Catalytic Vapor-Phase Oxidation of Xylenes

Bhattacharyya, S. K.; Gulati, Indar B.

doi:10.1021/ie50588a023

Cited by 19 publications

(6 citation statements)

References 9 publications

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“…(3) the formation of carbon oxides by way of maleic anhydride; (4) the direct oxidation to carbon oxides. A minor portion of both maleic anhydride and carbon oxides is formed from phthalic anhydride and its precursors.…”

Section: The Catalytic Vapormentioning

confidence: 99%

The Thermal Decomposition of Cadmium Hydroxide

Löw¹,

Kamel²

1965

J. Phys. Chem.

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Differential thermal and thermogravimetric analyses of CdO 9 1 .65H20 showed that four processes were involved in the thermal decomposition. Isothermal weight loss determinations showed that, a t 300' and above, the decomposition to CdOo.80 was continuous. The composition of intermediates is uncertain because of the rapid and continuous reaction.The decomposition was accompanied by marked textural changes of the solid. Surface areas of pure hydroxide as well as samples containing 1 atom yo Li+, Znf2, Mgf2, or Alfa were measured after heating in vacuo for various times at temperatures from 150 to 500'. Alf3-addition inhibited and Lif-addition enhanced oxide sintering up to 400', through the destruction or creation of oxygen vacancies. At 450 and ZOOo both Alfa and Lif additions increased sintering, suggesting that a cation vacancy mechanism became dominant.Some oxide was formed as low as 265'.During a study of the surface properties of CdO, it became necessary to prepare well-defined CdO samples by various means, including the thermal decomposition of the hydroxide. Although some work has been reported on the isobaric and isothermal dehydration of cadmium hydroxide,1s2 the information available was incomplete. Additional work was required and, consequently, the thermal decomposition of doped and undoped cadmium hydroxides was studied. Experimental DetailsCadmium hydroxide was precipitated from the nitrate with a m m~n i a ,~ thoroughly washed and dried a t 100' in air. A portion of the powder was mixed with enough LiOH, Zn(NO&, Mg(N0&, or Al(N03)a solution to yield a stiff paste, which was dried a t 110'. The amounts of solutions and their concentrations were sufficient to result in hydroxide samples that, when converted to CdO, would contain 1 atom % of foreign cations. Differential thermal analyses (d.t.a.) were made a t linear heating rates of 10°/min., using Pt-10% Pt.Rh thermocouples. A slowly moving stream of purified nitrogen passed over the nickel detector block. Thermogravimetric analysis (t.g.a.) was made in air with a modified Ainsworth automatic recording balance, a t linear rates of 4.6'/min. from room temperature to 500°. Isothermal weight loss (i.w.1.) was measured in air with a modified analytical balance. Sitrogen adsorption isotherms and B.E.T. surface areas4 were obtained with an apparatus of conventional desigm6 The initial degassing of each sample was carried out overnight a t room temperature because of the instability of the hydroxide. Surface areas were then measured for a sequence of heat treatments of various durations in vacuo {at each temperature. The surface areas, 'each calculated from data a t six relative pressures, are given in m.2/g. of starting material. Experiments and ResultsD.t.a. Experiments. These experiments are described in somewhat greater detail than would normally be warranted, because electrical disturbances of the instrument brought about by CdO can be used to deduce information about the extent of the decomposition. In studying the hydroxide-oxide transformation, it ...

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Section: The Catalytic Vapormentioning

confidence: 99%

The Thermal Decomposition of Cadmium Hydroxide

Löw¹,

Kamel²

1965

J. Phys. Chem.

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“…However, p-type metal oxide semiconductors have been receiving much attention for their unique catalytic properties and higher oxygen adsorption due to their multivalence properties, which make them good candidate materials for the selective detection of large molecule VOCs. In particular, among various p-type metal oxides, Co 3 O 4 is known to be an excellent catalyst for the oxidation of xylene in the liquid and vapor states. − …”

Section: Introductionmentioning

confidence: 99%

Co-Doped Branched ZnO Nanowires for Ultraselective and Sensitive Detection of Xylene

Woo

Kwak

Chung³

et al. 2014

ACS Appl. Mater. Interfaces

114

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Co-doped branched ZnO nanowires were prepared by multistep vapor-phase reactions for the ultraselective and sensitive detection of p-xylene. Highly crystalline ZnO NWs were transformed into CoO NWs by thermal evaporation of CoCl2 powder at 700 °C. The Co-doped ZnO branches were grown subsequently by thermal evaporation of Zn metal powder at 500 °C using CoO NWs as catalyst. The response (resistance ratio) of the Co-doped branched ZnO NW network sensor to 5 ppm p-xylene at 400 °C was 19.55, which was significantly higher than those to 5 ppm toluene, C2H5OH, and other interference gases. The sensitive and selective detection of p-xylene, particularly distinguishing among benzene, toluene, and xylene with lower cross-responses to C2H5OH, can be attributed to the tuned catalytic activity of Co components, which induces preferential dissociation of p-xylene into more active species, as well as the increase of chemiresistive variation due to the abundant formation of Schottky barriers between the branches.

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“…The effects of the addition of these co-catalysts are also reported for the vapor-phase partial oxidation reaction of unfluorinated compounds (benzene [14], xylene [15], etc.). The addition of other kinds of metal oxides such as MoO 3 is speculated to produce compound oxides [16], which affected the reactions.…”

Section: Catalyst Screeningmentioning

confidence: 99%