Supporting information

Direct synthesis of aromatics from syngas over Mo-modified

Fe/HZSM-5 bifunctional catalyst

Yanfei Xu1, Jie Wang1, Guangyuan Ma1, Jingyang Bai1, Yixiong Du1, Mingyue Ding1,2*

1School of Power and Mechanical Engineering, Hubei International Scientific and

Technological Cooperation Base of Sustainable Resource and Energy, Hubei Province Key

Laboratory of Accountrement Technique in Fluid Machinery & Power Engineering, Wuhan

University, Wuhan 430072, China

2Shenzhen Research Institute of Wuhan University, Shenzhen 518108, China

*Corresponding author

E-mail address: dingmy@whu.edu.cn (Mingyue Ding)

Tel.: +86-27-87631539. Fax: +86-27-87631539.

Supplemental experimental procedures:

Preparation of HZSM-5 zeolite

HZSM-5 zeolite was synthesized via a hydrothermal method. Typically, 2.2 g sodium

aluminate (CP), 28.0 g tetrapropylammonium bromide (TPABr, 99%) and 8.0 g NaOH (AR)

were dissolved in 1350 g H2O. Then, 85.7 g tetraethylorthosilicate (TEOS, AR) was added

into the mixture. After being stirred for 3h, the mixture was transferred in 100 mL Teflonlined

stainless-steel autoclave and crystallized at 170 °C for 72 h. The products were washed, dried

and calcined at 540 °C for 6 h. The powder was further exchanged in 1.0 mol/L NH4NO3

(AR) solution (with a liquid-solid ratio of 50 ml/g) for two times. Then, the filter cake was

dried and calcined at 540 °C for 6 h. The obtained zeolite was named as Z5. The HZSM-5

zeolite possessing none acid sites (named as S-1) was synthesized via the same procedures

without the addition of sodium aluminate.

Catalyst characterization

Nitrogen physisorption was performed at -196 °C on Micromeritics ASAP 240

instrument. X-ray diffraction (XRD) of catalyst was conducted on PANalytical X’Pert Pro

diffractometer. X-ray photoelectron spectroscopy (XPS) was collected on Thermal XPS

ESCALAB 250Xi Spectrometer. Transmission electron microscopy (TEM) was taken on

TECNAI G2 F30 instrument. The actual contents of iron and metal promoters were measured

by inductively coupled plasma (ICP) on IRIS Intrepid II XSP.

Hydrogen temperature-programmed reduction (H2-TPR) was conducted in a quartz tube

and the hydrogen concentration in the exit gas was determined using a thermal conductivity

detector (TCD). After treating 0.1 g sample with N2 at 350 °C, H2-TPR was carried out in 5%

H2/N2 (30 mL/min) from 50 to 800 °C with a heating rate of 10 °C/min. The reduction degree

referred to the ratio of actual hydrogen consumption to theoretical hydrogen consumption.

The actual hydrogen consumption was determined via H2-TPR, and the theoretical hydrogen

consumption was based on the actual content of iron in the sample.

Pyridine adsorption infrared spectroscopy (Py-IR) was performed on Bruker VERTEX

spectrometer. The sample was pressed into a self-supported wafer, placed in an in situ IR cell

and pretreated under vacuum at 450 °C for 2 h. The background spectrum was recorded after

cooling the sample to room temperature. Pyridine vapor was introduced to the sample and

saturated for 1 h at room temperature. Then, the IR spectrum was recorded after evacuation at

350 °C for 1 h.

The total acidity of catalyst was measured by NH3 temperature-programmed desorption

(NH3-TPD). Typically, 100 mg sample was pretreated with high purity N2 at 350 °C for 2 h.

And then the sample was cooled to 100 °C and saturated with NH3. The sample was flushed

in high purity N2 to remove the physically adsorbed NH3. Then, NH3-TPD was carried out in

a constant flow of high purity N2 (40 mL/min) from 100 °C to 800 °C at a heating rate of 8

°C/min.

Catalytic tests

Catalytic tests were performed in a fixed-bed reactor with 0.5 g catalyst and 0.5 g quartz

sand. All the catalysts were reduced in H2 at 350 °C, 0.1 MPa, 4000 h-1 for 10 h. Reactions

were performed in syngas (47.5CO/47.5H2/5N2) at 320 °C, 2.0 MPa, 3000 h-1 for 20 h. The

reaction products were separated by gas chromatograph (FULI GC 97) and detected with

TCD and flame ionization detector (FID). The conversion of CO and selectivity of

hydrocarbons were calculated on carbon-atom basis. The carbon balance calculated in each

test was between 95% and 98%.

CO conversion was calculated by equation (1):

(1)

where CO in and CO out represent mole of CO at the inlet and outlet, respectively.

CO2 selectivity was calculated by equation (2):

(2)

where CO2 out refers to mole of CO2 at the outlet.

The selectivity of individual hydrocarbon in total hydrocarbons was calculated by

equation (3):

i m outi m

in out 2 out

i C H C H selectivity = 100%CO - CO - CO

(3)

where CiHm out and i mean mole of individual hydrocarbon at the outlet and carbon number of

a hydrocarbon molecule, respectively.

Fig. S1. XRD patterns of the spent catalysts.

Fig. S2. Catalytic performance of (a) Fe/S-1 and (b) Fe/Z5. CO conversion over the two

catalysts were about 82%. Reaction conditions: 320 °C, 2.0 MPa, 3000 h-1.

Fig. S3. Py-IR spectra of the MoxFe/Z5 catalysts.

Fig. S4. NH3-TPD profiles of the MoxFe/Z5 catalysts.

Fig. S5. Stability test over Mo5Fe/Z5. a C5+ hydrocarbons except for aromatics.

Scheme S1. Reaction scheme for STA reaction over Mo-modified Fe/HZSM-5 bifunctional

catalyst.