1. University of California at Berkeley
Upgrading of Light Alkanes via Co-homologation with Dimethyl Ether Catalyzed by Beta Zeolite
Dante Simonetti
John Ahn
Enrique Iglesia
University of California at Berkeley
BP MC2 Review January 14, 2009

2. Acidic zeolites facilitate methylation of alkenes

3. Acidic zeolites facilitate methylation of alkenes
Svelle et. al.-J. Phys. Chem. B 107 (2003)
Haw, J.F. et. al.-J. Am. Chem. Soc. 111 (1989)
Derouane, E.G. et. al.-Catal. Lett. 58 (1999) 1-19
Kazansky, V.B.-Catal. Today 51 (1999)
Rigby, A.M.-J. Catal. 171 (1997) 1-10
Olefins attack methylating species and form alkoxides

4. Acidic zeolites facilitate methylation of alkenes
Svelle et. al.-J. Phys. Chem. B 107 (2003)
Haw, J.F. et. al.-J. Am. Chem. Soc. 111 (1989)
Derouane, E.G. et. al.-Catal. Lett. 58 (1999) 1-19
Kazansky, V.B.-Catal. Today 51 (1999)
Rigby, A.M.-J. Catal. 171 (1997) 1-10
Olefins attack methylating species and form alkoxides
Alkoxides can H-transfer, crack, isomerize, and methylate via carbenium ion transition states

5. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

6. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

7. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

8. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

9. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

10. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

11. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

12. DME homologation on H-BEA driven by formation of stable carbenium ion intermediates

13. Rates (mmol C mol Al-1 s-1)
Adamantane appears to facilitate the incorporation of isobutane into homologation pathway 1 2 3 4 5 6 7 8 9 10 20 30 40 50 60
39 kPa DME, 62 kPa Ar 13
C-DME
Rates (mmol C mol Al-1 s-1)
Reactant Feed Consumption
267
Triptyl Formation 52
Isopentyl Formation 25
2,3-dimethylbutyl Formation
6.3
Selectivities are isobutane-free
Carbon Selectivity (%)
Carbon Number
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1)

14. Rates (mmol C mol Al-1 s-1)
Adamantane appears to facilitate the incorporation of isobutane into homologation pathway 1 2 3 4 5 6 7 8 9 10 20 30 40 50 60
39 kPa DME, 62 kPa Ar 13
39 kPa DME, 39 kPa Isobutane, 23 kPa Ar
C-DME 13
C-DME+isobutane
Rates (mmol C mol Al-1 s-1)
Reactant Feed Consumption
267
338
Triptyl Formation 52 79
Isopentyl Formation 25 47
2,3-dimethylbutyl Formation
6.3
10.3
Selectivities are isobutane-free
Addition of isobutane--negligible effect (slight increase in rates)
Carbon Selectivity (%)
Carbon Number
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1)

15. Rates (mmol C mol Al-1 s-1)
Adamantane appears to facilitate the incorporation of isobutane into homologation pathway 1 2 3 4 5 6 7 8 9 10 20 30 40 50 60
39 kPa DME, 62 kPa Ar 13
39 kPa DME, 39 kPa Isobutane, 23 kPa Ar
C-DME 13
39 kPa DME, 39 kPa Isobutane, 22 kPa Ar, ~1 kPa Adamantane
C-DME+isobutane 13
C-DME+isobutane+Adamantane
Rates (mmol C mol Al-1 s-1)
Reactant Feed Consumption
267
338
1060
Triptyl Formation 52 79
153
Isopentyl Formation 25 47
470
2,3-dimethylbutyl Formation
6.3
10.3 61
Selectivities are isobutane-free
Addition of isobutane--negligible effect (slight increase in rates)
Addition of adamantane to DME/isobutane system:
Shifts carbon selectivities and rates toward C5 and C6 products
Indicates that adamantane facilitates methylation of isobutane by DME
Decreases C7 carbon selectivity, but triptyl selectivity within C7 remains similar (~70%) and triptyl formation rate increases
Decrease in formation of C8+ species
Indicates adamantane may also facilitate “back-cracking/reincorporation”
Carbon Selectivity (%)
Carbon Number
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1)

16. Alkene:Alkane molar ratio
Adamantane appears to act as a dehydrogenation/hydrogenation co-catalyst
39 kPa DME, 62 kPa Ar
Alkene:Alkane molar ratio C5
0.7 C6
0.2
2-methylbutenes:
2-methylbutane
0.6
2,3-dimethylbutenes:
2,3-dimethylbutane
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1

17. Alkene:Alkane molar ratio
Adamantane appears to act as a dehydrogenation/hydrogenation co-catalyst
39 kPa DME, 62 kPa Ar
Alkene:Alkane molar ratio C5
0.7
0.6 C6
0.2
2-methylbutenes:
2-methylbutane
0.5
2,3-dimethylbutenes:
2,3-dimethylbutane
39 kPa DME, 39 kPa Isobutane, 23 kPa Ar
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1

18. Alkene:Alkane molar ratio
Adamantane appears to act as a dehydrogenation/hydrogenation co-catalyst
39 kPa DME, 62 kPa Ar
Alkene:Alkane molar ratio C5
0.7
0.6
4x10-3 C6
0.2
2-methylbutenes:
2-methylbutane
0.5
2x10-3
2,3-dimethylbutenes:
2,3-dimethylbutane
8x10-4
39 kPa DME, 39 kPa Isobutane, 23 kPa Ar
39 kPa DME, 39 kPa Isobutane, 22 kPa Ar, ~1 kPa Adamantane
Decrease in alkene to alkane ratios by orders of magnitude
Increase in branched hydrocarbon to linear hydrocarbon ratios by order of magnitude
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1

19. Alkene:Alkane molar ratio
Adamantane appears to act as a dehydrogenation/hydrogenation co-catalyst
39 kPa DME, 62 kPa Ar
Alkene:Alkane molar ratio C5
0.7
0.6
4x10-3 C6
0.2
2-methylbutenes:
2-methylbutane
0.5
2x10-3
2,3-dimethylbutenes:
2,3-dimethylbutane
8x10-4
39 kPa DME, 39 kPa Isobutane, 23 kPa Ar
39 kPa DME, 39 kPa Isobutane, 22 kPa Ar, ~1 kPa Adamantane
Decrease in alkene to alkane ratios by orders of magnitude
Increase in branched hydrocarbon to linear hydrocarbon ratios by order of magnitude
Increases alkane production by facilitating hydride transfer
Facilitates dehydrogenation of isobutane to isobutene as well as terminal alkane products and alkanes from cracking to active alkene species
Upgrading of isobutane to triptane
Increased carbon efficiency
Increased methylation rates (higher alkene pressures)
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.11 cm3 s-1 total inlet gas flow rate; 0.15 g H-BEA with Si:Al=12.5:1

20. Competitive reactions between 13C-labeled DME and unlabeled alkanes elucidate co-homologation pathways

21. Competitive reactions between 13C-labeled DME and unlabeled alkanes elucidate co-homologation pathways

22. Competitive reactions between 13C-labeled DME and unlabeled alkanes elucidate co-homologation pathways

23. Competitive reactions between 13C-labeled DME and unlabeled alkanes elucidate co-homologation pathways
Examine isotopomer distributions of triptane and its precursors as well as smaller species
Evidence of alkane methylation by DME and back-cracking

24. Competitive reactions between 13C-labeled DME and unlabeled alkanes elucidate co-homologation pathways
Examine isotopomer distributions of triptane and its precursors as well as smaller species
Evidence of alkane methylation by DME and back-cracking
Deviations from theoretical values provide insight into reincorporation and direct homologation
Determine effects of alkanes and adamantane on rates of methylation, H transfer, and cracking

25. Triptane can be produced from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 23 kPa He
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

26. Triptane can be produced from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 23 kPa He
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

27. Triptane can be produced from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 23 kPa He
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

28. Triptane can be produced from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 23 kPa He
Major peak of isotopomer distributions indicates co-homologation is occurring
Underlying binomial distribution of species with more 13C atoms suggest additional homologation pathways (i.e., cracking/reincorporation and direct homologation of 13C-DME)
Hydride transfer agents produced during direct homologation must be strong enough to activate isobutane to isobutene
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

29. Adamantane increases triptane formation from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 22 kPa He, ~1 kPa Adamantane
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

30. Adamantane increases triptane formation from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 22 kPa He, ~1 kPa Adamantane
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

31. Adamantane increases triptane formation from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 22 kPa He, ~1 kPa Adamantane
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

32. Adamantane increases triptane formation from methylation of isobutane by 13C-DME
39 kPa DME, 39 kPa Isobutane, 22 kPa He, ~1 kPa Adamantane
13C contents and isotopomer distributions show addition of 1, 2, and 3 13CH3 groups to isobutane to give singly labeled 2MB, doubly labeled 23DMB, and triply labeled triptane
Underlying binomial distribution of species with more 13C atoms suggest additional homologation pathways (i.e., cracking/reincorporation)
Adamantane addition leads to increase in conversion of isobutane to isobutene
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

33. Co-homologation of 13C-DME and 2,3-DMB shows similar results as DME/isobutane system
39 kPa DME, 39 kPa 23DMB, 23 kPa He
39 kPa DME, 39 kPa 23DMB, 22 kPa He, ~1 kPa Adamantane
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

34. Co-homologation of 13C-DME and 2,3-DMB shows similar results as DME/isobutane system
39 kPa DME, 39 kPa 23DMB, 23 kPa He
39 kPa DME, 39 kPa 23DMB, 22 kPa He, ~1 kPa Adamantane
Results indicate triptane production from addition of a single 13CH3 group to 23DMB
Adamantane addition increases contribution of co-homologation pathways (greater than 93% of triptane is from single methylation of 23DMB)
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

35. Isotopomer distributions of species smaller than co-feed alkane provide insight into cracking/reincorporation

36. Isotopomer distributions of species smaller than co-feed alkane provide insight into cracking/reincorporation
Species derived from cracking should have well-defined, non-binomial distributions if they have not been through a reincorporation cycle

37. Isotopomer distributions of species smaller than co-feed alkane provide insight into cracking/reincorporation
Reincorporation into homologation pathway provides opportunity for increased isotopic scrambling—i.e. binomial isotopomer distributions

38. Isotopomer distributions of species smaller than co-feed alkane provide insight into cracking/reincorporation
39 kPa DME, 39 kPa 23DMB, 23 kPa He
Non-binomial distributions for species smaller than the co-feed 23DMB
Possibly the result of back-cracking without reincorporation of smaller species into homologation pathway
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

39. Isotopomer distributions of species smaller than co-feed alkane provide insight into cracking/reincorporation
39 kPa DME, 39 kPa 23DMB, 22 kPa He, ~1 kPa Adamantane
Adamantane addition leads to binomial distributions for smaller species
Suggests reincorporation of these species into co-homologation cycle
473 K, 101 kPa total pressure, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1)

40. Increase in hydride transfer rate shows adamantane serves as a dehydrogenation/hydrogenation co-catalyst
473 K, 39 kPa DME, 39 kPa alkane, balance He, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

41. Increase in hydride transfer rate shows adamantane serves as a dehydrogenation/hydrogenation co-catalyst
No Adamantane
110 11
210 24 M M = 2 = 2 HT HT
Units in mmols C (mol Al s)-1
473 K, 39 kPa DME, 39 kPa alkane, balance He, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

42. Increase in hydride transfer rate shows adamantane serves as a dehydrogenation/hydrogenation co-catalyst
~1 kPa Adamantane
No Adamantane 64
800
110 11
560 51
210 24
0.7
0.8 M M = = HT HT 2 2
Units in mmols C (mol Al s)-1
473 K, 39 kPa DME, 39 kPa alkane, balance He, 0.7 cm3 s-1 gcat-1 (0.013 cm3 s-1 total inlet gas flow rate; g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

43. Light alkanes can be upgraded via co-homologation with DME in the presence of a hydrogen transfer co-catalyst

44. Light alkanes can be upgraded via co-homologation with DME in the presence of a hydrogen transfer co-catalyst
Increase in 12C content and rates of formation of products
Unimodal isotopomer distributions for larger products and binomial distributions for smaller products
Increase in methylation rates

45. Light alkanes can be upgraded via co-homologation with DME in the presence of a hydrogen transfer co-catalyst
Increase in 12C content and rates of formation of products
Unimodal isotopomer distributions for larger products and binomial distributions for smaller products
Increase in methylation rates

46. Light alkanes can be upgraded via co-homologation with DME in the presence of a hydrogen transfer co-catalyst
Decrease in alkene to alkane ratio
Decrease in M to HT ratio
Increase in HT rate
Increase in 12C content and rates of formation of products
Unimodal isotopomer distributions for larger products and binomial distributions for smaller products
Increase in methylation rates

47. These studies point to future research directions
What are the HT agents?
How do different HT agents compare and contrast?
HT mechanism—(aromatic formation)?

48. These studies point to future research directions
Initial C-C bond formation?
Transition state?
What are the HT agents?
How do different HT agents compare and contrast?
HT mechanism—(aromatic formation)?

49. These studies point to future research directions
Initial C-C bond formation?
Transition state?
What are the HT agents?
How do different HT agents compare and contrast?
HT mechanism—(aromatic formation)?
Run with DME as limiting reagent?
Can recycle unconverted isobutane?
What are optimum process conditions?
Can we process other low value hydrocarbons?
What other solid acids work?

50. Further Discussion?