Bimolecular Condensation Reactions of Butan-1-Ol on Ag-Ceo2 Decorated Multiwalled Carbon

Supplementary information for:

Bimolecular condensation reactions of butan-1-ol on Ag-CeO2 decorated multiwalled carbon nanotubes

Galina Dovbeshko 1, Evgeniya Kovalska 2, Włodzimierz Miśta 3, Roman Klimkiewicz 3

1 Institute of Physics, National Academy of Sciences of Ukraine, 46, Prosp. Nauky, Kiev-03028, Ukraine

2 Chuiko O.O. Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17, General Naumov str., Kiev-03164, Ukraine

3 Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland

E-mail:

The transformation equations of primary alcohols towards ketonization:

As the sequence of the transformation towards ketonization is assumed as follows [6]:

primary alcohol →aldehyde → hemiacetal → ester → β-ketoester → symmetric ketone,

in the case of butan-1-ol the formal equations can be written:

C4H9OH → C3H7CHO + H2

2 C3H7CHO + 2 C4H9OH 2 C3H7CH(OH)OC4H9

2 C3H7CH(OH)OC4H9 → 2 C3H7COOC4H9 + 2 H2

2 C3H7COOC4H9 → C3H7COCH(C2H5)COOC4H9 + C4H9OH

C3H7COCH(C2H5)COOC4H9 → C3H7COC3H7 + C3H7CHO +CO

So, the summary equation of the ketonization is as follows:

2 C4H9OH → C3H7COC3H7 + CO + 3 H2

(part of the alcohol undergoes only dehydrogenation and subsequent Tishchenko reaction).

The reverse Tishchenko reaction can also occur.

The reactor effluent gases contain some CO2. This is the result of the WGSR accompanying partial dehydration.

2 C4H9OH → C4H9OC4H9 + H2O → 2 C4H8 + 2H2O

CO + H2O CO2 + H2

Side and consecutive reactions such as the Guerbet reaction, cross aldol-Tishchenko reaction, isomerization et cetera, are also conceivable.

Themechanism of non-oxidative dehydrogenation on metal oxide catalysts does not need to cause oxygen consumption [6]. The molecules of alcohol can be bound to the surface of such a catalyst through the oxygen atom of its OH group, i.e. dissociative adsorption of the alcohol molecule takes place on the catalytic active centers. In a simplified version, a hydrogen ion is adsorbed on the nucleophilic center while an alcoholate at Lewis acidic center:

2RCH2OH → 2RCH2Oads + 2Hads. The alcoholate can react with oxygen vacancy V•O and with oxygen present at the nearby lattice point:

2RCH2Oads + 2V•O→ 2RCH2Olat (Kröger–Vink notation)

2RCH2Olat + 2Olat → 2RCOlatOlat + 4Hads

The resultant connections RCOlatOlat undergo the conversion to a ketone:

2RCOlatOlat → RCORgas ↑ +COgas ↑ +2Olat + 2V•O

The vacancies are freed up and the adsorbed hydrogen can be desorbed.

The simplified diagram of non-destructive transformations of primary alcohols without oxidative coreactant is presented in in the diagram below:

ETHER→ALKENE

↑ ↑

PRIMARY ALCOHOL → ALDEHYDE ↔ ESTER

↓ ↓

SYMMETRIC KETONE

Fig. S1. Nitrogen adsorption-desorption isotherm for MWCNTs.

Fig. S2Conversion and selectivities of butan-1-ol transformations over CeO2/MWCNTs catalyst.Experimental conditions: LHSV = 0.75 h-1 (liquid flow rate 3 cm3 h−1, no carrier gas).

Fig. S3Conversion and selectivities of butan-1-ol transformations over Ag/MWCNTs catalyst.Experimental conditions: LHSV = 0.75 h-1 (liquid flow rate 3 cm3 h−1, no carrier gas).

Fig. S4 Conversion and yields of butan-1-ol transformations over Ag/MWCNTs catalyst.Experimental conditions: LHSV = 0.75 h-1 (liquid flow rate 3 cm3 h−1, no carrier gas).

Fig. S5Conversion and selectivities of butan-1-ol transformations over Ag-CeO2/MWCNTs catalyst.Experimental conditions: LHSV = 0.75 h-1 (liquid flow rate 3 cm3 h−1, no carrier gas).

Fig. S6 Total* dehydrogenation values at varying temperature. Experimental conditions: LHSV = 0.75 h-1 (liquid flow rate 3 cm3 h−1, no carrier gas).

* butyraldehyde + heptan-4-one + butyl butyrate

Table S1. Total dehydrogenation selectivity values at varying load (460 oC).

LHSV
[h-1] / CeO2/MWCNTs
[%] / Ag/MWCNTs
[%] / Ag-CeO2/MWCNTs
[%]
0.375 / 72 / 69 / 73
0.75 / 93 / 82 / 79
1.5 / 94 / 90 / 87

Table S2. Total dehydrogenation yield values at varying load (460 oC).

LHSV
[h-1] / CeO2/MWCNTs
[%] / Ag/MWCNTs
[%] / Ag-CeO2/MWCNTs
[%]
0.375 / 52 / 57 / 63
0.75 / 53 / 63 / 65
1.5 / 33 / 60 / 61

The dependence on the contact time was made at 460oC. At lower temperatures, these differences would be enhanced.

Additional tests

- The catalyst Ag-CeO2/MWCNTs was kept at 460oC under the reaction conditions for additional six hours and the activity was constant.

- The raw carbon material unenriched with silver or cerium oxide was found to be almost catalytically inactive (trace amounts of dehydration and cracking).