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Kresnawahjuesa, Oferi; Gorte, Raymond J.; Oliveira, Débora de; Lam, Yiu Lau

doi:10.1023/a:1020514911456

Cited by 103 publications

(79 citation statements)

References 25 publications

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“…(In these experiments, the mass 44 peak is due to propane which originates from fragmentation of desorbed and intact isopropylamine.) By this comparison and in agreement with previous studies [41], the peak appearing in the temperature range of 310-350°C represents the strong Brønsted acid sites able to perform the Hoffman elimination while the one appearing at 150°C represents that of molecularly desorbed isopropylamine.…”

Section: Temperature Programmed Desorption Of Isopropylaminesupporting

confidence: 91%

“…4a. As Gorte and coworkers have reported [29,40,41], isopropylamine decomposes on acidic Brønsted sites following a Hoffman elimination pathway. The decomposition of isopropylamine generates propylene and ammonia; therefore, by measuring the evolution of propylene as a function of temperature, a reliable determination of the relative density of strong Brønsted sites can be made.…”

Section: Temperature Programmed Desorption Of Isopropylaminementioning

confidence: 93%

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Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Herrera

Kwak

et al. 2008

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The catalytic behavior of tungstophosphoric acid supported on modified mesoporous silica materials for the dehydration of 2-butanol and methanol was studied. Specifically, the supports evaluated here consisted of unmodified MCM-41 and SBA-15 mesoporous silicas, and these materials coated with sub-monolayer quantities of alumina, titania, and zirconia. UV-Vis DRS and 31 P-NMR spectroscopy showed that the tungstophosphoric acid species retained their chemical identity in the synthesized supported form, although the spectra were influenced by the specific support material used. In addition, their acidic properties were evaluated using temperature-programmed oxidation of isopropyl amine. The differences in reaction rates between the samples reflect both the diversity in the amount of Brønsted acidic sites available for catalysis and dissimilarities in coking resistance. These two characteristics depend, in turn, on the type of support modifier used to prepare the catalyst.

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Section: Temperature Programmed Desorption Of Isopropylaminesupporting

confidence: 91%

Section: Temperature Programmed Desorption Of Isopropylaminementioning

confidence: 93%

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Herrera

Kwak

et al. 2008

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“…Similar results were obtained from the thermal desorption of ammonia method [15]. In [10] the lower density of B-centers in H-Y zeolites explained that only some of the acid centers in H-Y were capable to protonate such strong bases as pyridine and isopropylamine to form pyridinium and alkylammonium ions, i.e., some of the centers of H-Y are unsuitable for absorption. Evidently the B-centers of H-Y zeolites are incapable of protonating such weak bases as the C 3 -C 4 alkanes which we used as reducing agents for N 2 O.…”

supporting

confidence: 74%

“…This has been studied with catalysts based on ZSM-5, especially samples containing iron, and explained in a number of papers [10]. In the general case the reaction where Z is an active center, R is a reducing agent (C 3 H 8 -C 4 H 10 or CO in our case), and N (1) and N (2) are the routes with the corresponding stoichiometric numbers.…”

mentioning

confidence: 99%

Reduction of nitrogen(I) oxide with carbon monoxide and C3–C4 alkanes on Fe-containing zeolite catalysts

Орлик

Pidruchna

2005

Theor Exp Chem

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It is shown that in the presence of reducing agents -light alkanes (C 3 -C 4 ) or carbon monoxide -the temperature for the elimination of nitrogen(I) oxide over iron-containing zeolite catalysts of various structural types (Y, M, pentasil) is reduced by 70-150°C. In the presence of excess oxygen (SCR process conditions) a greater conversion of N 2 O (90-94%) is achieved at even lower temperatures (up to 50-150°C less) with the use of hydrocarbons, and the activity of the catalysts correlates with the presence of strongly acidic B centers on their surfaces.The recent agreements between countries of the world community on the reduction of the emission of greenhouse gases into the atmosphere requires the development and use of effective technologies, among which catalysis has an important role, especially catalysts to purify emission gases from nitrogen oxides.Denitrification of industrial effluent gases is usually carried out by selective catalytic reduction (SCR) of nitrogen oxides with ammonia or hydrocarbons, hence the conditions for the reaction of N 2 O with various reducing agents (NH 3 , CO, C n H m ) remains a topic of intense study [1][2][3].The wide range of temperatures (250-500°C) of nitrogenous effluent gases, containing NO and N 2 O [4, 5], makes it necessary to develop catalysts for the direct decomposition of N 2 O and the selective reduction of nitrogen(I) oxide, a process which occurs at lower temperatures.It was shown in [6], as a result of testing a series of iron-containing catalysts based on zeolites of various structural types and zirconium dioxide, that the direct decomposition of N 2 O over the most active catalysts occurred at 500-550°C with conversions of 86-96%.In the present work reducing agents -a propane-butane mixture or CO -were added to the reaction mixture with the objective of reducing the temperature for the elimination of N 2 O. Results on the reactivity of iron-containing zeolite catalysts of various structural types (Y, M, pentasil), including those containing zirconium ions, and binary catalysts (zeolite + ZrO 2 ) in the reduction of nitrogen(I) oxide with C 3 -C 4 hydrocarbons and carbon monoxide are presented. The methods for preparation of the catalysts has been reported [6]. The acidic properties of the surfaces of separate samples were investigated by thermal desorption of ammonia and IR spectroscopy. The catalytic activity of the samples was characterised by the degree of conversion of N 2 O to nitrogen, which was determined in a flow apparatus with a gradient less quartz reactor at atmospheric pressure in the temperature range 250-560°C. The standard reaction mixture contained 0.5% N 2 O, 0.2% C 3 H 8 -C 4 H 10 (2 : 1) or 0.5% N 2 O and 0.5% CO. In the study of the effect of excess oxygen 5% (by volume) was added to the reaction mixture. Catalysts samples (2 cm 3 , particle size 1-3 mm) was heated in air with a flow rate of 100 mL/min at 550°C for 1 h. Analysis of 0040-5760/05/4101-0037

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“…However, such discussion has been mainly devoted to the behaviour of iron-containing ZSM-5 catalysts (Kresnawahjuesa et al 2002). In general, the reaction: where Z is the active centre and R is the reductant (C 3 H 8 /C 4 H 10 or CO in the present case).…”

Section: Surface Active Sites Of Modified Zeolites and Zirconiamentioning

confidence: 99%

Surface Active Sites of Modified Zeolites and Zirconia in the Conversion of Nitrogen(I, II) Oxides

Orlyk

Mironyuk

Boichuk

2007

Adsorption Science & Technology

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Samples of zirconia doped with transition metal (Cr, Co, Ce) oxides, and also rhodium-promoted and Fe-containing zeolites of different structural types, were studied by NH 3 -TPD and IR spectroscopy. The various samples were analyzed with respect to their catalytic performances in deNO x reactions, in particular the selective catalytic reduction of NO (N 2 O) using hydrocarbons as reducing agents (HC SCR). Bifunctional zeolite-and ZrO 2 -based catalysts exhibited high activity in the SCR of nitrogen(I, II) oxides to dinitrogen due to the combination of the surface redox and acidic properties exhibited by these materials.

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Cited by 103 publications

References 25 publications

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Reduction of nitrogen(I) oxide with carbon monoxide and C3–C4 alkanes on Fe-containing zeolite catalysts

Surface Active Sites of Modified Zeolites and Zirconia in the Conversion of Nitrogen(I, II) Oxides

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