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Qin Hongyun 201 2 . 11 . 23

JOURNAL CLUB. Qin Hongyun 201 2 . 11 . 23. Introduction. This paper describes an alternative approach for the synthesis of EtOH via syngas .

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Qin Hongyun 201 2 . 11 . 23

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  1. JOURNAL CLUB Qin Hongyun 2012.11.23

  2. Introduction This paper describes an alternative approach for the synthesis of EtOH via syngas . This process is an integrated technology consisting of the coupling of CO with methanol to form dimethyl oxalate (DMO) and subsequent hydrogenation to give EtOH. The byproduct of the second step, CH3OH, can be separated and used in circulation as the feedstock for the coupling step.

  3. Catalyst Preparation The AEH method was described briefly as follows. A defined amount of Cu(NO3) 2·3H2O and 25 wt.% ammonia aqueous solution dissolved in deionized water were mixed and stirred for 10 min. Silica sol was then added to the copper ammonia complex solution and stirred for 6 h. The initial pH of the suspension was 11~12. The suspension was heated in a water bath preheated to 353 K to allow for the evaporation of ammonia, the decrease of pH, and the consequent deposition of copper species on silica. When the pH value of the suspension decreased to 6-7, the evaporation process was terminated. Then the mixture was sealed in an autoclave, heated to 190–210℃and the temperature maintained for 12 h. The autoclave was naturally cooled to room temperature and the obtained precipitates were filtrated. The filtrate was washed with deionized water three times and dried at 393 K for 4 h. The resulting solid was calcinated at 673 K for 4 h in flowing air. The final calcined sample was designed as xCu/SiO2 catalysts.

  4. Physicochemical Properties and Catalytic Performance

  5. Performance of the 20Cu/SiO2 catalyst in catalytic hydrogenation of DMO.(A) DMO conversion and product selectivities as functions of reaction temperature (453−573 K). (B)DMO conversion and EtOH selectivity vs time on stream at 553 K.

  6. (A) TEM image of the calcined 20CuSiO2 catalyst. (B) FTIR spectra of as-prepared, calcined, and reduced 20Cu/SiO2 , SiO2 , and pure Cu(OH)2 samples.

  7. Introduction The catalytic performance of the reduced Cu/SiO2 catalysts prepared by ammonia-evaporation method was evaluated using vapor-phase hydrogenation of DMO. Theresults show that the lifetime of the catalyst reacted under DMO–ethanol feedstock, without any other modification, is 20 times that of the catalyst reacted under DMO–methanol feedstock.

  8. The performance of catalytic hydrogenation of DMO to EG over 25 wt% Cu/SiO2 catalyst

  9. XRD patterns of 25 wt% Cu/SiO2 catalysts. (A) Freshly H2 -reduced, (B) after reaction under DMO–methanol–H2 stream for 5 h, (C) after reaction under DMO–methanol–H2 stream for 24 h, (D) after reaction under DMO–ethanol–H2 stream for 5 h, (E) after reaction under DMO–ethanol–H2 stream for 24 h, (F) after reaction under DMO–ethanol–H2 stream for 200 h.

  10. TEM images of 25 wt% Cu/SiO2 catalysts. (A) Freshly H2 -reduced, (B) after reaction under DMO–methanol–H2 stream for 5 h, (C) after reaction under DMO–methanol–H2 stream for 24 h, (D) after reaction under DMO–ethanol–H2 stream for 5 h, (E) after reaction under DMO–ethanol–H2 stream for 24 h, (F) after reaction under DMO–ethanol–H2 stream for 200 h.

  11. FTIR spectra of He–methanol and He–ethanol flow over 25 wt% Cu/SiO 2 catalyst at 473 K. (A) He–ethanol flow, (B) He–methanol flow.

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