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Alcohol synthesis from carbon-monoxi...

Santiesteban, Jose Guadalupe,

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Alcohol synthesis from carbon-monoxide and hydrogen over molybdenum-disulfide based catalysts /

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Alcohol synthesis from carbon-monoxide and hydrogen over molybdenum-disulfide based catalysts // Jose Guadalupe Santiesteban.
作者:	Santiesteban, Jose Guadalupe,
面頁冊數:	1 electronic resource (272 pages)
附註:	Source: Dissertations Abstracts International, Volume: 51-06, Section: B.
Contained By:	Dissertations Abstracts International51-06B.
標題:	Chemistry. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8921639
ISBN:	9798207813530

Alcohol synthesis from carbon-monoxide and hydrogen over molybdenum-disulfide based catalysts /
Santiesteban, Jose Guadalupe,

Alcohol synthesis from carbon-monoxide and hydrogen over molybdenum-disulfide based catalysts /Jose Guadalupe Santiesteban. - 1 electronic resource (272 pages)

Source: Dissertations Abstracts International, Volume: 51-06, Section: B.

The synthesis of linear C$\\sb1$-C$\\sb4$ alcohols from synthesis gas (CO + H$\\sb2$) over alkali-promoted MoS$\\sb2$-based catalysts has been studied. A large doping level of alkali was essential for the formation of alcohols rather than hydrocarbons over these catalysts. The indispensable presence of the alkali salt promoter for alcohol synthesis was due to the bifunctionality of the catalyst in which the alkali activates CO and MoS$\\sb2$ activates H$\\sb2$. Injection of $\\sp{13}$C-labeled CH$\\sb3$OH into the synthesis gas stream over alkali-promoted MoS$\\sb2$-based catalysts and analysis by $\\sp{13}$C NMR spectroscopy of the condensable products, accompanied by mass spectrometric analysis of light gaseous products, demonstrated that the alcohol chain growth occurred via a classical CO insertion mechanism, and that methane is a secondary product that is formed from an alkyl moiety generated from a C$\\sb1$-oxygenated precursor. The addition of cobalt to the alkali-doped MoS$\\sb2$ catalyst greatly enhanced the rate of the C$\\sb1$ $\o$ C$\\sb2$ growth step so that ethanol became the dominant product. The alkali-doped MoS$\\sb2$ catalysts prior to and after attaining their working state were fully characterized by XPS, XRD, STEM, and surface area measurements. Electron microscopy results indicated that the MoS$\\sb2$ portion of the catalyst consists of a semicrystalline hexagonal structure with regular lattice spacings (d(002) = 6.15 A) that indicate no intercalation of the alkali. The cesium salt in the best catalysts (10-20 wt% CsOOCH) is distributed as $\\approx$200 A diameter particles and also as a fine surface dispersion. The cesium particle agglomeration results from the low surface energy of MoS$\\sb2$ and is the cause of the large levels of cesium required for the optimal functioning of the catalyst. Pretreatment (400$\\sp\\circ$C, 2% H$\\sb2$/N$\\sb2$, 1 h) of the catalysts induces not only reduction of surface species such as Mo(VI) and SO$\\sb4\\sp{2-}$ detected on the fresh catalysts, but also dispersion of the cesium on the MoS$\\sb2$ surface. The oxidation states of S and Mo in the tested catalysts correspond to those of MoS$\\sb2$, i.e. Mo(IV) and S$\\sp{2-}$. XPS intensity equations were derived from geometrical models of the catalyst surface to determine the degree of dispersion and/or segregation of Cs on the MoS$\\sb2$ surface.

English

ISBN: 9798207813530Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Molybdenum silicide

Alcohol synthesis from carbon-monoxide and hydrogen over molybdenum-disulfide based catalysts /
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100 1 $a Santiesteban, Jose Guadalupe, $e author. $3 3765925
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300 $a 1 electronic resource (272 pages)
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337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 51-06, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $b Ph.D. $c Lehigh University $d 1989.
520 $a The synthesis of linear C$\\sb1$-C$\\sb4$ alcohols from synthesis gas (CO + H$\\sb2$) over alkali-promoted MoS$\\sb2$-based catalysts has been studied. A large doping level of alkali was essential for the formation of alcohols rather than hydrocarbons over these catalysts. The indispensable presence of the alkali salt promoter for alcohol synthesis was due to the bifunctionality of the catalyst in which the alkali activates CO and MoS$\\sb2$ activates H$\\sb2$. Injection of $\\sp{13}$C-labeled CH$\\sb3$OH into the synthesis gas stream over alkali-promoted MoS$\\sb2$-based catalysts and analysis by $\\sp{13}$C NMR spectroscopy of the condensable products, accompanied by mass spectrometric analysis of light gaseous products, demonstrated that the alcohol chain growth occurred via a classical CO insertion mechanism, and that methane is a secondary product that is formed from an alkyl moiety generated from a C$\\sb1$-oxygenated precursor. The addition of cobalt to the alkali-doped MoS$\\sb2$ catalyst greatly enhanced the rate of the C$\\sb1$ $\o$ C$\\sb2$ growth step so that ethanol became the dominant product. The alkali-doped MoS$\\sb2$ catalysts prior to and after attaining their working state were fully characterized by XPS, XRD, STEM, and surface area measurements. Electron microscopy results indicated that the MoS$\\sb2$ portion of the catalyst consists of a semicrystalline hexagonal structure with regular lattice spacings (d(002) = 6.15 A) that indicate no intercalation of the alkali. The cesium salt in the best catalysts (10-20 wt% CsOOCH) is distributed as $\\approx$200 A diameter particles and also as a fine surface dispersion. The cesium particle agglomeration results from the low surface energy of MoS$\\sb2$ and is the cause of the large levels of cesium required for the optimal functioning of the catalyst. Pretreatment (400$\\sp\\circ$C, 2% H$\\sb2$/N$\\sb2$, 1 h) of the catalysts induces not only reduction of surface species such as Mo(VI) and SO$\\sb4\\sp{2-}$ detected on the fresh catalysts, but also dispersion of the cesium on the MoS$\\sb2$ surface. The oxidation states of S and Mo in the tested catalysts correspond to those of MoS$\\sb2$, i.e. Mo(IV) and S$\\sp{2-}$. XPS intensity equations were derived from geometrical models of the catalyst surface to determine the degree of dispersion and/or segregation of Cs on the MoS$\\sb2$ surface.
546 $a English
590 $a School code: 0105
650 4 $a Chemistry. $3 516420
650 4 $a Mental health. $3 534751
650 4 $a Mathematics. $3 515831
650 4 $a Radiology. $3 894545
650 4 $a Physical chemistry. $3 1981412
650 4 $a Medical imaging. $3 3172799
653 $a Molybdenum silicide
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792 $a 1989
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8921639