1171J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011Journal of the Japan Institute of Energy, 90, 1171-1176 (2011)

Biofuel Production by Hydrocracking of Biomass FT Wax

over NiMo / Al2O3-SiO2 Catalyst

Erlan ROSYADI＊1, Unggul PRIYANTO＊2, SUPRAPTO＊1, Achmad ROESYADI＊1, Mohd. NURUNNABI＊3,

Toshiaki HANAOKA＊3, Tomohisa MIYAZAWA＊3, and Kinya SAKANISHI＊3†

　（Received January 31, 2011）

Initially, NiMo catalyst supported on amorphous silica-alumina (ASA) was used in the hydrocracking of

wax, which was produced from biomass using Fischer Tropsch Synthesis (FTS) from biomass. The hydroc-

racking process was carried out in a 50 cm3 autoclave at 400 ℃ and 5 MPa (initial hydrogen pressure). The

hydrocracking of hexatriacontane (HTC) over NiMo/ASA catalyst produced diesel oil with 59.5 wt % yield,

which is higher than the yield obtained from the hydrocracking of biomass FT wax (36.7 wt %). To achieve

the highest reactant activity, the ratio of the promoter Ni to the precursor Mo was maintained at 0.3.

To determine how the reactant, such as HTC and FT wax, and the pressure condition affect hydrocrack-

ing, we carried out the hydrocracking of blending wax and palm oil (PO) using the semi-batch system.

However, HTC was not converted through hydrocracking of a mixture of HTC and PO over NiMo/ASA at 5

MPa and 400 ℃. HTC was converted when the promoter was changed from Ni to Pt; this proved that HTC

can be converted to diesel and gasoline fraction.

Key Words

Hydrocracking, Hexatriacontane (HTC), Biomass FT wax, NiMo catalyst,

Amorphous Silica-Alumina (ASA)

This paper was originally presented at Renewable Energy 2010,Jun. 27 - Jul. 2, 2010, Yokohama, Japan

1.　IntroductionCurrently, energy demand in Indonesia is still being

met by fossil fuels. This dependency on fossil fuels has

become a problem because of the depletion of fuel reserves.

The increase in fuel prices is due to the fact that the fuel

supply cannot fully satisfy the demand. Moreover, the com-

bustion of fossil fuels releases green house gases. During

2000-2008, the transportation sector in Indonesia consumed

the largest amount of fossil fuels. The annual consump-

tion for this sector is 44.2% of the total consumption,

whereas that for others sectors such as the industrial,

household, and power generation, it is 16.9%, 14.9%, and

14.1%, respectively. In the years 2009-2030, transportation

Original Paper

sector is projected to be the largest consumer of fuel, with

an annual average consumption of 64%. The growth in

gasoline consumption is 0.9% per year, while that for die-

sel oil is 4% 1).

In order to alleviate this fuel shortage, several efforts

have been undertaken. Several refineries have been pro-

cessing low quality heavy oil to convert it into clean trans-

portation fuel. However, this increases the difficulty in re-

fining and lowers the efficiency of the production of clean

fuel. Furthermore, because this heavy oil contains sulfur

and nitrogen, it must be hydrotreated to produce standard

fuel 2)3).

Recently, a new technology that utilizes biomass such

as palm oil (PO) and biomass Fishcer- Tropsch (FT) wax

has been developed. Biomass FT wax is extracted using

the biomass to liquid (BTL) process, which involves biom-

ass gasification and Fischer-Tropsch synthesis (FTS). PO

and biomass FT wax have zero sulfur content, which means

that the hydrocracking process is easier in the fuel pro-

＊ 1 Chemical Engineering Department, Faculty of IndustrialTechnology, Institute of TechnologySepuluh Nopember Surabaya, ITS Campus Sukolilo,Surabaya 60111, Indonesia

＊ 2 Agency for Assessment and Application of TechnologyJl.MH Thamrin No.8, Jakarta Pusat 10340, Indonesia

＊ 3 Biomass Technology Research Centre, AdvancedIndustrial Science and Technology, AIST Chugoku3-11-32, Kagamiyama, Higashihiroshima, Hiroshima739-0046, Japan

†Corresponding author

1172 J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011

duction 4)～ 6).

Recently, the development of a hydrocracking catalyst

has attracted considerable attention. A catalyst in the hy-

drocracking process has two basic functions: hydro-dehy-

drogenation and cracking, which work simultaneously or

sequentially on the feedstocks. The different types and

compositions of metal catalysts and support will result in

different products. For example, a catalyst with a strong

cracking function but a weak hydrogenation function tends

to produce fuel with a low boiling point, such as gasoline.

Conversely, a catalyst with a weak cracking function but

a strong hydrogenation function tends to produce fuel with

a high boiling point, such as middle distillate 7).

In this paper, the close relationship of the support's

acidity, the metal precursor, and the promoter with the prod-

uct distribution of hydrocracking are investigated. The cata-

lyst activity is achieved by the synergetic action of the

catalyst components 8).

The promotion effects of the transition metals (Ni, Co,

W) as well as the noble metals (Pt, Pd, Ru) have been in-

vestigated 9)10). The catalyst activity of NiMo is higher than

CoMo in hydrodenitrogenation (HDN), while the catalyst

activity of PtMo is similar to NiMo with regards to

hydrodesulphurisation (HDS) 8)11).

To improve the yield of the middle distillate product,

it is essential to develop an effective hydrocracking cata-

lyst that is supported on Amorphous Silica-Alumina (ASA)

and has a high cracking activity, while maintaining its se-

lectivity towards middle distillate 12)～ 16).

Therefore, a sulfide NiMo/ASA was chosen for use in

this study as it satisfies all of the above conditions. Initially,

the effect of Ni loading in the NiMo/ASA catalyst on the

product distribution of hydrocracking of hexatriacontane

(HTC) is investigated. This investigation aims to obtain a

formulation of the catalyst in which the synergy of each

component is optimum. This formulation is used in the

hydrocracking of HTC and biomass FT wax. This investi-

gation into the effect of catalyst formulation on the trend

of product distribution in the hydrocracking of HTC and

biomass FT wax is relatively novel. However, it is insuffi-

cient to just know about the activity of the metal sulfide

catalyst, and knowledge about how to control the operat-

ing conditions of the hydrocracking reaction is also re-

quired. Therefore, the study also assesses the effect of sys-

tem conditions and the promoting effect of Pt on hydroc-

racking. Finally, this study also discovered the similarity

in product distributions of the hydrocracking of PO and

the oil blends (HTC/biomass FT wax with PO).

2.　Experimental　2.1　Reagents

Ni(NO3)2.6H2O and (NH4)6Mo7O24.4H2O were obtained

from Wako. ASA was obtained from Fuji Silysia Chemical

Company. HTC was obtained from Aldrich Company. Bio-

mass FT wax was obtained from BTL BTRC-AIST

Chugoku Japan. Palm oil was obtained from BPPT Indone-

sia.

The compositions of HTC and biomass FT wax used

in the hydrocracking reaction are shown in Table 1. The

content of n-C36H74 in HTC was 88%.

　2.2　Catalyst preparation and characterization

NiMo/ASA catalyst was prepared by impregnation of

Ni(NO3)2.6H2O and (NH4)6Mo7O24.4H2O solution on silica-alu-

mina support. The catalyst was dried overnight and then

calcined at 500 ℃ for 3 h under a 33 cm3/min O2 stream.

The surface area of the catalyst was measured by the

Brunauer Emmet Teller (BET) method using BELSORP-

max (Bell Japan Inc.). Metal compounds contained in the

catalyst were identified using X-ray diffraction (XRD) by

the Rigaku TTR III device with CuKα alpha radiation at

50 kV(tube voltage) and 300 mA(tube current).

　2.3　Hydrocracking of HTC and biomass FT wax

Fig. 1 shows the hydrocracking equipment of HTC and

biomass FT wax. It was carried out in a 50 cm3 autoclave,

which is equipped with a stirrer. Initial H2 pressure for

hydrocracking was 5 MPa, and the reaction temperature

was 400 ℃. The stirring speed was kept constant through-

out the experiment.

Table 1　Composition of sample wax

> C20 (%)

99.6

75.8

C10-C20 (%)

0.4

24.2

Sample

HTC

Biomass FT Wax

Fig. 1　Schematic of the hydrocracking equipment

1173J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011

Before hydrocracking, all of the prepared catalyst was

sulfided using 10% H2S/H2 at 360 ℃ for 3 h. The reactor

was maintained for 2 h after the reactor reached the final

temperature. The catalyst to sample ratio (5%) was kept

constant in all the experiments.

After hydrocracking, the gas product was analyzed by

a GC 323 equipped with an MS-5A column with T oven at

70 ℃, T injector at 100 ℃, and T detector at 100 ℃ and

GC-353B equipped with RT-Q Plot capillary column with

T oven at 170 ℃, T injector at 200 ℃, T detector at 200 ℃

. The liquid product was analyzed by GC 6890N Agilent

with UA-DX30 capillary column at T oven programmable

from 50 ℃, T injector at 325 ℃, and T detector at 325 ℃.

　　

　2.4　System parameters of experiments

This experiment follows the system parameters listed

in Table 2. The optimum NiMo/ASA formulation was real-

ized by following the system parameters Nos. 1 and 2. This

formulation was used with the system parameters Nos. 3-

5. Furthermore, the promoter Ni is replaced by Pt in the

system parameters Nos. 6 and 7.

3.　Results and DiscussionsSeveral researchers observed a strong synergy be-

tween the precursor (Mo) and the promoter (Ni) in HDS and

HDN, while others did not observe any physical change in

the catalytic activity due to the presence of Ni promoter

17). In this study, we determined the effect of the Ni pro-

moter in the NiMo/ASA catalyst on the product distribu-

tion of hydrocracking of HTC.

The role of the metal and the support in providing

active sites for reaction is essential in the development of

hydrocracking catalysts, such as a bi-functional catalyst.

Several catalyst supports have been studied and evaluated

using the NH3-TPD method to determine the amount of

acid strength and the total number of acid sites 18).

The prepared catalysts were qualitatively analyzed us-

ing an XRD apparatus TTR III (from Rigaku), using CuKα

radiation at 50 kV (tube voltage) and 300 mA (tube current),

to evaluate the crystallinity of the catalysts. Fig. 2 shows

the XRD pattern of sulfide NiMo/ASA catalysts at various

Ni/Mo ratios.

NiMo/ASA catalysts with Ni/Mo ratio in the range of

0.2-0.4 showed the peaks of MoS2 compounds at 14 and 33

degree. The higher the ratios, the higher are the peaks.

Peaks of unknown compounds from 21 to 31 degrees were

observed at ratios of Ni/Mo 0.3 and 0.4. It is expected that

these compounds affected NiMo/ASA catalyst activity in

the hydrocracking of HTC.

The surface area and the pore size distribution of the

catalyst were measured using the BET method. The char-

acterization of the catalyst is shown in Table 3. Before im-

pregnation, the surface area of the ASA support is around

424 m2/g. The ASA surface area becomes 395 m2/g after

impregnation by Ni and calcination, and 249 m2/g after

impregnation by Mo and calcination. This result implies that

more molybdenum oxide is formed on the ASA surface area

Table 2　System parameters of experiments

Feedstock

HTC

Biomass FT wax

HTC

PO

HTC + PO

HTC + PO

Biomass FT wax + PO

Catalyst

NiMo/ASA

NiMo/ASA

NiMo/ASA

NiMo/ASA

NiMo/ASA

PtMo/ASA

PtMo/ASA

Conditions

400 ℃, 5 MPa(initial)400 ℃, 5 MPa (initial)400 ℃, 5 MPa400 ℃, 5 MPa400 ℃, 5 MPa400 ℃, 5 MPa400 ℃, 5 MPa

Reactor system

Batch

Batch

Semi-batch

Semi-batch

Semi-batch

Semi-batch

Semi-batch

No

1

2

3

4

5

6

7

Fig. 2　XRD pattern of sulfided NiMo/ASA catalyst

Table 3　Characteristics of the catalyst

Mean pore

diameter

(nm)

9.3920

9.4295

11.445

13.077

12.590

12.669

Surface

area

(m2/g)

424.14

395.82

249.36

206.25

195.46

191.50

Catalyst

ASA

Ni/ASA

Mo/ASA

NiMo/ASA 0.2 Calcined

NiMo/ASA 0.3 Calcined

NiMo/ASA 0.3 sulfided

Pore

volume

(cm3/g)

0.9924

0.9355

0.7105

0.6692

0.6115

0.6042

1174 J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011

than nickel oxide. And after sulfidation, also some Ni-Mo-S

compound on the ASA surface area. The large of surface

area informs how much Ni-Mo-S compound is formed. On

the other hand, the pore diameter and pore volume is not

quite changed for occurring of reaction.

　3.1 Effect of Ni loading on hydrocracking of HTC over NiMo/

ASA catalyst

Initially, the hydrocracking of HTC was carried out

using only ASA catalyst without any metal impregnation.

The result showed that hydrocracking of HTC could not

be carried out in this manner. Therefore, other experiments

incorporated the use of metal impregnated catalysts for the

hydrocracking of HTC. The effect of Ni metal impregna-

tion in the NiMo/ASA catalyst on the product distribution

of HTC hydrocracking is shown in Fig. 3.

When the ratio Ni/Mo was in the range of 0 to 0.25,

the HTC conversion ratio showed the lowest value at Ni/

Mo ratio 0.2. This could be due to the low concentration of

Ni catalyst in the Ni-Mo-S compositions. For ratio values

above 0.25, the conversion ratio of HTC increased and

showed an optimum conversion ratio value at 0.3. At this

ratio, Ni could promote metal sites resulting in the maxi-

mum conversion of HTC. It is known that Ni is a suitable

metal for hydro-dehydrogenation reactions.

The resulting product distribution of hydrocracking

suggested that the hydrocracking reaction occurred at the

metal sites and the acid sites. Dehydrogenation and hydro-

genation reactions occurred at the metal sites while the

cracking reaction occurred at the acid sites.

The XRD in Fig. 2 shows that the hydrocracking re-

action using sulfided NiMo/ASA at a ratio 0.2 had formed

MoS2, performing an essential role in the selectivity of the

diesel oil product. Because cracking reactions may occur

at the acid sites on the supports, it is presumed that the

correlation between MoS2 and supports plays an important

role in controlling the production of diesel oil. Moreover,

cracking reaction using NiMo/ASA with Ni ratio 0.3 to 0.4

gave rise to new compounds, as indicated by the peaks

between 20 to 31 degree; these peaks were assumed to

indicate synergetic compounds between Ni, Mo and S. These

compounds play an important role in the activation of the

hydrocracking catalyst. The forming of NiMoS synergetic

compound could affect the activation energy of the crack-

ing reaction occuring at the acid sites of the ASA support.

This study has evaluated the effect of Ni loading on

the catalyst activity (promotion of cracking reaction) and

selectivity of NiMo/ASA catalyst (of the diesel oil product)

in the hydrocracking of HTC.

The chromatogram of HTC and the products of HTC

hydrocracking are shown in Fig.s 4 and 5. In Fig. 4, the

retention time of HTC appeared at 27 min. The intensity

of HTC decreased after hydrocracking, which produced

gasoline and diesel oil at 4-20 min, as shown in Fig. 5.

　3.2 Effect of Ni loading on hydrocracking of biomass FT

wax over NiMo/ASA catalyst

Hydrocracking of biomass FT wax was carried out

on the basis of the results of hydrocracking of HTC.

Fig. 6 shows the effect of Ni loading on the product

distribution of biomass FT wax hydrocracking. The cata-

lytic activity tends to be similar to that of HTC hydroc-

racking. Hydrocracking of biomass FT wax with NiMo/

ASA catalyst (Ni/Mo ratio = 0.3) gave a biomass FT wax

conversion of 69.5% and selectivity of diesel oil of 52.8%,

Fig. 3　Effect of Ni loading on hydrocracking HTC

Fig. 4　Chromatogram of HTC

Fig. 5　Chromatogram of product of HTC hydrocracking

1175J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011

resulting in the diesel oil yield of 36.7%. The selectivity of

gas product and gasoline is 4.2% and 43.1%, respectively.

The catalyst with Ni/Mo ratio 0.3 shows the highest cata-

lytic activity. On the other hand, the selectivity of the die-

sel oil product differed due to the biomass FT wax raw

material containing diesel fraction. This affected the prod-

uct distribution not only of the diesel fraction itself but also

of the gasoline product because of the cracking of diesel

fraction to gasoline fraction. The gas product produced by

hydrocracking reduced with an increase in the Ni loading,

the Ni/Mo ratio increasing from 0.25 to between 0.3-0.6.

The chromatograms of biomass FT wax and the prod-

ucts of biomass FT wax hydrocracking are shown in Figs.

7 and 8. Those chromatograms show that the retention time

of biomass FT wax between 12-45 min shifted to the

shorter retention time of gasoline and diesel oil at 4-20 min

after hydrocracking.

　3.3　Effect of reactants and system conditions

The effect of oxygenates in the hydrocracking of bio-

mass FT wax has already been studied 19). In order to know

the effect of reactants and the system conditions on the

reaction, the hydrocracking of a blending of 50% wax (HTC

or biomass FT wax) and 50% PO was also carried out us-

ing the semi-batch system.

At 5 MPa and 400 ℃, hydrocracking of the blend of

HTC and PO over NiMo/ASA with ratio 0.3 did not cause

conversion of HTC. In Fig. 9, the peak at 27 min shows

that a sizeable amount of HTC still remained in the prod-

uct.

Fig. 10 shows the decrease of HTC peak on hydroc-

racking of the HTC and PO blend over PtMo/ASA catalyst

with Pt/Mo ratio 0.3. The figure shows that Pt is more ac-

tive than Ni in promoting hydrocracking reaction.

As Fig. 11 shows, hydrocracking of the biomass FT

Fig. 6 Effect of Ni loading on product distribution of biomass FTwax hydrocracking

Fig. 7　Chromatogram of biomass FT wax

Fig. 8 Chromatogram of product of biomass FT wax hydrocrack-ing

Fig. 9 Chromatogram of product of hydrocracking HTC and POover NiMo/ASA

Fig. 10 Chromatogram of product of HTC and PO hydrocrack-ing over PtMo/ASA

1176 J. Jpn. Inst. Energy, Vol. 90, No. 12, 2011

wax and PO blend over PtMo/ASA with Pt/Mo ratio 0.3 at

5 MPa and 400 ℃ completely converted the blend to gaso-

line and diesel fractions.

The point to be noticed in Fig.s 10 and 11 is the simi-

larity in the product distribution of the hydrocracking of

the PO blends (HTC/biomass FT wax with PO) and the

hydrocracking of PO itself. This product is C15-C18 which

results from decarboxylation, decarbonylation, and

hydrodeoxygenation reactions, which take place during the

hydrocracking of PO.

4.　ConclusionsSelectivity and conversion in hydrocracking are

strongly affected by the metal compounds contained in the

NiMo/ASA catalyst used for hydrocracking. Increase in Ni

loading decreases wax conversion initially; however, this

trend reverses till the Ni/Mo ratio reaches 0.3, and follow-

ing this, decreases the conversion again.

An increase in the Ni loading caused an increase in

the selectivity of the diesel product. Selectivity was also

affected by the content of the raw material. It was proved

that the catalyst promotion action of Ni in the hydrocrack-

ing reactions of HTC and biomass FT wax was maximum

at Ni/Mo ratio 0.3 with conversions of 73.1% and 69.5%,

respectively, and its selectivities of 81.4% and 52.8%, respec-

tively.

The hydrocracking of the biomass FT wax and PO

blend was also carried out using the semi-batch process.

There was no significant conversion of HTC during the

hydrocracking of HTC and PO blend over NiMo/ASA at 5

Mpa and 400 ℃. However, the conversion of HTC to diesel

and gasoline fraction increased significantly when the pro-

moter was changed from Ni to Pt.

The trends of product distribution in the hydrocrack-

ing of the blending oil (HTC/biomass FT wax with PO) and

hydrocracking PO are similar.

　Acknowledgements

The authors would like to extend their sincere grati-

tude to the New Energy Foundation (NEF-Japan) in pro-

viding financial assistance for this research.

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Fig. 11 Chromatogram of product of biomass FT wax and POhydrocracking over PtMo/ASA