Selective Synthesis of Α-Olefins by Dehydration of Fatty Alcohols Over Alumina–Thoria Mixed Catalysts

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Electronic Supplementary Material (ESI) for Catalysis Science & Technology. This journal is © The Royal Society of Chemistry 2020

Supporting Information Selective synthesis of α-olefins by dehydration of fatty alcohols over alumina–thoria mixed catalysts

Arif Ali and Chen Zhao*

Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular engineering, East China Normal University, Shanghai, 200062, China

E-mail: [email protected] (C. Zhao)

1 Experimental section Chemicals: The received chemicals (solvents and some metal oxide catalysts) were used without further treatment. Chemicals are stearyl alcohol (Sinopharm Chemical Reagent), n-dodecane (>98%, Sinopharm Chemical Reagent), nano sized alumina (99.9%, Maikun Chemical), thorium nitrate (Aladdin Industrial Cooperation), nafion

(Alfa Aesar), Nb2O5 (Sinopharm Chemical Reagent), alumina acidic (Sinopharm Chemical Reagent), alumina basic (Sinopharm Chemical Reagent), alumina neutral

(Sinopharm Chemical Reagent), amberlyst (Aladdin Industrial Cooperation), Y2O3

(99.9%, Chengdu Micxy Chemical), TiO2 (99%, Maikun Chemical), La2O3 (Chengdu

Micxy Chemical), WO5 (99.9%, Maikun Chemical), CeO2 (Aladdin Industrial

Cooperation), ZrO2 (Maikun Chemical), MoO3 (99%, Chengdu Micxy Chemical),

ZrSO4.4H2O (Jing Shi Ji), ASA (SiO2:Al2O3=9, The Catalyst Plant (Institute of Green

Chemistry) of East China Normal University), n-C10H21–OH (Sinopharm Chemical

Reagent), n-C12H25–OH (Sinopharm Chemical Reagent), cis-2-methyl cyclohexanol

(>98%, Tokyo Chemical Industry), n-C14H29–OH (Sinopharm Chemical Reagent), n-

C16H33–OH (Sinopharm Chemical Reagent), trans-2-methyl cyclohexanol (>98%, Tokyo Chenical Industry), trans-2-methyl cyclohexanol (>98%, Tokyo Chemical Industry). Nitrogen and air (99.999 vol. %) were supplied by Shanghai Pujiang Specialty Gases Co., Ltd.

Preparation of catalysts The alumina (nano sized alumina) catalyst was prepared via calcinations method as

received. The calcination was carried out in N2 at 500 °C (2 °C/min) for an hour with flow of 400 mL min−1. The other kinds of alumina like alumina acidic, alumina basic and alumina neutral were treated the same way.

Likewise, thoria (ThO2) was prepared from its salt thorium nitrate (ThN2O12.6H2O) by heat treatment in air. Thorium nitrate was calcined in air at 400 °C (2 °C /min) for 16 h. After this treatment the moist salt thorium nitrate converted into white solid which was ground using mortar and pestle into powdered form. This white powder was used as catalyst.

Catalytic characterization Powder X-ray diffraction (XRD) patterns were used to investigate the structure and crystal size by Rigaku Ultima IV X-ray diffractometer utilizing Cu-Kα radiation (λ =

2 1.5405 Å) operated at 35 kV and 25 mA. N2 adsorption measurements were performed at 77 K on a BEL-MAX gas/vapor adsorption instrument. The surface areas were calculated using the Brunauer-Emmett-Teller (BET) method. The IR spectra of adsorbed ethanol (IR-ethanol), ethylene (IR-ethylene) and ethanol (IR- ethanol) dehydration were recorded with a Nicolet NEXUS 670 FTIR spectrometer equipped with an in-situ IR cell. The crystal morphology was determined by scanning electron microscopy (SEM) on a Hitachi S-4800 microscope. Transmission electron microscopy (TEM) images were obtained on a JEOL JEM-2100 microscope operating at an accelerating voltage of 200 kV. The IR spectra of the adsorbed pyridine (IR-Py) were recorded with a Nicolet NEXUS 670 FTIR spectrometer equipped with an in situ IR cell. The samples were activated in a vacuum at 673 K for 1 h before equilibration with pyridine at 423 K, and then evacuated at 423 K for 1 h.

Typical procedure for selective dehydration of fatty alcohols Unless stated otherwise, reactions were carried out in an autoclave from Anhui Kemi Machinery Technology Co., Itd. The typical liquid-phase selective dehydration of fatty alcohols to α-olefins were carried out in micro-reactor. In a typical process,

0.6 g alumina catalyst, 0.1 g ThO2, 3.0 g fatty alcohol and 80 mL of dodecane were placed in micro-reactor. The autoclave was purged with N2 three times to remove the

residual air. After the removal of air, the N2 was again released to make pressure as zero MPa. Then, the reaction mixture was magnetically stirred to 500 rpm at 300 °C for 6 h. When the above reaction was completed, the autoclave was cooled naturally; the liquid products were analyzed by GC-FID and finally identified by GC-MS.

a. 300 n b. 0.5 Al O 37.7nm 2 3 250 0.4 )

. 0.3 ) D 1 u

d - / . 200

V 0.2

113 g a 104 d 3 ( 116 0.1 m y

100 150 t

c 0.0 i 012 110 200 ( s 024 214 300 s 100 10 100 n

d Pore Diameter (nm)

e 211 a t

1010 V

n 50 I 0 10 20 30 40 50 60 70 80 0.0 0.2 0.4 0.6 0.8 1.0

2 Theta (degree) Relative Pressure (P/P0) c. d. D= 7.42±0.1nm

35 30

) 25 % (

e 20 g a

t 15 n e c

r 10 e P 5 0 3 4 5 6 7 8 9 10 11 12 13 Particle size (nm)

100.0 100.0 e. 99.5 n f. 99.5 n 99.0 Al2O3 (normal) Al2O3 (calcined)

) 98.5 ) 99.0 % % ( (

t t

98.0 0.7 % h 1.5% h 98.5 g g

i 97.5 i e e 98.0 W 97.0 1 % W 96.5 97.5 0.5 % 96.0 0 200 400 600 800 0 200 400 600 800 Temperature (oC) Temperature (oC)

Fig. S1 (a) XRD pattern; (b) N2 adsorption–desorption isotherms, inlet shows PSD n curve; (c) typical SEM and (d) TEM images of Al2O3 catalyst; TGA curves of (e) n n Al2O3 (normal) and Al2O3 (calcined) catalysts.

Al2O3 acidic ) % (

y Al O basic

t 2 3

i s n e t

n Al O neutral

I 2 3

10 20 30 40 50 60 70 80 2 Theta (degree)

Fig. S2 (a) XRD patterns of Al2O3 acidic, Al2O3 basic and Al2O3 neutral catalysts.

0.7 180 4.23 nm 0.6 a. 0.5 160 0.4 D

/ 0.3 V

140 d 0.2

) 0.1 1 - 120 0.0

g 10 100 3 100 Pore diameter (nm) m

( 80 s

d 60 a

V 40 20 0 0.0 0.2 0.4 0.6 0.8 1.0

Relative Pressure (P/P0)

180 b. 0.5 160 0.4 6 nm

140 0.3 D

d / V

) 0.2 d

1 120 - 0.1 g

3 100 0.0 m 10 100

c 80 Pore diameter (nm) (

s 60 d a

V 40 20 0 0.0 0.2 0.4 0.6 0.8 1.0

Relative Pressure (P/P0)

0.45 160 0.40 4.23nm c. 0.35 0.30 140 0.25 D

d / 0.20 V 120 d 0.15 ) 0.10 1

- 0.05 0.00 g 100 10 100 3 Pore diameter (nm) m 80 c (

s 60 d a 40 V 20 0 0.0 0.2 0.4 0.6 0.8 1.0 Relative Pressure (P/P0)

Fig. S3 BET curves of (a) Al2O3 acidic, (b) Al2O3 basic, (c) Al2O3 neutral and (d) ThO2.

6 a. Al2O3 acidic

b. Al2O3 basic

c. Al2O3 neutral

Fig. S4 SEM images of: (a) Al2O3 acidic, (b) Al2O3 basic, (c) Al2O3 neutral, and (d)

ThO2.

7 a. Al2O3 acidic

b. Al2O3 basic

c. Al2O3 neutral

Fig. S5 TEM images of: (a) Al2O3 acidic, (b) Al2O3 basic and (c) Al2O3 neutral.

120 1.8 1.6 a. b. 1.4 100 1.2 1.0 D

/ 0.8 V

) 0.6 d

) Thoria

1 0.4 - 80 0.2 % g

( 0.0 3 10 100

y Pore diameter (nm) m t

i c ( s s n d e 40 t a n V I 20

0 10 20 30 40 50 60 70 80 0.0 0.2 0.4 0.6 0.8 1.0 2 Theta (degree) Relative Pressure (P/P0)

c. Thoria d. ThO2

Fig. S6 (a) XRD pattern; (b) N2 adsorption–desorption isotherms, inlet shows pore size distribution curve; (c) typical SEM and (d) TEM images of ThO2 catalyst.

)

. Dodecane

u (Solvent) . a (

t Alpha olefin i s

e Oligomeric t products n Internal olefins I C36H74

5 10 15 20 25 30 35 40 Retention time (min.)

Fig. S7 GC spectra of liquid products obtained by selective dehydration of stearic n alcohol. Reaction conditions: 0.6 g Al2O3 , 0.1 g ThO2, 3.0 g stearic alcohol, 300°C, 80 mL dodecane, 0.1 MPa N2, 6 h.

100 n Al2O3 + CeO2 Al O n + Nb O 80 2 3 2 5 n Al2O3 + La2O3 ) Al O n + WO % 2 3 5 (

60 n Al2O3 + ThO2 y t i

v i

t 40 c e l e

S 20

0 1 2 3 4 5 6 7 Time (h) Fig. S8 The recorded selectivity changes as a function of reaction time. Reaction

n conditions: 3.0 g stearic alcohol, 0.6 g Al2O3 and 0.1 g MOx (metal oxide) catalysts,

80 mL dodecane, 300°C, 0.1 MPa N2.

)

a. . u

. Dodecane a

( (solvent)

y H

t 74% i

s HO H 2% n

e 24% cis-2-methyl cyclohexanol t n I

0 1 2 3 4 5 6 7 8 9 10

Retention time (min.) )

b. . u

. Dodecane a

( (solvent) H H y

t 0%

i 32% OH

s 68%

n H H

e trans-2-methyl cyclohexanol t n

I 2%

0 1 2 3 4 5 6 7 8 9 10 Retention time (min.)

Fig. S9 GC spectra of liquid products identified for the dehydration of (a) cis-2- methyl cylcohexanol and (b) trans-2-methyl cyclohexanol. Reaction conditions: 0.3 g

n Al2O3 , 3.0 g cis-2-methyl cyclohexanol, or 3.0 g trans-2-methyl cyclohexanol, 300°C,

80 mL dodecane, 0.1 MPa N2, and 6 h.

12 (a) (b)

Fig. S10 SEM images of (a) fresh and (b) used ThO2 catalyst.

Fig. S11 TEM images of (a) fresh and (b) used ThO2 catalyst.

(a) (b)

CO2 desorption peak LAS BAS Fresh ThO2 ) ) . .

u Fresh ThO u

. 2 . a a ( (

y y t t i i

s Used ThO2 s Used ThO2 n n e e t t n n I I

1400 1450 1500 1550 1600 1650 1700 0 150 300 450 600 750 Wavenumber (cm-1) Wavenumber (cm-1)

Fig. S12 In situ FTIR spectra of (a) pyridine adsorption and (b) CO2 desorption on fresh and used thoria surfaces.

13 Table S1 Texture properties of Fresh and Used ThO2 catalyst.

Catalyst BET Total Pore size Acid conc. Base conc.

Surface area pore volume (nm) (IR-Py) (TPD-CO2) (m2•g−1) (cm3•g−1) (mmol•g−1) (mmol•g−1) (LAS) (LBS)

Fresh ThO2 120 0.3210 3.2 0.047 0.053

Used ThO2 116 0.2950 2.89 0.041 0.049