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The effects of protons on the cataly...

Wong, Tim Ting Tin.

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The effects of protons on the catalytic performance of rhodium supported in zeolite Y.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The effects of protons on the catalytic performance of rhodium supported in zeolite Y./
Author:	Wong, Tim Ting Tin.
Description:	259 p.
Notes:	Source: Dissertation Abstracts International, Volume: 54-05, Section: B, page: 2631.
Contained By:	Dissertation Abstracts International54-05B.
Subject:	Engineering, Chemical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9327322

The effects of protons on the catalytic performance of rhodium supported in zeolite Y.
Wong, Tim Ting Tin.

The effects of protons on the catalytic performance of rhodium supported in zeolite Y. - 259 p.

Source: Dissertation Abstracts International, Volume: 54-05, Section: B, page: 2631.

Thesis (Ph.D.)--Northwestern University, 1993.

The objective of this research is to establish correlations between the catalytic performance of rhodium particles supported in zeolite Y and their geometric and electronic state. In particular, the role of protons has been investigated; they not only act as Bronsted acids, but also modify the catalytic performance of rhodium. In general, protons in zeolite-supported rhodium catalysts can: (1) control the redox chemistry of the metal; (2) act as chemical "anchors" for the metal; (3) alter the electronic structure of the metal; and (4) act as catalytically active sites, thus, forming bifunctional catalysts. Each of these roles has been investigated.Subjects--Topical Terms:

1018531
Engineering, Chemical.

The effects of protons on the catalytic performance of rhodium supported in zeolite Y.
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008 130610s1993 eng d
035 $a (UnM)AAI9327322
035 $a AAI9327322
040 $a UnM $c UnM
100 1 $a Wong, Tim Ting Tin. $3 1906914
245 1 4 $a The effects of protons on the catalytic performance of rhodium supported in zeolite Y.
300 $a 259 p.
500 $a Source: Dissertation Abstracts International, Volume: 54-05, Section: B, page: 2631.
500 $a Adviser: Wolfgang M. H. Sachtler.
502 $a Thesis (Ph.D.)--Northwestern University, 1993.
520 $a The objective of this research is to establish correlations between the catalytic performance of rhodium particles supported in zeolite Y and their geometric and electronic state. In particular, the role of protons has been investigated; they not only act as Bronsted acids, but also modify the catalytic performance of rhodium. In general, protons in zeolite-supported rhodium catalysts can: (1) control the redox chemistry of the metal; (2) act as chemical "anchors" for the metal; (3) alter the electronic structure of the metal; and (4) act as catalytically active sites, thus, forming bifunctional catalysts. Each of these roles has been investigated.
520 $a With regards to redox chemistry, temperature-programmed techniques in conjunction with spectroscopic techniques show that the reducibility of Rh is largely controlled by the concentration of protons via the equilibrium between Rh clusters, Rh cations, and protons. Upon neutralization of these protons formed during reduction, the equilibrium shifts towards the reduced metal, thereby, increasing the extent of reduction. However, upon admission of carbon monoxide to the reduced sample, $\ rm Rh\sp+(CO)\sb2 $ forms by the combined action of protons and CO. Admission of CO results in the formation of gaseous H $\ sb2.
520 $a The protons also "anchor" the Rh particles to the zeolite walls. As a result, the electronic structure of the metal is altered. Specifically, the interaction between protons and reduced Rh particles leads to the formation of "electron deficient" Rh which is catalytically superior to that of "neutral" Rh. For the hydrogenolysis of neopentane this enhancement is confirmed; the catalytic activity follows the sequence: Rh/HY $> $ Rh/NaY $\ sim $ Rh/Si0 $\ sb2. $ As the proton concentration of the support increases, the catalytic activity increases.
520 $a For the hydroformylation of propylene, however, the role of the protons is different. A high proton concentration results in deactivation of the catalyst. As protons are catalytically active, polymerization of propylene competitively consumes reactant molecules. The resulting macromolecules block the zeolite pores rendering the catalyst inactive. For Rh/NaY the proton concentration is much lower and hydroformylation over the metal sites leads to the formation of aldehydes, alcohols and ketones.
590 $a School code: 0163.
650 4 $a Engineering, Chemical. $3 1018531
650 4 $a Chemistry, Inorganic. $3 517253
690 $a 0542
690 $a 0488
710 2 0 $a Northwestern University. $3 1018161
773 0 $t Dissertation Abstracts International $g 54-05B.
790 1 0 $a Sachtler, Wolfgang M. H., $e advisor
790 $a 0163
791 $a Ph.D.
792 $a 1993
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9327322