Brønsted acid catalysis Carbocation chemistry

Brønsted acid catalysis Carbocation chemistry
Homologation of dimethyl ether and larger oxygenates to higher hydrocarbons on acidic zeolites Brønsted acid catalysis Carbocation chemistry CH3OH “Acid” H2O CH3OCH3 473 K Acidic Zeolites Solid acids, specifically zeolites, catalyze the selective production of triptane via a chain growth reaction mechanism that involves the formation of methylating agents from DME on acid sites with the rejection of oxygen as water. C-C bond formation occurs when olefins attack these methyl species to form alkoxides (represented here and throughout by the carbenium cation). Chain growth occurs when the carbenium ion desorbs as an olefin and attacks additional methyl species to form triptane. Chain termination as an alkane occurs via hydride transfer from a hydrogen donor to a surface alkoxide. Isomerization and cracking are two additional reactions that can occur on solid acids that will cause deviation from the pathways that lead to triptane. HT Dante Simonetti + + Is BP MC2 Review H+ “CH3” C Me November 19, 2009 Berkeley, CA +C1

Kinetic specificity for triptane formation based on properties of carbocationic intermediates
13CH3O13CH3 + + + + H+ “CH3” “CH3” “CH3” “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species.

HT 13CH3O13CH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me C The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Is Determine individual rates of methylation, hydride transfer, isomerization, and cracking Investigate effects of chain size on chain growth, isomerization, and cracking

HT CH3OCH3 + + + + H+ “CH3” “CH3” “CH3” Me The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Selective methyl addition to preserve structures required for triptane

HT CH3OCH3 + + + + H+ “CH3” “CH3” “CH3” Me The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Selective methyl addition to preserve structures required for triptane Structures formed via methyl addition have low susceptibility to cracking and isomerization Chains preferentially terminate at triptane

HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + Is “CH3” “CH3” “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. “CH3” + + C Selective methyl addition to preserve structures required for triptane Structures formed via methyl addition have low susceptibility to cracking and isomerization Chains preferentially terminate at triptane Rapid isomerization and cracking of C8-C9 chains leads to iso-C4 products which may be reincorporated

Olefins serve as hydride donors and lead to formation of polymethylated aromatic species
HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 CH3OCH3 (CH2)2 RH R Hydride Transfer

Olefins serve as hydride donors and lead to formation of polymethylated aromatic species
HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 (CH2)2 Hydride Transfer Olefins serve as hydride donors during hydride transfer Formation of hexamethylbenzene satisfies hydrogen requirement for paraffin production

Upgrading paraffins or using external RH2 source can mitigate loss of carbon as aromatics
HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 (CH2)2 X Hydride Transfer CnH2n+2 Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species

HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O H2 “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 Pt (CH2)2 X Hydride Transfer Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species External hydrogen sources can be used with a hydrogen-activation catalyst (e.g., Pt)

HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O H2 “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 Pt (CH2)2 X Hydride Transfer CnH2n+2 Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species External hydrogen sources can be used with a hydrogen-activation catalyst (e.g., Pt)

Alternative hydrogen sources and homologation of alcohols and larger oxygenates
C2H5OC2H5 C2H5OC2H5 HT + CH3OH ? + + ? + + … … “C2H5” H+ “CH3” “CH3” “CH3” “CH3” Me + H2O H2 “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 Pt (CH2)2 X Hydride Transfer CnH2n+2 Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species External hydrogen sources can be used with a hydrogen-activation catalyst (e.g., Pt) Homologation of methanol and ethanol/diethyl ether

Computational studies of reactions during chain growth and termination
C2H5OC2H5 C2H5OC2H5 HT + CH3OH ? + + + + ? … … “C2H5” H+ “CH3” “CH3” “CH3” “CH3” Me + H2O H2 “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 Pt (CH2)2 X Hydride Transfer CnH2n+2 Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species External hydrogen sources can be used with a hydrogen-activation catalyst (e.g., Pt) Homologation of methanol and ethanol/diethyl ether DFT studies of effects of olefin/paraffin size/shape on energy barriers for HT, Me, and deprotonation reactions

C-C Bond Formation Paths
Olefin/Alkoxide Examined Here Olefin/Protonated Alcohol In progress The C-C bond formation paths examined here include the addition of olefins as well as alcohols to alkoxide intermediates in Mordenite. Sauer et al. have examined the addition of olefins to protonated alcohols which can also occur (the barriers are very similar). Alcohol with Alkoxide In progress

Methylation of Ethylene
+ -0.07 eV Reactant State 0.36 eV 0.81 eV -1.25 eV d+ All energies relative to adsorbed methyl and ethylene in the gas phase Intermediate contains a penta-coordinated carbon – although one C-C bond is longer than the other C-C bond Intermediate rotates to form alkoxide d+ d+ d+ Product State Intermediate TS

Trends in Olefin Addition (to methoxy)
Activation Energy (eV) Carbenium Ion Energy (eV) Ethylene 0.81 0.40 Propylene 0.63 0.04 1-Butene 0.65 0.02 2-Butene 0.43 -0.12 1 2 2 2 All energies referenced to gas phase (We will redo some of these in a more systematic manner and in addition calculate VDW interactions which require a more rigorous set of calculations. Propylene and 1-butylene should adsorb more strongly than ethylene but less strongly than 2-butene.) Why does 2-butene have lower barrier than 1-butene and propylene even though all three form secondary carbenium ion? Answer is on the next slide 1 Primary carbenium ion in intermediate 2 Secondary carbenium ion in intermediate

Trends in Olefin Addition (to protonated alcohol/ether – work in progress)
Activation Energy (eV) Carbenium Ion Energy (eV) Ethylene 0.81 0.40 Propylene 0.63 0.04 1-Butene 0.65 0.02 2-Butene 0.43 -0.12 1 2 2 2 All energies referenced to gas phase (We will redo some of these in a more systematic manner and in addition calculate VDW interactions which require a more rigorous set of calculations. Propylene and 1-butylene should adsorb more strongly than ethylene but less strongly than 2-butene.) Why does 2-butene have lower barrier than 1-butene and propylene even though all three form secondary carbenium ion? Answer is on the next slide 1 Primary carbenium ion in intermediate 2 Secondary carbenium ion in intermediate

1-butene 2-butene More charge delocalization => TS more stable
Why does 2-butene interact more strongly? 1-butene 2 1 + CH3 + CH3 CH3+ 2-butene 2 2 In the adsorbed state, the transition state, and the intermediate carbenium ion, the CH3 interacts with both of the carbons of the double bond This structure can be described by a combination of three resonance structures For 2-butene, the last two resonance structures are secondary carbenium ions For 1-butene and propylene, one of the resonance structures is primary, leading to less stability of the TS For ethylene, both resonance structures are primary + + CH3 CH3 CH3+ More charge delocalization => TS more stable

+ Hydride Transfer Between Isobutane and Propoxy 0.50 eV Isobutane
Reactant State Requires significant energy to get reactants together in zeolite framework Forms bridged hydride intermediate Intermediate rotates and forms alkoxy and alkane Rotation may have no barrier, but decomposition of the bridged hydride likely does Propane d+ t-butoxy rotate d- 0.87 eV 1.25 eV 0.77 eV Propane + t-butoxy Intermediate TS

Trends in Hydride Transfer (isobutAne to alkoxide)
Olefin Activation Energy 1-propoxy 1.29 2-butoxy 1.40 3-pentoxy 1.20 1 2 2 All energies referenced to adsorbed alkoxy Hydride comes from 2-butane in all cases Large repulsion to get species together in the zeolite due to large size of both reactants repulsion here is difficult to calculate. Will likely need a more rigorous approach. We are currently trying to predict the vdw interactions via the approach by Sauer. Maybe best to use smaller hydride doner and/or larger pore zeolite 1 Primary carbenium ion in TS and intermediate 2 Secondary carbenium ion in TS and intermediate

Trends in Hydride Transfer (isobutEne to alkoxide – work in progress)
Olefin Activation Energy 1-propoxy 1.29 2-butoxy 1.40 3-pentoxy 1.20 1 2 2 All energies referenced to adsorbed alkoxy Hydride comes from 2-butane in all cases Large repulsion to get species together in the zeolite due to large size of both reactants repulsion here is difficult to calculate. Will likely need a more rigorous approach. We are currently trying to predict the vdw interactions via the approach by Sauer. Maybe best to use smaller hydride doner and/or larger pore zeolite 1 Primary carbenium ion in TS and intermediate 2 Secondary carbenium ion in TS and intermediate

HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 (CH2)2 X Hydride Transfer CnH2n+2 Converting a paraffin to a larger paraffin using (CH2) groups does not require formation of unsaturated species

Adamantane catalyzes hydride transfer in the direction of equilibrium
HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Co-feed DME with isobutane, n-butane, and 2,3-dimethylbutane, and propene to examine effects of adamantane

473 K, H-BEA 60 60 50 50 40 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 P:HMB 30 Products 20 20 HMB 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 50 50 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 30 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number

473 K, H-BEA 60 60 70 kPa DME 1 kPa C3H6 50 50 40 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 20 300 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 50 50 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 30 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number

473 K, H-BEA 60 60 70 kPa DME 1 kPa C3H6 50 50 Decrease in triptane selectivity 40 40 1 kPa Ada Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 20 300 20 70 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 50 50 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 30 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number

473 K, H-BEA 60 60 70 kPa DME 1 kPa C3H6 50 50 Decrease in triptane selectivity 40 40 1 kPa Ada Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 20 300 20 70 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 130 P:HMB P:HMB 50 50 114 40 kPa DME 40 kPa C4H10 130 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 40 kPa DME 40 kPa C6H14 40 kPa DME 40 kPa C6H14 300 Carbon Selectivity (%) Carbon Selectivity (%) 30 30 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number

473 K, H-BEA 60 60 70 kPa DME 1 kPa C3H6 50 50 Decrease in triptane selectivity 40 40 1 kPa Ada Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 20 300 20 70 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 130 P:HMB P:HMB 50 50 114 40 kPa DME 40 kPa C4H10 130 170 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 300 40 40 kPa DME 40 kPa C6H14 Carbon Selectivity (%) Carbon Selectivity (%) 30 1 kPa Ada 440 30 1 kPa Ada 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number Increase in n+1 species because of high conversion of co-feed paraffin to olefin

473 K, H-BEA 60 60 70 kPa DME 1 kPa C3H6 50 50 40 kPa DME 40 kPa C4H10 Decrease in triptane selectivity 40 40 1 kPa Ada Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 130 20 300 20 P:HMB 180 70 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 130 P:HMB P:HMB 50 50 114 40 kPa DME 40 kPa C4H10 130 170 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 40 kPa DME 40 kPa C6H14 300 Carbon Selectivity (%) Carbon Selectivity (%) 30 1 kPa Ada 440 30 1 kPa Ada 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number Increase in n+1 species because of high conversion of co-feed paraffin to olefin

473 K, H-BEA Low rates of n-butane activation (secondary H) 60 60 70 kPa DME 1 kPa C3H6 50 50 40 kPa DME 40 kPa C4H10 Decrease in triptane selectivity 40 40 1 kPa Ada 1 kPa Ada Carbon Selectivity (%) Carbon Selectivity (%) 30 30 P:HMB 130 20 300 20 P:HMB 180 70 150 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number 60 60 130 P:HMB P:HMB 50 50 114 40 kPa DME 40 kPa C4H10 130 170 40 Non-isotopic studies reveal the effects of adamantane on the product distribution and also reveal that adamantane serves as a HT co-catalyst. In the absence of an alkane co-feed, adamantane shifts the C selectivity to smaller hydrocarbons. 40 kPa DME 40 kPa C6H14 300 40 Carbon Selectivity (%) Carbon Selectivity (%) 30 1 kPa Ada 440 30 1 kPa Ada 20 20 10 10 1 2 3 4 5 6 7 8+ 1 2 3 4 5 6 7 8+ Carbon Number Carbon Number Increase in n+1 species because of high conversion of co-feed paraffin to olefin

HT + + + … … “CH3” “CH3” Me 13CH3O13CH3 + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Co-feed 13C-DME with isobutane, 2-methylbutane, and 2,3-dimethylbutane

Adamantane facilitates co-homologation of paraffins via dehydrogenation
473 K 13CH3O13CH3 40 kPa 13C-DME 40 kPa Paraffin . Products Products Products HMB . HMB . HMB . . 100 100 100 . . . 90 90 90 . 80 . 80 80 70 70 70 60 60 60 %C in products from isobutane %C in products from 2-methylbutane %C in products from 2,3-dimethylbutane 50 50 50 We can investigate the effectiveness of such a system by studying competitive reactions of unlabeled paraffins and 13C-DME and measuring the rates of M and HT as well as the content of carbon in the products that is from the paraffin co-feed (12C). 40 40 40 30 30 30 20 20 20 10 10 10

473 K 13CH3O13CH3 40 kPa 13C-DME 40 kPa Paraffin . Products 5 Products 20 Products 25 HMB . HMB . HMB . . 100 100 100 . . . 90 90 90 . 80 . 80 80 70 70 70 60 60 60 %C in products from isobutane %C in products from 2-methylbutane %C in products from 2,3-dimethylbutane 50 50 50 We can investigate the effectiveness of such a system by studying competitive reactions of unlabeled paraffins and 13C-DME and measuring the rates of M and HT as well as the content of carbon in the products that is from the paraffin co-feed (12C). 40 40 40 30 30 30 20 20 20 10 10 10 Simply increasing paraffin concentration pushes dehydrogenation/hydrogenation equilibrium toward olefins

473 K 13CH3O13CH3 40 kPa 13C-DME 40 kPa Paraffin 1 kPa Ada . Products 5 Products 20 Products HMB . 25 20 HMB 30 . HMB 41 . . 100 100 100 . . . 90 90 90 . 80 . 80 80 70 70 70 60 60 60 %C in products from isobutane %C in products from 2-methylbutane %C in products from 2,3-dimethylbutane 50 50 50 We can investigate the effectiveness of such a system by studying competitive reactions of unlabeled paraffins and 13C-DME and measuring the rates of M and HT as well as the content of carbon in the products that is from the paraffin co-feed (12C). 40 40 40 30 30 30 20 20 20 10 10 10 Simply increasing paraffin concentration pushes dehydrogenation/hydrogenation equilibrium toward olefins Adamantane increases amount of co-feed paraffin incorporated into homologation products Decrease in rate of HMB formation relative to homologation products

473 K 40 kPa 13C-DME 40 kPa Paraffin 1 kPa Ada HT + + + … … “CH3” “CH3” Me 13CH3O13CH3 + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species.

473 K 40 kPa 13C-DME 40 kPa Paraffin 1 kPa Ada HT + + + … … “CH3” “CH3” Me 13CH3O13CH3 + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Men HTn + bn =

473 K 40 kPa 13C-DME 0.5 40 kPa Paraffin 0.4 Men HTn + bn = 0.3 0.2 The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. 0.1

473 K 40 kPa 13C-DME 0.5 40 kPa Paraffin 1 kPa Ada 0.4 Men HTn + bn = 0.3 0.2 The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. 0.1 Adamantane increases termination probability

HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 (CH2)2 X Hydride Transfer CnH2n+2 Paraffins are a viable source of H-atoms Adamantane will catalyze dehydrogenation-hydrogenation in the direction of equilibrium

Molecular hydrogen as external source of H-atoms
HT + CH3OCH3 + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + H2O H2 “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. CnH2n CnH2n+2 HMB CH3OCH3 Pt (CH2)2 X Hydride Transfer External hydrogen sources can be used with a hydrogen-activation catalyst (e.g., Pt)

External H2 can be used as hydrogen source with Pt/SiO2
Triptane 100 kPa DME kPa propene H-BEA iC4/nC4 50 40 2MB 23DMB/MP Carbon Selectivity (%) 30 20 10 C1-2 C4 C5 C6 C7 C8+ Paraffins:HMB 0.75 Olefin:Paraffin 0.50 0.25 0.00 C4 C5 C6

Triptane 100 kPa DME kPa propene H-BEA iC4/nC4 50 40 2MB 23DMB/MP Carbon Selectivity (%) 70 76/23 30 87 40/54 20 10 C1-2 C4 C5 C6 C7 C8+ Paraffins:HMB 0.75 40 Olefin:Paraffin 0.50 0.25 0.00 C4 C5 C6

iC4/nC4 Triptane 100 kPa DME kPa propene H-BEA 50 81/18 40 2MB 23DMB/MP 83 Carbon Selectivity (%) 70 76/23 100 kPa DME 100 kPa H kPa propene H-BEA:Pt = 34:1 30 90 45/47 87 40/54 20 10 C1-2 C4 C5 C6 C7 C8+ Paraffins:HMB 0.75 40 1.0 Olefin:Paraffin 0.50 0.25 0.00 C4 C5 C6

iC4/nC4 Triptane 100 kPa DME kPa propene H-BEA 50 81/18 40 2MB 23DMB/MP 83 Carbon Selectivity (%) 70 76/23 90 100 kPa DME 100 kPa H kPa propene H-BEA:Pt = 34:1 30 45/47 87 40/54 20 10 C1-2 C4 C5 C6 C7 C8+ Paraffins:HMB 0.75 40 1.0 Olefin:Paraffin 0.50 0.25 0.00 C4 C5 C6 H2 addition using Pt shifts selectivity toward lighter species Olefin concentration within reactor significantly decreases Formation rate of HMB decreases relative to homologation products

Polefins L (catalyst bed or crystallite pore)

Polefins H2+Pt L (catalyst bed or crystallite pore) H2+Pt decreases concentration of olefins in reactor Preserves triptane structures Hydrogenates olefins prior to methylation to triptane

Polefins H2+Pt L (catalyst bed or crystallite pore) H2+Pt decreases concentration of olefins in reactor Preserves triptane structures Hydrogenates olefins prior to methylation to triptane H2+Pt not viable source of H-atoms (compared to paraffins+adamantane) Lowers concentration of chain initiators

C2H5OC2H5 C2H5OC2H5 HT + CH3OH + + + + ? … … “C2H5” H+ “CH3” “CH3” “CH3” “CH3” Me + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Homologation of methanol and ethanol/diethyl ether

Dehydration of methanol occurs without subsequent DME homologation to hydrocarbons
X 60 kPa Methanol DME, H2O, MeOH mixture at equilibrium DME H2O MeOH Triptane It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period.

Dehydration of methanol occurs without subsequent DME homologation to hydrocarbons
X 60 kPa Methanol DME, H2O, MeOH mixture at equilibrium DME H2O MeOH Triptane 80 kPa Methanol 1 kPa C3H6 H-BEA K 40 kPa DME kPa C3H kPa water H-BEA K It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period. H-BEA K 40 kPa DME kPa C3H6

Presence of water leads to decrease in rate and selectivity to triptane
DME+C3 1 0.8 0.6 0.4 0.2 DME Consumption Rate (10-3 mol C/[mol Al s]-1) C4 olefin:paraffin molar ratio C5 olefin:paraffin molar ratio C6 olefin:paraffin molar ratio It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period. 60 Triptane in C7 50 62% 40 23DMB in C6 Carbon Selectivity (%) 30 43% 20 10 1 2 3 4 5 6 7 8+ 473 K, HBEA Carbon number

DME+C3 MeOH+C3 1 0.8 0.6 0.4 0.2 DME Consumption Rate (10-3 mol C/[mol Al s]-1) C4 olefin:paraffin molar ratio C5 olefin:paraffin molar ratio C6 olefin:paraffin molar ratio It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period. 60 Triptane in C7 50 62% 40 23DMB in C6 24% Carbon Selectivity (%) 30 43% 24% 20 10 1 2 3 4 5 6 7 8+ 473 K, HBEA Carbon number

DME+C3 MeOH+C3 DME+H2O+C3 1 0.8 0.6 0.4 0.2 DME Consumption Rate (10-3 mol C/[mol Al s]-1) C4 olefin:paraffin molar ratio C5 olefin:paraffin molar ratio C6 olefin:paraffin molar ratio It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period. 60 Triptane in C7 50 62% 40 23DMB in C6 24% Carbon Selectivity (%) 30 43% 20% 24% 20 22% 10 1 2 3 4 5 6 7 8+ 473 K, HBEA Carbon number

DME+C3 MeOH+C3 DME+H2O+C3 1 0.8 0.6 0.4 0.2 DME Consumption Rate (10-3 mol C/[mol Al s]-1) C4 olefin:paraffin molar ratio C5 olefin:paraffin molar ratio C6 olefin:paraffin molar ratio Lower rate of DME consumption Decrease in olefin:paraffin ratio It is possible that in the absence of an alkene co-feed, an induction period is required and that the water increases the length of this induction period. Thus, we investigated the effect of water on the rates and selectivities of DME homologation using propene to eliminate this induction period. 60 Triptane in C7 50 Decrease in selectivity to triptane 62% 40 23DMB in C6 24% Carbon Selectivity (%) 30 43% 20% 24% 20 22% 10 1 2 3 4 5 6 7 8+ 473 K, HBEA Carbon number

Water leads to an increase in termination probability
HT + H+ “CH3” Me From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition.

. . . . . . . . . HT . . . + + + + . . . H+ “CH3” “CH3” “CH3” Me . . . From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition.

. . . . . . . . . HT . . . Is + + + + . . . H+ “CH3” “CH3” “CH3” Me . . . From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition.

. . . . . . . . . HT . . . Is + + + + . . . H+ “CH3” “CH3” “CH3” Me . . . From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition. Is b = HT HT + Me HT + Me Rates in 10-6 mol C [mol Al s]-1

. . . . . . 10 . . . HT 120 . . . Is + + + + . . . H+ “CH3” “CH3” “CH3” Me . . . From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition. Is <10-4 b = HT 0.08 = = HT + Me HT + Me Rates in 10-6 mol C [mol Al s]-1

. . . . . . . 10 . . HT 90 . . . Is 120 + + + + 26 . . . H+ “CH3” “CH3” “CH3” Me . H2O . . From these rates, we can calculate a termination probability, beta, defined as the rate of HT divided by the sum of the rates of M and HT. We can also measure the rate relative rate of isomerization (unlabeled isobutane) to HT. M decreases, HT increases, Beta and Is/HT increase with water addition. Is <10-4 b = HT 0.08 = = HT + Me HT + Me 0.3 0.80 Increase in termination and isomerization probabilities Rates in 10-6 mol C [mol Al s]-1

Water displaces methyl groups and disrupts chain growth
Decrease in selectivity to triptane Decrease in rate of DME consumption Decrease in olefin:paraffin ratio Increase in termination and isomerization probabilities Four effects of the presence of water. Could this simply be a result of methyl displacement?

Decrease in selectivity to triptane Decrease in rate of DME consumption Decrease in olefin:paraffin ratio Increase in termination and isomerization probabilities Displacement of methyl groups disrupts chain propagation Four effects of the presence of water. Could this simply be a result of methyl displacement?

Decrease in selectivity to triptane Decrease in rate of DME consumption Decrease in olefin:paraffin ratio Increase in termination and isomerization probabilities Displacement of methyl groups disrupts chain propagation Methylation: Deprotonation of alkoxide forming olefin Four effects of the presence of water. Could this simply be a result of methyl displacement?

Decrease in selectivity to triptane Decrease in rate of DME consumption Decrease in olefin:paraffin ratio Increase in termination and isomerization probabilities Displacement of methyl groups disrupts chain propagation Methylation: Deprotonation of alkoxide forming olefin; olefin attacks methylating species Methylating species Four effects of the presence of water. Could this simply be a result of methyl displacement?

Decrease in selectivity to triptane Decrease in rate of DME consumption Decrease in olefin:paraffin ratio Increase in termination and isomerization probabilities Displacement of methyl groups disrupts chain propagation Four effects of the presence of water. Could this simply be a result of methyl displacement?

C2H5OC2H5 C2H5OC2H5 HT + CH3OH ? + + + + … … “C2H5” H+ “CH3” “CH3” “CH3” “CH3” Me + “CH3” The relative rates of methylation, hydride transfer, isomerization, and cracking were determined from previous studies of competitive reactions between 13C-DME and unlabeled alkenes. These studies revealed the detailed mechanism for triptane formation involving 1.) Preferential methyl addition to preserve the four carbon backbone necessary for triptane 2.) Low rates of isomerization which causes deviation from triptane formation by lenghthening or shortening chains 3.) Low rates of b-scission for triptane and its precursors, but rapid isomerization and cracking of species larger than triptane. Leading to high amounts of isobutane and allowing the opportunity to correct for overgrowth. 4.) Low termination probabilities for triptyl precursors but high termination probabilities for triptyl surface species. Homologation of methanol and ethanol/diethyl ether

Carbon Selectivity (%)
Dehydration of ethanol and diethyl ether without formation of higher hydrocarbons Ethanol Trace amounts of DME homologation products C2H4 100 90 80 70 Carbon Selectivity (%) 60 50 40 30 20 10 71 kPa EtOH 55 kPa DME, 11 kPa DEE

Dehydration of ethanol and diethyl ether without formation of higher hydrocarbons H2O DEE Dehydration to DEE and ethylene only Ethanol H2O Trace amounts of DME homologation products C2H4 H2O C2H4 100 DEE 90 80 70 Carbon Selectivity (%) 60 50 40 C2H4 30 20 10 71 kPa EtOH 55 kPa DME, 11 kPa DEE

Dehydration of ethanol and diethyl ether without formation of higher hydrocarbons H2O DEE Ethanol H2O Trace amounts of DME homologation products C2H4 H2O C2H4 100 DEE 90 80 70 Carbon Selectivity (%) 60 50 40 C2H4 30 20 10 71 kPa EtOH 55 kPa DME, 11 kPa DEE

Dehydration of ethanol and diethyl ether without formation of higher hydrocarbons H2O DEE Dehydration to ethylene only Ethanol H2O Trace amounts of DME homologation products C2H4 H2O C2H4 C2H4 100 DEE 90 80 70 Carbon Selectivity (%) 60 50 40 C2H4 30 20 10 71 kPa EtOH 63 kPa DEE 55 kPa DME, 11 kPa DEE

Ethanol/DEE produces less highly branched structures that are more susceptible to cracking
n-butane

C6: methyl-pentanes n-butane

C8: dimethyl-hexanes methyl, ethyl-pentane C6: methyl-pentanes n-butane

C8: dimethyl-hexanes methyl, ethyl-pentane C10: trimethyl-heptanes dimethyl, ethyl-hexanes C6: methyl-pentanes n-butane

C8: dimethyl-hexanes methyl, ethyl-pentane C10: trimethyl-heptanes dimethyl, ethyl-hexanes C6: methyl-pentanes n-butane Cracking may prevent formation of larger hydrocarbons Mixture of hydrocarbons over wider molecular weight distribution

Co-homologation of methanol with higher alcohols for the selective production of triptane
CH3OH HT + + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me

CH3OH CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me

CH3OH CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me Dehydration of alcohol provides olefins for DME homologation

Mixture of DME and DEE leads to ethylene without subsequent methylation by DME H2O DEE Ethanol H2O Trace amounts of DME homologation products C2H4 H2O C2H4 C2H4 DEE Carbon Selectivity (%) C2H4 71 kPa EtOH 63 kPa DEE

Mixture of DME and DEE leads to ethylene without subsequent methylation by DME H2O DEE C2H4 Triptane Ethanol H2O DME Trace amounts of DME homologation products C2H4 H2O C2H4 C2H4 DEE Carbon Selectivity (%) C2H4 71 kPa EtOH 63 kPa DEE 55 kPa DME, 11 kPa DEE

Methylation rate of ethylene is more than an order of magnitude less than propylene
13CH3O13CH3 + + + + + “CH3” “CH3” “CH3” “CH3” “CH3” Me

Methylation rate of ethylene is more than an order of magnitude less than propylene
13CH3O13CH3 + + + + + “CH3” “CH3” “CH3” “CH3” “CH3” “CH3” Me

Rate of methylation 10-6 mol [mol Al s]-1
Methylation rate of ethylene is more than an order of magnitude less than propylene 13CH3O13CH3 + + + + + “CH3” “CH3” “CH3” “CH3” “CH3” “CH3” Me 2 30 60 60 70 35 Rate of methylation 10-6 mol [mol Al s]-1

Methylation rate of ethylene is more than an order of magnitude less than propylene 13CH3O13CH3 + + + + + “CH3” “CH3” “CH3” “CH3” “CH3” “CH3” Me 2 30 60 60 70 35 Rate of methylation 10-6 mol [mol Al s]-1 Formation of less stable carbocationic intermediate from methyl addition to ethylene

Methylation rate of ethylene is more than an order of magnitude less than propylene 13CH3O13CH3 + + + + + “CH3” “CH3” “CH3” “CH3” “CH3” “CH3” Me 2 30 60 60 70 35 Rate of methylation 10-6 mol [mol Al s]-1 Formation of less stable carbocationic intermediate from methyl addition to ethylene High energy barrier for ethylene methylation hinders co-homologation of methanol and ethanol

CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me DEE Dehydration of alcohol provides olefins for DME homologation

CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me Dehydration of alcohol provides olefins for DME homologation

CH3OH CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me Dehydration of alcohol provides olefins for DME homologation

CH3OH CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me Coupling of alcohols on base, followed by homologation on acid C2H5OH + CH3OH

CH3OH CH3OCH3 HT + + + + + … … “CH3” H+ “CH3” “CH3” “CH3” “CH3” Me More highly oxygenated, biomass-derived molecules C2H5OH + CH3OH

Future research areas Paraffins+adamantane is viable source of H-atoms, H2+Pt is not Alcohol homologation occurs at lower rates because of inhibition by H2O – olefin co-feed is necessary Ethanol/DEE homologation hindered by low reactivity of ethylene – but ethylation would produce wide array of products Effect of olefin pressure on DME homologation Homologation of mixtures of C3 alcohols and DME Coupled Guerbet reaction with homologation (MeOH+EtOH  MeOH + C3/C4 alcohols  MeOH + propene/butenes  triptane) Use glycerol/polyols to generate olefins for methylation

Thank you for your attention
HT + + + + + … … H+ “CH3” “CH3” “CH3” “CH3” Me + Is “CH3” “CH3” “CH3” “CH3” + + C

Brønsted acid catalysis Carbocation chemistry

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Brønsted acid catalysis Carbocation chemistry

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