reactor operated at atmospheric pressure, reaction temperature of 723 K and weight hourly spacevelocity (WHSV) of 2.5 h 1 over the synthesized mesoporous molecular sieve MCM-41 materials.Mesoporous aluminosilicate with Si/Al ratio of 50 was synthesized using the hydrothermal method.

Different pore sizes were obtained by changing the type of template and organic directing agent

(ODA) used. The synthesized materials were characterized using various analytical methods such as

X-ray powder diffraction (XRD), BET surface area, inductive coupled plasma (ICP), MAS NMR,

FTIR and temperature-programmed desorption (TPD). The materials exhibit a crystalline structure of

MCM-41 mesoporous molecular sieves with surface area varyng from 550 to 1200 m2/g and an

average pore size (APS) ranging from 1.8 to 2.8 nm. The synthesized MCM-41 catalysts show high

activity for palm oil cracking. The conversion of palm kernel oil, lower-molecular-weight oil, was

higher as compared to higher-molecular-weight, palm olein oil. MCM-41 materials were selective

for the formation of linear hydrocarbons, particularly, C13 when palm kernel oil was used and C17when palm olein oil was fed. The yield of liquid product decreased with the increase of surface area

of the catalyst. The gasoline selectivity increased whereas diesel selectivity decreased with the

conversion of palm oil.

D 2003 Elsevier Science B.V. All rights reserved.Catalytic conversion of palm oil over mesoporous

aluminosilicate MCM-41 for the production

of liquid hydrocarbon fuels

Farouq A. Twaiq a, Noor Asmawati M. Zabidi b,Abdul Rahman Mohamed a, Subhash Bhatia a,*

aSchool of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal,

SPS, Pinang, MalaysiabUniversiti Teknologi Petronas, Sri Iskandar, 31750 Tronoh, Perak, Malaysia

Accepted 31 January 2003

Abstract

The catalytic cracking of palm oil to liquid hydrocarbon fuels was studied in a fixed bed micro-

www.elsevier.com/locate/fuproc

Fuel Processing Technology 84 (2003) 105120Keywords: Catalytic cracking; Hydrothermal synthesis; Palm oil; Mesoporous molecular sieve catalyst

0378-3820/03/$ - see front matter D 2003 Elsevier Science B.V. All rights reserved.

doi:10.1016/S0378-3820(03)00048-1

* Corresponding author. Tel.: +60-4-593-7788; fax: +60-4-594-1013.

E-mail address: chbhatia@eng.usm.my (S. Bhatia).

large pores has initiated research in this direction and resulted in the discovery of the

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120106M41S mesoporous family [4,5]. To improve the production of gasoline and total yield of

organic liquid product (OLP) in the catalytic cracking of palm oil, the mesoporous catalyst

MCM-41 is chosen in this research work. MCM-41 has been reported as a selective

catalyst for the cracking of naphtha [6]. Comparing the performance of MCM-41 to

medium-pore zeolites, such as ZSM-5, it was found that the MCM-41 is more selective for

C5+ olefinic products. These olefinic products are used in alkylation and etherification

processes to produce high-octane fuels [7]. Al-MCM-41 has been reported as an acid-

cracking catalyst for many reactions such as the cracking of recycled plastic wastes [8],

catalytic cracking of n-hexadecane and isomerization of n-hexane [9,10].

The objective of the present study is to investigate the effect of surface area and average

pore size of MCM-41 on the conversion of palm oil and distribution of liquid hydro-

carbons products. In order to produce MCM-41 materials with different pore sizes, three

techniques are used: (1) by altering the chain length of the surfactant; (2) addition of an

auxiliary organic and (3) by post-synthesis treatment to reduce the pore size [5,11]. It is

possible to select and prepare a particular pore size by judicious choice of surfactant [12].

The properties of MCM-41 materials depend on the source of silica (fumed or fused) and

the synthesis process parameters, such as the gel ageing time, temperature, duration of

synthesis and pH of the gel [13].

2. Experimental

2.1. Catalyst preparation

Aluminum-containing (Si/Al = 50) mesoporous material was synthesized by hydro-

thermal treatment of reaction gel mixture. Twelve samples of Al-containing mesoporous

material were prepared using different surfactant template (T) and organic directing agent

(ODA) at different T/Si ratios as shown in Table 1. A solution of the surfactant template

and the ODAwas prepared in a desired ratio in a Pyrex vessel at room temperature. NaOH

(0.2 g) and 0.186 g of sodium aluminate (Al2O3Na2O) were added to the solutioncontaining the template and ODA. Cab-osil M5 (5.0 g; Fluka) was added to the solution.

The mixture was vigorously stirred for 1 h using a magnetic stirrer. The pH of the solution1. Introduction

Conversion of plant oil to fuels has been investigated for the last 10 years [1]. Processes

utilizing zeolites have been found effective for the production of a variety of liquid

hydrocarbon fuels from plant oils [2]. Improved results were obtained with catalytic

cracking of plant oils if the crystalline shape-selective medium-pore-size microporous

zeolite (e.g. HZSM-5) is used.

Malaysia is one of the large producers of palm oil. In 2001, the crude palm oil

production was about 13 million tons. Palm oil can be converted to clean premium

transportation fuels and chemicals. Catalytic cracking of palm oil over HZSM-5 gave high

yield of gasoline with high aromatics content [3]. However, the selectivity for gaseous

products was high and more liquid products desired. The need for solid acid catalysts with

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 107was maintained around 13.8. The gel formed was transferred to a 400-ml Teflon-lined

stainless steel Parr-reactor (Model No. 4842) and stirred continuously at 50 rpm for 24 h at

423 K for crystallization to take place. The precipitate was filtered, washed with deionized

water and kept overnight at room temperature, then calcined at 813 K for 6 h in a muffle

furnace. The resultant material (Na-form) was converted to H-form by refluxing the

sample at 353 K in the presence of 0.1 N aqueous NH4Cl solutions with liquid/solid ratio

of 20 and continuous stirring for 24 h. The resultant solid was filtered and washed with

deionized water until chloride ions were not detected in the filtrate. The sample was kept at

room temperature and then calcined at 813 K for 4 h.

2.2. Characterization

Table 1

Compositions of the synthesis gel for aluminosilicate (Si/Al = 50) mesoporous materials prepared by

hydrothermal treatment

Catalyst ID Template (T) Organic directing agent

(ODA)

T/Si ODA/T

MM-1 C12TMA-OH 0.25 0.0

MM-2 C12TMA-OH TMA-OH 0.25 1.0

MM-3 C12TMA-OH TEA-OH 0.25 1.0

MM-4 C12TMA-OH 0.125 0.0

MM-5 C12TMA-OH TMA-OH 0.125 1.0

MM-6 C12TMA-OH TEA-OH 0.125 1.0

MM-7 C16TMA-OH 0.5 0.0

MM-8 C16TMA-OH TMA-OH 0.5 0.5

MM-9 C16TMA-OH TEA-OH 0.5 0.5

MM-10 C16TMA-OH 0.25 0.0

MM-11 C16TMA-OH TMA-OH 0.25 0.5

MM-12 C16TMA-OH TEA-OH 0.25 0.5X-ray powder diffraction (XRD) analysis of the calcined samples was performed on a

Philips powder diffractometer (Model PW 1820) using Cu-Ka radiation (40 kV, 40 mA).The XRD spectra in the range of 1.5j10j were obtained at a step size of 0.04 for 10 s.The BET surface area and average pore size (APS) of the samples were determined by

nitrogen adsorption at 77 K using Quanta chrome Autosorb-1 equipment. The Si/Al

ratios of the synthesized materials were analyzed using an inductive coupled plasma

(ICP) spectrometer (PE, Optima 3000). 27Al NMR spectra were obtained using a Varian

Jakobsen-style MAS probe (5 mm) operated at 8 kHz. FT-IR technique was employed to

determine the nature of acid sites (Lewis and Bronsted types) present on the pyridine-

adsorbed samples using a Perkin-Elmer FTIR (Model 2000). The IR spectra of the

catalysts were scanned for recording bands in the region of 14001650 cm 1. Thetemperature-programmed desorption of ammonia was performed using a Chembet 3000

instrument (Quanta chrome). A 0.05-g sample was activated at 773 K for 1 h with

helium (99.9% purity, MOX) flowing at 60 ml/min followed by adsorption of 1%

ammonia in helium for 1 h at room temperature. The ammonia was desorbed by heating

the sample in flowing helium from ambient to 973 K at 10 K/min. The desorption peak

areas were normalized using the TPRWin, version 1 software and used to calculate the

acidity.

2.3. Catalytic cracking of palm oil

In the present study, the palm oil used was refined, bleached and deodorized oil. The

palm olein was obtained from Agriculture Oils Sdn. Bhd. (Penang, Malaysia) and palm

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120108

Fig. 1. Micro-reactor rig used in the catalytic conversion of palm oil.

kernel oil was obtained from Acid Chem International Sdn. Bhd. (Penang, Malaysia). Palm

olein oil consisted mainly of 42% C16 and 54% C18 fatty glycerides. The palm kernel oil

contained 50% C12, 16% C14, 8% C16 and 20% C18 fatty glycerides. The palm oil

cracking was performed at atmospheric pressure, reaction temperature of 723 K with palm

oil feed rate (WHSV) of 2.5 h 1 and oil/catalyst ratio of 7.2. Calcined powder (1.0 g),MCM-41 catalyst of particle size < 32 Am was loaded over 0.2 g quartz wool supportedover stainless steel mesh surface in a stainless steel reactor (150 mm long and 10 mm ID).

Fig. 1 shows the experimental setup used in the cracking process. The reactor was heated to

the desired reaction temperature using a vertical tube furnace under nitrogen gas flowing at

a rate of 100 ml/min. Once the temperature was stabilized, palm oil was fed using a syringe

pump (Model No. E-74900-05, Cole-Parmer). The products leaving the reactor were cooled

to 313 K in the condenser system in order to prevent solidification of the residual oil. A

schematic diagram of the process is shown in Fig. 2. The gaseous products were collected in

a gas sampler and the total gas evolved during the experiment was monitored using water

displacement. The condensed liquid products were collected in a liquid sampler at room

temperature. The samples were collected once steady state was reached. The reactor was

flushed by 30 ml/min nitrogen gas for 30 min to remove the remainder products from the

reactor. The aqueous phase was separated from the condensed liquid products using a

syringe. The liquid product was distilled in a vacuum microdistillation unit at 100 Pa and

473 K for 30 min. The distillate fraction was the organic liquid product (OLP) and the pitch

was assumed to be the residual oil. In order to determine the products that remained in the

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 109system, the catalyst was washed with acetone and then dried in an oven at 373 K for 1 h

prior to coke analysis.

Fig. 2. Schematic diagram for the collection and analysis of various products from palm oil over zeolite catalyst.

2.4. Products analysis

The gaseous products (C1C5, H2, CO and CO2) were analyzed with a gas chromato-

graph (Hewlett Packard, Model No. 5890 series II) using an HP Plot Q capillary glass

column (Divinyl benzene/styrene porous polymer, 30 m long 0.53 mm ID 40 Am filmthickness). The gas chromatograph was equipped with a thermal conductivity detector

(TCD) and nitrogen was used as a carrier gas. The organic liquid product (OLP) was

analyzed on a capillary glass column (Petrocol DH 50.2, film thickness 0.5 Am, 50 mlong 0.2 mm ID) at a split ratio of 1:100, using the FID detector. The oven temperaturewas programmed at a heating rate of 4 K/min in the range of 333523 K. The

compositions of OLP were defined according to the boiling point range of petroleum

products such as gasoline (333408 K), kerosene (408443 K) and diesel (443473 K).

The coke formed over the catalyst during the cracking reaction was determined by

thermal gravimetric analyzer (Perkin-Elmer TGA 7). About 5 mg of acetone-washed spent

catalyst sample was subjected to TG analysis at temperature program of 20 K/min. The

sample was heated from ambient to 373 K under nitrogen gas flowing at 30 ml/min. It was

C16TMA was used as a template for samples coded MM-7 to MM-12. Table 2 shows the

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120110lattice parameter ao (ao = 2d100/M3) obtained from the powder XRD patterns of meso-porous MCM-41 material samples. When the template chain length was changed from C12

Table 2

Textural properties of MCM-41 mesoporous materials

Catalyst ID Si/Al ao (nm) APS BJH

method

(nm)

Pore volume

(cm3/g)

p/po = 0.5

Surface area

(calcined)

(m2/g)

MM-1 67 4.28 2.07 0.220 1080

MM-2 53 4.13 1.93 0.308 930

MM-3 55 3.78 1.92 0.641 1240

MM-4 77 4.37 2.19 0.600 990

MM-5 64 3.97 1.93 0.501 990

MM-6 63 3.72 1.85 0.508 1085

MM-7 50 5.39 2.74 0.524 580

MM-8 51 4.56 2.32 0.639 1025

MM-9 85 4.55 2.30 0.433 880

MM-10 61 4.65 2.73 0.835 1160

MM-11 66 4.67 2.73 0.703 1250

MM-12 67 4.62 2.60 0.680 1150kept at 373 K for 10 min in order to remove the volatile materials. The sample was then

heated to 973 K with oxygen gas flowing at 30 ml/min.

3. Results and discussion

3.1. Characterization

Samples coded as MM-1 to MM-6 were synthesized using C12TMA as template. The

to C16, ao increased from 3.72 to 4.62 nm. When C12TMA template was used, the addition

of organic directing agent (ODA) decreased the value of ao, however, such effects were

not observed for C16TMA. The BET surface area, pore volume and average pore size data

are presented in Table 2. The average pore size was calculated from adsorption data using

the Barrett, Joyner and Halenda (BJH) method. The lower T/Si ratio gave higher pore

volume and surface area. The pore size decreased from 2.8 to 2.5 nm with the addition of

0.5 mol of TMA. With the use of lower molar ratio of T/Si (with C16TMA), the pore size

did not change with the addition of ODA, but the pore volume decreased and the pore

distribution became wider. The addition of ODA to C12TMA decreased the pore size from

2.2 to about 1.9 nm. When C16TMAwas used as template, it was observed that decreasing

the T/Si ratio resulted in a narrower pore distribution and a higher pore volume.

The elemental compositions and textural properties of the synthesized materials are

presented in Table 2. NMR study was performed to determine the status of the Al

incorporated in the MCM-41 material. Fig. 3 shows the 27Al MAS NMR spectra of MCM-

41 sample. The sharp peak at around 50 ppm was due to the presence of tetrahedral Al in

the framework. The peak at 0 ppm was ascribed to octahedral coordinated nonframework

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 111aluminum. Acidity of the hydrogen form MCM-41 was determined by temperature-

programmed desorption (TPD) of ammonia, and the results are shown in Fig. 4. For

comparison purposes, the desorption curve of NH3 from HZSM-5 is also shown in Fig. 4.

Zeolite HZSM-5 (Si/Al = 50) shows a weak acidity peak at temperature of 433 K and a

strong acidity peak at 673 K. The desorption peak at 443 K was referred as the weak acid

site of H-MCM-41. The type of acid sites (Lewis and Bronsted) was evaluated by

adsorption of pyridine at 423 K followed by FTIR analysis of the MCM-41 samples. Fig. 5

shows the FTIR spectrum of the pyridine-adsorbed H-MCM-41 sample (MM-12). The

peak at 1600 cm 1 was due to the hydrogen-bonded pyridine. Pyridine bound to Bronstedacid sites gave peaks at 1546 and 1640 cm 1, respectively, whereas those bound to Lewissites are detected at 1450 cm 1. The peak at 1490 cm 1 was attributed to pyridineassociated with both Lewis and Bronsted acid sites.

Fig. 3. 27Al MAS NMR spectrum of MM-12.

Fig. 5. FTIR spectrum of MM-12.

Fig. 4. Temperature-programmed desorption (TPD) of NH3 from MM-12 and HZSM-5 (Si/Al = 50).

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120112

Table 3

Catalytic cracking of palm kernel oil over mesoporous aluminosilicate materials having different pore size

distribution

Catalyst Conversion Yield

of gas

Yield of

gasoline

Yield of

kerosene

Yield of

diesel

Yield of

water

Yield of

coke

Empty reactor 42.00 4.90 14.80 7.20 15.10 0.00 0.00

MM-1 86.49 2.97 19.52 17.81 44.50 1.70 6.67

MM-2 97.72 11.13 42.54 29.90 14.16 0.00 8.33

MM-3 92.14 12.83 21.40 23.88 25.68 8.33 11.94

MM-4 88.13 9.18 29.02 31.28 10.31 8.33 5.83

MM-5 91.18 8.94 27.55 28.57 20.05 6.09 7.78

MM-6 94.15 8.62 36.02 25.67 14.94 8.89 11.39

MM-7 84.95 7.02 17.17 13.17 39.73 7.86 7.64

MM-8 95.49 9.96 50.85 22.15 9.75 2.78 12.08

MM-9 96.44 9.30 30.19 30.43 20.97 5.56 12.08

MM-10 95.99 12.54 36.45 23.87 17.06 6.07 14.44

MM-11 94.04 11.33 43.42 22.73 12.23 4.33 17.50

MM-12 92.13 9.65 36.79 24.32 14.90 6.47 11.81

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 1133.2. Catalytic activity

Palm kernel oil and palm olein oil having different molecular weight in their

triglyceride structure were used to study the activity and selectivity of H-MCM-41 having

different pore sizes. The synthesized MCM-41 catalyst samples were converted into H-

form in order to increase the acidity of the catalyst. The catalytic cracking of palm oil over

H-MCM-41 sample was performed at 723 K and weight hourly space velocity (WHSV) of

2.5 h 1 in a micro-reactor at Oil/Cat ratio of 7.2. The performance of H-MCM-41catalysts having different pore sizes was studied in terms of conversion and yield of liquid

hydrocarbon products. Tables 3 and 4 show the conversion and yield of products for palmTable 4

Catalytic cracking of palm olein oil over mesoporous aluminosilicate materials having different pore size

distribution

Catalyst Conversion Yield

of gas

Yield of

gasoline

Yield of

kerosene

Yield of

diesel

Yield of

water

Yield of

coke

Empty reactor 38.50 4.70 12.10 6.50 15.20 0.00 0.00

MM-1 75.59 9.99 25.19 10.54 22.85 7.02 12.08

MM-2 63.34 8.61 16.16 9.03 22.33 7.21 12.64

MM-3 72.93 8.06 23.23 12.11 22.31 7.21 11.53

MM-4 81.80 7.48 31.43 12.64 24.26 5.99 7.78

MM-5 82.67 8.21 25.06 13.28 30.13 5.99 11.11

MM-6 80.91 0.00 28.17 14.76 31.99 5.99 11.11

MM-7 83.71 8.45 36.73 12.70 19.23 6.60 8.75

MM-8 92.40 6.86 42.58 20.12 10.57 2.78 9.49

MM-9 73.80 8.64 24.61 11.51 22.61 6.43 9.17

MM-10 88.05 10.78 36.91 12.30 22.32 5.74 11.67

MM-11 82.85 8.72 32.66 11.03 25.66 4.78 8.19

MM-12 90.12 21.83 43.30 10.98 9.58 4.43 12.22

kernel oil and palm olein oil, respectively, over different H-MCM-41 catalysts. Tables 3

and 4 present the conversion and yield of products for palm kernel oil and palm olein oil

over aluminosilicate MCM-41 catalysts, respectively. Selectivity to linear C17, C15 and C13hydrocarbon with 1020 wt.% of the OLP was observed. The presence of linear

hydrocarbons in the products related to the low shape selectivity of the catalyst due to

the large size of the pores compared to the size of the products. The C17 hydrocarbons are

close to the size of the fatty acid molecules from palm oil. The weak acidity of the

mesoporous material probably affected the ester group faster than the cracking reaction at

high temperature by extracting CO2 from the ester. The cracking reaction occurred as

secondary cracking reaction of the linear chain, which has the length of C13C17depending on the type of the oil.

In order to determine the extent of thermal cracking of palm oil, a blank run was

performed in an empty reactor containing quartz wool. Low conversion of palm oil was

observed at 623 K (5 wt.%). The conversion of palm oil in an empty reactor at 723 K and

WHSV of 2.5 h 1 was about 40 wt.%. The yield of gaseous product was about 5 wt.%which contains 10% CO2, 20% ethane and ethylene, 40% propylene and 25% C4

+. The

liquid product contains about 40% hydrocarbons in the gasoline boiling range, 20%

kerosene, 40% diesel and no aromatics were detected.

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120114Fig. 6. The effect of palm oil feed type of the conversion and liquid products distribution.

The conversion of palm oil was increased with the increase in surface area of the

catalysts. The conversion of palm olein was found lower as compared to palm kernel oil.

The palm olein oil has larger molecule size and thereby gave lower conversion probably

due to diffusion resistance. When the palm oil was cracked over catalysts prepared using

C12TMA, the gaseous products were almost constant (812 wt.%) but the OLP yield

was decreased with increase in surface area. The gaseous product and OLP yield

increased with surface area over the catalysts prepared using C16TMA. The liquid

products obtained from palm oil cracking were compared to the product analysis

obtained from petroleum cracking and found to contain high amount of linear hydro-

carbons. The coke formation from palm kernel oil cracking was increased with increase

of surface area of the catalyst. The coke formation was lower from palm olein oil

compared to that of palm kernel oil and was about 1012 wt.%. The coke formation

obtained from the cracking of palm oils over mesoporous materials were much higher

compare to the zeolites.

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 115Fig. 7. Effect of the surface area of mesoporous aluminosilicate catalyst on the selectivity of total products from

cracking of palm oil kernel (a) prepared using C12TMA (b) prepared using C16TMA.

It has been reported in the literature [10] that MCM-41 has lower activity when small-

size molecule such as n-heptane was cracked. When large molecule such as gas oil was

cracked, MCM-41 activity was found to be the same as the activity of zeolite USY [11]. The

cracking of palm oil over MCM-41 was found much similar to those reported with USY

zeolite [1]. The cracking of palm kernel oil was found different compared to palm olein oil

over MCM-41 catalyst. However, over other zeolite catalysts, the cracking pattern of palm

olein was found same as palm kernel oil.

Fig. 6a and b shows the relation between the yields of liquid products against the

conversion obtained over different MCM-41 catalysts for both palm kernel and palm olein

oils, respectively. The conversion of palm kernel oil (average carbon number of 38) was

8598 wt.%, whereas the palm olein (average carbon number of 54) gave 6292 wt.%

conversion over the same catalysts. The cracking of palm kernel oil was easier because of

easy accessibility of oil into the pores of the catalysts. The yield of gasoline and kerosene

were observed to increase with increase of conversion. The increase in gasoline yield was

much higher compared to the kerosene. The yield of diesel was observed to increase when

the conversion was lower than 80 wt.% when palm olein was cracked. The yield of diesel

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120116Fig. 8. Effect of the surface area of mesoporous aluminosilicate catalyst on the selectivity of liquid products from

cracking of palm oil kernel (a) prepared using C12TMA (b) prepared using C16TMA.

decreased with conversion when the conversion was higher than 80 wt.% showing the

effect of secondary cracking reactions which led to cracking of diesel into smaller

components in gasoline boiling range.

The catalysts coded MM-1 to MM-6 have pore sizes in the range of 1.82.2 nm with

different surface areas and pore volumes. Conversion (94 wt.%) was obtained over catalyst

with average pore size (APS) of 1.85 nm, and dropped to 80 wt.% for catalyst having APS

of 2.2 nm. The conversion did not vary much with pore size for catalysts coded as MM-7

to MM-12. The gaseous product remained almost constant at about 10 wt.%, whereas the

coke formation increased with decreasing pore size. The catalysts (MM-1 to MM-6) used

for the cracking of palm kernel oil gave highest kerosene yield among the liquid products

and kerosene content was increased with the increase of pore size. The gasoline yield was

also increased with APS but the opposite trend was observed for diesel yield. However,

when palm olein oil was cracked over the same set of catalysts, diesel yield was highest

and it decreased with the increase in pore size and gasoline yield decreased with the

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 117Fig. 9. Effect of the surface area of mesoporous aluminosilicate catalyst on the selectivity of total products from

cracking of palm oil olein (a) prepared using C12TMA (b) prepared using C16TMA.

increase in the diesel production. The kerosene yield was low and remained almost

constant. Fig. 7a and b shows the effect of surface area for (MM-1 to MM-6) catalysts on

the selectivity of products for palm kernel oil cracking. It was observed that the selectivity

of gaseous products and coke were almost constant, whereas the selectivity for OLP was

decreased with the change of surface area of the catalyst.

The effect of the pore size was pronounced at medium pore size distribution, which was

closer to the size of the triglyceride molecule. The effect of pore size at large pore

openings diminished because the reactant could diffuse in the pores easily. The selectivity

for liquid products such as gasoline, kerosene and diesel from palm kernel oil and palm

olein oil are presented in Fig. 8a and b, respectively. The selectivity was found

independent with the change of surface area as well as average pore size (APS) of the

catalyst. Many factors were responsible for the cracking reaction beside surface area of the

catalysts. The crystallinity of the prepared material could also affect cracking activity.

MM-1 to MM-12 mesoporous MCM-41 materials have different crystalline order and

therefore gave different cracking activities.

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120118Fig. 10. Effect of the surface area of mesoporous aluminosilicate catalyst on the selectivity of liquid products from

cracking of palm oil olein (a) prepared using C12TMA (b) prepared using C16TMA.

of 2.32.8 nm.

for both sets. The selectivity for diesel was independent with the change of surface area.

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120 119The higher surface area gave higher conversion of palm olein oil. Palm olein oil was found

more influenced with the average pore size of the catalyst compared to palm kernel oil,

which has smaller molecular weight. The catalysts prepared using C16TMA template gave

higher selectivity for gasoline.

4. Conclusion

The average pore size of (APS) of aluminosilicate mesoporous materials was altered by

replacing C12TMA with C16TMA template and enhancement in the pore characteristics

was achieved by the addition of ODA. The synthesized MCM-41 gave good catalytic

activities for conversion of palm oil to liquid fuels. The conversion of lower-molecular-

weight palm kernel oil was higher. The selectivity of the catalysts towards a particular

liquid product was found to depend on the type of palm oil used for cracking. The

selectivity for particular liquid hydrocarbons such as gasoline, kerosene or diesel was

dependent on the pore size and the surface area of the catalyst. High coke formation was

observed on the MCM-41 catalysts during cracking reaction.

Acknowledgements

The financial support by the Ministry of Science, Technology and Environment,

Malaysia under long-term IRPA grant (Project: 03-02-05-7005) is gratefully acknowl-

edged. The assistance provided by Dr. Siegfried Hafnec of Varian in Dawnstadt, Germany

for obtaining the NMR spectra of the MCM-41 samples is also acknowledged.When the catalysts (MM-7 to MM-12) were used, a linear drop in the conversion

against pore size was observed. The gaseous product was almost constant and coke

formation was decreased. When palm kernel oil was fed to the reactor, the gasoline

and kerosene yields were almost equal and increased with increase in pore size. The

diesel yield was dropped from 25 to 12 wt.% as the pore size increased from 2.3 to

2.8 nm.

The highest gasoline yield was obtained from palm olein oil. The effect of the pore size

on the gasoline selectivity was more pronounced with palm olein oil. As the pore size was

increased, the space available for reactions also increased where the active sites located

inside the pores of MCM-41 catalyst. The selectivity for liquid products gasoline, kerosene

and diesel from palm olein oil is presented in Fig. 10a and b, respectively. The selectivity

of gasoline and kerosene were increased with the increase in surface area of the catalystsFig. 9a and b shows the selectivity of products from catalytic cracking of palm

olien oil over both sets of catalysts MM-1 to MM-6 and MM-7 to MM-12, res-

pectively. The selectivity of gaseous products was increased with pore size in the range

of 1.82.2 nm, and selectivity for OLP was decreased with the increase of average

pore size. The selectivity for gaseous products and OLP were remained constant with

pore size when the palm olein was cracked over catalysts having pore size in the range

References

[1] F.A.A. Twaiq, N.A.M. Zabidi, S. Bhatia, Ind. Eng. Chem. Res. 38 (1999) 3230.

[2] J.D. Adjaye, N.N. Bakhshi, Fuel Process. Technol. 45 (1995) 161.

[3] S. Bhatia, N.A.M. Zabidi, F. Twaiq, Proceeding of 12th Intl. Zeolite Conf., vol. 4, Materials Research

Society, USA, 1998, p. 2921.

[4] A. Sayari, in: H. Chon, S.I. Woo, S.E. Park (Eds.), Recent Advanced and New Horizons in Zeolite Science

and Technology, Studies in Surface Science and Catalysis, vol. 102, Elsevier, Amsterdam, 1996, p. 1.

[5] J.L. Casci, in: J.C. Jansen, M. Stocker, H.G. Karge, J. Weitkamp (Eds.), Advanced Zeolite Science and

Applications, Studies in Surface Science and Catalysis, vol. 85, Elsevier, Amsterdam, 1994, p. 329.

[6] A. Corma, A. Martinez, V. Martinez-Soria, J.B. Monton, J. Catal. 153 (1995) 25.

[7] A. Corma, A. Martinez, V. Martinez-Soria, J. Catal. 169 (1997) 480.

[8] D.P. Serrano, J. Aguado, J.M. Escola, Ind. Eng. Chem. Res. 39 (2000) 1177.

[9] K. Chaudhari, T.K. Das, A.J. Chandwadkar, S. Sivasanker, J. Catal. 186 (1999) 81.

[10] Q.N. Le, R.T. Thomas, US Patent 5,232,580 (1993).

[11] A. Corma, Chem. Rev. 97 (1997) 2373.

[12] S. Inagaki, Y. Yamada, Y. Fukushima, K. Kuroda, in: B. Delmon, J.T. Yates (Eds.), The 2nd Tokyo Conf.

on Advance Science and Technology, Science and Technology in Catalysis, Kodansha, Tokyo, Japan, 1994,

p. 143.

[13] K.M. Reddy, C. Song, in: L. Bonneviot, F. Beland, C. Danuma, S. Giasson, S. Kaliiaguine (Eds.), Studies in

Surface Science and Catalysis, vol. 117, Elsevier, Amsterdam, 1998, p. 291.

F.A. Twaiq et al. / Fuel Processing Technology 84 (2003) 105120120

Catalytic conversion of palm oil over mesoporous aluminosilicate MCM-41 for the production of liquid hydrocarbon fuelsIntroductionExperimentalCatalyst preparationCharacterizationCatalytic cracking of palm oilProducts analysis

Results and discussionCharacterizationCatalytic activity

ConclusionAcknowledgementsReferences