Carbon nanotube-promoted Co–Cu catalyst for highly efficient synthesis of higher alcohols from syngas

Zhang, Hongbin; Dong, Xinfa; Lin, Guo-Dong; Liang, Xiaoping; Li, Haiyan

doi:10.1039/b507765f

Cited by 74 publications

(34 citation statements)

References 17 publications

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“…Moreover, the H-adspecies with higher stationary-state concentration at the surface of functioning catalyst would be in favor of inhibiting water-gas shift side-reaction, contributing considerably to an increase in the product yields. These are very similar to the cases of methanol synthesis over the MWCNT-promoted Cu-ZnO-Al 2 O 3 catalyst [8,9] and of higher alcohol synthesis over the MWCNT-promoted Co i Cu j catalyst [10].…”

Section: H 2 (Or Co)-tpd Characterization Of the Supports And The Presupporting

confidence: 78%

“…Catalytic applications range from selective hydrogenation of a,b-unsaturated aldehydes [4], hydrofomylation of alkenes [5], ammonia synthesis [6], Fischer-Tropsch synthesis [7], methanol and higher alcohol synthesis [8][9][10], to dehydrogenation of alcohols [11], oxidation [12] and electrocatalysis [13], etc. The catalytic studies conducted so far on MWCNT-based systems have shown promising results in terms of activity and selectivity.…”

Section: Introductionmentioning

confidence: 99%

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Co-decorated carbon nanotube-supported Co–Mo–K sulfide catalyst for higher alcohol synthesis

Lin

Zhang

2006

Catal Lett

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Using chemical reduction-deposition method, a type of metallic cobalt-decorated multi-walled carbon nanotubes, noted as y%(mass percentage)Co/MWCNTs, was prepared. TEM, SEM and XRD measurements demonstrated that the metallic cobalt was evenly coated on the MWCNT substrate, with granule-diameter of the Co x 0 -crystallites of 5-8 nm. Using the y%Co/MWCNTs as support, a type of supported Co-Mo-K sulfide catalysts, noted as x%(Co i Mo j K k )/(y%Co/MWCNTs), for higher alcohol synthesis (HAS) was developed. It was experimentally shown that using the Co-modified MWCNTs in place of simple MWCNTs or activated carbon (AC) as the catalyst support led to a significant increase in activity of CO hydrogenation conversion and improvement in the selective formation of C 2+ -alcohols. Under the reaction condition of 5.0 MPa, 613 K, CO/H 2 /N 2 = 45/45/10 (v/v) and GHSV = 3600 ml STP h )1 g )cat.)1 , the observed STY of C 1-4 -alcohols reached 154.1 mgh )1 g )cat.)1 at 12.6% conversion of CO over the 11.6%(Co 1 Mo 1 K 0.6 )/(6.4%Co/MWCNTs) catalyst, which was 1.76 and 2.33 times as high as that (87.7 and 66.1 mgh )1 g )cat.)1 ) of the reference systems supported by simple MWCNTs and AC respectively. Ethanol became the predominant product of the CO hydrogenation, with carbon-based selectivity ratio of C 2-4 -alcohols to CH 3 OH reaching 3.6 in the products. It was experimentally found that using the Co-modified MWCNTs in place of simple MWCNTs or AC as the catalyst support caused little change in the apparent activation energy for the conversion of CO, but led to a slight increase in the molar percentage of catalytically active Mo-species (Mo 4+ ) in the total Mo-amount at the surface of the functioning catalyst. Based upon the results of TPD investigation, it could be inferred that, under the reaction condition of HAS, there existed a considerably larger amount of adsorbed H-species and CO-species on the functioning catalyst, thus in favour of increasing the rate of a series of surface hydrogenation reactions in HAS.KEY WORDS: Co-modified carbon nanotubes; sulphided x%(Co i Mo j K k )/(y%Co/CNTs) catalyst; CO hydrogenation; higher alcohol synthesis.

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Section: H 2 (Or Co)-tpd Characterization Of the Supports And The Presupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Co-decorated carbon nanotube-supported Co–Mo–K sulfide catalyst for higher alcohol synthesis

Lin

Zhang

2006

Catal Lett

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“…The conditioning of reduced catalysts with CO 2 at elevated temperature (e.g., 200°C) has been applied to the passivation of Ni-Cr/Al 2 O 3 steam-reforming-methanation catalysts [51]. Furthermore, the XPS and XRD data of Cu-based [52] and Cu-Co-based [53] catalysts that had been exposed to CO/CO 2 -containing gas mixtures during the synthesis of alcohols are relevant also to passivation. Metallic copper and Cu 2 O were identified by XRD for a Cu-ZnO-Al 2 O 3 catalyst after use in methanol synthesis [52].…”

Section: Methods Combining Carbon and Oxide Formationmentioning

confidence: 99%

“…However, we suggest to assign the corresponding XPS spectra to Cu(1+) rather than to Cu(0) or a mixture of both species, in agreement with literature [48,54] and the well-known instability of Cu(0) in oxidizing atmosphere (i.e., air). For the Cu-Co-based catalysts used in the synthesis of higher alcohols, metallic Co as well as oxidized Co species were identified by XPS [53].…”

Section: Methods Combining Carbon and Oxide Formationmentioning

confidence: 99%

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Huber

Lögdberg

et al. 2006

Catal Lett

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Catalysts containing metals such as Cu, Ni, Fe, Co in their reduced state are often subjected to passivation procedures prior to characterization. Passivation with N 2 O or O 2 to create a protective oxide layer also results in a certain degree of sub-surface oxidation. The heat released during oxidation is a critical parameter. The extent of bulk oxidation depends on the type of oxidant as well as on the size of the metal particles, as shown for copper catalysts. The final, meta-stable passivation layer requires a certain thickness to sustain exposure to ambient atmosphere. The encapsulation of metal particles in carbon is an efficient method for preserving the metallic state, as demonstrated for metallic nickel and iron with carbon nanofibers. The use of passivated samples for characterization of the active, i.e., reduced, catalyst has limited value.

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“…Recent studies revealed that both the activity and selectivity to higher alcohols can be improved by adding effective promoters, such as Fischer-Tropsch components and alkali metals into MoS 2 -based catalysts [1][2][3][4][5], changing the nature of the catalyst supports [6][7][8][9][10][11], and modifying the catalyst preparation method [12,13]. Very recently, other new catalysts were also developed and a good activity and selectivity could also be obtained.…”

Section: Introductionmentioning

confidence: 99%

Effect of Lanthanum Promotion on the Unsupported Mo–Co–K Sulfide Catalysts for Synthesis of Mixed Alcohols from Syngas

et al. 2008

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The unsupported Mo-Co-K sulfide catalysts promoted by La were prepared through ultrasonic technology in non-aqueous medium and its performances for the synthesis of mixed alcohols from syngas were also investigated. The results showed that the catalysts promoted by La exhibited higher CO conversion and selectivity to ethanol than the unsupported Mo-Co-K sulfide catalyst without addition of La did under identical reaction conditions. The catalysts were characterized by N 2 adsorption/ desorption, X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Raman, and X-ray photoelectron spectroscopy (XPS).

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Carbon nanotube-promoted Co–Cu catalyst for highly efficient synthesis of higher alcohols from syngas

Abstract: The development of a type of carbon-nanotube-promoted Co-Cu catalyst, which displays excellent performance for highly effective and selective formation of the C(2-4)-oxygenates, especially BuOH and DME, from syngas, is reported.

Cited by 74 publications

References 17 publications

Co-decorated carbon nanotube-supported Co–Mo–K sulfide catalyst for higher alcohol synthesis

Co-decorated carbon nanotube-supported Co–Mo–K sulfide catalyst for higher alcohol synthesis

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Effect of Lanthanum Promotion on the Unsupported Mo–Co–K Sulfide Catalysts for Synthesis of Mixed Alcohols from Syngas

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