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The rnfluence of Methanol Concentration to BiodieselYield and Quality (Acid Number, Total Glycerol and

Esters Content)

Oni Fariz4 Bina Restituta Barus, Wawan Kurniawan, Fatimah TresnaBalai Rekayasa Desain dan Sistem Teknologi BppTTelp. (021) 756321317563217 Fax- (021) 7s53273

Email: onnil 506@yahoo.com

Abstract

The use of akernattve fuels from renewablevegetable sources has become increasinglywidespread in recent yeats. In addition to otherolternative fuels srch as ethanol, methanol orbiogas (methane), fatty acid methyl esters areirs*v**singly being found on the market; these areeetso Imown as biodiesel or FAME (fotty acid'*aee&zyl esters). Fatty acid metlryl esters ire uswllyobtained from oil seeds and mainly used in theirpureform or mixedwith corumtional dieselfuel inthe transport sector. During manufacture thevegetable oil is trawesterified with methanol. Thisproduces the metlryl esters of the fatty acidspresent in the oil together with glycerol as a by-pro&rct. Methanol concentrotion itself influence tosome aspects in biodiesel such as conversion,yield, and quality. This paper discussed in daail.trFased on this study, as the methanol concmtrationincreased, which the yield of biodiesel and esther€{xrtent were also increased, while the totalg€,3,cerol ond acid value were found to bedecreased.

tr{e}rwords: methanol eoncentration, biodiesel,ga;,;t[ity

1" INTRODUCTION

lJiodiesel is defined as fatty acid methyl or ethyle"sters that produced from vegetable oils orad*:al fats- Biodiesel has general advantages: (l)Acts as an alternative to petroleum-based fuel,which implies lower dependence on fossilresources. (2) Renewable fuel, raw materials ofbiodiesel come from nafure which can beregenerated- (3) A reduction in greenhouse gasesnissiorx in line with the Kyoto ProtocolAgreement- (4) Lower harmful emissions, whichis very advantageous in environmentally sensitive*rea such as large cities and mines. (5)

Biodegradable and non-toxic fuel, beingbeneficial for reservoirs, lakes, marine life andother environmentally sensitive place. (6) Theuse of agricultural surplus, as we have knownthat natuml resorlrcos such as palm oil (Elaeisguineensis) are available in large quantities inIndonesia. From 3.7 million ha of palm plantationarea, around l1 millions tonsfear-crudi palm oil(CPO) can be produced (BPS, 2009). Most of fiepalm oil production is exported to Europe andAsia, and partly used to supply the domesticcooking oil demand.

Taking the above advantages into ourconsideration" there is growing interest inexpanding the biodiesel industry that focused onimproving the biodiesel .i*lity and also the yieldof biodiesel.

Biodiesel is a product from trans-esterification ofvegetable oils and fats with methanol in thepresenee of base catalyst (Sodium methylate) andglycerine as by-product.

The most commonly used alcohol fortranseterifrcation is methanol because low priceand high reactivity as compared to longer-chainalcohols (Lang et al., 2001). Alkali-catalysedmethanolysis can be conducted at roomtemperature and gives yields upper than g0%even after as little reaction time as five minutes(Mittelbactr, 1989). The separation of esters andglycerol phase proceeds fast and completely.Finally, in contrast to ethanol, methanol is easilyavailable in absolute form, so that hydrolysis andsoap formation due to water contained in thealcohol can be minimized-

7*e lnfluence of Methanol Concentration to Biodiesel Yield and

ii

Herg the mechanism of transesterificationprocess:1. TG + MeOH <-+ DG + ME?. DG + MeOH <-+ MG + ME3- MG + MeOH ++ GL + MEnotes:TG : TriglyceridesDG : DiglyceridesedeoH : MethanolI\48 : Methyl Esters

T?re stoichiometry of reaction requires 3 mol of*rethanol and 1 mol of tiglyceride to give 3 molof fatty acid methyl ester and 1 mol of glycerol.This leads to three consecutive reversiblereactions where monoglyceride and diglycerideare intermediate products. After the reactioq theglycerol is separated by settling or centrifugingand is purified to be used in another applicationsuch as pharmaceutical, cosmetics and foodindushies. In additioq the obtained glycerol canbe used in recently developed applications in thefields of animal fee4 carbon feedstock infermentations, polymers, surfactants,intermediates and lubricants (Claude, 1999). Themethyl ester phase is also purified before used asdiesel fuel.

The optimum molar ratio between methanol andoil depends on the type of catalyst used- Thestoichiometry of reaction requires three moles ofalcohol per mole of triglyceride. However, inorder to shift the equilibrium to the right, anexcess ofalcohol as the cheaper reaction parhreris frequently recommended. Laboratory team ofBRDST (2008) suggested a 2.5:l molar ratio ofmethanol to vegetable oil for alkali-catalysedtransesterifications in order to obtain maximumester yields.

?he reaction mechanism of alkali-catalysedtransesterification has long been known (Figure1)" The actual catalytic species is the respectivealkilate anion (i-e. methoxide for methanolysis)-Transeterification is initiated b.y a nucleophilicattack of the alkoxide ion on the carbonyl carbonatom of the triglyceride moleculg resulting in atetrahedral intermediate. In a seond step, thisintermediate splits into the desired methyl esterand the anion of the diglyceride. The latter reactswith methanol to form a diglyceride molecule,which will analogously be converted intomonoglyceride and glycerol, and a methoxideioq which start another catalytic cycle.

H2O +i NaOR + RO + Na.

,ro?("e-fsEp,i: n ,c . no-*- &-!-on I ^.=;i-_*"" j

"' ; [ *-*Jstep2:' n-f,:- + RoH- R;c-oR + Ro-

?-srep3: i;i;:. -

FticooR+ R'oH

IfrC-tor*tOt*y*A FAntilgrqdJcorFl

Figure 1. Mechanism of alkali-catalyzedtransesterifi cation with methanol

From the parametsrs in the standar4 there areparameters tbat associated with the successful ofbiodiesel production process. Paraneters in thestandard SNI 04-7182-2006 can be explained asfollows:1. Acid ValueTbis numbers indicate the number of mineralacids and ftee fatty acids contained in a sample ofbiodiesel- Acid rralue of biodiesel dqlends on a\ia.tiety ftc0ors such as fte t5pe of feedstock usedfor firel prodnction, pro&rction process (remainsof mineral catalyst and free frtty acid), and thedegree of fuel aging during storage (Mittlebach,zo0/.).2. Total GlycerolIndicate the total amourt of glycerol both of freeand bonded glycerol contained in the biodieselt€sted. The loral glycerol depends on thesynthetic process- Low levels of total glyceroleosure high conversion of the hot od" while highlevels of glycerine indirect hints at high glyceridecont€nts in biodie,sel samples are correspondinglyincreased values for viscosity (Worgetter 6.aL,1998) and carbon residue (Mittlebach et al.,t9e2).3- Ester ContentThis parameter is an important tool for provingthe illegal admixtrrrre of other substances, such asfossil diesel to the final fuel product. Low valuesfor pure biodiesel samples originate frominappropriate reaction conditions, may in somecases be caused by the respective standardizedanalytical procedure or stem from various minorcomponerts within the original fit or oil source.[figh concentration of unsaponifiable matter (e.g.sterol), residual alcohol, partiat glycerides andunseparated glycerol can lead values below thelimit Mttlebach"ZO04).

The objectives ofthis research were to study theinfluence of methanol concentration to the yieldof biodiesel production and to evaluate thequaltty of biodiesel includes acid valug totalglycerol, and ester content-

T'he lwtlwence of Methanol Concentration to Biodiesel Yield and Quality

2" METHODOLOGY

2.l.Material

Falm cooking oil, methanol technical grade

with various of purity gsyo-I$Ayo, sodiummethylate purity 30% (BASF), fresh waterfrom Puspiptek water installation, chemicals

for analysis according to the test method were

used in this research.

?"3. Equipment

Flask equipped with a condenser, funnel forseparatiorg a set of titration equipment andlaboratory glasswares were applied.

2.3. Methods

a" Feedstock quslity onalysis including theanalysis of free fatty acid levels (FFA) wasarelyzed, by using titrimetric method (SNI 01-29Al-2006), analysis of water content andsediment using gravimetric method (SNI 01-2901-2006)

b. Biodiesel was produced by transesterificationreaction The various reaction times were 15,30, and 60 minutes, at temperature of 6O -65'C, followed by stirring. Biodiesel vsshingstep was conducted in funnel for separation,using hot water in gradually amount with 90Yo

volume of biodiesel. The operating conditionon washing step were set at temperafure from60-70f, for 30 minutes of settling. Followedby the purification process ofbiodiesel phasgdrying/evaporation pr@ess to expell dissolvedwater in oil was applied then filtering processto remove the impurities and salts. Finally theyield of biodiesel (% wt) was calculated.

(1.. Parameters of biodiesel related to theproduction process namely acid value (ASTMD 664), total glycerol (FBI-A02-03), and estercontent (by calculation of acid valuq totalglycerol, and saponification value) inaccordance with SNI 04-7182-2006 methodwere analyzed.

3. REST'LT AND DISCUSSION

3.1. Production of Biodiesel

The free fatty acid and moisture content are themain parameters for determining the success of thevegetable oil trans-esterification process. To carryout the trans-esterification reaction to completiorlFFA value lower than3o/o was needed. The higher

acidity of the oil were causing smaller theconversion. The excess amount of catalyst couldcause soap formation and fail the reaction process.The raw material used for this experiment waspalm cooking oil, with the following specification(Table 1):Table I Specification of palm cooking oil

No Parameter Unit Result

. Free Fattv Acid oz mass

t ;;;; (parmiticacid)

0.3

it

2 SedimentContent

o/o mass

3 Water content 7o maSS

According to Table I where FFA content of 0.3Yo,the transsterification process was used with 2.5:1molar ratio of methanol to vegetable oil and theaddition of 2,5Yo sodium methylate as a basecatalyst. The reaction time of 15, 30, 60 minuteswas varid and temperature 60-70"C was set.

Figure 2. Flow Diagrarn of TransesterificationProcess

The flow diagram ofbiodiesel production processvia trans-esterification was illustrated in Figure 2.

3.2.The Effect of Methanol Concentration onBiodiesel yield and quality

To stimate the biodiesel yield after the reastionand separation stages, the biodiesel weight yieldwas compared to the initial amount of vegetableoil. There w€re close relationship betweenmethanol concentration and the yield as well as thequalrty of biodiesel represented by the qualityparameters such as acid valug total glycerol, andester content.

The lrqfFzser*rc *f Methanol Concentration to Biodiesel Yield and Quality

ill tiie *;!se *f the yield of biodiesel, it was foundillar biodiesel yield increased when the methanolconcentration was increased (Figure 3). This couldbe *aplailred as methanol was increased, therc:?etit;rl eq*i9ibrium would favour to the directionnf biodiesel formation. As the reaction time wasset to be longer, therefore, the yield ofthe reactionincreased- The longer the reaction time was, thehigher tha reaction completion was, and henceffi*re bi*d-i*s*! product was resulted.

Figure 3. Profile of Meftanol Conceffation toBiodiesel Yieldby Various Process Time

The relationship between methanol couceffiationand acid value was shorrrm in Figure 4- The acidvatrnc* ;s a me€Nure of the fatty acid level in thebiodiesel and depends on the free fatty acid contentim tlce vogetable oil and transesterification proc€ss.E* was shown in Figure 4 that if the me&anolconcentcation wsnt down, the acid value ofbi<di***i yq'as incretxing- For the same value ofme€&ano! eoncentration, the longer the reactiontime -qvas *pplid, thrc lower the acid value wasobtained..

i"*-:-*=----i 0'00

3SG 99 98 97 96 95Methanol Concentration {36}

Figure 4 Profile of Mefhanol Concentrationto AcidValae byVarious Process Time

The profile of methanol concentration to the totalglycerol with varied reaction time was illustrated

. in Figure 5. Total glycerol was related to thesu@ess of reaction completion and purification. Itwas found that if the methanol concentration wasincreased, the total glycerol would be decreasedbecause the reaction equilibrium would be shiftedto biodiesel production. When the reaction timewas getting longer at the same methanolconcentration" the total glycerol would be lower-

Figure 5 Profile of Metianol Conceffiation toTotal Glycerol by Various Process Time

Methanol concsntration also affected on esterconteff of biodiesel. Figure 6 showed thatincreasing methanol concentration could decreasethe ester content. The longerthe reaction time was,the higher the reaction conrpletion was, and hencemore esler coffent was resulted.

100"00

99,50

99,00

98,50 ;gw,oo f,(J97.50 b

97.00 rp

0,s0

o.ro {o,oo F

s0.50 >

oo.+o Io.ra fo.zo ]

-g0.10 E

tI

Figure 6. Profile of Methanol Concentration toEster Content by Various Process Time

I96.50 iI

96.00 I'I{iI

_ ._,.__J

"--*-- 15 nrinutes pracerr

--*- 30 nrinutes proceis-.--:+.i* 60 nlinutes proceJg

10098

96

9492

90

88

86

8482

80

0,30

0,25

0.20

0.15

0,10

0.05

0.o0

oo

l9Io

100 99 98 97 96 95Methanol Ccncentration

---,i* 15 mlnuts proeeis

:+- 3O minutet proce5s

.--** 60 nrinuter procei$

---+* 15 nrinutet procert

---** 30 nrhrutes procet3

*;** 60 minutet pro{est

-*.#* 35 minutes process

*-€- 30 mirriltes process

--** S0 nrinutes l)rocest

'i-fue lsfiuence of Methanol Concentrotion to Biodiesel Yield and Quality Fariza

,*" il*NCLUSION

From the above result and discussion, it was**n*!xded that methanol concentration hadistfi$*lr**d the biodiesel yield and qualityespecially with respect to the quality parameters ofacid valug total glycerol and ester content. Thehigher the methanol concentration was set, thehigiler the yield of biodiesel and the ester contentin th* product were obtaine4 but the acid valueanql total glycerol were tended to be lower. Theiextgm rsction time was set, the reaction was more*.ernrple€ed, and hence the yield and the quality ofbiodiesel increased.

S" $€SF"ERENCES

Badan Standardisasi Nasional (BSN), 2406,

,,Standar Nasional Indonesia Biodiesel No.04:7t82-2006*

t3sdaar Standardisasi Nasional (BSII), SNI 01-2901-2006, Minyak Kelapa Sawit Mentah

{Crude Palm Oil)Badan Standardisasi Nasional (BSl0, SNI 04-

7182-2006, Standar Mutu BiodieselBalai Rekayasa Desain dan Sistem Teknologi

(BRDST) BPPT, "2004, ID P 0 022 3r8,"Biodisel dari Palm Fatty Acid Distillate(PFAD) dengan proses Mettranolisismenggunakan katalis asam dan basa."

G" Knothq J. Krahl, J. Van Gerpen (Eds), TheBiodiesel Handboolg AOCS Press,Champaigrl fr-,2005.

Lattg, X., A.K. Dalai, M.J. Reaney and P.B. Hertz.Preparation and Evaluation of Vegetable OilDerived Biodiesel Esters as Lubricityadditives. Tribotes Joumal S (2) (2001b),131 - 150.

,e4" Mittelbacb C. Remschmidt, Biodiesel - The*onrprehensive Handboolg M. MittelbachKarl-Franzens University Graz" Austria2004.

F*;taa:"!*, T.P, lgg7, "Pocket book of palm OilLlses", Palm Oil Research Institute ofMalaysia

W*egetter, M., H. Prankl and Rathbauer.Eigenschaften von biodiesel. Optimierungspotentiale und Umwelteffekte. Landbauforschung Volkenrode- Sonderheft 190(19e8). 3t -43.