Preliminary status note: Thermal biomass conversion technologies ...

1 

5/4 2012 

Preliminary status note: Thermal biomass conversion technologies used to 

production of transport fuels -‐ Input to the BioRefinery Alliance technology status 

study 

CHEC Research Centre 

Department of Chemical and Biochemical Engineering 

Technical University of Denmark, 

Peter Arendt Jensen 

Anker Degn Jensen 

Peter Mølgaard Mortensen 

Jacob Munkholt Christensen 

Jesper Ahrenfeldt 

Søltofts Plads, Building 229, DK-‐2800, Lyngby, Denmark 

http://www.chec.kt.dtu.dk

1.0. Introduction 

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This status note provides input as requested by the BioRefinery Alliance road map. Here are described 

technologies to the production of transport fuels by biomass gasification followed by catalytic synthesis of 

hydrocarbons, and flash pyrolysis followed by hydrogenation to produce diesel fuels. There are included 

short status descriptions of the following technologies: 

1. Fixed bed gasification 

2. Fluid bed gasification 

3. Entrained flow gasification 

4. Synthesis of liquid fuels using gasification gas 

5. Flash pyrolysis 

6. Flash pyrolysis oil upgrading 

Another CHEC report describing conversion of lignin, cellulose and hemicelluloses into chemicals is 

available. 

Different thermal technologies can both be a part of a bio-‐refinery concept and be independent plants that 

supplies electrical power, transportation fuels, chemicals and heat. Some possible different uses of 

gasification technologies are listed below: 

A. Use as a technology to treat some selected streams in a bio-‐ refinery concept 

B. Use to provide transportation fuels ( as heavy ship fuels, airplane fuels or car engine fuels) 

C. Use as unit that can provide flexible energy products as power, district heating and transport fuels. 

This could also be in concepts that are integrated with the gas net or utilizes hydrogen produced 

from surplus windmill power. 

D. Use as local small scale flexible energy product provider 

The discussions in this note mainly deals with issue A and B.

2.1. Entrained flow gasification 

2.1.1. Short description of technology 

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Entrained flow gasification reactors use finely grinded fuels that are converted to a gas rich in H2 CO and 

CO2 within a few seconds of reactor residence time. The reactor operates with internal temperatures of 

1200 to 1700°C, provides a gas with low tar levels, and often operates as a slagging gasifier using a melted 

slag on the reactor walls to reduce heat loss. Entrained flow reactors are in most cases operated at 

pressures from 5 -‐ 80 bars and with oxygen and steam as the gasification agents. The entrained flow 

gasifier can thereby provide a pressurized gas with low N2 content, no tar and a high concentration of H2 

and CO. Such a gas is optimal for use in synthesis plants for the production of liquid fuels, or to be used in 

combined cycle power plants that combine a steam cycle and a gas turbine to obtain a high electrical 

efficiency. Coal fired entrained flow gasification plants have been operational for many years (Liu et al. 

2010) while development of biomass fired plants are a relatively recent development (Clausen 2011). 

2.1.2. Global status of technology development 

A complete overview of global biomass entrained flow gasification activities is not provided, but selected 

activities are shortly summarized. 

The German company CHOREN entrained flow gasifier is developed to specifically gasify biomass (CHOREN, 

2012). Presently a 45 MWth plant is in a commissioning process and it is the plan to produce Fisher-‐Tropsch 

diesel. However, the company has currently some financial problems. 

Entrained flow gasification is presently applied to produce DME from black liquor from the paper industry. 

The Chemrac company has constructed a 3 MWth plant in Piteå Sweden using a 30 bar oxygen blown 

Entrained flow reactor. The DME synthesis plant is based on technology from Haldor Topsoe. 

Entrained flow Co-‐gasification of biomass and coal has been demonstrated on large scale in the Buggenum 

(Netherland) shell gasifier used to produce 253 MWe on a combined cycle power plant (Drift et al. 2004). 

The entrained flow gasifiers that have been develop to utilize coal from companies like Shell, Texaco, 

Mitsubishi Heavy Industry and Siemens may have the possibilities to be modified to use biomass. Based on 

entrained flow coal gasification both combined cycle power plants and plants for synthesis of chemicals 

have been constructed (Higman and Burgt 2008). 

2.1.3. Danish strong positions and facilities 

At DTU Department of Chemical engineering experimental an modeling work are conducted with regards to 

entrained flow gasification of wood, straw, lignin and coal; and the influence of operation conditions on 

product gas quality is investigated (Ke et al. 2012). The study have shown that biomass as wood, straw and 

lignin can be gasified at lower temperatures than coal, and that the limiting factor for minimizing oxygen 

consumption is the product gas soot content. 

The Danish company TK Energy have developed equipment for feeding of solid fuels into pressurized 

gasifiers, and have done initial development work on an atmospheric pressure entrained flow cyclone 

gasifier (FIB 2011).

Haldor Topsoe is involved in several international projects to provide synthesis equipment for the 

production of liquid fuels based on gas from entrained flow reactors. 

2.1.4. Perspectives 

4 

Entrained flow gasification is in most cases used in relatively large plants. To obtain optimal operation the 

entrained flow reactor is often combined with an oxygen production plant and the gasifier is pressurized. 

The largest potential of the technology in a bio based society is probably as large integrated biomass 

gasification plants that can provide one or several different products as electricity, transport fuels, process 

heat, natural gas and chemicals. Energy.Dk (Vestervang 2011) has proposed that a flexible gasification 

plant is integrated with wind mill production. The plant will then supply synthetic gas to the gas net when 

there is a surplus of wind mill electricity, and provides power when the wind mills are stopped. 

The main limitations of the biomass entrained flow technology compared to other gasifier types are that 

relatively large and complicated plants are used (pressurized reactor and oxygen plan), while advantages 

are a high fuel flexibility and a tar free product gas. Most system studies shows that the total efficiency of 

pressurized gasification based liquid fuel production, judged by the amount of transport work per feedstock 

consumed, are generally better for gasification processes than for bio-‐ethanol or bio-‐diesel systems 

(Ahrenfeldt et al. 2011). 

A challenge for the development of biomass entrained flow gasification technology is the development of 

efficient fuel feeding technology of biomass into a pressurized rector. One way to do this is by obtaining a 

slurry of char and tar from a flash pyrolysis unit and then pump this high energy density slurry into the 

reactor. Another important issue is appropriate control of ash behavior in the gasifier. 

Relevance and strong positions in Denmark: 

-‐ The Danish energy system with many wind mills makes it appropriate to build large flexible 

entrained flow gasifier plants, which can supply multiple energy products 

-‐ DTU has a large research group (CHEC) that have the expertise and experimental facilities to 

perform research and development with respect to entrained flow gasification 

-‐ TK energy works on developing a small scale cyclone entrained flow gasifier 

-‐ Haldor Topsoe have several activities related to gas conditioning, gas cleaning and synthesis of 

liquid fuels that is tested on biomass gasifier plants (this is explained in more detail in the section : 

Synthesis of transport fuels using gasification gas) 

2.1.5. Bibliography 

(lui et al. 2010) Liu, K., Cui, Z., and Fletcher, T.H., Coal Gasification, in Hydrogen and Syngas Production and 

Purification Technologies, K. Liu, C. Song, and V. Subramani, Editors. 2010, A John Wiley & Sons, Inc., 

Publication. p. 156-‐218. 

(Ahrenfeldt et al. 2011) Jesper Ahrenfeldt, Ulrik Birk Henriksen, Janus Münster-‐Swendsen, Anders Fink, 

Lasse Røngaard Clausen, Jakob Munkholt Christensen, Ke Qin, Weigang Lin, Peter Arendt Jensen, Anker 

Degn Jensen. Final report EFP06. Production of methanol/DME from biomass. National Laboratory for 

Sustainable Energy (Risø DTU), 2011.

(Hansen 2011) Morten Tony Hansen. Strategy for research, development and demonstration of thermal 

biomass gasification in Denmark. Force technology, Energinet.dk, EUDP. 2011. 

(Qin et al. 2012) K. Qin, W. Lin, P. A. Jensen, A. D. Jensen. High-‐temperature entrained flow gasification of 

biomass. Fuel, 2012, vol 93, 589-‐600. 

(FIB 2011) FIB, Forskning I Bioenergi, Brint & Brændselsceller. Nummer 38, December 2011. 

(Clausen 2011) Lasse Røgaard Clausen. PhD thesis. Design of novel DME/methanol synthesis plants based 

on gasification of biomass. DTU Mechanical Engineering 2011. 

5 

(Drift et al. 2004) Van der Drift, A. Boerrigter , H. Coda, B. Cieplik, M , K. Hemmes, K. Entrained flow 

gasification of biomass; Ash behavior, feeding issues, system analysis, report: ECN-‐C—04-‐039. Petten, ECN, 

2004. 

(CHOREN 2012) Homepage of CHOREN, http://www.choren.com 

(Vestervang 2011) Steen Vestervang. Presentation: Hvorfor er VE-‐gas vigtig i den fremtidige energiforsyning 

?. Seminar om den grønne gas – Forgasningsgas 20. december 2011 

(Higman and Burgt 2008) C. Higman, M. Burgt. Gasification, Elsevier Inc. 2008.

2.2. Fluid bed gasification 


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In fluid bed gasifiers a fluidized bed of sand is used to obtain stable temperature and mixing conditions in 

the reactor. Fluidized biomass gasification reactors often operate in the range of 800 to 950°C. The reactors 

appear in many different designs and sizes. Reactors are used for both small scale plants using internal 

combustion gas engines to produce electricity and large scale units that can be applied for synthesis gas 

production. Most fluid bed gasifiers do not operate well on alkali rich biomasses that may cause de-‐ 

fluidization of the bed. 


Because of the limited time to write this note a status is not provided in this case. 


The only Danish developed fluid bed gasifier is the Low Temperature Circulating Fluid Bed gasifier 

(PYRONEER). The concept was originally invented by Peder Stoholm and further development of the gasifier 

has been conducted by DONG energy and DTU Risø. The PYRONEER has been designed specifically to gasify 

biomass resources with high contents of low melting ash compounds that has proven difficult to convert in 

other processes – e.g. straw, manure fibers, sewage sludge, organic waste etc. The process is based on 

separate pyrolysis and gasification reactors with a suitable heating medium circulating to transfer heat 

from the gasification process to the pyrolysis. The temperature is kept below the melting point of the ash 

components – i.e. max process temperatures around 700-‐750 °C. In this way sintering and de-‐fluidization is 

prevented. The design of the plant ensures that the fuel ash can be removed in a solid phase from the 

gasifier. The gas produced on the gasifier contains relatively high tar content and will initially be utilized as 

fuel in a power plant boiler. There presently exist a 500 KWth plant at Risø and a 6 MWth pilot plant is 

operated by DONG in Kalundborg. The 6 MWth PYRONEER plant will be gasify straw and supply the process 

gas to Unit 2 of the 1000 MW coal fired power plant Asnæsværket. Operation will begin in March 2011, the 

project will finish in 2013, and if successful it will be succeeded by a full scale plant. 

The PYRONEER is a highly scalable concept, with potential plant sizes of 5-‐100 MW depending on the fuel. 

Desired fuel characteristics include small particle size (3-‐4 mm) and limited water content (< 30 wt%). 

Successful operation on two different types of straw, chicken manure, two types of pig manure, two types 

of degassed manure from biogas plants and one type of wood have been carried out on a small scale 

PYRONEER gasifier at the Technical University of Denmark. These fuels had ash content as high as 44 wt%dry 

and a high content of potassium, chlorine and phosphorous. 

To increase the future usability of the PYRONEER process gas, a new project called Gasolution has recently 

been initiated by a consortium. The aim is to develop new gas cleaning and upgrading techniques that will 

reduce the content of tar and dust particles in the gas, and make it usable for synthesis or direct production 

of electricity.


The PYRONEER concept may through the activities conducted in the presently started Gasolution project 

(participants DONG, DTU-‐KT, Haldor Topsoe) leads to production of a gas that has a quality so it can be 

used for synthesis of chemicals and fuels. 

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2.3. Moving bed gasification 


8 

Moving bed biomass gasifiers operate with a bed of biomass where the gasifier agent, in most cases air and 

steam, passes through the biomass bed material. The flow of biomass and gasification agents can flow both 

counter-‐current and co-‐current in the gasifier. Counter current gasifiers obtain high conversion efficiency 

from biomass to fuel, but also have high tar content in the product gas. Typical reactor temperatures are in 

the range of 800 to 1000°C. Moving bed gasifiers do have some fuel constraints, many fines can stop the 

gas flow through the bed, and high alkali fuels like straw can lead to melting problems in the ash. 


Because of the limited time to write this note a status is not provided in this case. 

Most moving bed gasifiers have a fuel capacity of less than 5 MWth and the gas are used to produce 

electricity on a gas engine. 


Several Danish companies and university groups have developed moving bed gasifier technology. Some are 

listed here: 

-‐ Vølund & Wilcox gasifier. Vølund updraft gasifier (Commercial) 

-‐ Weiss A/S and DTU Risø. Staged down draft gasifier (Demonstration) (the Viking gasifier) 

-‐ Biosynergi process APs. Open core down draft gasifier (Demonstration) 

All gasifiers are used to production of heat and electricity using internal combustion gas engines. 

Generally production of chemicals and fuels are based on larger pressurized gasifiers. However, both 

experimental and efficiency calculations have been conducted on production of bio-‐fuels via fixed bed 

gasification using tri-‐generation of methanol or DME, electricity and district heating from wood chips via 

the small-‐scale TwoStage gasification process (Viking Gasifier). The process gas from the TwoStage gasifier 

is characterized by very low tar content and relatively high contents of CO and H2. Both traits are 

advantageous in relation to the gas cleaning systems and the synthesis of methanol or DME in subsequent 

catalytic processes. In Figure 1 is shown how the gasifier can be integrated with fuel synthesis process. 

Efficiency calculations comparing a large scale entrained flow gasifier DME plant with a tri-‐generation 

TwoStage gasification plant have been done. Only a 6-‐8% higher fuel and electricity efficiency can be 

expected by the larger DME plant. The small scale plants may have several advantages with respect to 

transport of biomass, integration into district heating systems and initial capital costs.

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Figure 1: Simplified flow sheet of a small scale tri-‐generation of liquid fuel, electricity and heat from 

gasification of wood chips 


Wood 

Stream 

drying 

Syngas 

Two-stage 

gasification 

Compression Synthesis 

Unconverted syngas 

Electricity 

production 

Liquid 

Separation 

DME/MeOH 

With respect to moving bed gasification technology Denmark have several advantages: 

-‐ Several companies have developed and demonstrated small scale gasification plants that can 

produce heat and power 

-‐ Work on an integration of moving bed gasification with production of methanol and DME have 

been initiated at DTU Risø.

2.4. Fast Pyrolysis Technology 

2.4.1 Short description of technology 

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By pyrolysis of biomass in the absence of oxygen a large fraction of the biomass can be converted to bio-‐ 

oil, and smaller amounts of char and gas. Biomass such as wood, agricultural residues and waste products 

can be used as feedstock for fast pyrolysis processes. A maximum oil yield is in most cases obtained at 

reactor temperatures between 450 and 600°C with a high feedstock heating rate and a short gas residence 

time. The bio-‐oil mass yield obtained from various biomass sources are in the range of 30 – 75 %wt. Wood 

having a low ash content and a high cellulose content is often found to provide a high bio-‐oil yield of 70 – 

75 %wt. The generated bio-‐oil has high oxygen content, cannot be distillated and may in some cases have a 

limited storage stability. The oil can be utilized as a heavy fuel oil in boilers, while it in most cases needs 

some upgrading by hydrogenation if the oil shall be used in diesel engines or gas turbines. Two classes of 

reactor types that can obtain high biomass feedstock heating rates have mainly been developed for flash 

pyrolysis plants, ablative reactors and fluid bed reactors. In an ablative reactor high heating rates is 

obtained by pressing the fuel particles towards a hot metal surface, while the high heating rate in a fluid 

bed reactor is obtained by a fast mixing of hot inert bed material and the fuel. Recently it has been 

proposed, that the char from the pyrolysis process can be used as bio-‐char that is distributed on 

agricultural fields, and thereby act as a method to sequestrate carbon (Bruun et al. 2011). 

2.4.2 Global status of technology development 

The most active research community regarding fast biomass pyrolysis is at Aston University in the UK, and 

the research group is headed by A. V. Bridgwater (Bridgwater 2012). 

The construction of commercial and pilot pyrolysis plants has gradually increased the last 10 years and 

initially most plants were constructed in Canada. Today both pilot and commercial plants are constructed in 

several countries as seen in Table 1. The largest planed pyrolysis plant is the construction of a 400 tpd plant 

that has been announced by Alberta placed Tolko industries LTD using the Ensyn developed CFB 

technology. 

Table 1: Global survey of major technology developments of fast pyrolysis. Tpd = Tons produced daily. 

(Butler et al. 2011). 

Company Technol Developments 

Dynamotive BFB Several plants, largest is 200tpd at west Lorne (CAN) 

Ensyn CFB Several plants, largest is 100tpd plant in Renfrew (CAN); construction of 400 tpd plant in 

High Level, Albarta (CAN) with Tolko Industries LTD. Announced; Construction of 9 

plants in Malaysia by 2015 announced 

BTG RCR 120 tpd plant in Hengolo (NL) announced production of bio-oil, electricity, organic acids 

B-O H N.V. RCR Largest plant is 12 tpd. Construction of two 5 tpd plants underway in NL and BEL 

Biomass Eng. BFB 4.8 tpd facility (UK) 

KIT/Lurgi Auger 12 tpd pilot plant in Karlsruhe (GER) 

Pytec Abliative 6 tpd plant (GER) 

Anhui Yineng M.FB Three 14 tpd units constructed (CHI) 

Metso Consort CFB 7.2 tpd pilot plant at tampere (FIN)


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At DTU department of chemical engineering the patented flash pyrolysis centrifugal reactor (PCR) is under 

development (Bech 2008)(Bech et al. 2009). Research is conducted on a 3 kg feedstock/h laboratory unit 

and includes studies on using different feedstock’s including straw, lignin and waste fractions as well as 

studies on reactor optimization and oil storage stability. Also studies on using slurry of char and bio-‐oil as a 

feedstock for pressurized gasification is done and the use of the char for carbon sequestration. The patent 

rights for using the PCR technology to treat different waste types are partly owned by DONG energy. The 

PCR technology can be used in stationary and also be developed to a mobile unit, which can make pyrolysis 

oil directly from straw on the fields. At DTU also work on hydrogenation of bio-‐oil is done (See other section 

in this note) 

Only few Danish companies work with pyrolysis technologies. Organic fuel technology A/S is developing a 

catalytic low temperature pyrolysis process (Hansen 2011) . Details about the plant are not known. Stirling 

DK Aps have developed the BlackCarbon pyrolysis process (Hansen 2011). Biomass is pyrolyzed at a low 

heating rate and the generated gas and tar are combusted and drives a sterling engine. The generated bio-‐ 

char is used as a soil improver and to sequestrate carbon. 


The Pyrolysis reactor technology can be used both as stand alone plants and plants integrated with 

other energy conversion processes. While the most commercially developed pyrolysis plants are based on 

fluid bed technology integration with other energy processes is only in it infancy. 

- The fast pyrolysis technology may be used at relatively small local units to treatment of savage 

sludge, hazardous waste or to convert lignin (From a bio-‐ethanol plant) or be used to treat selected 

waste fractions (as a part of the Renescience process). 

- It has been proposed to use local pyrolysis plants combined with central gasification or central bio-‐ 

oil upgrading plants. 

- Compared to gasification based production of liquid fuel, the pyrolysis technology can for some 

feedstock types (as wood) provide liquid fuel with high energy efficiency. The drawback is the 

relatively low quality of the bio oil. However, only smaller modifications of the pyrolysis oil may be 

needed if the oil could be used as a low sulfur oil for heavy ship diesel engines. 

- The DTU PCR concept is designed so it can evolve into in-‐situ mobile pyrolysis units, which can be 

applied to harvest bio-‐oil from straw directly on the farmer’s fields. Such a technology could strongly 

increase the global straw resources that economically can be applied for power production. 

- As a byproduct from the pyrolysis project a Bio-‐char is produced that potentially can be used for soil 

improvement and carbon sequestration. 

- Flash pyrolysis of biomass to produce slurry (bio-‐oil-‐char) may be a pretreatment step used on 

pressurized biomass gasification plants. 

2.4.5 Bibliography 

(Butler et al. 2011). Butler E, Devlin G, Meier D, McDonnell K. A review of recent laboratory research and 

commercial developments in fast pyrolysis and upgrading. Renewable and sustainable energy reviews 15 

(2011) 4171 – 4186.

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(Brown and Holmgren 2006). Brown RC, Holmgren J. Fast pyrolysis and bio-‐oil upgrading. National program 

2007: Bioenergy and energy alternatives – distributed biomass to diesel workshop. Richland, WA, USA; 

2006 

(Bech 2008). Bech N. In-‐situ flash pyrolysis of straw. PhD thesis. 2008. Department of chemical engineering, 

DTU. Kgs. Lyngby, Denmark 

(Bech et al. 2009). Bech N, Larsen MB, Jensen PA, Dam-‐Johansen K. Modeling solid-‐convective flash 

pyrolysis of straw and wood in the Pyrolysis Centrifuge Reactor. Biomass and Bioenergy 33 (2009) 999 -‐ 

1011. 

(Bruun et al. 2011) E. Bruun, H. Hauggaard-‐Nielsen, N. Ibrahim, H. Egsgaard, P. Ambus, P. A. Jensen, K. Dam-‐ 

Johansen. Influence of fast pyrolysis temperature on biochar labile fraction and short-‐term carbon loss in a 

loamy soil. Biomass & Bioenergy. 2011. 35 (3), p. 1182-‐1189. 

(Hansen 2011) Morten Tony Hansen. Strategy for research, development and demonstration of thermal 

biomass gasification in Denmark. Force technology, Energinet.dk, EUDP. 2011. 

(Bridgwater 2012) A. V. Bridgewater. Review of fast pyrolysis of biomass and product upgrading. Biomass 

and Bioenergy 38, 2012, p68-‐94.

2.5. Synthesis of transport fuels using gasification gas 


Syngas produced on a gasification plant can in a subsequent catalytic process be converted into one of 

several synthetic fuels. Synthetic diesel can be produced in the Fischer-‐Tropsch synthesis over iron or 

13 

cobalt catalysts (Dry 1996). Syngas can be converted into methanol over a copper-‐based catalyst (Wender 

1996). The methanol can be dehydrated into dimethyl ether (DME) over a solid acid catalyst (Wender 

1996). Mixed higher alcohols can be synthesized over a range of modified methanol and Fischer-‐Tropsch 

synthesis catalysts (Wender 1996). Methanol, DME and higher alcohols can furthermore be converted to 

synthetic gasoline over a zeolite catalyst in the methanol to gasoline (MTG) process (Chang & Silvestri 

1977). Haldor Topsøe A/S has developed the TIGAS process, where methanol/DME synthesis is combined 

with MTG in a single processing loop without isolation of the intermediate methanol/DME (Wender 1996). 

An advantage of the synthesis processes is their flexibility. It is possible to vary the conversion and 

produce fuel from part of the syngas, while the remaining syngas is used for electricity production (Rostrup-‐ 

Nielsen et al. 2007). Thereby gasification plants can be used to even out variations in the output from other 

renewable power sources (wind, solar etc.). 

It is generally a requirement for the catalytic processes that sulfur is completely removed from the 

syngas (Kung 1992, Hamelinck et al. 2004), and the synthetic fuels are therefore essentially sulfur-‐free, 

which is a significant advantage over oil-‐derived fuels. Alcohols are efficient fuels in gasoline engines, but in 

the presence of water methanol has a very limited miscibility with gasoline, which hampers the 

introduction of methanol into the existing fuel infrastructure (Keller 1979). The mixed higher alcohols 

produced from syngas are easier to integrate into the existing fuel infrastructure, as they have a better 

miscibility with gasoline than methanol (Keller 1979). The synthetic gasoline produced from methanol/DME 

is fully compatible with the existing infrastructure (Phillips et al. 2011). DME and Fischer-‐Tropsch diesel are 

efficient fuels for use in diesel engines (Dry 2001, Semelsberger 2006). The primary challenge with respect 

to DME is that it must be handled under pressure and requires a special fuel delivery system (Semelsberger 

et al. 2006). In some applications methanol or DME could however be more directly applicable – for 

example as a sulfur-‐free fuel on board ships. 


The production of methanol, DME, synthetic gasoline and Fischer-‐Tropsch diesel from syngas derived from 

coal gasification is already practiced commercially. Today methanol is produced in large quantities from 

natural gas or coal (Methanol Institute 2012). In recent years the production of DME from coal via 

gasification has grown significantly -‐ especially in China (Larson 2008). A 2500 barrels per day (bpd) plant is 

producing synthetic gasoline via methanol from coal gasification is currently operating in China (Phillips et 

al. 2011). The production of Fischer-‐Tropsch fuels from coal has been carried out in South Africa for many 

years (Dry 2002). These syngas conversion processes thus represent established commercial technologies. 

When moving to biomass applications a processing step that still requires significant research is the 

conversion of tar by-‐products from the gasification into syngas. 

The synthesis of mixed higher alcohols is not to the same extent an established technology. For the 

synthesis of mixed alcohols several companies (including Haldor Topsøe A/S) operated pilot plants in the 

1980’s (Courty et al. 1990). A plant for production of 100 mio. gallons of mixed alcohols per year from

14 

gasification of wood waste was recently under construction in the US, but due to poor economy the plant 

was closed before any higher alcohols were produced (Bloomberg 2011). 

2.5.3 Danish strong positions and facilities 

Haldor Topsøe A/S is a world leader in heterogeneous catalysis and the company has a strong position on 

several of the fuel synthesis processes. Haldor Topsøe A/S is currently involved in two projects that 

combine biomass gasification and fuel synthesis at pilot scale: 

-‐ EU-‐project; BioDME: Haldor Topsøe A/S and partners have in the BioDME EU-‐project already 

demonstrated the entire technology chain from gasification of black liquor to production of DME and 

application of the DME in trucks. The scale of the BioDME pilot plant in Piteå, Sweden is 5 tons per day, and 

the product is distributed to 4 fueling stations, where it is used to fuel 10 Volvo trucks. The necessary 

technology is therefore present and ready for full-‐scale application (BioDME 2012). 

-‐DoE-‐project; Green Gasoline from Wood using Carbona gasification and Topsoe TIGAS processes: Haldor 

Topsøe A/S is currently constructing a 22.5 bpd pilot unit in Chicago, USA for demonstration of gasoline 

production from wood gasification. The conversion of syngas to gasoline has previously been demonstrated 

by Haldor Topsøe A/S, but the gasification of wood results in the formation of tar, which subsequently must 

be converted to syngas in a so-‐caller tar reformer. The tar reformer is the part of the technology that 

requires the most substantial improvements before the technology is industrially viable. Haldor Topsøe A/S 

has, in collaboration with the plant providing distributed heating in Skive, Denmark, worked on the 

demonstration of tar reforming at low pressure, but a potential verification of tar reforming at elevated 

pressure awaits the abovementioned DoE pilot plant tests (US Dept. of Energy, 2012). 

Haldor Topsøe A/S is also involved in various collaborations where the company supplies 

technology/catalysts for processes for production of liquid fuel from syngas. These collaborations involve: 

-‐Carbona/Andritz: Tecnology supplier of processes for gasification of bio-‐material 

-‐Chemrec: Technology supplier of processes for black liquor gasification. Host for gasification pilot facilities. 

-‐GTI (Gas Technology Institute): Host for gasification based pilot facilities 

-‐Haldor Topsøe A/S, DONG, Risø and DTI: Partners in the Gasolution project 

At the Technical University of Denmark (DTU) there have been significant research efforts on the syntheses 

of methanol and mixed higher alcohols. At the Department of Chemical and Biochemical Engineering, DTU 

experimental facilities are available for catalyst preparation and for investigations of syngas conversion 

processes at industrially relevant conditions (Christensen et al. 2009, 2010, 2011 & 2012, Studt et al. 2012). 


Fuels produced from biomass have a large potential, and the synthesis technology is essentially in place. 

Currently the primary limitation for a wider application of these fuel production technologies is that the 

economic driving force is insufficient. The construction of a large scale biomass conversion plant requires a 

substantial investment. As an example studies for plants processing 75-‐85 tons of wood per hour estimate 

the required capital investment to be in the range of 200-‐400 mio. US$ (Hamelinck & Faaij 2006, Phillips 

2007 & 2011). To accept such an investment the investors would need to be relatively certain that it is 

economically attractive to produce sustainable fuels – not only at the moment but also over a period of 10-‐

15 years. Currently it may require political initiatives to ensure this long-‐term attractiveness of the 

production of fuels from sustainable resources. 

2.5.5. References 

BioDME project web page, http://www.biodme.eu/, accessed March 2012. 

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Bloomberg web page, http://www.bloomberg.com/news/2011-‐12-‐02/range-‐fuels-‐cellulosic-‐ethanol-‐plant-‐ 

fails-‐as-‐u-‐s-‐pulls-‐plug.html, published December 2011, accessed March 2012. 

C. D. Chang, A. J. Silvestri, The Conversion of Methanol and Other O-‐Compounds to Hydrocarbons over 

Zeolite Catalysts; J. Catal. 47 (1977) 249-‐259. 

J. M. Christensen, P. M. Mortensen, R. Trane, P. A. Jensen, A. D. Jensen, Effects of H2S and process 

conditions in the synthesis of mixed alcohols from syngas over alkali promoted cobalt-‐molybdenum sulfide, 

Appl. Catal. A 366 (2009) 29-‐43. 

J. M. Christensen, P. A. Jensen, N. C. Schiødt, A. D. Jensen, Coupling of alcohols over alkali-‐promoted 

cobalt–molybdenum sulfide, ChemCatChem 2 (2010) 523-‐526. 

J. M. Christensen, P. A. Jensen, A. D. Jensen, Effects of feed composition and feed impurities in the catalytic 

conversion of syngas to higher alcohols over alkali-‐promoted cobalt-‐molybdenum sulfide, Ind. Eng. Chem. 

Res. 50 (2011) 7949-‐7963. 

J. M. Christensen, L. D. L. Duchstein, J. B. Wagner, P. A. Jensen, B. Temel, A. D. Jensen, Catalytic conversion 

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technical options, process analysis and optimisation, and development potential; Energy 29 (2004) 1743-‐ 

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16 

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2.6. Hydrogenation of flash pyrolysis oils 

17 


One prospective route for production of sustainable fuels in the future is the conversion of biomass into 

bio-‐oil followed by hydrogenation of the bio-‐oil into a product equivalent to crude oil. Optimal production 

of bio-‐oil is performed through flash pyrolysis, where the biomass is rapidly heated in the absence of 

oxygen (1). This produces a gaseous phase of hydrocarbons which by condensation yields the bio-‐oil. 

Compared to biomass, the bio-‐oil has both a higher mass and energy density, which renders transportation 

more feasible. The bio-‐oil has a high content of water (up to 30 wt%) and oxygen containing compounds 

(up to 40 wt% O) as phenols, guaiacols, etc, which, among other things, this may cause it to be unstable and 

gives the bio-‐oil a low heating value compared to crude oil (2). It is impossible to use a raw bio-‐oil on a 

distillation plant because of it tendency to generate char upon heating above 100°C. 

To utilize the bio-‐oil, removal of the oxygen is wanted, which will enable separation of an oil phase. The 

most promising initiative for this is hydrodeoxygenation (HDO) where a high pressure and a catalyst are 

used to remove the oxygen functionalities in the oil (2). Complete HDO of the oil has been reported to 

produce a crude oil like product with heating values equivalent to conventional crude oil (2,3). 

This process is carried out at temperatures between 200-‐400 °C and at a pressure up to 200 bar. 

Conventional hydrotreating catalysts as Co-‐MoS2 and Ni-‐MoS2 have received much attention, but also noble 

metal and nickel based catalysts have been shown as promising catalysts (2). A general problem for the 

catalysts is that they all suffer from a relatively low lifetime, as carbon deposition arise during the process. 

The carbon is formed due to both cracking and polymerization reactions of the highly reactive oxygen 

containing molecules (2). So far, Pd/C and Co-‐MoS2/Al2O3 have been reported to have the longest lifetimes, 

where time on streams of respectively 100 h (3) and 200 h (4) have been reported. 

In an industrial perspective, bio-‐oil production could take place at smaller flash pyrolysis plants placed close 

to the biomass source. These smaller plants should then supply a centralized bio-‐refinery with bio-‐oil. In 

this approach transportation cost are minimized as biomass only should be transported to the flash 

pyrolysis plant (5) (6). At the bio-‐refinery, HDO is carried out at relatively large scale plants to produce the 

crude oil like product, and this oil is subsequently treated to produce the desired fractions of hydrocarbons 

as gasoline, diesel, etc. (2). In a recent study by the U. S. Department of Energy it has been indicated that a 

process from biomass to fuels through the steps described above and with natural gas as hydrogen source 

a minimum selling price of 0.54 $/l could be achieved for the fuels (7). This price should be compared to the 

current fuel price of 0.73 $/l, excluding distribution and taxes (2). Thus, this work concluded that 

production of fuels through the HDO synthesis is economically feasible and cost-‐competitive with crude oil 

derived fuels. However, a certain uncertainty in the calculated price of the synthetic fuel must be 

remembered and the reported value is therefore not absolute. Also the problems with short lifetimes for 

HDO catalysts are not resolved. 


Globally, the HDO approach has been given much attention. As previously mentioned, the U. S. Department 

of Energy has shown interest in the technology. This has been guided by the work of Douglas C. Elliot at the 

Pacific Northwest National Laboratory, but other groups in U.S.A., at for instance Oklahoma University, 

have also influenced the research. The technology has also received much attention in Europe. In Great

18 

Britain, Anthony Bridgwater at Aston University in Birmingham has been the author of several articles 

within the field. Furthermore research groups at the Technical University of Helsinki in Finland, the 

University of Groeningen in the Netherlands, and Boreskov Institute of Catalysis in Russia (among others) 

have influenced the research in the field in the recent years. There exist presently no large scale HDO bio-‐ 

oil plants. 


In the CHEC group at DTU-‐KT a Ph.D. project is conducted with focus on catalysts for HDO (2). With the 

extensive knowledge present at Haldor Topsøe about conventional hydrotreating operations, they also play 

a significant role in Denmark and are authors of patents in the field (9). 


Overall, hydrodeoxygenation is a prospective route to produce transport fuels equivalent to what is used in 

the current infrastructure. The major challenges within the technology are to find an active and stable 

catalyst with reasonable lifetime. Some system studies have indicated that the pyrolysis and 

hydrodeoxygenation route to provide transport fuels are economically attractive compared to other 

technologies. The largest concern with respect to feasibility/sustainability appears to be procuring a cheap 

and readily available source of hydrogen. 

2.6.5. References 

1. Elliott DC. Historical Development in Hydroprocessing Bio-‐oils. Energy Fuels. 2007; 21: p. 1792-‐1815. 

2. Mortensen PM, Grunwaldt JD, Jensen PA, Knudsen KG, Jensen AD. A Review of Catalytic Upgrading of 

Bio-‐oil to Engine Fuels. Appl. Catal. A. 2011; 407: p. 1-‐19. 

3. Elliott DC, Hart TR, Neuenschwander GG, Rotness LJ, Zacher AH. Catalytic Hydroprocessing of Biomass 

Fast Pyrolysis Bio-‐oil to Produce Hydrocarbon Products. Environ. Prog. 2009; 28: p. 441-‐449. 

4. Bridgwater AV. Production of High Grade Fuels and Chemicals from Catalytic Pyrolysis of Biomass. Catal. 

Today. 1996; 29: p. 285-‐295. 

5. Holmgren J, Marinageli R, Nair P, Elliott DC, Bain R. Consider Upgrading Pyrolysis Oils into Renewable 

Fuels. Hydrocarbon Processing. 2008;: p. 95-‐103. 

6. Raffelt K, Henrich E, Koegel A, Stahl R, Steinhardt J, Weirich F. The BTL2 Process of Biomass Utilization 

Entrained-‐flow Gasification of Pyrolyzed Biomass Slurries. Appl. Biochem. Biotech. 2006; 129: p. 153-‐164. 

7. Jones SB, Valkenburg C, Walton CW, Elliott DC, Holladay JE, Stevens DJ, et al. Production of Gasoline and 

Diesel from Biomass via Fast Pyrolysis, Hydrotreating and Hydrocracking: a Design Case. , U. S. 

Department of Energy; 2009. 

8. Corma A, Huber GW. Synergies Between Bio-‐ and Oil Refineries for the Production of Fuel from Biomass. 

Angew. Chem. Inter. Ed. 2007; 46: p. 7184-‐7201.

9. Haldor Topsøe AS, inventor; Hydrodeoxygenation Process. US patent 20090163744. 2009. 

19

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