scholarly journals In Situ DRIFTS-MS Methanol Adsorption Study onto Supported NiSn Nanoparticles: Mechanistic Implications in Methanol Steam Reforming

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3234
Author(s):  
Luis F. Bobadilla ◽  
Lola Azancot ◽  
Svetlana Ivanova ◽  
Juan J. Delgado ◽  
Francisca Romero-Sarria ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Acid Sites ◽  
Methanol Steam Reforming ◽  
Alumina Support ◽  
In Situ Drifts ◽  
Methanol Adsorption ◽  
Production Of Hydrogen ◽  
Metal Support ◽  
Diffuse Reflectance Infrared

Methanol adsorption over both supported NiSn Nps and analogous NiSn catalyst prepared by impregnation was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to gain insights into the basis of hydrogen production from methanol steam reforming. Different intermediate species such as methoxides with different geometry (bridge and monodentate) and formate species were identified after methanol adsorption and thermal desorption. It is proposed that these species are the most involved in the methanol steam reforming reaction and the major presence of metal-support interface sites in supported NiSn Nps leads to higher production of hydrogen. On the basis of these results, a plausible reaction mechanism was elucidated through the correlation between the thermal stability of these species and the evolution of the effluent gas released. In addition, it was demonstrated that DME is a secondary product generated by condensation of methoxides over the acid sites of alumina support in an acid-catalyzed reaction.

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

Catalysts ◽  
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).

scholarly journals Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 768 ◽  
Author(s):  
Shuang Ding ◽  
Jiankang Zhao ◽  
Qiang Yu
Keyword(s):  
Propionic Acid ◽  
Vapor Phase ◽  
Surface Concentration ◽  
X Ray Diffraction ◽  
In Situ Drifts ◽  
X Ray ◽  
Surface Intermediates ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

Vapor-phase ketonization of propionic acid derived from biomass was studied at 300–375 °C over ZrO2 with different zirconia polymorph. The tetragonal ZrO2 (t-ZrO2) are more active than monoclinic ZrO2 (m-ZrO2). The results of characterizations from X-ray diffraction (XRD) and Raman suggest m-ZrO2 and t-ZrO2 are synthesized by the solvothermal method. NH3 and CO2 temperature-programmed desorption (NH3-TPD and CO2-TPD) measurements show that there were more medium-strength Lewis acid base sites with lower coordination exposed on m-ZrO2 relative to t-ZrO2, increasing the adsorption strength of propionic acid. The in situ DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy) of adsorbed propionic acid under ketonization reaction reveal that as the most abundant surface intermediates, the monodentate propionates are more active than bidentate propionates. In comparison with m-ZrO2, the t-ZrO2 surface favors monodentate adsorption over bidentate adsorption. Additionally, the adsorption strength of monodentate propionate is weaker on t-ZrO2. These differences in adsorption configuration and adsorption strength of propionic acid are affected by the zirconia structure. The higher surface concentration and weaker adsorption strength of monodentate propionates contribute to the higher ketonization rate in the steady state.

Novel Base Catalysts by Nitridation of Zeolite Y: Characterization and Catalytic Evaluation

2010 ◽  
Vol 148-149 ◽  
pp. 1096-1099
Author(s):  
Gong Ming Peng ◽  
De Lian Yi ◽  
Lin Wu ◽  
Zhao Hui Ou Yang ◽  
Jian Guo Wang
Keyword(s):  
Surface Area ◽  
Zeolite Y ◽  
High Surface ◽  
High Surface Area ◽  
Diethyl Malonate ◽  
Bet Surface Area ◽  
In Situ Drifts ◽  
Base Catalysts ◽  
Diffuse Reflectance Infrared

Novel base catalysts were obtained by subjecting Y zeolites to nitridation. These materials were characterized by elemental analysis, X-ray diffraction, BET surface area analysis, In situ diffuse reflectance infrared fourier transform Spectroscopy (in situ DRIFTS), Pyrrole adsorption. The results indicated nitrogen-incorporated NaY zeolite was well ordered and possess high surface area and pore volume. In situ DRIFTS experiments confirmed that N atoms had been introduced into the framework by nitridation to form -NH2- or -NH- species. It was found that Lewis basicity of these oxynitride materials increased by the pyrrole adsorption. Furthmore, the basic catalytic properties of nitrogen-incorporated zeolites were evaluated by Knoevenagal condensation of benzaldehyde with diethyl malonate and enhanced yield of product was achieved.

Influence of the component interaction over Cu/ZrO2 catalysts induced with fractionated precipitation method on the catalytic performance for methanol steam reforming

RSC Advances ◽  
2016 ◽  
Vol 6 (36) ◽  
pp. 30176-30183 ◽  
Author(s):  
Jiajia Zhou ◽  
Ye Zhang ◽  
Guisheng Wu ◽  
Dongsen Mao ◽  
Guanzhong Lu
Keyword(s):  
Steam Reforming ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Methanol Steam Reforming ◽  
Steam Reforming Of Methanol ◽  
Component Interaction ◽  
Production Of Hydrogen ◽  
Composition Ratios

A series of binary Cu/ZrO2 catalysts by choosing different composition ratios and different precipitation sequences have been prepared for the production of hydrogen by steam reforming of methanol (SRM).

scholarly journals Influence of the ZrO2 Crystalline Phases on the Nature of Active Sites in PdCu/ZrO2 Catalysts for the Methanol Steam Reforming Reaction—An In Situ Spectroscopic Study

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1005
Author(s):  
Daniel Ruano ◽  
Beatriz M. Pabón ◽  
Càtia Azenha ◽  
Cecilia Mateos-Pedrero ◽  
Adélio Mendes ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Surface Composition ◽  
Ambient Pressure ◽  
Chemical Properties ◽  
Spectroscopic Studies ◽  
Metal Species ◽  
Methanol Steam Reforming ◽  
Reaction Products

In this work, the electronic properties of the metal sites in cubic and monoclinic ZrO2 supported Pd and PdCu catalysts have been investigated using CO as probe molecule in in-situ IR studies, and the surface composition of the outermost layers has been studied by APXPS (Ambient Pressure X-ray Photoemission Spectroscopy). The reaction products were followed by mass spectrometry, making it possible to relate the chemical properties of the catalysts under reaction conditions with their selectivity. Combining these techniques, it has been shown that the structure of the support (monoclinic or cubic ZrO2) affects the metal dispersion, mobility, and reorganization of metal sites under methanol steam reforming (MSR) conditions, influencing the oxidation state of surface metal species, with important consequences in the catalytic activity. Correlating the mass spectra of the reaction products with these spectroscopic studies, it was possible to conclude that electropositive metal species play an imperative role for high CO2 and H2 selectivity in the MSR reaction (less CO formation).

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