1. Distributed production of DME based fuels using microwave technology and direct catalytic synthesis
Roger Ruan, Professor and Director
Paul Chen, Associate Research Professor and Program Director
Qinglong Xie, Peng Peng, Shiyu Liu, Bo Zhang, Erik Anderson, Yanling Cheng, Yuhuan Liu
Center for Biorefining and
Department of Biosystems and Bioproducts Engineering
and
Kasiviswanathan Muthukumarappan, Distinguished Professor
South Dakota State University

2. Dimethyl ether (DME) The simplest ether
Boiling point: -24 ºC, it is a colorless gas at room temperature
Relatively non-toxic

3. Applications Chemical feedstock Production of dimethyl sulfate
CH3OCH3 + SO3 → (CH3)2SO4
The largest use of DME
Consumes several thousand tons of DME annually

4. Applications Laboratory reagent and solvent
DME is a low-temperature solvent and extraction agent
Applicable to special laboratory procedures
Its usefulness is limited by its low boiling point

5. Applications Fuel in household and industry
DME can be used in diesel engines to increase the cetane number
As substitute for propane
Very low emissions of NOx, CO
and sulfur

6. DME synthesis Methanol synthesis: 2 H2 + CO → CH3OH
Catalyst: Cu-ZnO-based catalyst
Methanol dehydration:
2 CH3OH → CH3OCH3 + H2O
Catalyst: solid acid catalyst, such as γ-Al2O3, zeolites

7. DME synthesis 2 H2 + CO → CH3OH 2 CH3OH → CH3OCH3 + H2O
DME can be produced using two-step method or single-step method.
Single-step DME synthesis can overcome the equilibrium limitation in syngas to methanol process.
It has thermodynamic and economic advantages over two-step DME synthesis.

8. Overall goal
To develop a single-step method for distributed production of DME from biomass-derived syngas. 8

9. Specific objectives
Produce high-quality syngas from biomass through fast microwave-assisted gasification (fMAG)
Further improve syngas quality through cleaning and conditioning processes
Study single-step synthesis of DME from syngas
Examine the effect of zeolite type on the syngas-to-DME process 9

10. Distributed production of DME from biomass-derived syngas
Overall process
Fast microwave-assisted gasification
Syngas cleaning and purification
Effect of zeolite type
Single-step
DME synthesis
Biomass
Syngas

11. Distributed production of DME from biomass-derived syngas
Overall process

12. Fast microwave-assisted biomass conversion system12

13. Fast microwave-assisted gasification (fMAG)13

14. Proximate analysis (wt.%) Elemental analysis (wt.%)
fMAG of corn stover
Characteristics of corn stover
Proximate analysis (wt.%)
Elemental analysis (wt.%)
Moisture
5.3 C
40.38
Volatile
81.9 H
5.16
Fixed Carbon
10.7 N
0.38
Ash
2.1 O
52.01
Fe/Al2O3, Co/Al2O3, Ni/Al2O3 will be used as the catalysts.

15. fMAG: Effect of catalyst type on product distribution

16. fMAG: Effect of catalyst type on gas composition

17. fMAG: Effect of catalyst to feed ratio

18. Gas cleaning and purification
Gasifier
Tars, H2S, NH3 sorbents
O2 trap
Molecular sieve or Silica gel
Particle filter

19. Gas cleaning and purification systems

20. Gas cleaning and purification
Concentrations of impurities before and after cleaning
Impurities
Tar O2
NH3
H2S+COS
Before cleaning
ppm
0.1-2%
ppm
ppm
After cleaning
< 1 ppm
< 0.1 ppm
< 1 ppb

21. Single-step synthesis of DME from syngas
After purification, the syngas from biomass gasification can then be converted to DME.
Temp.: 260 ºC
Pressure: 50 bar
Catalyst:
Cu-ZnO-Al2O3 & zeolite (Bifunctional)

22. Single-step synthesis of DME from syngas

23. Effect of zeolite type on DME synthesis
Different zeolites were used as methanol dehydration catalyst

24. Single-step synthesis of DME from syngas
Characterization of zeolites
No.
Product name
Type
Framework
type
Si/Al
ratio
Pore size (Å)
BET surface
area (m2/g) 1
CBV28014
H-ZSM-5
MFI
280
5.6×5.3, 5.5×5.1
400 2
CBV8014 80
425 3
CBV3024E 30
405 4
CBV400
H-Y
FAU
5.1
7.4×7.4
730 5
CBV780
780 6
CP811C-300
H-Beta
BEA
300
7.6×6.4, 5.6×5.6
620 7
CP914C
H-Ferrierite
FER 20
4.2×5.4, 3.5×4.8

25. Single-step synthesis of DME from syngas
Effect of zeolite type on DME synthesis
No.
Catalyst
CO conversion
(%)
Selectivity (%)
DME yield
(g·kgcat-1·h-1)
DME
CH3OH
CO2 1
CZA-CBV28014
44.6
70.4
24.5
5.2
161.0 2
CZA-CBV8014
65.5
62.9
24.9
12.3
211.2 3
CZA-CBV3024E
87.8
65.9
3.4
30.7
297.0 4
CZA-CBV400
91.9
63.9
3.0
33.1
301.7 5
CZA-CBV780
50.6
23.3
64.5
12.2
60.6 6
CZA-CP811C-300
30.0
25.9
64.1
9.9
40.0 7
CZA-CP914C
93.0
61.4
2.8
35.8
293.4

26. Single-step synthesis of DME from syngas
NH3-TPD profiles for the bifunctional catalysts
The dehydration activity of zeolite is determined by its surface acidity.
Temperature programmed desorption

27. Single-step synthesis of DME from syngas
Surface acidity of catalysts as determined by NH3-TPD
No.
Catalyst
Density of acid sites (µmol NH3/g)
Density of acid sites
(µmol NH3/g) T1 T2 T3 T4
Total
Weak
Strong 1
CZA-CBV28014
465.8
266.4 –
242.6
974.8
509.0 2
CZA-CBV8014
345.5
128.2
284.8
225.1
983.6
638.1 3
CZA-CBV3024E
955.6
961.4
518.9
2435.9
1480.3 4
CZA-CBV400
722.2
547.4
434.7
1704.3
982.1 5
CZA-CBV780
432.8
205.6
221.0
338.7
1198.1
765.3 6
CZA-CP811C-300
337.3
383.0
364.4
1084.7
747.4 7
CZA-CP914C
720.0
679.8
344.3
1744.1
1024.1
Methanol synthesis:
2 H2 + CO → CH3OH
Acid sites help methanol dehydration
Methanol dehydration:
2 CH3OH → CH3OCH3 + H2O

28. Single-step synthesis of DME from syngas
CO conversion as a function of time on stream (TOS)
The catalyst stability is also influenced by zeolite type.

29. Conclusions
Syngas of high yield and quality was obtained from fast microwave-assisted gasification (fMAG) of biomass.
The impurities in syngas were removed by gas cleaning and purification processes.
DME was produced from biomass-derived syngas using single-step method with different zeolites. 29

30. Acknowledgments:
Related Group Members and Collaborators: B. Polta, J. Willett, A. Sealock, R. Hemmingsen, P. Chen, M. Min, W. Zhou, M. Mohr, Y. Chen, L. Wang, Yecong Li, Bing Hu, Q. Kong, X. Wang, Y. Wan, K. Hennessy, Y. Liu, X. Lin, Yun Li, Y. Cheng, S. Deng, Q. Chen, C. Wang, Y. Wang, Z. Du, X. Lu, Z. Wang, R. Griffith, J. Thissen, Q. Xie, Y. Nie, F. Borge, F. Hussain, Y. Jiang, Y. Sun, Z. Fu, R. Zhu, A. Olson, B. Martinez, B. Zhang, J. Zhu, B. Hu, L. Schmidt, D. Kittelson, R. Morey, D. Tiffany, F. Yu, H. Lei, X. Ye, M. Muthukumarappan, P. Heyerdahl, ……
Funding Agencies: 30

31. Thank you! Questions?