.
• The unknown EG was not observed in this
  reactionEG is a product from Glycerol reaction.
• Greater amount of unknowns were produced with
  increased PB.
• Less amount of unknowns were produced with
  increased PA.

Values of PA
CONCLUSION
PROCEDURE
The reaction of glycerol to PG indicated that PG
increased as a result of increased PA and
decreased with increased PB. Low PB and high PA
shows a higher yield in PG. The unknowns studied
increased in their amounts with increased PB and
decreased with lower PA levels. The reaction of
acetol to PG follows the trends as the reaction
of glycerol to propylene glycol. The reaction of
PG to acetol indicated that acetol increased as a
result of increased PB and decreased with
increased PA. The unknown EG was not observed in
this reaction. The unknowns formed in this
reaction increased in their amounts with
increased PB and decreased with higher PA.
The liquid samples were weighed and analyzed with
a Hewlett-Packard 6890 (Wilmington, DE) gas
chromatograph (GC) equipped with a flame
ionization detector. Hewlett-Packard Chemstation
software was used to collect and analyze the
data. A Restek Corp (Bellefonte, PA) MXT WAX
70624 GC column (30m x 250 µm x 0.5µm) was used
for separation. For preparation of the GC
samples, a solution of n-butanol with a known
amount of internal standard (IS) was prepared a
prior and used for analysis. The samples were
prepared for analysis by adding 100 µL of product
sample to 1000 µL of stock solution into a 2mL
glass vial. Two micro liters of the sample was
injected into the column. The oven temperature
program consisted of start at 45 C (0 min),
ramp at 0.2 C /min to 46 C (0 min), ramp at 30
C /min to 220 C (2.5 min). Chromatogram and
area percentage data generated by the GC were
used to prepare the graphs using Microsoft Excel.
Unknowns were compared in the ratio of internal
standards and PG peak areas.
PB

• Reaction glycerol to PG
• The conversion indicated that PG increased
  with increased PA levels.
• PG decreased with increasing PB.
• The unknown 9.11 was identified as Ethylene
  Glycol (EG) and was the only unknown studied that
  
• followed PG production. EG increased with
  increased PG production but was not observed to
  
• follow any obvious trend in relation to PA
  and PB.
• Greater amount of unknowns were produced with
  increased PB.
• Less amount of unknowns were produced with
  increased PA.
• Reaction acetol to PG
• Trends of all unknowns in this reaction agreed
  with the trends of all unknowns observed in the
• reaction glycerol to

REFERENCES ACKNOWLEDGEMENT
This work was funded by the Missouri Soybean
Merchandising Council. Dasari MA, Kiatsimkul P,
Sutterlin WR, Suppes GJ. Low-pressure
hydrogenolysis of glycerol to propylene glycol.
Applied Catalysis AGeneral. 2005281(1-2)225-231
. Suppes GJ, Sutterlin WR, Dasari MA. Method of
producing lower alcohols from glycerol. US Patent
Application 20050244312., 2005. Chiu C-W, Dasari
M.A., Sutterlin W.R., Suppes G.J. Dehydration of
Glycerol to Acetol via Catalytic Reactive
Distillation. AIChE Journal. (accepted)