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Insight into the Correlation between Cu Species Evolution and Ethanol Selectivity in the Direct Ethanol Synthesis from CO Hydrogenation
Author(s) -
Li XiaoLi,
Yang GuoHui,
Zhang Meng,
Gao XiaoFeng,
Xie HongJuan,
Bai YunXing,
Wu YingQuan,
Pan JunXuan,
Tan YiSheng
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201801888
Subject(s) - selectivity , catalysis , ethanol , chemistry , copper , crystallite , inorganic chemistry , titration , nuclear chemistry , organic chemistry , crystallography
Cu/SiO 2 catalyst was prepared by the ammonia evaporation method for the direct synthesis of ethanol from CO hydrogenation. The catalyst exhibited the initial ethanol selectivity as high as 40.0 wt %, which dramatically decreased from 40.0 to 9.6 wt % on the stream of 50 h. XRD, XPS, TEM and N 2 O titration techniques were employed to elucidate the ethanol selectivity change and catalyst structure evolution during reaction process. The experiment and characterization results indicated that both Cu + /(Cu + +Cu 0 ) value and copper crystallite size had great effects on the ethanol selectivity. During the initial 38 h, the ethanol selectivity obviously decreased from 40.0 to 18.2 wt %, and Cu + /(Cu + +Cu 0 ) value on the catalyst surface rapidly dropped from 0.67 to 0.39, while the copper crystallite size remained almost unchanged. However, during the reaction period of 38–50 h, the Cu + /(Cu + +Cu 0 ) value possessed no distinct change, but a further decrease in ethanol selectivity and a rapid aggregation in Cu particles were observed simultaneously. The present systematic investigation demonstrated that the decrease of Cu + /(Cu + +Cu 0 ) value was the main factor for the loss of ethanol selectivity during the initial 38 h, whereas the rapid growth of Cu particles during the reaction period of 38–50 h were mainly contributed to the further decline of ethanol selectivity.