Solid acid catalyzed biodiesel production from waste

Applied Catalysis B: Environmental 85 (2008) 86–91

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Applied Catalysis B: Environmental journal homepage: www.elsevier.com/locate/apcatb

Solid acid catalyzed biodiesel production from waste cooking oil Kathlene Jacobson, Rajesh Gopinath, Lekha Charan Meher, Ajay Kumar Dalai * Catalysis and Chemical Reaction Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9, Canada

A R T I C L E I N F O

A B S T R A C T

Article history: Received 29 January 2008 Received in revised form 28 June 2008 Accepted 1 July 2008 Available online 10 July 2008

Various solid acid catalysts were evaluated for the production of biodiesel from low quality oil such as waste cooking oil (WCO) containing 15 wt.% free fatty acids. The zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of free fatty acid (FFA) present in WCO to methyl esters. The optimization of reaction parameters with the most active ZS/Si catalyst showed that at 200 8C, 1:18 oil to alcohol molar ratio and 3 wt.% catalysts loading, a maximum ester yield of 98 wt.% could be obtained. The catalysts were recycled and reused many times without any loss in activity. ß 2008 Elsevier B.V. All rights reserved.

Keywords: Biodiesel Esterification Transesterification Waste cooking oil Methyl esters Solid acid catalyst Free fatty acids

1. Introduction Sustainable fuel alternatives have recently become a high priority for many countries and will play a large role in the chemical industry in the near future. Biodiesel is one of these sustainable fuels and is a non-petroleum based fuel that consists of alkyl esters derived from either the transesterification of triglycerides (TGs) or the esterification of free fatty acids (FFAs) with short-chained alcohols. Biodiesel comes with many advantages; low emissions, biodegradable, non-toxic, better lubricity, and is the only alternative fuel to have fully completed the health effects testing requirements of the 1990 Clean Air Act Amendments. Biodiesel has not become a popular alternative fuel worldwide due to its higher cost when compared with traditional petroleum diesel. The major hurdle in the commercialization of biodiesel is mainly due to the non-availability of raw material and cost of production. The use of cheap low quality feed stocks such as waste cooking oil (WCO), animal fat and tall oil instead of refined vegetable oil will help in improving the economical feasibility of biodiesel. The amount of WCO generated in each country is huge and varies depending on the use of vegetable oil. An estimate of the potential

* Corresponding author. Tel.: +1 306 966 4771; fax: +1 306 966 4777. E-mail address: [email protected] (A.K. Dalai). 0926-3373/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.apcatb.2008.07.005

amount of WCO from the collection in European Union (EU) is approximately 0.7–1.0 Mt per year. The United States and Canada produce, on average, 9 and 8 pounds of yellow grease, respectively, per person [1,2]. Currently, the inexpensive and large quantity of WCO from households and restaurants are collected and used as either animal feed or disposed causing environmental pollution. Thus, WCO offers significant potential as an alternative low –cost biodiesel feedstock which could partly decrease the dependency on petroleum-based fuel. The production of biodiesel from WCO is challenging due to the presence of undesirable components such as free fatty acids (FFAs) and water. Usage of homogeneous alkali catalyst for transesterification of such feedstock suffers from serious limitation of formation of undesirable side reaction such as saponification which creates the serious problem of product separation and ultimately lowers the ester yield substantially [3]. Homogeneous acid catalysts have the potential to replace alkali catalysts since they do not show measurable susceptibility to FFAs and can catalyze esterification and transesterification simultaneously. However, slow reaction rate, requirement of high temperature, high molar ratio of oil and alcohol, separation of the catalyst, serious environmental and corrosion related problems make their use non-practical for biodiesel production [4]. Currently a dual step process has been used for biodiesel preparation from high FFA containing WCO [5–7]. The first step of the process is to reduce FFA content in the oil by esterification with methanol to methyl esters

K. Jacobson et al. / Applied Catalysis B: Environmental 85 (2008) 86–91

catalyzed by an acid (generally sulfuric acid) followed by transesterification process, in which triglyceride (TG) portion of the oil reacts with methanol and base catalyst (usually sodium or potassium hydroxide) to form ester and glycerol. The current process increases the production cost of biodiesel as it involves a number of steps including washing of the esters to remove acid/ alkali catalysts in addition to creating contaminated water disposal issues. Solid acid catalysts have the strong potential to replace liquid acids, eliminating separation, corrosion and environmental problems. Recently a review was published that elaborates the importance of solid acids for biodiesel production [4]. We have reported the production of biodiesel by simultaneous esterification and transesterification of high free fatty acid-containing oil on supported heteropolyacid catalysts system [8]. A recyclable diarylammonium catalyst has been recently used for the synthesis of biodiesel from high free fatty acid-containing feedstocks [7]. A two steps process was employed where diarylammonium catalyst was used for the esterification of free fatty acid to methyl esters and the ester–glyceride mixture was further converted to methyl esters by base-catalyzed transesterification. Sugar catalysts from D-glucose have been used for the production of biodiesel from high fatty acid-containing waste oil with a high acid value [9]. A novel Fe–Zn, double-metal cyanide (DMC) complexes has been reported as highly active heterogeneous catalysts for production of biofuels and lubricants from vegetable oil by esterification/transesterification reactions [10]. These catalysts were hydrophobic (at reaction temperatures of about 443 K) and insoluble in most of the solvents including aqua regia. Solid acid catalyst based on tungsten oxide supported on zirconia was found to be very active for the esterification of palmitic acid with methanol [11]. However, most of the studies on biodiesel synthesis from low quality real feedstocks such as WCO have been focused on dual step process using homogenous catalysts. To our knowledge, there are no reports on the utilization of solid acid catalysts for the production of biodiesel from WCO in a single step. ZrO2 support is an interesting material because it possesses acidic, oxidizing and reducing properties on the surface. Generally it has been observed that the acidic properties of zirconia can be modified by the impregnating it with species such as tungsten oxide (WO3) and molybdenum oxide (MoO3). Literature studies reveal that due to the strong acidity of WO3, MoO3 supported on ZrO2 catalysts, they have been widely used for a wide variety of reactions including esterification, tranesterification, alkylation and isomerization [12–15]. The combination of Al2O3 and ZrO2 and modification of ZrO2–Al2O3 with WO3 not only provides greater mechanical strength but also enhances the acidity of the catalyst [16–19]. The homogeneous acetate and stearate of zinc were found to be very effective catalysts for the synthesis of biodiesel [20] due to the lewis acidity of metal and molecular structure of anion. Further the heterogenize of zinc acetate complex by supporting it on functionalized silica leads to higher surface area, thermal stability, mild acidity and average pore size in the region of mesopores [21]. Molybdenum oxide as such or supported on silica (MoO3/SiO2) is a well-known solid acid catalyst possessing both strong Lewis and Bronsted acidity [22]. MoO3/SiO2 catalyst has been effectively used for various reactions such as nitration, esterification, acylation and transesterification due to the combination of strong acidity and higher dispersion of active MoO3 species on high surface area silica support [23–28]. Our earlier work on the supported 12-tungstophosphoric acid (TPA) catalysts system, revealed that TPA supported on zirconia was the most promising catalyst for the production of biodiesel due to the lewis acid sites generated by the strong interaction of TPA and surface hydroxyl groups of zirconia [8]. Solid acids catalysts having

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interconnected system of large pores, a moderate to strong acid sites and a hydrophobic surface would be ideal for biodiesel preparation [4]. Therefore, in an attempt to develop a robust solid acid catalyst that can simultaneously catalyze esterification as well as transesterification reaction, different types of solid acid catalysts such as MoO3/SiO2, MoO3/ZrO2, WO3/SiO2, WO3/SiO2– Al2O3, zinc stearate supported on silica, zinc ethanoate supported on silica and TPA supported on zirconia are synthesized and evaluated for biodiesel preparation from waste cooking oil. Also, influence of various reaction parameters such as molar ratio of WCO to alcohol and catalyst loading was studied in the present investigation. 2. Experimental 2.1. Materials Waste cooking oil (WCO) was obtained from Saskatoon Processing Co., Saskatoon, Saskatchewan, Canada. Ammonium heptamolybdate, Ammonium metatungstate, zirconyl chloride octahydrate, aluminum nitrate and tetraethoxysilane were obtained from Sigma-Aldrich, MO, USA. 12-tungstophosphoric acid was purchased from BDH chemicals Ltd., England. Zinc acetate and Zinc stearate were purchased from Fisher chemicals and Alfa Aesar, USA, respectively. Silica was obtained from Engelhard, USA. 2.2. Catalysts preparation The hydrous zirconia and zirconia-alumina (1:1 molar ratio) support was prepared by the hydrolysis of zirconyl chloride and zirconyl chloride-aluminum nitrate aqueous solution by adding aqueous ammonia to a pH of up to 9. The gel was washed with deionized water and dried at 120 8C for 12 h. MoO3 supported ZrO2, SiO2 and WO3 supported ZrO2, ZrO2–Al2O3 of 5 and 10 wt.% were prepared by impregnation method. The material thus obtained was dried at 110 8C and calcined at 500 8C. 12-tungstophosphoric acid (TPA) supported hydrous zirconia was synthesized, as described previously [8]. Zinc Stearate and Zinc ethanoate supported on silica gel was prepared using sol – gel method. The preparation method was based on the preparation of zinc ethanoate supported on silica gel reported by Nava et al. [29]. In the typical synthesis, tetraethyl orthosilicate (TEOS) (98%, check, Aldrich) was employed as the silica gel source. TEOS was combined with distilled water in the molar ratio of 1:4. The hydrolysis of TEOS was carried out in a 500 cc Parr reactor (Parr Instrument Co.) equipped with a temperature controller at 85 8C under vigorous stirring. After 1 h of stirring, succinic acid (99%, Aldrich, check) was added to the reaction mixture, in a molar ratio of TEOS: SA of 1:0.1. After stirring for 1 h, the reaction temperature was decreased to 50 8C and zinc acetate (ZnE) (99%, Merck) or zinc stearate (ZS) was added to the reaction mixture in a molar ratio of TEOS: ZnE/ZS of 1:0.08 and the reaction was carried out for another 1 h at 50 8C under stirring. The reaction mixture was cooled to room temperature and the resultant gel was dried overnight at room temperature. Finally, the material was dried at 80 8C for 24 h and subsequently at 110 8C for 3 days. The catalysts were designated as Mo/Zr, WO/Zr, WO/Zr–Al, Mo/Si, TPA/Zr, ZS/Si and ZnE/Si referring to MoO3/ZrO2, WO3/ZrO2, WO3/ZrO2–Al2O3, MoO3/SiO2, TPA/ZrO2, Zinc stearate/SiO2 and Zinc ethanoate/SiO2, respectively. 2.3. Catalyst characterization Specific surface area and pore size measurements of the catalysts were performed using Micrometrics adsorption equipment (Model ASAP 2000) at 78 K using liquid nitrogen. Prior to the


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analysis the catalyst was evacuated at 200 8C in vacuum of 5 10 4 atm to remove all adsorbed moisture from catalyst surface and pores. XRD analysis was performed using Rigaku diffractometer (Rigaku, Tokyo, Japan) using Cu Ka radiation at 40 kV and 130 mA in the scanning angle (2u) of 5–808 at a scanning speed of 5 8 min 1. Thermogravimetric (TG) analysis were performed under argon flow on a Perkin–Elmer analyzer with a heating rate of 10 8C/min up to 650 8C. The carbon content of the catalysts was measured on a C, H, N, and S analyzer (Vario EL). 2.4. Synthesis of biodiesel The simultaneous transesterification and esterification of WCO containing 15 wt.% free fatty acids was carried out using prepared solid acid catalysts in a 500 cc Parr reactor (Parr Instrument Co.) equipped with a temperature controller. Initially the reactor was charged with 100 g of WCO and heated to a temperature of 50 8C. Anhydrous methanol and catalyst were then added to the reaction vessel and the temperature was increased to 200 8C and stirring speed of 600 rpm optimized previously [8]. To ensure that at the reaction temperature the reactants were in the liquid phase, the reactor was pressurized to 600 psig with nitrogen gas. The reactions were carried out for a period of 10 h unless otherwise stated. The products were analyzed using gel permeation chromatography (GPC) equipped with a RI detector and two 300 mm 7.8 mm phenogel columns connected in series. Tetrahydrofuran (THF) was used as a mobile phase and the triglycerides, diglycerides, monoglycerides and methyl esters in the product were quantified by comparing the peak areas of their corresponding standards. The percentage free fatty acid content was determined from the acid value following the AOCS method Te 1a-64. 2.5. Catalysts reusability and leaching tests The catalysts separated from the reaction mixture by filtration were initially washed with hexane to remove non-polar compounds such as methyl esters on the surface. Further, the catalysts were washed with methanol to remove polar compounds such as glycerol and finally dried at 80 8C overnight. The leaching of the catalyst into the reaction mixture was investigated by inductively coupled plasma-mass spectrometry (ICP-MS). 3. Results and discussion The prepared solid acid catalysts were evaluated for the synthesis of biodiesel from WCO under identical reaction conditions such as reaction temperature of 200 8C, stirring speed of 600 rpm, 1:6 molar ratio of oil to alcohol, and 3% w/w catalyst. The best catalyst was chosen based on the yield of maximum methyl ester with minimum free fatty acid content in the product. The methyl ester yield (with an experimental error of 2 wt.%)

Table 2 Ester yield (wt.%) and corresponding acid value at the end of 10 h reaction time. Reaction conditions: reaction temperature 200 8C, molar ratio of oil to alcohol 1:6, stirring speed 600 rpm and catalyst loading 3% w/w Catalysts

Estera (wt.%)

Acid value (mg KOH g

5% Mo/Zr 10% Mo/Zr 5% WO/Zr–Al 10% WO/Zr–Al 5% WO/Zr 10% WO/Zr ZS/Si ZnE/Si 5% Mo/Si 10% Mo/Si 10% TPA/Zr

65 71 27 65 42 67 81 80 79 60 43

5.6 5.0 15.7 4.5 –b 5.6 3.3 5.6 3.7 4.0 –b

a b

1

)

Experimental error = 2 wt.%. Not determined.

obtained at different time intervals are summarized in Table 1. The yield of methyl ester and their corresponding acid value at the end of 10 h reaction time is shown in Table 2. Considering the experimental error listed, it can be concluded that the catalysts ZS/Si, ZnE/Si and 5% Mo/Si were the most active exhibiting almost similar ester yield of 80 wt.%. However, the product of the ZS/Si catalyzed reaction gave the lowest acid value of 3.3 mg KOHg 1 corresponding to a FFA content of 1.7 wt.% at the end of 10 h reaction time. The acid value of WCO at the beginning of reaction was 30 mg KOHg 1. This indicates that the catalysts were highly effective for simultaneous esterification as well as transesterification reaction following the reaction mechanism reported previously [8]. 3.1. Catalyst characterization 3.1.1. Textural analysis of catalysts Now we proceeded to examine the textural properties of the catalysts. As shown in Table 3, the surface area and the average pore diameter of catalysts varied in a wide range from 35 to 457 m2g 1 and 20 to 83 A8, respectively. ZS/Si catalyst had the largest average pore diameter among all the prepared solid acid catalysts. The primary requirement of an ideal solid acid catalyst for biodiesel synthesis is large interconnected pores that would minimize diffusional limitations of molecules having long alkyl chains [4]. A typical triglyceride molecule has a diameter of approximately 58 A8. Comparing the textural properties of most active catalysts in this work (ZS/Si, ZnE/Si and 5% Mo/Si), it can be seen that ZS/Si has the largest pore diameter and it can accommodate a bulky triglyceride molecule easily. Thus, based on the highest activity (esterification as well as transesterification reaction) and average pore diameter, ZS/Si catalysts was selected to further study in detail the physico-chemical properties and the effect of various reaction parameters on ester yield.

Table 1 Ester yield (wt.%) of different solid acid catalysts. Reaction conditions: reaction temperature 200 8C, molar ratio of oil to alcohol 1:6, stirring speed 600 rpm and catalyst loading 3% w/w Time (h)

1 2 3 4 5 10

Catalysts 5% Mo/Zr

10% Mo/Zr

5% WO/Zr–Al

10% WO/Zr–Al

5% WO/Zr

10% WO/Zr

ZS/Si

ZnE/Si

5% Mo/Si

10% Mo/Si

10% TPA/Zr

42 47 50 55 58 65

47 54 59 62 63 71

23 26 26 26 27 27

38 51 52 54 57 65

13 27 31 36 40 42

40 48 52 56 58 67

50 71 75 79 80 81

48 68 75 79 80 80

26 72 74 75 76 79

56 57 58 59 59 60

18 28 32 36 40 43


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Table 3 Textural properties of various solid acid catalysts Catalysts

Surface area (m2 g 1)

Micropore area (m2 g 1)

Average pore diameter (A8)

5% Mo/Zr 10% Mo/Zr 5% WO/Zr–Al 10% WO/Zr–Al 5% WO/Zr 10% WO/Zr ZS/Si ZnE/Si 5% Mo/Si 10% Mo/Si 10% TPA/Zr ZS/Si (used)

113 127 209 194 100 63 35 457 265 141 242 34

– – – – – – – 138 118 58 – –

35 30 41 40 50 47 83 21 33 35 27 88

3.1.2. X-ray diffraction and thermal analysis Pure zinc stearate is a homogenous lewis acid catalyst and one of its major drawbacks is the difficulty to separate it from reaction products and to reuse [20]. To overcome this shortcoming, we have immobilized zinc stearate (ZS) on the surface of silica by sol-gel process. The X-ray diffraction pattern of pure zinc stearate and zinc stearate immobilized on silica gel is presented in Fig. 1. It can be seen from the diffraction patterns that the major peak corresponding to ZS coincide in pure as well as supported ZS. However, the peaks in ZS/Si are broader than those of pure ZS caused by silica gel support and the high dispersion of ZS on support. The carbon and ICP-MS analysis of ZS/Si catalyst showed a Zn: C ratio of 1:3 indicating the presence of interaction between stearate and succinate during synthesis due to stronger acidity of succinic acid than zinc stearate. However, the X-ray diffraction studies showed peaks due to formation of zinc stearate only without showing any peaks due to formation of new compound formed by interaction between succinic acid and zinc stearate. The thermal analysis curves of pure ZS and ZS/Si are shown in Fig. 2. The first peak at 80 8C in the DTG curve of pure ZS is related to loss of water molecules included in the stearate. The major loss centered approximately at 230 8C is related to the decomposition

Fig. 2. Thermal analysis curves of pure zinc stearate and zinc stearate supported over silica gel.

of zinc stearate. The thermal behavior of ZS/Si catalyst showed weight loss at two temperature regions i.e. 75 -90 8C and 275– 475 8C, respectively. The loss between 75–90 8C occurred due to the physisorbed water and second loss from 275–475 8C correspond to combined loss due to dehydroxylation of silica and decomposition of supported zinc complex. The TG analysis showed that the thermal stability of supported zinc complex is higher than those of the pure zinc complex. These results indicate that the support has a stabilizing effect on the decomposition of catalytic active zinc stearate. Chin et al. [21] reported similar results in the thermal studies of pure and supported zinc acetate complex. 3.2. Effect of reaction parameters 3.2.1. Catalyst loading Catalysts loading and molar ratio of oil to alcohol are the important reaction parameters that need to be optimized to increase the ester yield. The effect of ZS/Si loading (1, 3 and 5% w/ w) on ester yield was studied at a molar ratio of oil to alcohol of 1:6 as shown in Fig. 3. Increase in catalyst loading from 1 to 5% w/w did show a variation in the initial activity; however, the final methyl ester yield (80 wt.%) was similar irrespective of the loading. Thus, it is clear that the catalyst loading does not have much influence to improve the yield of methyl ester. The reaction was further studied with 3% w/w of catalyst loading for further optimization of molar ratio of alcohol to oil. 3.2.2. Molar ratio of oil to alcohol The methanol to oil molar ratio is one of the most important parameters that affects the yield of methyl esters. Theoretically,

Fig. 1. XRD patterns of pure zinc stearate, zinc stearate supported over silica gel and used zinc stearate supported over silica gel catalysts. (*) zinc stearate.

Fig. 3. Effect of catalyst loading on ester yield using ZS/Si catalyst. Reaction conditions: reaction temperature 200 8C, molar ratio of oil to alcohol 1:6, stirring speed 600 rpm.

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Fig. 4. Effect of oil to alcohol molar ratio on ester yield using ZS/Si catalyst. Reaction conditions: reaction temperature 200 8C, stirring speed 600 rpm, catalyst loading 3% w/w.

the transesterification of vegetable oil requires three moles of methanol per mole of triglyceride. Since the transesterification of triglyceride is a reversible reaction, the excess of methanol shifts the equilibrium towards the direction of ester formation. Literature studies reveal that in order to shift the equilibrium towards forward direction, use of high molar ratios of oil to alcohol such as 1:40 and even 1:275 is reported [30–32]. In the present work, an increase in oil to alcohol molar ratios from 1:6 to 1:18 resulted in a significant effect on the ester yield (Fig. 4). The yield of methyl esters increased from 81 to 98 wt.% corresponding to a FFA content of about 1 wt.% after 10 h reaction time. The excess methanol used in the reaction can be collected by distillation and reused. 3.2.3. Catalyst stability and reusability The catalyst recycling is an important step as it reduces the cost of the process. In order to verify the reusability, the ZS/Si catalyst was recycled and used for four times (Fig. 5). The reusability studies were carried out at reaction temperature of 200 8C, stirring speed of 600 rpm, 1:18 molar ratio of oil to alcohol, and 3% w/w catalyst loading. The results revealed that, no loss in the activity was detected even after four recycles demonstrating the efficiency of the catalyst. Also, negligible leaching or dissolution of zinc into the liquid portion was detected by ICP-MS analysis. 3.3. Characterization of used ZS/Si catalyst In order to explain the observed activity and stability of the most active catalysts i.e. ZS/Si (Zinc Stearate immobilized on Silica), we have performed the characterization of used ZS/Si catalysts by X-ray diffraction, nitrogen adsorption studies and ICP – MS. The used ZS/Si consisted of the catalyst which was successfully recycled and used for four times at the optimized reaction conditions of 200 8C, stirring speed of 600 rpm, 1:18 molar ratio of oil to alcohol, and 3% w/w catalyst loading.

Fig. 6. Nitrogen adsorption–desorption isotherms of fresh and used ZS/Si catalyst.

The XRD pattern of the used ZS/Si catalyst is shown in Fig. 1. The XRD pattern of the used catalyst showed clear major peaks due to active zinc stearate (ZS) species even after use for four times. Further, we have performed the nitrogen adsorption studies of the used ZS/Si catalyst. The surface area, micropore area and average pore diameter of the used catalyst ZS/Si is shown in Table 3. The comparison of the textural properties of the used ZS/Si catalyst with the ZS/Si before the reaction shows no significant change in the surface area, micropore area and average pore diameter. The nitrogen adsorption–desorption isotherms of the fresh and used ZS/Si catalyst are shown in Fig. 6. It can be observed from the figure that both the catalysts showed type IV isotherm which is a characteristics of mesoporous material according to IUPAC classification. It can be seen from the figure that as the relative pressure (P/Po) increases, both the isotherms exhibited a sharp step characteristic of capillary condensation of nitrogen within mesopores, where the P/Po position of the inflection point is correlated to the diameter of the mesopore. Also, we have performed the ICP– MS analysis of the fresh and used ZS/Si catalysts to determine the Zn content. The results showed that the fresh and used ZS/Si catalysts had a similar Zn content of about 6.0%. The presence of large pores and the existence of active ZS species (even after reaction for four times) contribute to the overall activity and stability of ZS/Si catalyst. Further, studies are in progress to investigate the correlation between catalytic activity and concentration, type of acid sites in the catalyst. We are also presently investigating the properties of biodiesel prepared from waste cooking oil. 4. Conclusions

Fig. 5. Reusability of ZS/Si catalyst. Reaction conditions: reaction temperature 200 8C, molar ratio of oil to alcohol 1:18, stirring speed 600 rpm, catalyst loading 3% w/w.

Different types of solid acid catalysts were evaluated for the synthesis of biodiesel from low quality oil such as waste cooking oil containing high free fatty acids. The zinc stearate immobilized on silica gel was found to be the most active and stable heterogeneous catalyst. The catalyst was reused many times without any loss in activity and at the optimized conditions of reaction temperature of 200 8C, stirring speed of 600 rpm, 1:18 molar ratio of oil to alcohol, and 3% w/w catalyst loading, a maximum ester content of 98 wt.% was obtained. The findings have potential for wide spread applications in academic and industrial scale production of biodiesel from low quality feedstock’s containing high free fatty acid.


Acknowledgements The financial support for this project from Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Research Chair (CRC) funding to Dr. A.K. Dalai is acknowledged. References [1] M.G. Kulkarni, A.K. Dalai, Ind. Eng. Chem. Res. 45 (2006) 2901. [2] B.E. Holbein, J.D. Stephen, D.B. Latzell, Canadian Biodiesel Initiate, Final Report by Biocap Canada, Kingston, Ontario, 2004. [3] B. Freedman, E.H. Pryde, T.L. Mounts, J. Am. Oil Chem. Soc. 61 (1984) 1638. [4] E. Lotero, Y. Liu, D.E. Lopez, K. Suwannakarn, D.A. Bruce, J.G. Goodwin, Ind. Eng. Chem. Res. 44 (2005) 5353. [5] Y. Wang, S. Ou, P. Liu, Z. Zhang, Energy Convers. Manage. 48 (2007) 184. [6] Y. Wang, S. Ou, P. liu, F. Xue, S. Tang, J. Mol. Catal. A Chem. 252 (2006) 107. [7] N.A. Zafiropoulos, H.L. Ngo, T.A. Foglia, E.T. Samulski, W. Lin, Chem. Commun. (2007) 3670. [8] M.G. Kulkarni, Rajesh Gopinath, L.C. Meher, A.K. Dalai, Green Chem. 8 (2006) 1056. [9] Min-Hua Zong, Zhang-Qun Duan, Wen-Yong Lou, Thomas J. Smith, Green Chem. 9 (2007) 434. [10] P.S. Sreeprasanth, R. Srivastava, D. Srinivas, P. Ratnasamy, Appl. Catal. A: Gen. 314 (2006) 148. [11] S. Ramu, N. Lingaiah, B.L.A. Prabhavathi Devi, R.B.N. Prasad, I. Suryanarayana, P.S. Sai Prasad, Appl. Catal. A: Gen. 276 (2004) 163.

91

[12] Xin Zhang, De-hua He, Qi-jian Zhang, Qing Ye, Bo-qing Xu, Qi-ming Zhu, Appl. Catal. A: Gen. 249 (2003) 107. [13] S.Z. Mohamed Shamshuddin, N. Nagaraju, J. Mol. Catal. A Chem. 273 (2007) 55. [14] S.H.I. Wei, L.I.U. Hai-yan, R.E.N. Dong-mei, M.A. Zhuo, Wen-dong Sun, Chem. Res. Chinese U. 22 (2006) 364. [15] Kazushi Arata, Hideo Nakamura, Miyuki Shouji, Appl. Catal. A: Gen. 197 (2000) 213. [16] S.-T. Wong, T. Li, S. Cheng, J.-F. Lee, C.-Y. Mou, J. Catal. 215 (2003) 45. [17] C.-L. Chen, T. Li, S. Cheng, N.-P. Xu, C.-Y. Mou, Catal. Lett. 78 (2002) 223. [18] W. Hua, Y. Xia, Y. Yue, Z. Gao, J. Catal. 196 (2000) 104. [19] A. Sahibed – Dine, B. Bouanis, K. Nohair, M. Bensitel, Ceram. Int. 28 (2002) 159. [20] M. Di Serio, R. Tesser, M. Dimiccoli, F. Cammarota, M. Nastasi, E. Santacesaria, J. Mol. Catal. A 239 (2005) 111. [21] S.Y. Chin, A.L. Ahmad, A.R. Mohamed, S. Bhatia, Appl. Catal. A 297 (2006) 8. [22] A. Auroux, A. Gervasini, J. Phys. Chem. 94 (1990) 6371. [23] L. Letti, G. Ramis, G. Busca, F. Bregani, P. Forzetti, Catal. Today 61 (2000) 187. [24] M.K. Dongare, P.T. Patil, K.S. Malshe, US Patent 6,791,000 (2004). [25] S.K. Maurya, M.K. Gurjar, K.M. Malshe, P.T. Patil, M.K. Dongare, E. Kemnitz, Green Chem. 5 (2003) 720. [26] M.K. Dongare, V.V. Bhagvat, C.V. Ramana, M.K. Gurjar, Tetrahedron Lett. 45 (2004) 4759. [27] P.T. Patil, K.M. Malshe, S.P. Dagde, M.K. Dongare, Catal. Commun. 4 (2003) 429. [28] A.V. Biradar, S.B. Umbarkar, M.K. Dongare, Appl. Catal. A 285 (2005) 190. [29] R. Nava, T. Halachev, R. Rodriguez, V.M. Castano, Appl. Catal. A 231 (2002) 131. [30] W. Xie, H. Peng, L. Chen, J. Mol. Catal. A: Chem. 246 (2005) 24. [31] S. Furuta, H. Matsuhashi, K. Arata, Catal. Commun. 5 (2004) 721. [32] E. Leclercq, A. Finiels, C. Moreau, J. Am. Oil Chem. Soc. 11 (2001) 1161.