the assessment of syngas utilization by fischer tropsch...

July 2013. Vol. 4, No. 1 ISSN2305-8269

International Journal of Engineering and Applied Sciences © 2012 EAAS & ARF. All rights reserved www.eaas-journal.org

20

THE ASSESSMENT OF SYNGAS UTILIZATION BY FISCHER TROPSCH

SYNTHESIS IN THE SLURRY–BED REACTOR USING Co/SiO2

CATALYST

Bambang Suwondo Rahardjo

Technology Center for Energy Resources Development

Deputy for Information, Energy and Material of Technology

Agency for the Assessment and Application of Technology (BPP Teknologi)

BPPT II Building 22nd

Fl, Jl. M.H. Thamrin No. 8 Jakarta 10340

Email: [email protected]

ABSTRACT

Syngas or synthetic gas is a gas mixture containing CO, CO2 and H2 followed by compound SOx, NOx and CH4 in a

lesser amount of each gas is different depending on feed material, gasifying agent and gasification process. Syngas

can be produced from coal or biomass gasification process at high temperature conditions with the amount of air /

oxygen / steam injection as a controlled gasifying agent. Syngas can be used as intermediate products to produce

other chemicals or burned as an energy source to drive gas engine. In this research discusses the use of syngas from

gasification proceeds through the Fischer-Tropsch Synthesis process as a substitute for synthetic liquid fuel. The

results from the 10 run–times conducted mostly produces gaseous hydrocarbon (HC) light C1~C2 (CH4, C2H6) SNG

equivalent except RUN–02. Gaseous hydrocarbons (HC) light C1~C3 (CH4, C2H6, C3H8) is produced by RUN–01,

RUN–05, RUN–07, RUN–10 (where RUN–03 is relatively small). While RUN–05, RUN–07, RUN–10 are capable of

producing hydrocarbon gases (HC) light C1~C4 (CH4, C2H6, C3H8, n-C4H10 i-C4H10) LPG equivalent. The other 4

run–times (RUN–04, RUN–06, RUN–08, RUN–09) less so produce the desired product. Product hydrocarbon gases

(HC) light C1~C4 are the largest produced by the RUN–05 with N2 gas content is relatively small, in contrast with

the RUN–01, RUN–07, RUN–10 less desirable in the Fischer-Tropsch Synthesis process since the content of N2 gas

is still relatively high. Product hydrocarbon gases (HC) light C1~C3 is the smallest produced by RUN–01 compared

to RUN–05, RUN–07, RUN–10, however, indicated to produce HC chain C > C5 ~C12 (oil), this means that the

smaller the resulting gas products have a tendency to produce more oil. Liquid product produced by RUN–01,

RUN–05, RUN–07, RUN–10 have indicated tendency of products HC chain C > C5~C12 (oil) which is relatively very

small quantity and quality can not be known for sure (equivalent prediction kerosene), since the current vacuum

distillation process (P = 10 mmHg using a solvent reagent C16H34) were bumping.

Keywords : syngas, CoSiO2 catalyst, hexadecane solvent, slurry–bed reactor, F/T synthesis

1. INTRODUCTION

Indonesia as a country endowed with rich variety of

natural resources is time start 'glance' coal or biomass

to be processed either as a source of energy and other

industrial raw materials so as to reduce the 'servings'

of petroleum.

Considered one of the most effective ways to

overcome the energy crisis is through the

development and utilization of alternative energy

resources, such as coal or biomass to the fullest. One

technology that can take advantage of the coal /

biomass into synthetic liquid fuel replacement for

gasoline is technology Gas-To-Liquid (GTL), which

consists of (a) via gasification syngas generation

technology [Coal-To-Gas (CTG) or Biomass-to-Gas

(BTG)] and (b) Fischer-Tropsch Synthesis (FTS).

Fischer-Tropsch Synthesis (FTS) is the process of

converting syngas (CO + H2) which form a long

chain aliphatic compounds HC (CxHy) HC branched

chain, unsaturated HC, and a small amount of

primary alcohol. FTS processes are developed using

fixed-bed reactor can achieve high conversion and

capable of producing optimal parafinis HC class.

System through cracking (cracking), the product can

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be directed to produce gasoline and diesel fuel types

HC indispensable as a fuel for motor vehicles.

Fischer-Tropsch Synthesis process for converting

syngas into synthetic liquid HC consists of 2 catalytic

reactions that form large molecules of HC from CO

and H2 molecules coal gasification process results /

biomass with oxygen in the feed steam, in which the

product is determined by the use of this kind of

catalyst, H2/CO ratio and reactor operating

conditions.

.

The value of n is very dependent on the method of

making synthetic gas and the type of materials used,

e.g. natural gas H2/CO ratio = 1.8~2.3, coal =

0.6~0.8. Olefin-rich product with a range of 5 ~ 10

(naphtha) Fischer-Tropsch process results in high

temperatures can be used to make synthetic gasoline

and chemicals, contrary to the paraffin-rich product

range of 12 ~ 19 (distillat) results of Fischer-Tropsch

Synthesis process of low-temperature very suitable

for making synthetic diesel and / or wax.

Technological developments GTL (Gas-To-Liquid)

in the world today has reached the commercial stage,

(such as Sasol Ltd.., Shell, ExxonMobil, Rentech

Inc.., Syntroleum Corp., JNOC, etc.) as the holder of

a patent has been successfully operate the GTL

refineries in various parts of the world such as

Nigeria, Egypt, Argentina, Qatar, Iran, Malaysia, and

Australia.

Currently, the Fischer-Tropsch Synthesis process has

been operated commercially in Sasol - South Africa

(coal), Shell in Malaysia (natural gas), ExxonMobil,

Rentech, and Syntroleum. Choren Industries has built

an Fischer–Tropsch plant in Germany that converts

biomass to syngas and fuels using the Shell Fischer–

Tropsch process [6].

In this study focused on the syngas utilization by

Fischer-Tropsch Synthesis using 1L

autoclavemodified slurry-bed reactor with catalyst

(Co/SiO2) and solvent hexadecane into synthetic

liquid fuels instead of fuel oil.

Figure 1. The alternative of syngas utilization as

liquid fuel/synthetic gas and chemicals

July 2013. Vol. 4, No. 1 ISSN2305-8269


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2. LITERATURE REVIEW

The Fischer–Tropsch process is a collection of

chemical reactions that converts a mixture of CO and

H2 into liquid hydrocarbons. It was first developed

by Franz Fischer and Hans Tropsch at the "Kaiser-

Wilhelm-Institut für Kohleforschung" in Mülhei an

der Ruhr (Germany) in 1925.

The process, a key component of gas to liquids

technology, produces a synthetic lubrication oil and

synthetic fuel, typically from coal, natural gas, or

biomass. The Fischer–Tropsch process has received

intermittent attention as a source of low-sulfur diesel

fuel and to address the supply or cost of petroleum-

derived hydrocarbons.

2.1. Technology Developments

Since the invention of the original process by Fischer

and Tropsch, working at the Kaiser-Wilhelm-Institut

for Chemistry in the 1920s, many refinements and

adjustments have been made. Fischer and Tropsch

filed a number of patents, e.g., U.S. Patent 1,746,464,

applied 1926, published 1930. It was commercialized

by Brabag in Germany in 1936. Being petroleum-

poor but coal-rich, Germany used the Fischer–

Tropsch process during World War II to

produceersatz fuels. Fischer–Tropsch production

accounted for an estimated 9% of German war

production of fuels and 25% of the automobile fuel

[12].

The Fischer–Tropsch process has been applied in

large-scale gas–liquids and coal–liquid facilities such

as Shell's Pearl GTL facility in Ras Laffan, Qatar.

Such large facilities are susceptible to high capital

costs, high operation and maintenance costs, the

uncertain and volatile price of crude oil, and

environmental concerns. In particular, the use of

natural gas as a feedstock becomes practical only

with use of "stranded gas", i.e., sources of natural gas

far from major cities which are impractical to exploit

with conventional gas pipelines and LNG

technology; otherwise, the direct sale of natural gas

to consumers would become much more profitable.

Several companies are developing the process to

enable practical exploitation of so-called stranded gas

reserves.

Conventional FT reactors have been optimized for

massive coal-to-liquids and gas–liquid facilities such

as Shell's Pearl GTL facility. These slurry bed and

fixed-bed reactors are much larger than the sizes

needed for biofuel facilities or for smaller-scale

natural-gas fields. The use of microchannel reactors

scales down the size of the reaction hardware and

overcomes the heat and mass transport problems

associated with conventional FT technology.

Enhanced heat transfer inside the microchannels

reactor allows for optimal temperature control, which

maximizes catalyst activity and life. While no smaller

scale plant is currently in commercial operation,

indications show capital costs, operating costs and

size could all be reduced relative to conventional FT

facilities [15][9]. An order has reportedly been placed

for a 1400-bbl/day modular GTL plant using the

technology of a company called Velocys [11].

In Australia, Linc Energy commenced construction in

1999 of the world's first gas–liquid plant operating on

synthesis gas produced by underground coal

gasification . The GTL plant uses the F-T process,

and produced liquids in 2008. The largest scale

implementation of Fischer–Tropsch technology are in

a series of plants operated by Sasol in South Africa, a

country with large coal reserves, but little oil. The

first commercial plant opening in 1952, 40 miles

south of Johannesburg [14]. Sasol uses coal and now

natural gas as feedstocks and produces a variety of

synthetic petroleum products, including most of the

country's diesel fuel.

In December, 2012 Sasol announced plans to build a

96,000 barrels a day plant in Westlake, Louisiana

using natural gas from tight shale formations in

Louisiana and Texas as feedstock. Costs are

estimated to be between 11 and 12 billion dollars

with $2 billion in tax relief being contributed the state

of Louisiana. The planned complex will include a

refinery and a chemical plant [4].

PetroSA, a South African company which, in a joint

venture, won project innovation of the year award at

the Petroleum Economist Awards in 2008 has the

world's largest Gas to Liquids complexes at Mossel

Bay in South Africa. The refinery is a 36,000 barrels

a day plant that completed semi-commercial

demonstration in 2011, paving the way to begin

commercial preparation. The technology can be used

to convert natural gas, biomass or coal into synthetic

fuels [3].

One of the largest implementations of Fischer–

Tropsch technology is in Bintulu, Malaysia. This

Shell facility converts natural gas into low-sulfur

Diesel fuels and food-grade wax. The scale is 12,000

barrels per day (1,900 m3/d). The new LTFT facility

Pearl GTL which began operation in 2011 at Ras

Laffan, Qatar, uses cobalt catalysts at 230°C,

converting natural gas to petroleum liquids at a rate

July 2013. Vol. 4, No. 1 ISSN2305-8269


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of 140,000 barrels per day (22,000 m3/d), with

additional production of 120,000 barrels (19,000 m3)

of oil equivalent in natural gas liquidsand ethane. The

first GTL plant in Ras Laffan was commissioned in

2007 and is called Oryx GTL and has a capacity of

34 000 bbl/day. The plant utilizes the Sasol slurry

phase distillate process which uses a cobalt catalyst.

Oryx GTL is a joint venture between Qatar

Petroleum and Sasol.

In October 2006, Finnish paper and pulp

manufacturer UPM announced its plans to produce

biodiesel by the Fischer–Tropsch process alongside

the manufacturing processes at its European paper

and pulp plants, using waste biomass resulting from

paper and pulp manufacturing processes as source

material [13].

A demonstration-scale Fischer–Tropsch plant is

owned and operated by Rentech, Inc., in partnership

with ClearFuels, a company specializing in biomass

gasification. Located in Commerce City, Colorado,

the facility produces about 10 barrels per day (1.6

m3/d) of fuels from natural gas. Commercial-scale

facilities are planned for Rialto, California; Natchez,

Mississippi; Port St. Joe, Florida; and White River,

Ontario [8]. Rentech closed down their pilot plant in

2013, and does not appear to be continuing work on

their FT process and the proposed commercial

facilities.

In the United States, some coal-producing states have

invested in Fischer–Tropsch plants. In Pennsylvania,

Waste Management and Processors, Inc. was funded

by the state to implement Fischer–Tropsch

technology licensed from Shell and Sasol to convert

so-called waste coal (leftovers from the mining

process) into low-sulfur diesel fuel [1].

Table 1. Process developer of Fischer–

Tropsch Synthesis commercial scale

Comp

any

Syngas

Prepar

ation

React

or

FTS

Capa

city

(bpd)

Cata

lyst

Energy

Int. PO (O2)

Slurry

–bed – Co

Exxon CPO

(O2)

Slurry

–bed 200 Co

Rentec

h

PO

(O2),

SR,

ATR

Slurry

–bed 235 Fe

Sasol

PO

(O2),

SR,

Coal

Gasifica

tion

Slurry

–bed 2.500

Fe,

Co

Shell PO (O2)

Fluidi

zed–

bed

110.0

00 Co

Syntrol

eum

ATR

(air)

Fixed

–bed

Fixed

–bed

12.50

0

2

Co

(C)PO : (Catalytic) Partial Oxidation, SR :

Steam Reforming, ATR ; Autothermal

Table 2. Process development of Fischer–Tropsch

Synthesis commercial scale in the world

Countr

y O2

Syngas

Producti

on

FTS

(catalys

t)

Production

Capacity

JOGME

C

(Japan)

not

nee

d

Tubular

Reformer

<Chiyod

a>

Slurry–

bed

(Co)

<NSC>

7 bpd

Pilot

Sasol

(South

Africa) nee

d

Auto

Thermal

Reformer

<Topsoe

>

Slurry–

bed

(Co)

<Sasol>

17.000 bpd

Commercia

l (x2)

Shell

(Malays

ia)

nee

d

POX

<Shell>

Fixed–

Bed

(Co)

<Shell>

3.000 bpd

Commercia

l (x4)

Exxon

Mobil

(USA)

nee

d

Auto

Thermal

Reformer

<Exxon

Mobil>

Slurry–

bed

(Co)

<Exxon

Mobil>

200 bpd

Demonstrat

ion

Conoco

(USA)

nee

d

CPOX

<Conoco

>

Slurry–

bed

(Co)

<Conoc

o>

400 bpd

Demonstrat

ion

BP

(USA)

nee

d

Compact

Reformer

<BP>

Slurry–

bed

(Co)

<BP>

300 bpd

Demonstrat

ion

July 2013. Vol. 4, No. 1 ISSN2305-8269


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2.2Syngas

Syngas (synthetic gas) as a raw material composed of

a mixture of CO and H2 gas produced through

gasification of biomass / coal and partial oxidation

process of natural gas. Syngas manufacturing process

that has commercial is steam reforming, partial

oxidation and CO2 reforming.

Syngas produced from the biomass gasification has

some impurities formed in the form of inorganic

compounds, such as: NH3, HCl, and H2S, and small

amounts of COS, CS2, and HCN.

Overall FTL system (Fischer Tropsch Liquid) except

the BTL system (Biomass To Liquid) is designed

using a Water-Gas Shift reaction that enough from

syngas with the ratio H2/CO = 1:1 for the total

amount of syngas entering the synthesis reactor FTL.

While the BTL system using H2/CO ratio = 1.8 for

syngas exit gasifier without WGS between gasifier

and synthesis reactor [16]

Influence of impurities contained in the raw syngas,

such as sulfur will poison the catalyst in the syngas

preparation process at high temperature, sulfur will

be converted to H2S or COS. How to cope with

sulfur converted to H2S by adding CaCO3 into the

gasifier or through high-temperature desulfurization

process using ZnO. While COS (carbon oxysulfide)

can be addressed through a hydrolysis process at low

temperature (200oC) using zeolite / alumina that

occurs interaction in molecular absorption of H2S

and H2O, or can be by way of hydrogenation at a

temperature of 750oC.

COS+H_2 O→H_2 S+〖CO〗_2 (exothermic

reaction)

COS+H_2→H_2 S+CO (endothermic reaction)

Table 3. Syngas composition from coal and

biomassa gasification, natural gas

Compositio

n

Syngas

Coal1

Biomass

a2

Natur

al Gas3

Hydrogen

(H2)

14.0

% 18.0% –

Carbon

Monoxide

(CO)

27.0

% 24.0% –

Carbon

Dioxide

(CO2)

4.5% 6.0% –

Oxygen

(O2) 0.6% 0.4% –

Methane

(CH4) 3.0% 3.0% 90.0%

Nitrogen

(N2)

50.9

% 48.6% 5.0%

Ethane

(C2H6) – – 5.0%

HHV

(Btu/scf) 163 135 1,002

1&3Steam - Its generation and use, Babcock

and Wilcox, pp. 5-20 and 5-21 discussion

of coal producer gas. 2HMI International. Data derived from a

fixed–bed updraft gasifier design.

http://www.gutenberg.org/files/22657/22657-h/chapters/gases.html

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Table 4. Requirements of syngas as feedstock Fischer-Tropsch Synthesis

Impurities Range

H2S + COS + CS2 < 1 ppmV

NH3 + HCN < 1 ppmV

HCl + HBr + HF < 10 ppbV

Alkaly metal < 10 ppbV

Solids (soot, ash, dust) Essentially completely

Organic compounds (tar) < dew point

Hetero–atoms (Class 2) < 1 ppmV

2.3. Catalyst

A common catalyst used in the Fischer-Tropsch

Synthesis process is kind of a transition metal that is

Cobalt (Co), Iron (Fe), Ruthenium (Ru) and Nickel

(Ni), but the most commonly used is the Co and Fe

called the Basic Metals.

The Co catalysts is most active and very sensitive to

the presence of sulfur compounds (S which is

poisonous, are able to produce wax. Co catalysts

prepared for the usual raw materials derived from

natural gas with a high content of H2 so much higher

H2/CO ratio so it does not require WGS, when the

syngas feeding with a high H2 content so much

higher H2/CO ratio. SiO2 as a buffer is more

dominant than TiO2 as well as Al2O3

(SiO2>TiO2>Al2O3).. Co catalyst at high pressure

will give effect to the high amount of carbon. Metal

Co as catalyst Fischer-Tropsch Synthesis process

[5].generally dispersed in the buffer material with a

large surface area (alumina, silica, titan, etc..) on

loading of 10 ~ 30 g per 100 g of buffer [10].

Fe catalyst will tend to form some chemical

compounds such as iron oxides and iron carbides

during the reaction. Ferrous metals (Iron / Fe)

suitable to syngas with a low hydrogen content

(H2/CO <1) prepared as lower quality feedstock for

promoting WGS (water gas shift). Fe is more

economical than the Cobalt but susceptible to catalyst

poisons such as sulfur (S).

Ni catalyst make CO hydrogenation to produce the

most of CH4 at high operating temperature

conditions that led to the formation of volatile

carbonyls, thus making this metal is not attractive to

the Fischer-Tropsch Synthesis.

Ru catalyst capable for synthesizing a molecular

weight of the paraffin over 200,000 at high pressure.

From an economic perspective, the use of Ru catalyst

is not very effective because it is much more

expensive than the Cobalt.

Selection of a catalyst based on the ability to

accelerate the reaction between some reaction

(selectivity), has a high activity and efficiency, ease

of regenerated, i.e. the process of restoring the

activity and selectivity of catalysts as they are, and

have chemical stability, thermal and mechanical that

will determine the life of the catalyst.

2.4. Solvent

Solvent function as dissolving in the process of

purification products such as Fischer-Tropsch

Synthesis in the form of slurry is distilled to obtain

the other factions. Table 5 shows the general

characteristics of the type of solvent used and

marketed commercially.

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Table 5. Characteristic of commercial solvents

Nonane Decane Undecane Dodecane Tridecane Tetradecane Pentadecane Hexadecane

Formula C9H

20 C

10H

22 C

11H

24 C

12H

26 C

13H

28 C

14H

30 C

15H

32 C

16H

34

CAS number [111~84~2] [124~18~5] [1120~21~4] [112~40~3] [629~50~5] [629~59~4] [629~62~9] [544~76~3]

Molar mass (g/mol) 128.26 142.29 156.31 170.34 184.37 198.39 212.42 226.45

Melting point (°C) −53 −30 −26 −9.6 −5 5.5 9.9 18

Boiling point (°C) 151 174 196 216.2 234 253 268~270 287

Density (g/ml) 0.718 0.73 0.74 0.75

0.763 0.769 0.773

Viscosity 20°C (cP) 0.711 0.92

1.35

2.18

3.34

Flash point (°C) 31 46 60 71 102 99 132 135

Autoignition

temp. (°C) 205 210

205

235

201

Explosive limits (%) 0.9~2.9 0.8~2.6

0.45~6.5%

2.5. Reactors

The reactor type of Fischer-Tropsch Synthesis

consists of a slurry-bed, fixed-bed, and fluidized-bed

operated over a temperature range of 150-300°C,

pressure of 0.7-41 bar.

• Three–Phase Fluidized–bed / Ebullating–

bed or Slurry Bubble Column equipped by internal

cooling tubes, wax as support metal-oxides catalyst

particles during the bubble syngas flows to the

bottom of the reactor. Reaction temperature higher

than the boiling point of the FT product called

exothermic reaction. Slurry as fever (heat sink) and

the reactor temperature stabilizer, but because of the

interface between mineral oil slurry with metal-oxide

catalysts, HC formed soluble in the slurry phase,

sucked out the catalyst so that the catalyst activity

increase, decrease oxidation of the catalyst, as well as

stabilizing chain growth. It is cheaper to LTFT (Low

Temperature Fischer Tropsch).

• Multitubular fixed–bed equipped with a

cooler, consisting 1000 of a small tube with a catalyst

as an active catalyst surface (surface active agent) in

the tube, the water surrounding the tube to regulate

the temperature by adjusting the steam pressure.

• Circulating fluidized–bed using a circulating

bed material, recycled gas and cooling gas / solids

circulation used in LTFT.

• Fluidized–bed equipped with a refrigerant

used in HTFT (High Temperatur Fischer–Tropsch)

2.6. Process Condition

Generally, the Fischer–Tropsch process is operated in

the temperature range of 150–300°C. Higher

temperatures lead to faster reactions and higher

conversion rates but also tend to favor methane

production. For this reason, the temperature is usually

maintained at the low to middle part of the range.

Increasing the pressure leads to higher conversion

rates and also favors formation of long-chained

alkanes, both of which are desirable. Typical

pressures range from one to several tens of

atmospheres. Even higher pressures would be

favorable, but the benefits may not justify the

additional costs of high-pressure equipment, and

higher pressures can lead to catalyst deactivation via

coke formation.

A variety of synthesis-gas compositions can be used.

For cobalt-based catalysts the optimal H2:CO ratio is

around 1.8–2.1. Iron-based catalysts promote the

water-gas-shift reaction and thus can tolerate lower

ratios. This reactivity can be important for synthesis

gas derived from coal or biomass, which tend to have

relatively low H2:CO ratios (<1).

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Table 6. Process condition of Fischer–Tropsch Synthesis by product

H2/CO Katalis

Suhu

(oC)

Tekanan

(bar) Produk

Syn

ga

s

1,0~1,4 Cu–Zn

200~420 51,7~261,99 Ethanol

Cu–Co Campuran alkohol

2,3 Cu–ZnO <250 51,7~261,99 MeOH

DME

Katalis

Zeolith Gasoline

2 Fe 340 23,44 Gasoline

Wax

Hydro–

cracking

Gasoline

Co–K 240 25,51 Diesel

Wax Diesel

2.7. Reaction Mechanism

The conversion of CO to alkanes involves

hydrogenation of CO, the hydrogenolysis (cleavage

with H2) of C-O bonds, and the formation of C-C

bonds. Such reactions are assumed to proceed via

initial formation of surface-bound metal carbonyls.

The CO ligand is speculated to undergo dissociation,

possibly into oxide and carbide ligands [2].

Other potential intermediates are various C-1

fragments including formyl (CHO), hydroxycarbene

(HCOH), hydroxymethyl (CH2OH), methyl (CH3),

methylene (CH2), methylidyne (CH), and

hydroxymethylidyne (COH). Furthermore, and

critical to the production of liquid fuels, are reactions

that form C-C bonds, such as migratory insertion.

Many related stoichiometric reactions have been

simulated on discrete metal clusters, but

homogeneous Fischer–Tropsch catalysts are poorly

developed and of no commercial importance.

Product recovery depends on several factors, among

others: the type of reactor, type of catalyst, the

process parameters [temperature, pressure, residence

time, H2/CO ratio, concentration of reactants (H2,

CO, CO2, H2O)].

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Main Reaction

Parafin

Olefin

Water gas shift reaction

(2n + 1)H2 + nCO → CnH2n+2 + nH2O

2nH2 + nCO → CnH2n + nH2O

CO + H2O → CO2 + H2

Side Reaction

Alkohol

Boudouard reaction

2nH2 + nCO → CnH2n+2O + (n-1)H2O

2CO → C + CO2

Catalyst Modification

Catalyst oxidation/reduction

Bulk Carbide Formation

MxOy + yH2 → yH2O + xM

MxOy + yCO → yCO2 + xM

yC + xM → MxCy

2.8. Products

Table 7. Fischer–Tropsch Synthesis products

Number of

Carbon Products

Boiling Point

(°C) Utility

C1 ~ C2

C3 ~ C4

SNG

LPG 0~50 Gas tube, Fuel gas, Petrochemicals

C5 ~ C10

C5 ~ C7

C8 ~ C10

Petroleum

Light

Heavy

50~85 Fuel oil

C11 ~ C20

C11 ~ C12

C13 ~ C20

Middle Destillate

Kerosine

Diesel

85~105 Fuel oil

C21 ~ C30

C31 ~ C60

Softwax

Hardwax

105~135

130~300

Fuel oil, Industrial fuel

Lubricants, Wax, Petrochemicals, Asphalt

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HC light is methane (CH4), ethene (C2H4) and

ethane (C2H6), LPG (C3–C4, propane and butane),

gasoline (C5–C12), diesel fuel (C13–C22), dan wax

(C23–C33).

• Product diesel: require hydrocracking liquid

products Fischer–Tropsch Synthesis to break the

double bond in the catalytic use H2.

• Petroleum refining products: products

Fischer–Tropsch Synthesis which has been

completely cleaned of sulfur, nitrogen, nickel,

vanadium, and asphaltene aromatic.

• Fischer–Tropsch diesel with high cetane

number can be used as a blending component for

improving the quality of diesel fuel.

• Liquid products Fischer–Tropsch Synthesis

is very suitable for fuel cell vehicles.

In general the product distribution of hydrocarbons

formed during the Fischer–Tropsch process follows

an Anderson–Schulz–Flory (ASF) distribution [7]

which can be expressed by formula mentioned below

and shown in Figure 4 and Figure 5.

Wn = The weight fraction of hydrocarbon

molecules containing n carbon atoms (%w).

α = The chain growth probability or the

probability that a molecule will continue reacting to

form a longer chain. In general, α is largely

determined by the catalyst and the specific process

conditions.

Examination of the above equation reveals that

methane will always be the largest single product so

long as alpha is less than 0.5; however, by increasing

α close to one, the total amount of methane formed

can be minimized compared to the sum of all of the

various long-chained products. Increasing α increases

the formation of long-chained hydrocarbons.

The very long-chained hydrocarbons are waxes,

which are solid at room temperature. Therefore, for

production of liquid transportation fuels it may be

necessary to crack some of the Fischer–Tropsch

products. In order to avoid this, some researchers

have proposed using zeolites or other catalyst

substrates with fixed sized pores that can restrict the

formation of hydrocarbons longer than some

characteristic size (usually n<10). This way they can

drive the reaction so as to minimize methane

formation without producing lots of long-chained

hydrocarbons. Such efforts have met with only

limited success.

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Distribution products of Fischer-Tropsch Synthesis

depends on several parameters, among others: syngas

feed composition, catalyst type, temperature,

pressure, alkali promoter, and buffer. Low

temperatures will influence the amount of carbon

(Carbon Number, CN) is high, but slightly branched

chain or low oxygenate compounds.

3. RESEARCH

The assessment of syngas utilization by Fischer

Tropsch Synthesis using CoSiO2 catalyst in the

autoclave 1L modified slurry–bed reactor conducted

at the Coal Liquefaction Laboratory – PUSPIPTEK -

Serpong.

3.1. Materials

• Mixed–gas (H2:60%, CO:30%, N2:10%)

with H2/CO ratio = 2:1

• Mixed–gas (H2:54%, CO:30%, CH4:10%,

N2:6%) with H2/CO ratio = 1.8:1

• Co/SiO2 catalyst made of Cobalt–based

9.22%Co and Cobalt–based 31.08%Co3O4 from

Co(NO3)2.6H2O (Cobalt Nitrate) with 90.78%SiO2

(nature zeolith) and 68.92%SiO2 (Nacalai zeolith)

respectively as buffer material. The catalysts made by

treatment as follows:

A. Catalyst : Nature zeolith, calcination

(300oC, 2 hours), reduction (300oC, 1 hour)

B. Catalyst : Nature zeolith without treatment

C. Catalyst : Nacalai zeolith, calcination

(300oC, 2 hours), reduction (300oC, 1 hour)

D. Catalyst : Nacalai zeolith, calcination

(200~400oC, 2 hours), reduction (400oC, 6 hours)

• Hexadecane (C16H34) chosen as the solvent

with consideration of characteristics reduce the

formation of CH4 leads to a more severe HC, evenly

distributed heat in the reactor; generate more long-

chain olefin as a result of dissolving ability of HC in

SCFs (super-Critical Fluids) high; overcome

deactivation of the catalyst through heat and mass

transfer better; conditioning the extraction of heavier

HC to come out of the catalyst pores so that it can

extend the catalyst life; H2 increase transfer

capability into the catalyst pores to give more

promoted reaction; and improve the main product

desorption from catalyst pores to avoid further

reaction that will have an impact on product

selectivity

3.2. Equipments

• Autoclave 1L ‘KOBELCO’ (Pmax = 29.42

modified slurry–bed reactor to examine the reactivity

of the catalyst.

• GC–TCD: (Thermal Conductivity Detector)

for the gas products analysis and HC C1~C3

• GC–FID: Flame Ionized Detector for

oxygenates product analysis and HC C2~C30

• Vacuum Distillator separation bottom

product (slurry, HC berat, wax)

• Furnace for catalyst reduction process

• Vacuum Drying Oven for catalyst drying

process.

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Figure 6. Schematics of equipment system for Fischer-Tropsch Synthesis research scale

3.3. Metodology

3.3.1. Catalyst Preparation

Catalyst preparation carried out due to the difficulty

to obtain FTS catalysts are commercially produced,

by using the following steps:

• Impregnation to deposit metallic Co from

Co(NO3)2.6H2O (Co–Nitrat) into SiO2 as buffer

through drying process in the vacuum dryer at

(100~110oC, 12 hours) in oder to H2O and HNO3

vaporized.

• Calcination to remove the H2O content is

still trapped in the the SiO2 crystal pores by heating

at a temperature of 200~400oC (still below the

melting point) for 2 hours, but in the furnace to

expand the catalyst surface and stabilize heat catalyst.

• Reduction to obtain Co metal in an active

condition by bubbling H2 gas as a reductant inside

plug flow reactor made of stainless steel (ID = 2") at

a temperature of 400oC for 6 hours.

• Characterization performed after calcination

and reduction using X-Ray diffraction spectrum

(XRD) to determine %crystallinity and successful Co

metal impregnation on SiO2 as catalyst support by

looking at the properties treatment effect and the

origin crystal structure to changes in metal Co3O4

into CoO or Co.

• The catalyst reactivity testing carried out

after Co/SiO2 catalyst prepared and characterized

using specific content of Co and reacted with mixed-

gas inside autoclave 1L to investigate the

performance of catalytic reaction that is measured in

the amount of conversion and yield [conversion

mixed-gas (H2/CO) into compound HC].

3.3.2. Fischer–Tropsch Synthesis

The process of converting syngas into liquid HC

products via Fischer-Tropsch Synthesis occurs in the

1L autoclave modified slurry-bed reactor with the

process mechanism as shown in Figure 7.

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Figure 7. Fischer Tropsch Synthesis mechanism

•

Flashing, by flowing N2 gas and mixed-gas

respectively 2 times at a pressure of 30 bar.

• Leak test, by flowing mixed-gas at a

pressure of 5~6 MPa = 50~60 bar higher than reactor

operating pressure during the contact time = 3 hours.

Whenever there is an indication of a leak pressure>

20 bar.

• Feeding, CoSiO2 catalyst (20 bar, 260-

300oC, 2 hours), C16H34 solvent (1 ml/min), and

mixed gas (50 cm2/gr catalyst).

• Identification of reaction products is done

"on-line" with the GC (steady-state for 10 hours), to

separate the components of compound HC product,

measure the quantity and quality of the components

in the eluent, to calculate the amount of product

conversion yield, analysis of liquid and gas products

qualitatively.

3.3.3. Separation

Gas products carried by flowing through the gas

outlet pressure regulating valve (trap). Heavy HC and

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slurry products including wax done physically using

the media separator funnel.

3.3.4. Sampling

Sampling of the product carried out after the room

temperature is reached. Product gas through the gas

outlet pressure regulating valve (trap). Liquid product

(bottom products: slurry, heavy HC, wax) from the

trap and distillation.

3.3.5. Analysis

Gas products & HC C1 ~ C3 using GC-TCD.

Oxygenates products and HC C2~C30 using GC-

FID. Oil products using GC-FID-Pyrolizer.

3.3.6. Purification

Vacuum filtration of the liquid products (slurry,

heavy HC including wax). Vacuum distillation of the

slurry product at a pressure of 10 mmHg using a

solvent reagent Hexadecane (C16H34) with a boiling

point of 287°C, in order to obtain other fractions.

Made as wax products produced.

4. RESULT AND DISCUSSION

During the research has been done 10 times RUN

Synthesis Fischer-Tropch use Autoclave 1L modified

slurry-bed reactor at operating conditions (P = 20 bar,

T = 260~300oC, t = 2 hours, r = 900 rpm) with the

following feeding materials:

• Mixed–gas (H2:60%, CO:30%, N2:10%)

with H2/CO ratio = 2:1 for RUN–01, RUN–05,

RUN–07, RUN–10.

• Mixed–gas (H2:54%, CO:30%, CH4:10%,

N2:6%) with H2/CO ratio = 1.8:1 for RUN–02,

RUN–03, RUN–04, RUN–06, RUN–08, RUN–09.

• Catalysts based Co (9.22%Co) from

Co(NO3)2.6H2O with 90.78%SiO2 (nature zeolith)

as a catalyst support for RUN–02, RUN–03, RUN–

04, RUN–06, RUN–08, RUN–09.

• Catalysts based Co (31.08%Co3O4) from

Co(NO3)2.6H2O with 68.92%SiO2 (SiO2 Nacalai)

as a catalyst support for RUN–01, RUN–05, RUN–

07, RUN–10.

• Hexadecane (C16H34) as a solvent for the

whole RUN.

4.1. Result

Product gas is generated each time the RUN analyzed

using GC-TCD and GC-FID to determine the

composition and %volume of gas contained.

4.1.1. Gas Product

Following the GC-TCD and GC-FID analysis results

of standard gas and gas products for-01 RUN, RUN-

05,-07 RUN, RUN-10 were carried out in the

Laboratory of Coal Liquefaction in PUSPIPTEK –

Serpong.

Figure 8. Profile of GC-TCD and GC-FID gas standards RUN-01

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Figure 9. Profile of GC-TCD and GC-FID gas product RUN-0

Figure 10. Profile of GC-TCD gas standard RUN–05, RUN–07, RUN–10

Figure 11. Profile of GC–TCD and GC–FID product gas RUN–05

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Table 8. Product gas composition (%volume)

Table 9. Volume of product gas (NL)

4.1.1. Liquid Product

Table 10. Operation condition of GC–FID Pyrolisis

Figure 14. Profile of chromatogram GC–FID feed

and product RUN–01

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4.2. Discussion

4.2.1. Gas Product

Figure 18 shows the effect of reaction time for each

time the RUN in the Autoclave 1L reactor to a

uniform temperature rise, it means better

performance and a control system stable.

Figure 18. The effect of reaction time against

operation temperatur of autoclave 1L

Table 8 and Table 9 show that of the result 10 times

RUN has done most of the gas producing

hydrocarbons (HC) light C1 ~ C2 (CH4, C2H6) SNG

equivalent except RUN-02. Product hydrocarbon

gases (HC) light C1 ~ C3 (CH4, C2H6, C3H8) is

produced by the RUN-01-05 RUN, RUN-07, RUN-

10 (where the RUN-03 is relatively small). While the

RUN-05, RUN-07, RUN-10 are capable of producing

hydrocarbon gases (HC) light C1 ~ C4 (CH4, C2H6,

C3H8, n-C4H10 i-C4H10). The other 4 RUN (RUN-

04-06 RUN, RUN-08, RUN-09) less so produce the

desired product.

Table 11 shows the material balance RUN-01, RUN-

05, RUN-07, RUN-10, where the RUN-05 is capable

of producing the biggest hydrocarbon gases (HC)

light C1 ~ C4 with N2 gas content is relatively small,

while the product gas hydrocarbons (HC) light C1 ~

C4 generated by the RUN-01 RUN-07, RUN-10 is

relatively small and this case less desirable in the

Fischer-Tropsch Synthesis process because N2 gas

content is still relatively high.

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Table 11 The material balance of Fischer–Tropsch Synthesis (Autoclave 1L)

Liquid Product

During the study, only the slurry product is vacuum

filtered and the liquid product was not carried further

distillation due to bumping.

Figure 14, Figure 15, Figure 16 and Figure 17 shows

the GC-FID chromatogram profile sample liquid

product produced by the RUN–01, RUN–05, RUN–

07, RUN–10 have indicated a tendency HC products

chain C> C5 ~ C12 (oil) which is relatively very

small quantity and quality can not be known for sure

(equivalent prediction kerosene), since the current

vacuum distillation process (P = 10 mmHg using a

solvent reagent C16H34) were bumping.

Products RUN–01 shows a comparison of the peak

area on the residence time (retention time) was

31.804 (bait) and 31.789 (products) that decrease

product area. While the peak area products has

increased in the residence time (retention time) 34

699; 34 775; 35 182; it means components on the

product a lot more than feed.

Figure 19 and Figure 20 shows that although the

RUN-01 only produces gas hydrocarbon (HC) light

C1 ~ C3 is the smallest than RUN–05, RUN–07,

RUN–10, however, indicated to produce HC chain

C> C5 ~ C12 (prediction of kerosene equivalent):

this means that the smaller product gas has a

tendency to produce more oil.

Figure 19. Profile of chromatogram GC–FID oil

product RUN–01

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Figure 20. Profile of chromatogram GC–FID oil

product RUN– 01

5. CONCLUSIONS

The results of the assessment on syngas utilization by

Fischer Tropsch Synthesis in the slurry–bed reactor

using Co/SiO2 catalyst as liquid synthetic fuel, it can

be concluded as follows:

• During the research has been done 10 run–

times uses 2 types of mixed-gas namely: (1) 60% H2,

30% CO, 10% N2 (H2/CO ratio = 2) for RUN–01,

RUN–05, RUN–07, RUN–10 with Co/SiO2 Nacalai

catalysts, while (2) 54% H2, 30% CO, 10% CH4, 6%

N2 (H2/CO ratio = 1.8) for RUN–02, RUN–03,

RUN–04, RUN–06, RUN–08, RUN–09 with

Co/SiO2 nature zeolith catalysts.

• According to the evaluation results by GC-

FID analysis from the 10 run–times conducted

showed that most of the gas producing hydrocarbons

(HC) light C1~C2 (CH4, C2H6) SNG equivalent

except RUN–02. Product hydrocarbon gases (HC)

light C1~C3 (CH4, C2H6, C3H8) is produced by the

RUN–01, RUN–05, RUN–07, RUN–10 (RUN–03 is

relatively small). While the RUN–05, RUN–07,

RUN–10 is capable of producing hydrocarbon gases

(HC) light C1~C4 (CH4, C2H6, C3H8, n-C4H10 i-

C4H10) LPG equivalent. The other 4 run–times

(RUN–04, RUN–06, RUN–08, RUN–09) less so

produce the desired product.

• Product gas hydrocarbon (HC) light C1~C4

are the largest produced by the RUN–05 with N2 gas

content is relatively small, in contrast with the RUN–

01, RUN–07, RUN–10 in the Fischer-Tropsch

Synthesis process less desirable since the content of

N2 gas still relatively high.

• Product gas hydrocarbon (HC) light C1~C3

produced by the smallest compared to RUN–01,

RUN–05, RUN–07, RUN–10, however indicated to

produce HC chain C > C5~C12 (oil): this means that

the small gas produced products have a tendency to

produce more oil.

• Liquid products produced by RUN–01,

RUN–05, RUN–07, RUN–10 have indicated

tendency of products HC chain C > C5~C12 (oil)

which is relatively very small quantity and quality

can not be known for sure (equivalent prediction

kerosene), since the current vacuum distillation

process (P = 10 mmHg using a solvent reagent

C16H34) were bumping.

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