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ConocoPhillips GTL Technology: The COPox Process

as the SynGas Generator In 1998, we started the development of the COPox process after aprocess economics review indicated that it could result in a lowercost, more efficient GTL process than other available technologies.H. A. Wright, J. D. Allison, D. S. Jack, G. H. Lewis; S. R. Landis

Since 1998, we have initiated a technology program for the COPoxprocess as part of an overall GTL effort. Over 40 full timeindividuals work in the continuing development of COPoxtechnology. This includes work in all areas of the technology

commercialization including catalyst development, reactor processand mechanical design, reactor modeling including computationalfluid dynamics; and process design engineering for scale up of ourtechnology to the demonstration scale. Another 60 individuals workin the operations and maintenance of our new 400 BPDDemonstration Plant.

Ponca City Technology Center, ConocoPhillips, PO Box 1267,Ponca City, OK 74602

Abstract

This paper discusses the development of ConocoPhillips GTLtechnology specially the development of our proprietary COPoxSynGas technology. This paper discusses what the COPox processis; how ConocoPhillips has developed the technology; and whereConocoPhillips is in the development of the technology. This paperwill also discuss general syngas chemistry and where the COPox

process fits into the spectrum of syngas technologies. A comparisonwith the leading SynGas technology shows that for an integratedGTL plant, COPox technology can improve the overall carbonefficiency of the GTL plant.

We currently have reactors of many different sizes in operation inPonca City, OK. We learned early on in the development of theCOPox technology, that most experiments needed to be done inhigh-pressure pilot reactors instead of the quartz atmospheric reactorsoften used in academia. We have two demonstration scale reactorsthat will be started up this summer that are each capable of

processing enough natural gas to produce 400 BPD of liquid productout the back end of the plant. Table 1 shows the number and type of

COPox reactors in operation in Ponca City.

Introduction

ConocoPhillips has developed proprietary Gas-to-Liquids(GTL) technology to use to convert stranded natural gas to easilytransportable fuels. This Gas-to-Liquids technology actually consists

of at least three separate technologies that are integrated together toproduce a highly efficient GTL process.

Table 1. COPox High Pressure Reactors in Operation1. ConocoPhillips has developed a syngas process, catalyst,

and reactor system for syngas generation called theCOPox process.

in Ponca City

Reactor Type Number FT Liquid Production

Demonstration Scale 2 400 BPD

Pilot Scale 2 >2 BPD

Catalyst TestingScale

12 0.2 0.5 BPD

2. ConocoPhillips has also developed a proprietary Fischer-Tropsch catalyst and reactor.

3. ConocoPhillips has also developed a proprietary ProductUpgrading technology to convert the long chainhydrocarbons to useful fuel range materials. SynGas Chemistry

4. ConocoPhillips has integrated these processes to enablehigh carbon efficiency; which results in a lower gasconsumption per barrel of product produced.

In addition to the partial oxidation reaction already mentioned,there are several other reactions that need to be accounted for inunderstanding the various means for syngas generation. The first isthe steam methane reforming reaction CH4+ H2O 3H2 + CO. Thenext is full combustion: CH4 +2 O22 H2O + CO2. The last keyreaction is the water gas shift reaction CO + H2O CO2 + H2

What is the COPox ProcessThis paper concentrates on the COPox technology at

ConocoPhillips. The COPox process is a synthesis gas generationtechnology. It is based on the catalytic partial oxidation of naturalgas:

The combination of these reactions can aid in our understandingof why ConocoPhillips COPox technology can result in a veryhighly efficient GTL process. Each of the other syngas technologiesuse these reactions and approach thermodynamic equilibrium. Letscompare several possible syngas generators to COPox process forGTL plants.

CH4 + O22 H2 + CO

This reaction is exothermic and with preheat can be runautothermally so that no additional external heat source is needed toaid in the generation of synthesis gas. We have found that successfulcatalytic partial oxidation should be operated with millisecondcontact times with Gas Hourly Space Velocities around 500,000 hr-1 .The high space velocity of the COPox process relative to othersystems means that the reactor volumes are considerably smaller

leading to lower reactor and catalyst costs.

1. Steam Methane Reformer (SMR)2. Autothermal Reformer (ATR)3. COPox Process4. Non-Catalytic POX reactor (POX)

An important understanding of a natural gas feed, Cobalt FTcatalyst based GTL Process is that H2 is consumed with CO in anoverall ratio of 2.0 to 2.2. The closer this ratio is achieved in thesyngas manufacturing step coupled with maximizing CO production,the more efficient the GTL Process will be.

We started the development of ConocoPhillips GTL technologyin 1997. We initially started working on Fischer Tropsch technology

but quickly realized that if we were to get a breakthrough in thisoverall area we would have to tackle the syngas generation costs aswell. Some studies were showing that upwards of 60% of the cost ofa GTL plant could be in the syngas and related areas of the plant.[1]It was clear, that even a breakthrough in Fischer Tropsch would notmake GTL economically viable without more.

There are several competitor syngas technologies used in a GTLprocess. Some potentially use a SMR to generate syngas. This usesthe steam methane reforming reaction to make syngas with a H2/COratio of about 3.

An ATR makes syngas from the combustion, reforming, andwater gas shift reaction. Oxygen is fed to the reactor so that the

Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem.2003, 48(2), 791

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system is autothermal. The H2/CO ratio of the syngas is dependentupon the steam to carbon ratio. Typically the steam to carbon ratioranges from 0.6 to 1.0 or even more. This S/C ratio results in asyngas with a H2/CO ratio of 2.3 2.5 or so. As the amount of steamdeclines the H2/CO ratio of the product syngas moves closer to thedesired 2.0.

Conclusions

In conclusion, the COPox process provides the means to havea high efficiency and lower cost GTL facility. ConocoPhillips hasspent the last 5 years developing the technology through thedemonstration scale. The Demonstration Plant is in thecommissioning stage and includes 2 reactors capable of producingsyngas for a 400 BPD Fischer Tropsch plant.

The COPox process will result in a syngas slightly below 2.0in practice. The higher-pressure operation reduces the ratio from theideal H2/CO ratio of 2 [2].

References:A non-catalytic POX reactor will result in a syngas H2/CO ratioin the 1.7-1.8 range. Figure 1 shows the H2/CO ratios of syngas

produced by these various means.

(1) Choi, G.; Kramer, S.; Tam, S.; and Fox, J; Prepr. Pap. - Am. Chem. Soc.,

Div. Fuel Chem., 1997, 42 (2), 667-671.(2) Allison, J. D.; Swinney L. D.; Niu, T; Ricketson, K; Wang, D; Ramani,

S.; Straguzzi, G. I.; Minahan, D. M.; Wright, H. A.; Hu, B.; U.S. PatentApplication 20020115730; 2002.

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.2

SMR ATR COPox POX

H2/COR

atioofSyngas

Figure 1. The Hydrogen to CO ratio of the syngas from varioussyngas generators determines the ultimate efficiency of the GTL

process.

Clearly the farther from the Fischer Tropsch ideal ratio slightlygreater than 2, then the more inefficient the overall GTL process

probably is.

Another way to look at syngas generators is to look at the CO yieldof the various means of producing syngas. If you pay for carbonfrom some natural gas source, it is clear that you want as much of it

as possible to end up as CO not carbon dioxide. Figure 2 shows thesingle pass CO yield of the COPox process versus an ATR with aS/C (steam to carbon) ratio of 1.0 and 1.5 (assuming no CO2 orheavy hydrocarbon recycling). You can now see why there will be acontinuing drive to lower the steam to carbon ratios in ATRs evenfurther.

50

55

60

65

70

75

80

85

90

95

ATR S/C = 1.5 ATR S/C = 1.0 CoPOX

Figure 2. Carbon Monoxide yields for several ATR cases versus aCOPox process. Assumes no recycle.

Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem.2003, 48(2), 792