**7.2 Effect of time**

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

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**% Yield of Castor oil Methyl ester** 

**(Castme)**

Fig. 9. Effect of volume of alcohol on the reaction course

Fig. 10. Effect of catalyst amount

**7.5 Catalyst recycling** 

**% Yield of Castme**

or in HSO4-

Avenue for Castor Oil Biodiesel: Use of Solid Supported Acidic Salt Catalyst 393

**5 10 15 20 25 30 35 40 45 50**

**Volume of Methanol in ml (343 K, 6 hrs)**

The cost of a process depends upon the recyclability of a catalyst. It has been found that the dispersed catalyst KHSO4 on silica gel surface after the transesterification reaction of castor oil in methanol, a certain amount gets leached out with methanol either in the form of H2SO4

**% Catalyst (343 K, 6 hrs)**

completely and methyl ester of castor oil (CastMe) was extracted in dichloromethane

. However, after the completion of the reaction, methanol is distilled out

**1 2 3 4 5 6 7 8 9 10**

beyond it there found to be no further improvement. It means 5 hours time is optimum period required.

**Time in hour (343 K)**

Fig. 8. Effect of time duration on the reaction course

#### **7.3 Effect of alcohol to castor oil ratio**

Methanol to castor oil weight ratio is one of the important parameters that affect the yield of methyl ester of castor oil. Theoretically the transesterification reaction requires 3 moles of methanol per mole of triglyceride (Lotero et al, 2005). Since the reaction is a reversible one, the excess methanol shifts the equilibrium towards the direction of ester formation (Cannkei et al, 1999). Generally heterogeneous acid catalytic of transesterification reaction is well known for slow reaction rate. In order to improve the rate of this reaction, use of excess alcohol is an option. It was reported (Xie et al, 2005) that increase of the ratio up to 275:1 of alcohol to oil improves the rate of transesterification reaction.In the present work with preoptomized reaction parameters the methanol to castor oil ratio was varied in the range 5:1 to 40:1 and its influence on the yield of CastMe was investigated at the end of 5 hours. It was clearly observed that at 700C (external) temperature with increase in ratio of alcohol to oil from 5:1 to 40:1 increased the yield of CastMe from 75% to 95%. Presence of 8.4% FFA in the refined castor oil did not affect the activity of the catalyst. Further increase of methanol did not show any significant improvement (Fig 9). The excess methanol can be recovered for reuse and low cost of methanol makes it the first choice for transesterification.

#### **7.4 Effect of catalyst amount**

The catalyst amount is also an important parameter that needs to be optimized for increasing the yield of castor oil methyl ester(CastMe). The effect of KHSO4/SiO2 wt/wt of castor oil on the reaction was studied. At low catalyst amount (< 5 wt %) there were not enough active site for reaction. The optimum amount of catalyst employed was found to be 5 wt% of castor oil to isolate a yield of 95% of the product (Fig. 10).

beyond it there found to be no further improvement. It means 5 hours time is optimum

Methanol to castor oil weight ratio is one of the important parameters that affect the yield of methyl ester of castor oil. Theoretically the transesterification reaction requires 3 moles of methanol per mole of triglyceride (Lotero et al, 2005). Since the reaction is a reversible one, the excess methanol shifts the equilibrium towards the direction of ester formation (Cannkei et al, 1999). Generally heterogeneous acid catalytic of transesterification reaction is well known for slow reaction rate. In order to improve the rate of this reaction, use of excess alcohol is an option. It was reported (Xie et al, 2005) that increase of the ratio up to 275:1 of alcohol to oil improves the rate of transesterification reaction.In the present work with preoptomized reaction parameters the methanol to castor oil ratio was varied in the range 5:1 to 40:1 and its influence on the yield of CastMe was investigated at the end of 5 hours. It was clearly observed that at 700C (external) temperature with increase in ratio of alcohol to oil from 5:1 to 40:1 increased the yield of CastMe from 75% to 95%. Presence of 8.4% FFA in the refined castor oil did not affect the activity of the catalyst. Further increase of methanol did not show any significant improvement (Fig 9). The excess methanol can be recovered for reuse and low cost of methanol makes it the first choice for

**12345678**

**Time in hour (343 K)**

The catalyst amount is also an important parameter that needs to be optimized for increasing the yield of castor oil methyl ester(CastMe). The effect of KHSO4/SiO2 wt/wt of castor oil on the reaction was studied. At low catalyst amount (< 5 wt %) there were not enough active site for reaction. The optimum amount of catalyst employed was found to be

5 wt% of castor oil to isolate a yield of 95% of the product (Fig. 10).

period required.

**% Yield of Castme**

Fig. 8. Effect of time duration on the reaction course

**7.3 Effect of alcohol to castor oil ratio** 

transesterification.

**7.4 Effect of catalyst amount** 

Fig. 9. Effect of volume of alcohol on the reaction course

Fig. 10. Effect of catalyst amount

#### **7.5 Catalyst recycling**

The cost of a process depends upon the recyclability of a catalyst. It has been found that the dispersed catalyst KHSO4 on silica gel surface after the transesterification reaction of castor oil in methanol, a certain amount gets leached out with methanol either in the form of H2SO4 or in HSO4- . However, after the completion of the reaction, methanol is distilled out completely and methyl ester of castor oil (CastMe) was extracted in dichloromethane

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whereby KHSO4 is retained on the surface of silica. The catalyst was washed several times with petroleum ether and then dried completely at 1500C for 8-10 hours. On use of this catalyst for 5 runs with same amount of castor oil and methanol the yield of CastMe decreased was subtle even at fifth reuse (Fig. 11).

Fig. 11. Catalyst recycling
