The role of platinum on the NOx storage and desorption behavior of ceria: An online FT-IR study combined with in situ Raman and UV-Vis spectroscopy

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

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In situ FT-IR Study on the Direct Gas Phase Epoxidation of Propylene over Ag-MoO3 Catalyst

Acta Physico-Chimica Sinica ◽

10.1016/s1872-1508(06)60034-x ◽

2006 ◽

Vol 22 (7) ◽

pp. 809-814

Author(s):

G JIN ◽

Y GUO ◽

X LIU ◽

W YAO ◽

Y GUO ◽

...

Keyword(s):

Gas Phase ◽

Epoxidation Of Propylene ◽

Ft Ir ◽

Ir Study

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Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽

10.3390/catal11070824 ◽

2021 ◽

Vol 11 (7) ◽

pp. 824

Author(s):

Przemysław J. Jodłowski ◽

Izabela Czekaj ◽

Patrycja Stachurska ◽

Łukasz Kuterasiński ◽

Lucjan Chmielarz ◽

...

Keyword(s):

Ion Exchange ◽

Ultrasonic Irradiation ◽

Active Phase ◽

Spectroscopic Studies ◽

In Situ Drifts ◽

Ft Ir ◽

Diffuse Reflectance Infrared ◽

Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

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Synthesis of Poly(methacrylic acid-co-butyl acrylate) Grafted onto Functionalized Carbon Nanotube Nanocomposites for Drug Delivery

Polymers ◽

10.3390/polym13040533 ◽

2021 ◽

Vol 13 (4) ◽

pp. 533 ◽

Cited By ~ 1

Author(s):

Josué A. Torres-Ávalos ◽

Leonardo R. Cajero-Zul ◽

Milton Vázquez-Lepe ◽

Fernando A. López-Dellamary ◽

Antonio Martínez-Richa ◽

...

Keyword(s):

Carbon Nanotubes ◽

Drug Delivery ◽

Methacrylic Acid ◽

Butyl Acrylate ◽

Chemical Vapor ◽

Vis Spectroscopy ◽

Ir And Raman Spectroscopies ◽

Ft Ir

Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and purified with steam. Purified CNTs were analyzed by FE-SEM and HR-TEM. CNTsf contain acyl chloride groups attached to their surface. Purified and functionalized CNTs were studied by FT-IR and Raman spectroscopies. The synthesized nanocomposites were studied by XPS, 13C-NMR, and DSC. Anhydride groups link CNTsf to MAA–BA polymeric chains. The potentiality of the prepared nanocomposites, and of their pure polymer matrices to deliver hydrocortisone, was evaluated in vitro by UV–VIS spectroscopy. The relationship between the chemical structure of the synthesized nanocomposites, or their pure polymeric matrices, and their ability to release hydrocortisone was studied by FT-IR spectroscopy. The hydrocortisone release profile of some of the studied nanocomposites is driven by a change in the inter-associated to self-associated hydrogen bonds balance. The CNTsf used to prepare the studied nanocomposites act as hydrocortisone reservoirs.

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Di-imide: Some Physical and Chemical Properties, and the Kinetics and Stoichiometry of the Gas-phase Decomposition

Canadian Journal of Chemistry ◽

10.1139/v73-536 ◽

1973 ◽

Vol 51 (21) ◽

pp. 3605-3619 ◽

Cited By ~ 35

Author(s):

C. Willis ◽

R. A. Back

Keyword(s):

Gas Phase ◽

Room Temperature ◽

Chemical Properties ◽

Phase Decomposition ◽

Important Intermediate ◽

Long Lifetime ◽

Physical And Chemical ◽

Text Formation ◽

Kinetics Of

Preparation of di-imide by passing hydrazine vapor through a microwave discharge yields mixtures with NH3 containing typically about 15% N2H2, estimated from the gases evolved on decomposition. The behavior of the mixture (which melts at −65 °C) on warming from −196 to −30 °C suggests a strong interaction between the components. Measurements of magnetic susceptibility and e.p.r. experiments showed that N2H2 is not strongly paramagnetic, which with other observations points to a singlet rather than a triplet ground-state.Di-imide can be vaporized efficiently, together with NH3, by rapid warming, and the vapor is surprisingly long-lived, with a typical half-life of several minutes at room temperature. The near-u.v. (3200–4400 Å) absorption spectrum of the vapor was photographed; it shows well-defined but diffuse bands, with εmax = 6(± 3) at 3450 Å.Di-imide decomposes at room temperature in two ways:[Formula: see text][Formula: see text]Formation of NH3 was not observed but cannot be ruled out. The decomposition of the vapor is complicated by a sizeable and variable decomposition that occurs rapidly during the vaporization. The stoichiometry of this and the vapor-phase decomposition depends on total pressure and di-imide concentration. The kinetics of the decomposition of the vapor were studied from 22 to 200 °C by following the disappearance of N2H2 by absorption of light at 3450 Å, or the formation of N2H4 by absorption at 2400 Å, and by mass spectrometry. The kinetics are complex and can be either first- or second-order, or mixed, depending on surface conditions. The effect of olefin additives on the decomposition was studied, and is also complex.Mechanisms for the decomposition are discussed, including the possible role of trans-cis isomerization. The relatively long lifetime found for di-imide in the gas phase suggests that it may be an important intermediate in many reactions of hydronitrogen systems.

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The Role of Al3+-Based Aqueous Electrolytes in the Charge Storage Mechanism of MnOx Cathodes

10.26434/chemrxiv.13272980 ◽

2020 ◽

Author(s):

Véronique Balland ◽

Mickaël Mateos ◽

Kenneth D. Harris ◽

Benoit Limoges

Keyword(s):

Manganese Oxide ◽

Critical Analysis ◽

Charge Storage ◽

Aqueous Electrolytes ◽

Storage Mechanism ◽

Main Charge ◽

Charge Storage Mechanism ◽

The Subject

Rechargeable aqueous aluminium batteries are the subject of growing interest, but the charge storage mechanisms at manganese oxide-based cathodes remain poorly understood with as many mechanisms as studies. Here, we use an original in situ spectroelectrochemical methodology to unambiguously demonstrate that the reversible proton-coupled MnO2-to-Mn2+ conversion is the main charge storage mechanism occurring at MnO2 cathodes over a range of slightly acidic Al3+-based aqueous electrolytes. In Zn/MnO2 assemblies, this mechanism is associated with high gravimetric capacity and discharge potentials, up to 560 mAh·g-1 and 1.76 V respectively, attractive efficiencies (CE > 98.5 % and EE > 80%) and excellent cyclability (> 750 cycles at 10 A·g-1). Finally, we conducted a critical analysis of the data previously published on MnOx cathodes in Al3+-based aqueous electrolytes to conclude on a universal charge storage mechanism, i.e., the reversible electrodissolution/electrodeposition of MnO2.

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