**5. Results and discussion**

388 Biodiesel – Feedstocks and Processing Technologies

methanol olefin etherification (Goodwin et al,2002) even though the constituent of the oil do

possess olefinic bonds .

Fig. 5. 1HNMR (300MHz) of CastMe

(g/cc)

0.963 0.34 0.86-0.95 0.885 0.883 0.876 0.88

other vegetable oil methyl esters

Kinematic Viscosity (CST)(380C)

Property ASTM standard limit units

Table 2. Suggested standard for pure (100%) biodiesel as per ASTM.

297 9.4 3.81 4.8-4.3 4.53 51.15

Pour point (OC)


Table 1. Physical values of castor oil methyl ester (CastMe) determined along with values of

100 0.050 0.020 1.9-6.0 0.05 40

0

By customer

Cloud point (OC)

> -20 -23 -15 -0.5 -4.0 13.9 1

> 0C wt% wt% mm2/s wt% 0C 0C wt%

Flash point Cetane no.

Item Density

Castor oil CastMe Petrodiesel Soy ME Rape ME Tallow ME Canola ME

Flash point Carbon residue Sulphated ash Kinematic viscosity

Sulphur cetane Cloud point Free glycerol Potassium bisulphate (PBS) impregnated microporous silica has been evaluated as solid acid catalyst for biodiesel production from refined castor oil containing 8.4% FFA compared to other support viz. alumina with 95% yield. The determination of surface area, pore volume and pore diameter and also FTIR spectra of KHSO4 supported on microporous silica revealed that KHSO4 is well dispersed very evenly generating Bronsted acid site that is responsible for its higher activity.The FT IR spectrum of pure KHSO4,pure silica gel and KHSO4 supported silica gel (Fig-6) have been depicted below.

Fig. 6. FT IR spectra of pure KHSO4,Pure SiO2 and KHSO4 supported on SiO2

The pure silica FTIR spectra of KHSO4 exhibited typically six major bands located at 577,852,886,1009,1070 and 1179 cm-1 which are stretching modes of oxygen bonded to sulphur and hydrogen. In supported KHSO4 catalyst no clear bands were observed. These results indicated that KHSO4 is highly dispersed on the surface of support SiO2. A 40:1 alcohol to oil ratio at 700C (external) temperature and 5 wt% catalysts loading gave a maximum yield of CastMe up to 95%.

The textural properties (Kulkarni et al, 2006) of the catalyst were summarized in Table 3. The surface area of microporous silica of 60-100 mesh particle size has 300m2/g and pore volume 1.15cm2/g and its average pore diameter is 150 A0. After loading 50 wt% of KHSO4 the accessible surface area of silica gel left was only 55.45m2/g and pore volume and average pore diameter were reduced to 0.13cm2/g and 98.9 A0. The reason is attributed to uniform dispersing of KHSO4 on the surface leaving only 55.45m2/s surface and pore plugging of the support. The same reaction when carried out in a similar fashion supporting KHSO4 on alumina surface, the reaction gives very poor or no yield at all. It may be due to too narrow micropores of alumina which cannot accommodate KHSO4 molecule to disperse uniformly to enhance catalytic activity (Kulkarni et al, 2006) although its surface area is higher (260m2/g). Even though alumina is an interesting support it is assumed that the surface basicity could bring about decomposition of KHSO4. It means that particles of

An Alternative Eco-Friendly

**7. Influence of reaction parameters** 

**7.1 Reaction temperature** 

**% Yield of Castme** 

of yield (Fig. 7).

**7.2 Effect of time** 

order kinetics.

Avenue for Castor Oil Biodiesel: Use of Solid Supported Acidic Salt Catalyst 391

the polar alcohol phase. The second phase is product formation stage whereby the product formed acts as an emulsifier. It is a kinetically controlled stage and is characterised by abrupt range of product formation. Finally the equilibrium is reached at the completion stage. It was found in castor oil transesterification with 40:1 alcohol to oil ratio acceptable reaction rate was achieved. Thus from this observation it can be stated that the forward reaction is pseudo first order kinetics while the backward or the reverse reaction is second

The transesterification of castor oil in presence of KHSO4 supported on silica gel in methanol is influenced by certain reaction parameters which have been studied thoroughly varying

Initially the transesterification reaction was attempted at room temperature under stirring at 600 rpm for more than 48 hours. However the reaction rate at room temperature was found to be very slow and only 30-35% conversion was observed. It means that the rate of reaction is influenced by the reaction temperature. Gradually when the reaction temperature was raised by 100C the reaction rate is increased with increase of product formation and at 700C (external) temperature the formation of the product was found to be maximum of 95%. Beyond this temperature there was found to be no further increase

The effect of reaction time was studied and result was shown in Fig. 8. It was found that increasing the reaction time upto 5 hours enhanced the castor oil methyl ester yield and

**30 35 40 45 50 55 60 65 70 75**

**External temperature in Degree Centrigade ( 6 hrs)**

the conditions at different stages and the results have been appended below..

Fig. 7. Effect of external temperature on the reaction course

KHSO4 conform to silica gel particles in order to disperse on its surface. Large pores can easily accommodate a bulky triglyceride molecule giving KHSO4/SiO2 large active site and surface area resulting in highest activity (Igarashi et al, 1979; Furuta, 2004 and Lecleroq et al, 2001).


Table 3. The textural properties determined for SiO2 and KHSO4/SiO2
