BIODIESEL PRODUCTION USING CALCIUM–BASED SOLID … · magnesium carbonate and calcium (92%) in a period of about 6 hours. The biodiesel obtained was analyzed qualitatively, especially

Available on-line at http://www.bjbabe.ro

Banats Journal of Biotechnology

2013, IV(7),

5

BIODIESEL PRODUCTION USING CALCIUM–BASED SOLID CATALYSTS

DOI: 10.7904/2068–4738–IV(7)–5

Marian BUTU1, Iulian GROSU1, Steliana RODINO1,2, Alina BUTU1

1National Institute of Research and Development for Biological Sciences, 060031, Splaiul

Independentei 296, Bucharest, Romania, [email protected] 2University of Agronomic Sciences and Veterinary Medicine, 011464, Mărăşti Blvd. 59, Bucharest,

Romania

Abstract. The present work describes the study of obtaining new catalysts from affordable raw materials, respectively two different types of antacid drugs and egg shells. It was also studied their efficiency in heterogeneous catalysis process. In order to determine the optimal reaction conditions, the catalysts were activated in a thermal annealing oven following to be tested the different conditions of their usage: concentration of catalyst, activation temperature, reaction time, and number of reutilizations. Aiming to standardize the process, the samples used were measured to exactly 20 mL methanol and 50 mL safflower crude oil. All the catalysts tested had high yields of over 86%; the best performance was recorded in case of a catalyst derived from pills containing magnesium carbonate and calcium (92%) in a period of about 6 hours. The biodiesel obtained was analyzed qualitatively, especially for the presence of calcium ions in solution. The catalysts revealed a good potential for utilization in biodiesel production.

Keywords: biodiesel, safflower oil, solid catalysts Introduction The European Union is heavily

dependent on fossil fuels used in transportation. At this moment, there is an urgent need to identify renewable and less pollutant fuel for transportation, which will provide both energy security and reduced costs in order to minimise this dependency on fossil fuels and to achieve the goal of sustainability.

Biodiesel seems to be a feasible alternative because it meets the particular qualities required as substitution of petrodiesel, its strong point being the positive impact on environment [MATSCHOSS

et al., 2011].

Biodiesel shows superior properties over petrodiesel such as: diversity of raw materials used in production, cetane number, biodegradability and lubrication [FELIZARDO et al., 2006].

Developing a technology for obtaining biodiesel and carrying out strategies to use renewable resources which are optimal from socio–economic point of view, biodiversity preservation and environmental protection are still under study.

From this reaction results 3 alkyl esters for each transformed triglyceride molecule (Fig. 1).

triglycerides methanol glycerol biodiesel

Figure 1. The transesterification reaction

Banat’s University of Agricultural Sciences and Veterinary Medicine from Timisoara,

Contact: web: http://www.bjbabe.ro, e-mail: bjb@usab–tm.ro

6

Biodiesel is an industry term used

for a mixture of alkyl esters of fatty acids produced by the reaction of transesterification of triglycerides with methanol or another alcohol [EARL et al., 2006].

Another important reaction product is the glycerin which is in 1:1 molar ratio with triglycerides, and it can be used further on in different industries.

The choice of vegetal oil or used fat for biodiesel production must take into account both the chemical feasibility, and the economic aspect.

Given the chemical process, it is chosen the oil or grease with the greatest amount of free fatty acids associated with triglycerides [KULKARNi et al., 2006].

It should be mentioned that biodiesel properties differ greatly depending on the source of origin [KINAST et

al., 2003]. For example, if biodiesel is

produced from safflower or rape, it has characteristics very close to petrodiesel, the one made from palm oil or animal fat has a high viscosity and cannot be used at low temperatures.

Along time, a considerable effort was made in order to identify new and affordable catalysts [KUMARI et al., 2007; LAI et al.,

2005]. The usual method for obtaining

biodiesel is by catalysis with a homogeneous catalyst such as KOH or NaOH. This process produces large amounts of methyl esters.

Unfortunately for the use of biodiesel, the catalyst must be removed by a difficult process of purification.

Moreover, wastewater is toxic due to high basic character of to the catalyst.

The three factors that influence the most the biodiesel costs are catalyst activity, period of use and the flexibility of oil [HAAS et al., 2006].

A greater attention enjoyed alkaline metal oxides because they are less soluble in the reaction medium and far less corrosive [KOUZU et al., 2008].

Materials and methods For a better on–going of the

laboratory experiments it was aimed the standardization of safflower oil transesterification method.

The reactants used were 20mL methanol and 50mL safflower oil, molar ratio 1:6 oil and alcohol (reaction medium with excess of alcohol) being therefore complied [LEUNG et al., 2010].

Preparation of Catalyst For the development of the

experiments were chosen three raw materials for catalysts preparation, namely egg shell and the two drugs having antiacid effect having in composition calcium and magnesium carbonate or magnesium hydroxide and aluminium.

Catalyst derived from the egg shells resulted from removal of the protective membrane inside the shell by washing with warm water and drying at 120°C for 24 hours and grinding it in a porcelain mortar and pestle [WEI et al., 2009].

The second catalyst was obtained by grinding the antiacid tablets with a content of 70% calcium carbonate, 29% magnesium carbonate and 1% zinc carbonate.

The third catalyst resulted from the use of equal parts of tablets containing 50% magnesium hydroxide and 50% aluminium hydroxide together with calcium oxide previously obtained calcinated egg shells.

The resulting mixture was treated with water followed by homogenization and solidification.

The catalysts were activated by heat treatment at 800°C at various intervals (2 h, 4 h, 8 h) in an annealing owen.

Temperature of 800°C was chosen because it is necessary to transform calcium carbonate to oxides. All catalysts were kept in sealed containers to prevent further reaction with air before use.

The control used in the experiments was sodium hydroxide.



2013, IV(7),

7

Compared to the control the catalysts tested required a longer period of time for transesterification.

It was observed in preliminary tests that after an optimal period of 4 hours of the catalyst activation at 800°C their catalytic activity decreases. As a result they, the experimental design included this duration for activation.

Biodiesel obtaining method In the experiments realised in our

laboratory we studied the influence of several parameters on the transesterification reaction.

In addition to testing the efficiency of catalysts after their nature, the study aimed to discover the optimum values for the following parameters: oil/ methanol ratio, activation temperature and optimal duration of response and also how external conditions influence the catalyst activity and more. Safflower crude oil needed a prior processing for removal of waxes and neutralizing its acidity [PAVAN et al., 2007].

Both waxes removal and neutralization of acidity was achieved by titration with sodium hydroxide while stirring, (Fig. 2).

In order to study the yields and the properties of the transesterification reaction were used 8 samples of which 4 were analyzed at intervals of 3 hours and the rest were analyzed after 6 hours as follows:

Over the solid catalyst, under continuous stirring on the magnetic stirrer, was poured methanol.

Reagents were gradually heated to a temperature of 55°C.

In parallel, the safflower oil is also heated to 55°C on a hot plate.

After reaching the proper temperature, the safflower oil was transferred on the magnetic stirrer and was added methanol together with catalyst previously obtained under continuous agitation of 300 rpm with (Fig. 3).

Reaction took place over several hours. It could be observed two separate layers of liquid, biodiesel at the surface and glycerol colored darker on the bottom.

The mixture obtained was poured into a separating funnel and after a one day natural settling and clearing, under the action of gravity the glycerol was separated from biodiesel.

Figure 2. Safflower oil processing



8

Figure 3. Reagents in the transesterification process

Results Compared with the sodium

hydroxide control the catalysts tested required a longer period of time for transesterification (Table 1).

By 3 hours after the start of the experiment the oil was not completely catalyzed. After 6 hours were not obtained additional quantities of biodiesel and therefore the reaction can be e declared as completed after this time.

Table 1. The results obtained at 3 h and 6 h of reaction

Yield

Catalyst At 3 hours At 6 hours

NaOH 95% 95%

CaO (egg shells) 65% 89% CaOMgO/ZnO2 75% 92% Mg(OH)2+Al(OH)3CaO 62% 86%

Comparing the results obtained

when using the three catalysts taken into study, the oxides of calcium, magnesium and zinc and the egg shell, it can be observed that they are similar with the control.

The yield obtained after 6 hours of reaction was 92% and 89% (Table 1).

The lowest yield of 86% was recorded for the catalyst based on aluminium and magnesium, and most probably the reason being due to coverage of active sites.

It was not notified the formation of soaps in any of the selected catalysts.

In the case of the most efficient catalyst it was also pursued in the reaction if there are traces of calcium ions. In order to do this both biodiesel and glycerol obtained were treated with a solution of sulphuric acid 0.1 N.

The amount of calcium sulphate resulted was very small and the fact that it was found in the glycerin solution denoted that the reaction mechanism was heterogeneous.

Subsequently, it was pursued the possibility to reuse the catalyst.

Since the catalyst is not miscible in the reagents, being in a different state of aggregation, nor react with them it could



2013, IV(7),

9

be separated by simple filtration and reused with satisfactory results up to 3 times. Catalyst losses were app 3% and were probably due to the method of separation.

After the 5th reutilization the reaction efficiency reduces below 60% and therefore is required a reactivation.

Regeneration was performed at a temperature of 700ºC after 2 hours in the annealing own.

Conclusions Optimum activation temperature

was 800°C. After 8 hours a decrease in yield was observed.

This decrease is attributed to compaction of the material and thus

decreases accessibility to active sites of calcium oxide.

Best yields were recorded at a 1:6 molar ratio of oil / methanol; the least results were obtained with a molar ratio of 1:3 (Fig. 4).

The best results were obtained with catalyst of complex composition based on calcium and magnesium oxide (Fig. 5). This is explained because, after annealing, the magnesium oxide acted as a protective support for the active part of the calcium oxide and gave it a tolerance to acidity, and to the water coming from the atmosphere or from reagents or other factors that had an intoxication activity the calcium oxide.

Figure 4. Transesetrification reaction at a molar ratio of 1:3

Figure 5. Biodiesel obtained by using calcium and magnesium catalyst



10

The results were comparable to those obtained using the control. In both cases was not revealed the presence of calcium soaps and calcium ions in the biodiesel obtained and this confirms that the reaction has behind it a heterogeneous mechanism and not a homogeneous one.

The catalysts could be reused with high returns up to three times (Fig. 6), after the fifth reuse was found that the yield dropped to 60%.

These results are especially promising for the transformation of the catalytic conversion process from one batch to a continuous one.

Figure 6. Biodiesel obtained by re–using

for the third time the calcium and magnesium catalyst When running the final tests it was

noticed a decrease in catalytic activity of the catalyst by 30% if left in open air over a period of 20 minutes which is explained by reacting calcium oxide with carbon dioxide from the air and restoring of calcium carbonate.

There was not observed any increase in the efficiency of transformation by the addition of water in the reaction, the calcium hydroxide being behind the mechanism of catalysis.

As future directions for research it can be considered studying increasing the efficiency of catalysis by increasing the reaction surface.

This can be done using nanocatalyst.

To increase the tolerance to water and free fatty acids is another important aspect that should be studied because these factors reduce the efficiency of transesterification reaction.

Also studying other materials for heterogeneous catalysts can give another

direction to study, aiming at improving the reusability period.

It can be studied either a new active component of the catalyst or another catalyst support materials.

Deeper research can be also realized regarding the reactivation of the catalysts in order to find other methods besides the heat, methods that could be more accessible from energetic and financial point of view.

Acknowledgements: This work

has been funded by the research contract PN–II–PT–PCCA 106/2012. References 1. Earle, M.J.; Seddon, K.R.; Plechkova,

N.V.; Production of biodiesel, Eur. Pat., 2006, 186:60–86.

2. Felizardo, P.; Correia, J.N.; Raposo, I.; Mendes, J.F.; Berkemeier, R. J.; Bordado, M.;. Production of biodiesel from waste frying oils. Waste Manage, 2006, 26, pp 487–494.



2013, IV(7),

11

3. Haas, M.J; McAloon, A.J; Yee, W.C; Foglia, T.A.; A process model to estimate biodiesel production costs. Bioresour Technol, 2006, 97:671–678.

4. Kinast J., A.; Production of Biodiesels from Multiple Feedstocks and Properties of Biodiesels and Biodiesel/Diesel Blends, 2003, NREL/SR–510–31460.

5. Kouzu, M.; Kasuno, T.; Tajika, M.; Sugimoto, Y.; Yamanaka, S.; Hidaka, J.; Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production, Fuel, 2008, 87:2798–2806.

6. Kulkarni, M.G; Dalai, A.K.; Waste cooking oil an economical source for biodiesel: A review. Ind Eng Chem Res., 2006, 45(9):2901–2913.

7. Kumari, V; Shah, S; Gupta, MN.; Preparation of biodiesel by lipasecatalyzed transesterification of high free fatty acid containing oil from Madhuca indica. Energy Fuels, 2007, 21(1):368–372.

8. Lai, C.C; Zullaikah, S; Vali, S.R; Ju, Y.H.; Lipase–catalyzed production of biodiesel from rice bran oil. J Chem

Technol Biotechnol, 2005, 80(3):331–337.

9. Leung, D.Y.C.; Wu, X. M.; Leung, K.H.; A review on biodieselproduction using catalyzed transesterification, Appl Energ, 2010, 87:1083–1095.

10. Matschoss, K.; Kadner, P.S.; IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Cambridge, UK and New York, USA: Cambridge University Press, 2011.

11. Pavan, K.M.; Vinay, T.; Synthesis of Biodiesel Fuel From Safflower Oil Using Various Reaction Parameters, Journal of Oleo Science, 2007, 56(1):9–12.

12. Wei, Z.; Xu, C.; Li, B.; Application of waste eggshell as low–cost solid catalyst for biodiesel production, Bioresour. Technol., 2009, 100:2883–2885.

Received: November 29, 2012

Accepted: January 20, 2013

Documents

BIODIESEL PRODUCTION USING CALCIUM–BASED SOLID … · magnesium carbonate and calcium (92%) in a period of about 6 hours. The biodiesel obtained was analyzed qualitatively, especially