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

Acidic zeolites facilitate methylation of alkenes

Acidic zeolites facilitate methylation of alkenes Svelle et. al.-J. Phys. Chem. B 107 (2003) 9281-9289 Haw, J.F. et. al.-J. Am. Chem. Soc. 111 (1989) 2052-2058 Derouane, E.G. et. al.-Catal. Lett. 58 (1999) 1-19 Kazansky, V.B.-Catal. Today 51 (1999) 419-434 Rigby, A.M.-J. Catal. 171 (1997) 1-10 Olefins attack methylating species and form alkoxides

Acidic zeolites facilitate methylation of alkenes Svelle et. al.-J. Phys. Chem. B 107 (2003) 9281-9289 Haw, J.F. et. al.-J. Am. Chem. Soc. 111 (1989) 2052-2058 Derouane, E.G. et. al.-Catal. Lett. 58 (1999) 1-19 Kazansky, V.B.-Catal. Today 51 (1999) 419-434 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

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

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

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

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

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

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

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

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

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)

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)

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)

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

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

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

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

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

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

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

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

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

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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

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

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

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1)

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; 0.020 g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

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; 0.020 g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

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; 0.020 g H-BEA with Si:Al=12.5:1; Conversion=1-3%)

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

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

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

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

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

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)?

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?

Further Discussion?