(264g) High Quality Biodiesel Fuel Production From Crude Jatropha Oil without Upstream and Downstream Processing

1.     
Introduction

Jatropha curcas oil has been
received much attention as a renewable source of biodiesel fuel with no competing food uses.  Crude Jatropha oil has
high contents of free fatty acid (FFA) and
water.  FFA and water in
the raw oil significantly decrease the yield and quality of
the product biodiesel in the industrial production process using the homogeneous
alkali catalyst.  Thus, the present production process is usually accompanied
by a refining process
to remove FFA in the raw oil to less than 0.5 wt% and a dewatering process of the raw oil.  In addition, the downstream purification
process to remove the by-products, such as soap and glycerin, from the biodiesel
is required to satisfy the fuel's quality requirements.  These upstream
and downstream processes raise the production cost of the biodiesel fuel.

In this study, the bench-scale production
system connected the expanded-bed reactor packed with the cation-exchange
resin and that packed with an anion-exchange resin in series was constructed.  The cation-exchange
resin has a catalytic ability to convert FFA to biodiesel by esterification reaction without inhibition by water¹.   The anion-exchange resin has a
catalytic ability to convert glycerides to biodiesel
by transesterification reaction without soap
formation² as well as an absorbent ability to remove the impurities
such as glycerin, water and pigment contained in the product³.   Thus, high quality biodiesel fuel
would be produced from the crude Jatropha oil without any pretreatment of the raw oil and the purification of the products.

2. Experimental methods

A
water-jacketed column packed with the cation-exchange
resin, Diaion PK208LH, and two columns packed with the
anion-exchange resin, Diaion PA306S, were connected
in series in the bench-scale production system (Fig.1).  The temperature of each column was kept
constant at 50 °C using a hot-water recirculating
system.  The mixed-solution of the
crude Jatropha
oil (FFA content of 2 wt%, water content of 3300 mg/kg) and methanol at the stoichiometric molar ratio of methanol to the total fatty
acid residue in the oils was supplied to the bottom of the first column at the
constant flow rate.  The effluent solutions from the top of the
columns were collected, and the concentrations of the reactants and products in
the solution were determined.

3. Results and discussion

Figure 2 shows the HPLC
chromatograms of the feed (a) and the effluents from the first column (b), the
second column (c), and the third column (d).  Several peaks of the FFA, diglyceride (DG), and triglyceride (TG) were observed in the
feed.  In the effluent from the
first column, the peaks of the FFA completely disappeared and the peaks of the
fatty acid methyl ester (FAME) appeared. 
The peaks of diglyceride and triglyceride
became smaller in the effluent from the second column and completely
disappeared in the effluent from the third column.   Thus, the FFA and glycerides in the crude Jatropha oil were completely
converted to FAME.

Table 1 shows the analytical
results of the product biodiesel compared with standards of USA (ASTM D6751)
and Europe (EN14214).  The acid
value and the contents of free glycerin and total glycerin in the product fully
satisfied with both standards without downstream processing.  In addition, the contents of remaining
reactants (monoglyceride, diglyceride,
triglyceride), water and FAME also satisfied with the
standards of Europe.  The glycerin
and water as well as FFA and pigment were confirmed to be removed by the
adsorption on the resin.  Therefore,
the proposed system permitted the production of high quality biodiesel fuel
without upstream and downstream processing.

4. Reference

1) N.Shibasaki-Kitakawa
et al., Energy Fuels, 24, 3634 (2010)

2) N.Shibasaki-Kitakawa et al., Bioresour. Technol., 98, 416 (2007)

3) T.Tsuji et al., Energy Fuels, 23, 6163 (2009)

Fig. 1 Photograph of bench-scale
production system with cation- and anion-exchange
resins

Fig. 2  HPLC chromatograms of feed and
effluents from each column

Table 1 Comparison of
product properties with standards of
biodiesel fuel