Catalytic Partial Oxidation of Methane to Syngas and the DME Synthesis from the Syngas Containing N2

we try to use air instead of pure oxygen for a syngas production by CPO without an air-separation installation. The key question induced by air CPO is whether the syngas containing N2 could be effectively used for the

downstream product synthesis. For methanol synthesis, since a great deal of feedstock needs to be recycled for its low single pass conversion, the existence of N2 which

causes a large increase of compression cost of gases, is clearly unfit for its requirement. But for dimethyl ether, A great deal of experimental results have provided that the single pass CO conversion could be reached to 90% over many kinds of catalysts, which means the feedstock gases no longer need to be recycled. Therefore, we have done a lot of work on an integration of the air CPO with the DME synthesis from syngas containing N2, and

to see whether it could offer a cheaper route for DME production.

The effects of temperature on catalytic activities

T/℃ CH4 CO2 H2O CO H2 N2

500 14.43 7.69 25.09 0.60 9.66 42.53

550 12.79 7.96 22.72 1.39 13.70 41.45

600 10.74 7.88 20.17 2.80 18.32 40.09

650 8.33 7.30 17.65 4.94 23.28 38.51

700 5.78 6.33 15.34 7.56 28.17 36.82

750 3.46 5.24 13.45 10.16 32.41 35.29

800 1.74 4.31 12.17 12.20 35.43 34.15

850 0.75 3.65 11.56 13.50 37.05 33.50

(CH4/Air/H2O=1/2.4/0.8， 0.8MPa)

Catalytic Partial Oxidation of Methane and Air

The effects of H2O/CO2 ratios on catalytic activities

R CH4 CO2 H2O CO H2 N2

12/0 0.44 4.43 15.85 11.67 36.19 31.42

11/1 0.44 4.93 15.50 12.80 34.87 31.45

10/2 0.46 5.38 14.95 14.03 33.80 31.39

9/3 0.45 5.89 14.57 15.17 32.51 31.41

8/4 0.43 6.48 14.31 16.23 31.10 31.46

(R=H2O/CO2， 850℃， 1MPa， (H2O+CO2)/ CH4 =1.2/

1)

0

10

20

30

40

50

0 50 100 150 200 250 300 350 400 450

Reaction Periods (h)

Com

posi

tion

s(m

ol%

)H2

N2

CO2

CH4

CO

(850℃， 0.8MPa， Natural gas/Air/H2O/CO2＝ 1/2.4/0.8/0.

4)

The catalyst stability for CPO of methane with air

DME Synthesis from the Syngas Containing N2

40

50

60

70

80

90

100

210 220 230 240 250 260 270 280 290 300

Temperature℃

％

Conv.CO

Sel.DME

Y.DME

7.0MPa

The influence of temperature on catalytic properties

55

60

65

70

75

80

85

90

95

1000 1500 2000 2500 3000

SV (h-1)

％

Conv.COSel.DMEY.DME

The influence of space velocity on catalytic properties

5.0MPa

50

60

70

80

90

100

0 100 200 300 400 500

Reaction Periods(h)

%

Conv.CO Sel.DME Y.DME5.0MPa

The catalyst stability for DME synthesis

CH4

AirSyngas

(N2)

H2O

CO2

H2O

Catalytic Combustion

DME SynthesisReactor

DME

CO2

Electricity

Compressor Tail gas

Compressor

The process of DME synthesis from syngas obtained by catalytic partial oxidation of methane with air

0 1 2 3 4 5300

400

500

600

700

800

600¡æ700¡æ800¡æ

Tem

pera

ture

(¡æ

)

Height(cm)

640 680 720 760 80060

70

80

90

100

Equ.Exp.

H2sel.

COsel.

CH4conv.

Co

nve

rsio

n a

nd

Sel

ecti

vity

(%)

Temperature(¡æ)

Catalytic Partial Oxidation of Methane in Fluidized Bed Reactor

The temperature profiles in fluidized bed

The results of CPO in fluidized compared with the data calculated by thermodynamic

0 1 2 3 4 580

85

90

95

100

CH4conv. CO sel. H2sel.

Con

vers

ion

and

sele

ctiv

ity(

%)

Height(cm)

2.0 2.1 2.2 2.3 2.4 2.5 2.60

15

30

45

60

75

fixed bed fluidized bed

Car

bon

depo

sit(

mg)

CH4/O

2 ratio

The comparison of the results of carbon deposition in fixed bed and fluidized bed

The results of catalytic oxidation of methane along catalyst bed

85

87

89

91

93

95

97

99

0 30 60 90 120 150 180 210

Reaction Periods(h)

%

CH4conv. CO sel. H2sel.

The catalyst stability for CPO in fluidized bed

0 1 2 3 4 5

40

50

60

70

80

90

CH4+CO

2

CH4+O

2

7.2x103h

-1

1.44x104h

-1

7.2x103h

-1

1.44x104h

-1CH

4co

nv

ersi

on

(%)

Z(cm)

The results of catalytic oxidation of methane and methane reforming with carbon dioxide along catalyst bed