Ahmad Hafiidz Mohammad Fauzi and Nor Aishah Saidina Amin

Abstract The necessity to search for fossil fuel alternative is getting more critical with the increasing fossil fuel price and also its limited supply. The use of mineral diesel for transport sector is unfeasible as it is nonrenewable and emits greenhouse gases to the atmosphere during combustion, particularly carbon dioxide which can lead to global warming phenomena. Biodiesel is a type of biofuel that can be pro­duced using renewable resources such as biomass. It can be produced from oils and fats through transesterification process. The presence of catalyst is important to ensure that the reaction can progress at shorter time and produce high biodiesel yield. Numerous catalysts have been used to assist the transesterification process. They include homogeneous and heterogeneous catalysts and can be further divided into acid and base nature. The catalysis in biodiesel production is progressing at faster rate in order to find a catalyst that is more practical for larger production scale. Ionic liquids and ionic solids are among new catalysts introduced with aim to improve the efficiency of the process. This chapter focused on the benefits and draw­backs of different catalysts for biodiesel synthesis. The applications of novel pro­cesses for more sustainable and enhanced biodiesel production are also discussed.

Keywords Biodiesel • Catalyst • Homogeneous • Heterogeneous • Novel process

9.1 Introduction

Competition among countries for energy supplies is likely to become more intense in the coming years. This is contributed by the growth and development in different sectors that consumes a great amount of energy, such as light and heavy industries,

A. H.M. Fauzi • N. A.S. Amin (*)

Chemical Reaction Engineering Group (CREG), Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia e-mail: noraishah@cheme. utm. my

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_9, © Springer Science+Business Media New York 2013

agriculture, commercial, public services, and transportation. Primary energy sources such as crude oil, natural gas, and coal are all nonrenewable and originated from the same source, which are fossil fuels.

Formed by decomposition of organic materials million years ago, fossil fuels are considered nonrenewable because they cannot be replaced when they are used up and they will run out one day. Relying on them for energy generation is unsustain­able. Hence, the need to find more renewable and sustainable alternatives for energy generation is becoming priority today.

Natural gas and coal are widely used for generating electricity, providing heat and power to industry and also to residential. Crude oil products including gaso­line, kerosene, diesel oil, and fuel oil are mainly intended for the transportation sector. The main end user of energy is the road transport sector, followed by the aviation sector as the second-largest transport user of energy. According to IEA (2010), the global transport energy increased steadily between 2 and 2.5% a year, from 1971 to 2007. This situation is impractical because using crude oil derivatives as the fuel source emits carbon dioxide (CO2) gas into the atmosphere during the combustion process. CO2 is undesirable as it contributes to the increase of green­house gas in the atmosphere and resulted in the increase of the earth surface’s temperature.

Substantial efforts are done to find suitable alternatives for these crude oil prod­ucts, as fossil fuel supply is finite. Biofuel has started to gain attention as substitute to fossil fuel derivatives, where it can be produced from different biomass sources. Common types of biofuels available nowadays are bioethanol and biodiesel. The former is usually used as an additive to gasoline, while the latter as a substitute for diesel fuel. Global biofuel production increased from 16 billion L in 2000 to more than 100 billion L in 2010, as a result from countries implementing use of biofuels and introduction of support policies on biofuel usage (IEA 2011) . The trend of increasing biofuel production is depicted in Fig. 9.1. Today, biofuels contributed to about 3% of total road transport fuel globally. It is expected that by 2050, biofuels

could provide 27% of total transport fuel and contribute for the replacement of die­sel, kerosene, and jet fuel, particularly.

Biodiesel is a diesel fuel consists of long-chain alkyl esters derived from vegeta­ble oil and animal fat, and it is produced from renewable resources. Biodiesel holds several advantages over diesel from fossil fuel, such as being biodegradable, close to sulfur-free, and emits less carbon dioxide. Biodiesel can be used in standard diesel engines with minimal modification or blended with diesel fuel in certain proportion. Transesterification is the common method utilized to produce biodiesel. Feedstock such as oil or fat is converted into fatty acid alkyl ester (FAAE) accom­panied by an alcohol and a catalyst. The process produces biodiesel as the main product and glycerol as the by-product. The resultant product is later refined to meet the international standards of biodiesel. Other methods available to produce bio­diesel are direct use and blending, microemulsions, and pyrolysis.

Transesterification can proceed without the presence of catalyst but requires severe operating conditions, such as higher reaction temperature and high pressure. Conventional catalysts for transesterification are sodium hydroxide (NaOH) and potassium hydroxide (KOH). They enable the reaction to be accomplished in shorter time and high product yield. Acidic catalyst such as sulfuric acid (H2SO4) is more suitable for feedstock containing high free fatty acid (FFA) content. In recent years, more researchers are focused on using heterogeneous catalysts as they are more practical in terms of separating the reactants and recyclable. Nonetheless, each cata­lyst has its own advantages and disadvantages. This chapter is intended to discuss more on this subject, together with the challenges and future perspectives on cata­lysts used for biodiesel production.

Rahmath Abdulla and Ravindra Pogaku

Abstract This chapter focuses mainly on biodiesel production from the “future green gold” namely Jatropha curcas. The importance of this plant as biodiesel feedstock, oil extraction methods from the seeds, and different routes of bio­diesel production are discussed in the first part. Nowadays, immobilization of lipase has gained immense potential in the biofuel industry mainly to reduce the production costs and to make the method more economical. Different approaches of lipase immobilization are briefed in the second part. The final part of this chapter shows stability studies of Burkholderia cepacia lipase immobilized in hybrid matrix and its application and biodiesel optimization from crude J. curcas oil.

Keywords Biodiesel • Jatropha curcas • Transesterification • Immobilization • Lipase

12.1 Introduction

With rapidly increasing energy demand day by day, the world is in an energy crisis. The growing population depends mainly on energy from fossil sources such as petroleum, coal, and natural gas. Today, these fossil fuels are on the verge of maxi­mum production and limited reserves concentrated on fewparts of the world. In short, these fuels are shortening day by day and will soon be exhausted in near future. In search for alternative sources of renewable and sustainable energy, biofuels which can be obtained from biomass feedstock occupy the top ladder.

R. Abdulla • R. Pogaku (*)

Chemical Engineering, School of Engineering and Information Technology, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia e-mail: ravindra@ums. edu. my

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels, 191

DOI 10.1007/978-1-4614-6249-1_12, © Springer Science+Business Media New York 2013

In addition, biofuels are also an answer to the environmental concerns like air pollution and global warming which is mainly caused by fossil fuel combustion (Demirbas 2009; Gui et al. 2008; Lam et al. 2009).

The first use ofbiofuel was in 1900 at the World Exhibition in Paris when Rudolf Diesel demonstrated the use of peanut oil as fuel in diesel engines. Recently, with the realization of fast depletion of petroleum reserves, environmental friendly fuels received great attention and opened an era of research in these areas of renewable and sustainable energy. Biofuels include biodiesel, bioethanol, biomethanol, and biohydrogen (Agarwal and Das 2001; Murugesan et al. 2009).

Among these biofuels, biodiesel is gaining much importance recently since it has been strongly recommended as petroleum diesel substitute. The term bio­diesel (Greek, bio, life+ diesel from Rudolf Diesel) refers to a diesel equivalent, processed fuel which can be derived from biomass. Biodiesel is defined as a mix­ture of monoalkyl esters of long fatty acids which can be obtained from renewable lipid feedstock, such as vegetable oils or animal fats. The production and applica­tion of biodiesel are expected to increase steadily in the next few decades. Already, biodiesel has been implemented as a blending component with diesel in many countries such as Brazil, United States, Germany, Austria, Italy, and Australia (Yusuf et al. 2011).

The main advantages of biodiesel over conventional fuels are lower toxicity, bio­degradability, and substantial reduction in sulfur oxide gases, carbon monoxide, polyaromatic hydrocarbons, smoke, and particulate matter. Biodiesel, which is environmental friendly, reduces the greenhouse effect. Since its properties are close to that of diesel, biodiesel is regarded as a strong candidate to replace diesel in trans­portation industry. “Future fuels” such as biodiesel should be focused with the growing concern of protecting the environment and as an energy reserve for the upcoming generations. For this reason, researchers and scientific organizations worldwide are involved in development of commercial biodiesel and optimization parameters to meet the various standards and diesel engine specifications (Sharma et al. 2008; Fukuda et al. 2001).

Use of edible oils such as soybean oil, rapeseed oil, and palm oil for biodiesel production has led to the concern of “food versus fuel.” This is mainly because the developing countries with lack of enough edible oils for consumption cannot afford to use these oils for production of biodiesel. In such a situation, easily available nonedible oils obtained from sources like Jatropha, microalgae, neem, karanja, rub­ber seed, mahua, silk cotton tree, and so on play an important role. Out of these, Jatropha curcas seed oil with considerable potential is gaining importance in bio­diesel production (Abdulla et al. 2011).

Biodiesel can be produced by a number of ways. Out of these, the most com­monly used is the transesterification of vegetable oils. This can be done by chemical method or enzymatic method. In terms of reaction kinetics, the chemical transesteri­fication is faster, but due to many disadvantages such as difficulty in recovery of glycerol, biodiesel impurities, highly energy intensive process, and need for waste treatment. On the other hand, these disadvantages can be overcome through enzymatic transesterification reactions which can yield specific alkyl esters of high purity, no soap formation, easy separation of glycerol from biodiesel, less treatment for waste, and even use of oils with high free fatty acids which can be easily converted to biodiesel (Rathore and Madras 2007; Nelson et al. 1996). Researchers have proved that enzymatic transesterification is thus a promising alternative to overcome the drawbacks associated with chemical methods. In short, we can say that enzymes mainly lipases are potential replacements for conventional catalysts used in bio­diesel synthesis. The use of lipases for biodiesel production through transesterifica­tion has already stepped into commercial scale with the introduction of pilot plants in few countries including China. But the main hurdle for commercialization is still the high price of lipases which can be overcome to a certain extent through reusing immobilized lipases.

This chapter throws an insight into the future fuel plant—J. curcas—for bio­diesel production, immobilization techniques, and finally development of a new enzyme catalyst for biodiesel production and its application in transesterification of crude J. curcas oil (CJO).

Figure 13.8 shows the concentration of ethanol produced from the fermentation experiments after various hydrolysis conditions on extracted seaweed. Hydrolysis at 0.1 M, 100% clearly produced the most ethanol (8.41% v/v), followed by hydrolysis 0.1 M, 30% (7.70% v/v); 0.4 M, 30% (4.73% v/v); and 0.4 M, 100% (3.36% v/v). Interestingly, the ethanol yield did not change with temperature. It was observed that ethanol yield was lower with 100%, 0.4 M acid hydrolysis (3.36% v/v) com­pared to 30%, 0.4 M acid hydrolysis (4.73% v/v). However, the ethanol yield showed a reverse trend with lower yield at 30%, 0.1 M acid hydrolysis (7.70% v/v) compared with 100%, 0.1 M acid hydrolysis (8.41% v/v).

The effect of temperature was not significant as compared to molarity change. Heating has been shown to increase the reducing sugar concentration (Fig. 13.7).

So, in theory, there would be more ethanol produced. The ethanol yield in the 100% acid hydrolysis was lower than in those hydrolysed at 30%, possibly due to the increased solubilisation of inhibitory compounds, which reduced the effi­ciency of the yeast (Adams et al. 2009). Larsson et al. (1999) suggested that the elevated temperature will produce poor fermentability hydrolysate. Sugars can be degraded to furfural which is formed from pentoses and 5-hydroxymethylfur — fural (5-HMF) which is formed from hexoses. 5-HMF can be further degraded, forming levulinic acid and formic acid. In addition, formic acid can be formed from furfural under acidic conditions at elevated temperatures. Acetate is liber­ated from hemicellulose during hydrolysis. S. cerevisiae is a non-pentose-utilis­ing yeast strain (Krishna et al. 1998). In this case, the fermentability of yeast will decrease as the hexose sugar for fermentation had reduced. Since there was no proof of the type of reducing sugars produced, hence it cannot be concluded here that this was the reason for the reduced ethanol production.

Increased in molarity also reduced the ethanol yield from 8.42% v/v to 3.36% v/v and 7.70% v/v to 4.73% v/v as shown in Fig. 13.8. An increase in molarity leads to a reduction in pH. The lower yields generated by the slurries with high molarity may be due to an increase in salt concentration in the slurry. The slurries initially contained low salt concentration from the seawater retained on the mac­roalgae and ions within the algae, but with the adjustment to 0.4 M and back to pH 7 with H2SO4 and NaOH, the salt concentration would have been increased further, potentially causing inhibition of the yeast and thus reducing ethanol production (Adams et al. 2009).

Higher molarity as acid hydrolysis was assumed to have been used to disrupt the cells, thus releasing the cellular contents. However, although there was an increase in reducing sugar yields in slurries with 0.4 M hydrolysis (Fig. 13.7), this increase was small, and the salt inhibition as seen in Fig. 13.8 fermentations overall proved this is a disadvantageous acid hydrolysis molarity (Adams et al. 2009).

Apart from being developed for the growth of a wide range of palm oil and biomass — based downstream industries as the core sector (Table 2.1), POIC Lahad Datu also serves as a center where investments in upstream and related industries will be

supported and integrate vertically with the downstream industries to achieve the synergistic effects under the industrial cluster concept (Fig. 2.3), a concept with ben­efits proven all over (Solved et al. 2008; Falck et al. 2010; Delgado et al. 2010a, b; McCann and Folta 2011). In addition, it will be followed by the development of other industrial clusters, such as oil and gas, regional logistics hub (Rotterdam of the East), SMI and food clusters, and others in stages (Fig. 2.3).

Both the OPW in the form of solid and liquid residues can serve as a source of raw material for biofuel production. In order to enhance the physical and chemical com­position of OPW fibres for energy production, gasification, pelletisation (or briquet­ting), torrefaction and liquefaction have been applied. The heating value of OPF presents it appropriate for use as pelletised fuel which could be mixed with glycerol to enhance its heating value (Azuan 2008). Research on the production of high-quality briquette fuel produced by the mixing of 100% pulverised EFB with sawdust or PKS (also called palm kernel expellers) have been carried out (Nasrin et al. 2008) . High-energy solid fuels have been produced from pelletised PKC (Razuan et al. 2011), briquetted PKS and PPF (Husain et al. 2002) and torrefacted EFB (Uemura et al. 2013) . The energy content of torrefacted fuels from wheat straw, reed canary grass and willow as reported by Bridgeman et al. (2008) are 77%, 78% and 86%, respectively, which are lower than that for EFB (85-95%), PPF (96%) and PKS (100%) (Uemura et al. 2013). PKS is widely used traditionally as solid fuel (or pelletised fuel) by black and goldsmiths in most part of Africa. It can also be mixed with other grades of biomass for co-firing with steam or used in bio­mass power plants.

The BOD of POME could be reduced (to <100 mg/l) when treated in ponds and digesters for the production of biogas. For every ton of POME generated in the palm oil mill, about 12.36 kg of methane could be generated from it (Basri et al. 2010).

In Malaysia and Thailand, large quantities of generated POME are used as feed­stock for biogas production (Basri et al. 2010). In order to promote sustainable utili­sation of OPW in the palm oil mills for value-added products, the feasibility of biogas production from EFB and its co-digestion with POME have been investi­gated by O-Thong et al. (2012) . Co-digestion of EFB with POME is found to enhance microbial biodegradability and increase-methane yield (by 25-32% higher) at mixing ratios of 0.4:1, 0.8:1 and 2.3:1 on volatile solid basis than digest­ing EFB alone or POME alone (O-Thong et al. 2012). A further optimisation study on the improvement of biogas and methane yields from the digestion of a mixture of POME and EFB has been done by Saleh et al. (2011). The optimal conditions to obtain about 25.6% methane were 47.8°C with 50.4 ml POME and 5.7 g EFB. EFBs again have been improved (through NaOH pretreatment for 60 min) to produce biogas with methane yield of 0.404 Nm)kg (volatile solids) which accounts for about 97% of the theoretical yield of methane from carbohydrates (0.415 NmVkg carbohydrates) (Nieves et al. 2011; Davidsson 2007).

Bio-oils are found to be promising candidates for petroleum fuel replacement which are applicable in various thermal devices. The production of bio-oil from OPW such as EFB (Misson et al. 2009; Abdullah 2005; Abdullah and Gerhauser 2008; Lim and Andresen 2011; Sulaiman and Abdullah 2011), PKS (Abnisa et al. 2011; Kim et al. 2010; Salema and Ani 2011), OPF (Lim and Andresen 2011), PPF (Salema and Ani 2011) and PKC (Razuan et al. 2010) by pyrolysis has been reported. Bio-oil yields of 46.1 wt% (at 500°C pyrolysis temperature for 1 h with a particle size of 1.7 < dp < 2 mm), 80-90 wt% (pretreated with NaOH and H2O2) and 42.3% (with sub/supercritical treatment with 1,4-dioxane at 290°C) have been pro­duced from PKS (Abnisa et al. 2011), EFB (Misson et al. 2009) and PPF (Mazaheri et al. 2010), respectively. Abdullah and Gerhauser (2008) have concluded that the fast pyrolysis of washed EFB with a low ash content produced bio-oil which had similar yields as that mostly obtained from wood. Again, the characterisation of EFB bio-oil by Pimenidou and Dupont (2012) indicates better hydrogen yield (15.9 wt%) via steam reforming compared to that of pinewood (13.7 wt%).

Various effective catalysts such as calcined dolomite have been proven to be a viable catalyst which improves hydrogen production and reduces the amount of tar generated in syngas produced from OPW solid residues (Mohammed et al. 2012). The low moisture, high volatile matter, low fixed carbon and ash contents of EFB make it highly volatile and reactive (Demirbas 2004) and highly appropriate for the production of gas fuel. The pyrolysis of PKS for the production of hydrogen using nickel and La/Al2O3 at900°C in a fixed bed reactor yielded 37.28 vol% and 38.45 vol%, respectively (Yang et al. 2006). Bio-hydrogen production from the hydrolysate of microwave-assisted sulphuric acid-pretreated OPT has been reported (Khamtib et al. 2011) . Steam gasification (at 800°C) of OPT yielded more syngas (50%), energy and hydrogen (60%) (Nipattummakula et al. 2012) than those from mangrove wood, paper an. food waste (Nipattummakula et al. 2012; Ahmed and Gupta 2009). The EFB generated as wastes from the palm oil mill after processing about 60 tonnes of FFB every hour is estimated to be capable of producing about 3 MW of electricity (from controlled gasification process). Pattanamanee et al. (2012) have concluded that EFB presents an efficient OPW for producing bio-hydrogen by anaerobic photo-fermentation with an isolated photosynthetic bacterium R. sphaeroides S10.

The production of bio-alcohols such as ethanol from EFB (Tan et al. 2010), etha­nol from OPT (Yamada et al. 2010), ethanol from PKC (Cervero et al. 2010), buta­nol from EFB (Noomtim and Cheirsilp 2011), butanol from POME (Hipolito et al. 2008), butanol from PPF (Ponthein and Cheirsilp 2011) and ethanol from POME (Alam et al. 2009) through various processes prior to various pretreatment methods such as acid and enzymatic pretreatments. A million tonne of EFB would have the potential to produce about 81 x 103 kl of ethanol (Shinichi et al. 2009). Also, OPT has the potential of producing higher ethanol yield (9.5-10.3 kl/ha) compared to that of sugarcane bagasse (4.5-7.2 kl/ha) (Mori 2007). An average-weighted OPT could produce about 107.8 kg and 123.5 kg fermentable sugars from the sap and solid fibres, respectively, which can produce about 69.8 l and 41.4 l bioethanol, respectively (Mori 2007). Simultaneous saccharification and fermentation (SSF) of OPT fibre for bioethanol production gave a yield of 78.3% making OPT a potential source of raw material for bioethanol production (Jung et al. 2011). PKC which is readily available from palm kernel crushing units contains large amount of mannan (which is about 35.2% of the total carbohydrates in PKC) which can be easily hydrolysed into sugar for the production of bioethanol (with yield of 125 g/kg PKC) without any pretreatment (Cervero et al. 2010).

Biogas, bio-oil, bio-hydrogen, etc. which are produced from OPW can be used to generate electricity in order to reduce the dependency on fossil fuel used by power plants as well as safeguarding the environment. For instance, in Malaysia, it is estimated that for a million ton of FFB processed, about 16,000 GW/year of elec­trical energy can be generated from the OPW produced (Low 2011).

The process intensification for transesterification has been progressing rapidly to make biodiesel synthesis economically viable, and one of the methods available is microwave irradiation. Microwave-assisted transesterification of oils offers the ben­efits of shorter times and energy efficient operation. Electromagnetic radiation at microwave wavelength is transmitted and influence molecular motions. However, it does not alter the molecular structure of substances. Molecules move and vibrate with the alternating electric field of the microwaves, which leads to intense local­ized heating and accelerates the chemical reaction as the result of molecular friction and collisions (Kumar et al. 2011). The intensification allows the chemical reaction to produce higher yield at much shorter time.

The transesterification under microwave heating was conducted with nonedible feedstocks, Jatropha oil, and waste frying palm oil (WFPO) as feedstocks (Yaakob et al. 2009). The reaction was conducted using NaOH as the catalyst. The conver­sion of both feedstocks produced highest biodiesel yield in 7 min and temperature of 65°C, whereas the purity reached as high as 99%. Catalyst concentration lower than 1 wt% reduced biodiesel purity, while higher value did not improve its purity significantly. Assessment of the fuel properties showed that biodiesel obtained from Jatropha and WFPO were within the specified limits of the international standards of EN 14214.

Kumar et al. (2011) evaluated the capability of NaOH and KOH for the FAME production from Pongamia pinnata seed oil with the inclusion of microwave irra­diation. 96% and 97% of biodiesel yield were obtained when the catalyst concentra­tion of 0.5% w/w NaOH and 1.0% w/w KOH were used, respectively. A complete gel formation was observed when the catalysts concentration of NaOH increased to 1.5% w/w. Both catalysts managed to enhance biodiesel yield when the reaction time was increased from 3 to 10 min. Several properties of the resultant biodiesel meet the limit of international standard ASTM D6751. The author mentioned that these properties were influenced by the reaction time of the transesterification.

Microwave-assisted process is also appropriate for transesterification reaction utilizing heterogeneous catalysts. Zhang et al. (2010) used heteropolyacid catalyst for converting yellow horn under microwave heating. The biodiesel productivity obtained using Cs25H05PW12O40 catalyst was the highest among other catalysts used and even higher than the conversion using homogeneous acid catalyst (i. e., H2SO4) at the same operating conditions. The comparison between microwave-assisted transesterification (MAT) and conventional method of transesterification (CMT) showed that the former reached high conversion at lower methanol to oil molar ratio and shorter time in comparison to the latter method.

Heterogeneous catalyst ZnO/La2O2CO3 was applied for catalyzing biodiesel pro­duction from canola oil assisted by microwave source (Jin et al. 2011). The process reached equilibrium in 5 min, and extended time shows no improvement in FAME yield. The solid catalyst was shown to be more active than homogeneous catalyst of KOH in terms of reaction rate. Furthermore, the reaction assisted by microwave irradiation reached 95% FAME yield in less time compared to conventional heating. The determination of Zn-La oxide content in the biodiesel by XRF analysis proved that there was no leaching of Zn and La into the biodiesel even when the process was exposed to microwave irradiation. The results showed that high biodiesel pro­ductivity can be achieved in very short operating time with the microwave assistance.

Although microwave-assisted reaction shows positive impacts for the transesteri­fication process, especially less reaction time, there are some disadvantages related to the technology (Vyas et al. 2010). The first problem is related to the applicability of the method at industrial scale, as it is difficult to scale up the microwave process and is limited to laboratory scale synthesis. Another drawback in implementing this technology at larger scale is the penetration depth of microwave radiation into the absorbing materials, which is limited to only a few centimeters.

Lipase activity of both soluble and immobilized enzyme was measured by using 0.1% w/v of p-nitrophenyl palmitate (p-NPP) in ethanol (95%) as substrate by mod­ifying the method of Hung et al. (2003). The reaction mixture consists of 100 pl substrate, 1 ml 0.05 M phosphate buffer of pH 7, and 50 pl of free lipase solution (stock 1 mg/ml) or 1 g immobilized lipase beads. The mixture was kept at 30°C for 5 min followed by termination of the reaction by addition of 2 ml of 0.5 N Na2CO3

Sodium alginate+

Dropped into 0.1M CaCl2 solution

alginate

=» carrageenan

Burkholderia cepacia lipase

Fig. 12.2 Immobilization of Burkholderia cepacia lipase by cross-linking with glutaraldehyde followed by entrapment in hybrid matrix of alginate and carrageenan solution. After this, the reaction mixture was centrifuged at 10,000 rpm for 10 min. Absorbance of the end product p-nitrophenol, which is released by lipase hydrolysis of p-NPP, was measured at 410 nm in a spectrophotometer (Spectronic 4001, USA) against an enzyme-free blank solution. A molar extinction coefficient of 15,000/M/ cm for p-nitrophenol was used (Okahata et al. 1995) . The amount of enzyme required to hydrolyze 1 |rmol/min of p-NPP under the similar assay conditions was defined as one unit of lipase activity (U).

The efficiency of lipase entrapment was evaluated in terms of activity yield as follows:

Activity yield (%) = Specific activity of immobilized lipase x100 Specific activity of free lipase

A variety of biomass resources can be used for energy by conversion process.

They can be divided into four categories:

• Crops: woody energy crops, industrial crops, agricultural crops, and aquatic crops (Ra et al. 2012; Ignaciuk and Dellink 2006; Paine et al. 1996; El-Shinnawi et al. 1989)

• Agricultural wastes: crop waste and animal waste like cow dung and chicken manure (Ren et al. 2010; Abouelenien et al. 2010)

• Forestry waste and residues: mill wood waste, logging residues, trees, and shrub residues (Alich and Witwer 1997; Gomez et al. 2010; Malinen et al. 2001)

• Industrial and municipal wastes: municipal solid waste (MSW), sewage sludge, and industry waste (Dent and Krol 1990; Manara and Zabaniotou 2012; Nges et al. 2012)

Hydrogen is a prosperous source of energy for the future. New ways of hydrogen production have been made in the last decades. One of the promising processes is biomass gasification.

Biomass gasification using supercritical water is a new way to produce hydrogen gas. Besides producing hydrogen, however, this method has a possibility to release heteroatomic compounds. It is therefore important to clarify the mechanisms for obtaining hydrogen gas. An online system of mass spectrometer and a reactor cell has been developed for analysis of the sulfur heteroatom compounds generated from L-Cysteine, as a standard substance and durian fruit as a practical sample, which contain sulfur at high levels. In this study, effects of Ca(OH)2 an alkaline additive on the formation of heteroatom compounds were also studied in detail, in conjunction with suppression of toxic emission.

Ravindra Pogaku, Tapan Kumar Biswas, and Rahmath Abdulla

Abstract Biofuels can be broadly defined as solids, liquids, or gas fuels consisting of, or derived from, plant biomass. Its use here is primarily with respect to a liquid transportation fuel (bioethanol or biodiesel). A major environmental issue being addressed by the global community is the sustainable supply of energy in parallel with a significant reduction in greenhouse gas emissions. This will be a significant technological and socioeconomic challenge because of our dependence on fossil fuel combustion for energy and the fact that it is this combustion that is the primary cause of greenhouse gas emissions.

Keywords Biofuels • Bioethanol • Palm • Malaysia • Low cost

7.1 Introduction

Presently over 80% of our global energy supply needs (~10 TW per year) are derived from fossil fuels (oil, coal, and natural gas) (United Nations Development Program 1996), and it is clear why this is the case. Firstly, the cost of energy derived from fossil fuels is considerably less than that of alternative renewable energy sources, for example, $0.04 per kWh from coal compared to $0.50 per kWh from solar pho­tovoltaic. Secondly, estimates of global fossil fuel reserves indicate that they will be available in significant quantities for more than 200 years. To break this cycle of fossil fuel dependence, and hence alleviate the environmental impact of greenhouse

R. Pogaku (*) • R. Abdulla

School of Engineering and Information Technology, University Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia e-mail: ravindra@ums. edu. my

T. K. Biswas

Department of Chemistry, Rajshahi University, 6205 Rajshahi, Bangladesh

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_7, © Springer Science+Business Media New York 2013 gas emissions, breakthroughs are needed in alternative energy sources to improve their cost and availability (Hoffert et al. 1998). Needless to say, the world popula­tion is increasing at an alarming rate and so is the liquid fuel demand in the transport sector.

Biomass can serve as an excellent alternative source to meet the present and future fuel demands. Any type of fuel generated from biomass is termed biofuel. The two most common and successful biofuels are biodiesel and bioethanol which are aimed at replacing mainly the conventional liquid fuels like diesel and petrol. Bioethanol, an eco-friendly fuel made from plant biomass, is an alternative to con­ventional gasoline. Ethanol is produced by utilizing sugar-containing feedstock such as renewable biomass energy through a fermentation process and can be a potential source of sustainable transportation fuel (Nigam and Singh 2010).

The biofuel that is expected to be most widely used around the globe is ethanol, which can be produced from abundant supplies of starch/cellulose biomass. The most important bioethanol production countries in the world are Brazil, the USA, and Canada (Chiaramonti 2007). In addition, ethanol is less toxic and is readily biodegradable, and its use produces fewer airborne pollutants than petroleum fuel. Ethanol-blended gasoline has the potential to contribute significantly to reduce these emissions. It can also be used as a fuel for electric power generation, in fuel cells (thermochemical action) and in power cogeneration systems, and as a raw material in chemical industry.

Bioethanol can be employed to replace octane enhancers such as methylcyclo — pentadienyl manganese tricarbonyl (MMT) and aromatic hydrocarbons such as benzene or oxygenates such as methyl tertiary butyl ether (MTBE) (Champagne 2007). Although growth of feedstock crops for ethanol production can address the environmental issues, it has raised doubts about its possible impact on food supply and security. Around the world, an urgent demand for alternative, sustainable fuels and feedstocks is growing to replace food-based feedstock. In comparison to other feedstocks, oil palm empty fruit bunch can provide a high-yield source of biofuels without compromising food supplies, rainforests, or arable land (Subhadra and Edwards 2010).

Today, Malaysia is one of the world’s largest palm oil producers. The palm oil industry is the backbone of the Malaysian economic and social development. During the production process of palm oil, five different biomass residuals become available, which are empty fruit bunch, palm kernel shell, palm oil mill effluent, mesocarp fiber, and palm kernel cake. In total, more than 50% of the fresh fruit bunch remains as a residual. Each of the residuals has an interesting energy poten­tial of around 20,000 kJ/kg. This is good energy potential and relatively low investments in comparison to other options. Based on the options of the residuals, it came forward that it would be most attractive to focus on the option of empty fruit bunch. Economically, EFB can be used as a resource for conversion to bio­ethanol since production is 6.1 million tons dry EFB and forecasted to increase to 7.6 million tons dry EFB by 2025. The Danish Technical University had con­ducted tests on EFB in Malaysia for the production of cellulose-ethanol and found it suitable for ethanol production with an estimated yield of 39% (388 L ethanol, on 1 ton dry raw material). Other parts of palm like trunks has the highest ethanol yield of 451 L/ton dry matter, while fronds have the lowest ethanol yield of 377 L/ ton (Luo et al. 2010).

Several positive environmental effects of biofuel consumption have been already proved, for example, reduction of greenhouse gas emissions and the subsequent improvement of the air quality (especially in cities with high smog contamination), as well as positive energy balance. The positive impact of extended biofuel con­sumption nowadays (versus pure gasoline consumption) can contribute to positive long-term changes in the environment. Due to a lower air pollution, the soil and groundwater contamination from the regular rainfall can be diminished, which clearly provides positive implications, for example, for food production. Thus, in a long-term perspective, the positive effects of biofuel consumption could indirectly help to reduce negative effects of the current biofuel production. Unclear however is which effects would dominate and how the mentioned changes can influence other sectors, especially agricultural production, that can be directly affected by potential negative effects of biofuel production or by other sectors.

Our approach incorporates efficient production of fermentable sugars, with the focus on mitigating the production of potential fermentation inhibitors. However, few amount of research work has been reported on various strategies for bioethanol production. Studies on the effects and optimization of the process variables that influence the performance of the pretreatment process will be essential to the com­mercial outlook of bioethanol development from EBF.

Many are looking to renewable energy and in particular biofuels as at least a partial solution. As such, an increasing share of major crops like maize, sugarcane, jatropha, and rapeseed, in addition to some new feedstock like oil palm, is now being diverted to biofuel production, and the trend is expected to continue. While this is most evident in the industrialized world and has been the case with sugarcane in Brazil for more than three decades, developing countries too are making signifi­cant investments in and establishing mandates for biofuel production and consump­tion. China, for example, with its booming economy and rapidly expanding energy consumption is expected to diversify its energy supplies beyond the use of coal and oil, for both economic and environmental reasons (Chandrashekhar et al. 2011).

Brazil and the USA are the leading producers of bioethanol accounting for over 90% of world supply. Brazil, the most competitive producer, has the longest history of ethanol production, dating back to the 1930s. About half of its sugarcane is used to produce ethanol. It is already the world’s leader in biofuel production and has tremendous capacity to further increase its ethanol production from sugarcane and biodiesel from soybean and perhaps oil palm. Annual ethanol production is pro­jected to reach some 44 billion L by 2016 (from 21 billion today), and the govern­ment has set various mandates for biodiesel use (Jegannathan et al. 2009).

As a renewable energy source, biofuels are a potential low-carbon energy source, but whether they offer carbon savings and thus are effective in combating climate change depends on the type of feedstock (raw material), production process, changes in land use, and conversion into a usable fuel. The largest GHG reductions (90%) can be derived from Brazil sugarcane-based bioethanol, followed by ethanol from cellulosic feedstock (70-90%). Ethanol from sugar beets and biodiesel is next (40­50%), followed by soybean-based biodiesel. Ethanol from starchy grains yields about a 12% reduction (Hill et al. 2006), although more recent analysis for maize — based ethanol systems in the USA shows GHG reduction between 25 and 75% (Liska et al. 2007). However, this and the other analyses above largely fail to capture a key element in the life cycle analysis—the direct and indirect changes in land use. Some methods of producing biofuels/bioethanol actually increase global warming due to land conversion and the release of huge amounts of carbon that otherwise would remain stored in plants and soil.

Based on the literature review and the research set forth there, as well as the presented analytical discussion, biofuels can have both positive and negative envi­ronmental effects, depending on a number of other factors such as implemented technologies, soil types, climate conditions, intensity of soil cultivation, and others. The positive effects of biofuel consumption expected in the future, such as air qual­ity improvement, can contribute to the improvement of environmental conditions in rural areas generally, since lower air pollution brings about lower soil and ground­water pollution from rainfall and snowfall. The empirical analysis that will be pre­sented in this research shows the scope and range of potential environmental effects of biofuel and ethanol consumption and production. Similarly, CO2 emission reduc­tions resulting from ethanol consumption amount to 255.1^25.1 million tons in the USA and 20.2-33.7 million tons in the EU. Regarding negative environmental effects, the cumulated amount of fertilizers used for the biofuel maize production in the USA in 2006-2018 was estimated to amount to 53,983.2 million kg and 1,173.2 million kg for biofuel soybean production. Referring to the presented analyses and due to missing empirical studies on environmental effects of biofuels, many ques­tions are still open. Further research is necessary, especially in terms of questions such as energy inputs and outputs, costs of biofuel production, biomass production for energy purposes, second — and third-generation biofuels, implications of biofuel feedstock production on other sectors, especially on agriculture and rural develop­ment, as well as decision-making and biofuel policy design.

The homogeneous and heterogeneous catalysts that are used for the transesterifica­tion of Jatropha oil to biodiesel were shown in Table 10.6.

10.4.1 Two-Step-Catalyzed Reaction

Berchmans and Hirata (2008) reported that Jatropha oil with FFA content up to 15% was beyond the acceptable limit for alkaline-catalyzed reaction. Thus, two-step transesterification was performed including H2SO4-catalyzed esterification reaction to reduce the FFA level to <1% for 1 h at 50°C, followed by NaOH-catalyzed trans­esterification reaction for 2 h at 65°C. The authors showed that the pretreated Jatropha oil (two-step reaction) rendered high methyl ester yield of 90% than the non-pretreated oil (single-step alkaline-catalyzed reaction) with 55% of yield.

Patil and Deng (2009) produced Jatropha-based biodiesel via two-step trans­esterification reactions. The oil with initial acid value of 28 mg KOH/g was reduced to 2 mg KOH/g by using H)SO4 (0.5%) catalyst before KOH (2 wt%)-catalyzed reaction. The results showed that with insufficient amount of alkali catalyst loading, the reaction could not complete. However, excess amount of catalyst will lead to the formation of emulsion, which increases the viscosity of the biodiesel and resulted in

Catalysts Acid value/FFA Time (h) Temperature (°С) Methanol/oil ratio Catalyst amount (wt%) Yield (%) References (a) Two-step catalyzed reaction (esterification and transesterification) H, so4 ■ 28 mg KOH/g N/D 40—45 6 0.50 90-95 Patil and Deng KOHb 0.25% 2 60 9 2 (2009) H, so4 ■ FFA = 21.5% 3 65 3:07 1 21 Jain and Sharma NaOHb <1% 3 50 3:07 1 90 (2010a) H, so4 ■ 6.2 mg KOH/g. 3.1% 1.5 60 6.5 0.30 N/D El Sherbiny FFA et al. (2010) KOHb 1 60 7.5 1.50 100 KOHbc 0.03 60 yield 1. NaOH (one step 10.45 mg KOH/g 1 h 60 N/D N/D 47 Deng et al. reaction) (2010) 2. H, S04 (one step 0.95 mg KOH/g 4 h N/D 1 0.4 93 reaction) 3. Two-step reaction H, scv 10.45 mg KOH/g 1 N/D 40 4 N/D NaOHb 1.2 mg KOH/g 0.5 N/D 24 1.4 96 1. H2SO/ 5-12 mg KOH/g 1.5 45 4 1 95 Deng et al. 2. Mg/Al hydrotalciteb 0.7 mg KOH/g 1.5 45 (2011) h, scv FFA =15% 1 50 0.6 w/w 1 N/D Berchmans and NaOHb <1% 2 65 0.24 w/w 1.4 90 Hirata (2008) so42-/Tio, a 12% 2 90 20 4 C=9T Lu et al. (2009) KOHb 0.50% 0.33 64 6 1.3 98 SiO,-HFa 15.8 mg KOH/g 2 60 12 0.1 C=96e Corro et al. NaOHb 0.63 mg KOH/g N/D N/D N/D N/D N/D (2010)

“Esterification reaction b Transesterification reaction “Microwave heating d Ultrasonic heating eC conversion of oil

gel formation. This two-step esterification-transesterification process yielded 90-95% Jatropha-based biodiesel.

Jain and Sharma (2010a) studied the kinetic of two-step transesterification of high FFA containing oil (21.5% FFA to <1%). The results indicated that both esteri­fication and transesterification reaction are of first order. Within 3 h of reaction time, biodiesel yield of 21.2% and 90.1% was obtained under the optimum condition of 65°C and 50°C, respectively, with 1% catalyst loading for H2SO4 and NaOH from esterification and transesterification.

The present analysis and the optimization study by several researchers revealed that two-step reaction is the most suitable method for converting non-edible oils to biodiesel. However, further development of new method in two-step reaction had been performed in order to improve the quality of biodiesel.

El Sherbiny et al. (2010) reported that microwave irradiation heating in trans­esterification reaction is suitable for the use of high FFA content feedstock like Jatropha oil. In this study, the optimum condition from conventional technique (7.5:1 methanol/oil molar ratio, 1.5% KOH, and 65°C) was applied using micro­wave irradiation transesterification of Jatropha oil. The results showed that applica­tion of radio frequency microwave energy increased the reaction rate with easy route and simplify the separation process. The reaction time was reduced to 2 min instead of 150 min (90 min for the pretreatment process and 60 min for transesteri­fication), indicating no pretreatment technique is required if microwave technique is applied. Microwave energy provided selective heating to the mixture of vegetable oil, methanol, and potassium hydroxide which contain both polar and ionic compo­nents resulted in increment of energy interaction with the sample on a molecular level, thus enhanced the heating rate (Varma 2001).

Deng et al. (2010) utilized the ultrasonic reactor for the transesterification of high acid value Jatropha oil (10.45 mg KOH/g) with methanol by using NaOH, H2SO4, or by two-step reaction. The NaOH-catalyzed reaction rendered 47.2% of biodiesel yield with the formation of soap-like material. With H2SO4 as a catalyst, high yield of biodiesel (92.8%) was obtained with longer reaction time (4 h) and unstable bio­diesel yield (formation of flocs precipitate after 15 days). The results revealed that 96.4% of stable and clear yellowish biodiesel was obtained from two-step reaction within 1.5 h (1 h for esterification and 0.5 h for transesterification) which was faster than conventional heating. It could be concluded that the two-step process coupled with ultrasonic radiation is an efficient and practical method for biodiesel produc­tion from crude oil with high FFA value. The study was continued by transforming homogeneous catalyzed system to heterogeneous system. Deng et al. (2011) applied the methanolysis of Jatropha oil (acid value of 5-12 mg KOH/g) using hydrotalcite — derived catalyst. The catalyst was prepared via coprecipitation method and heated using microwave-hydrothermal treatment in order to obtain nanosized particle. Before reaction, the high acid oil underwent pretreatment in order to remove FFA. Under transesterification condition (45°C), the biodiesel yield was 95.2% using 1 wt% catalyst amount, 4:1 methanol/oil molar ratio, and 1.5 h in ultrasonic reactor (210 W ultrasonic power). The catalyst was reused for eight times with biodiesel yield maintained at >80%. But at the ninth run, the biodiesel yield was decreased sharply to 43.7% indicating deactivation of catalyst due to surface absorption of glycerol by-product and the collapsed the hydrotalcite layered structure.

Most of the previous studies reduce the FFA content in Jatropha oil via pre­esterification reaction using homogeneous acids, such as sulfuric acid, phosphorous acid, or sulfonic acid (Kumar Tiwari et al. 2007). Some of the researchers had stated that using solid acid catalyst in esterification reaction is more environmental friendly than the homogeneous acid catalyst.

Lu et al. (2009) compared the effectiveness of H2 SO4 liquid acid catalyst and SO4- / TiO2 solid acid catalyst in the pre-esterification reaction before performing KOH alkaline-catalyzed transesterification reaction. The results showed that the esterification activity of solid acid catalyst, SO4- /TiO2, is comparable to H2SO4. More than 97% of FFA conversion was achieved under 90°C for 2 h, 20:1 methanol/ FFA ratio using 4 wt% SO4- / TiO2 catalyst. In both reaction conditions, the FFA content of the Jatropha oil was reduced from initial 12% to <0.5% before converted into biodiesel via transesterification. The yield of biodiesel by transesterification was higher than 98% in 20 min of reaction time using 1.3% KOH as catalyst, and 6:1 methanol/oil molar ratio at 64°C.

Besides, Corro et al. (2010) performed two-step transesterification reaction using solid acid catalyst (SiO2HF) for Jatropha oil (15.8 mg KOH/g) pretreatment before performing NaOH catalyzed reaction. The authors found that SiO2 HF consist of high number of Lewis acid surface without deactivation activity by CO2 and H2O adsorption. The SiO2 HF was prepared by impregnation of HF solution on SiO2 sup­port, this catalyst showed high esterification activity (96% of FFA conversion) under optimum esterification condition of 60°C, 0.1 wt% catalyst loading, methanol/oil molar ratio of 12:1 for 2 h. Besides, the high stability of SiO2HF is capable of per­forming 30 cycles without any activity degradation. In second step, the treated Jatropha oil (0.63 mg KOH/g) was transesterified with methanol catalyzed by NaOH.

Although two-step transesterification process is suitable to transesterify crude Jatropha oil with high FFA, this approach required two-step oil conversion process which resulted in higher production cost as compared to conventional process. Furthermore, the use of strong acid catalyst such as H2SO4 will lead to wastewater problem and extra production cost is needed to separate and purify the homoge­neous catalyst from the biodiesel product. Thus, research on utilization of heteroge­neous catalyst for biodiesel production has arisen in order to overcome the drawbacks in two-step transesterification reaction.