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Direct conversion of syngas to DME over CuO–ZnO–Al 2 O 3 /HZSM‐5 nanocatalyst synthesized via ultrasound‐assisted co‐precipitation method: New insights into the role of gas injection
Author(s) -
Allahyari Somaiyeh,
Haghighi Mohammad,
Ebadi Amanollah,
Qavam Saeedi Habib
Publication year - 2014
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.3219
Subject(s) - syngas , dimethyl ether , catalysis , selectivity , particle size , dispersion (optics) , materials science , bifunctional catalyst , bifunctional , specific surface area , chemical engineering , fourier transform infrared spectroscopy , bet theory , coprecipitation , nuclear chemistry , inorganic chemistry , chemistry , organic chemistry , physics , optics , engineering
SUMMARY In this study, direct synthesis of dimethyl ether (DME) is conducted over a bifunctional CuO–ZnO–Al 2 O 3 /H Zeolite Socony Mobil‐5 (HZSM‐5) nanocatalyst. A hybrid method of ultrasound‐assisted co‐precipitation is used for the synthesis of catalysts, and the effect of gas injection during sonication is investigated. The physicochemical characteristics of the catalysts are analysed by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), particle size distribution (PSD), energy dispersive X‐ray (EDX), Brunauer–Emmett–Teller (BET) and Fourier‐transformed infrared (FTIR) methods. In the absence of gas injection, the acetate‐based catalysts have a better morphology and higher surface area than the nitrate‐based catalyst. Gas injection significantly changes the morphology and structural properties of the acetate‐based catalyst. High surface area, narrow PSD and better dispersion of small CuO crystals are obtained in a gas‐injected synthesized sample. DME synthesis experiments showed that the CO conversion and DME selectivity are correlated with surface area, nanocatalyst particle size and its dispersion. The gas‐injected CuO–ZnO–Al 2 O 3 /HZSM‐5 nanocatalyst that has the highest surface area and the smallest dispersed particles showed more than 70% DME selectivity. The gas‐injected CuO–ZnO–Al 2 O 3 /HZSM‐5 nanocatalyst exhibited high stability in terms of CO conversion and DME yield over 1440‐min time on a stream test at 275°C, 40 bar and 18 000 cm 3 g.h −1 . Copyright © 2014 John Wiley & Sons, Ltd.