scholarly journals Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural in Aqueous Medium over Nb2O5-Based Catalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1821
Author(s):  
Elisa I. García-López ◽  
Francesca Rita Pomilla ◽  
Bartolomeo Megna ◽  
Maria Luisa Testa ◽  
Leonarda Francesca Liotta ◽  
...  
Keyword(s):  
High Selectivity ◽  
Physical Adsorption ◽  
Temperature Programmed Desorption ◽  
Temperature Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Operation Temperature ◽  
Infrared And Raman Spectroscopy ◽  
Experimental Parameters ◽  
Temperature Programmed

The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in water was performed in the presence of pristine Nb2O5 and composites containing Nb and Ti, Ce or Zr oxides. In all experiments, fructose was converted to HMF using water as the solvent. The catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, N2 physical adsorption, infrared and Raman spectroscopy and temperature-programmed desorption of NH3. Experimental parameters such as fructose initial concentration, volume of the reacting suspension, operation temperature, reaction time and amount of catalyst were tuned in order to optimize the catalytic reaction process. The highest selectivity to HMF was ca. 80% in the presence of 0.5 g·L−1 of bare Nb2O5, Nb2O5-TiO2 or Nb2O5-CeO2 with a maximum fructose conversion of ca. 70%. However, the best compromise between high conversion and high selectivity was reached by using 1 g·L−1 of pristine Nb2O5. Indeed, the best result was obtained in the presence of Nb2O5, with a fructose conversion of 76% and a selectivity to HMF of 75%, corresponding to the highest HMF yield (57%). This result was obtained at a temperature of 165° in an autoclave after three hours of reaction by using 6 mL of 1 M fructose suspension with a catalyst amount equal to 1 g·L−1.

scholarly journals Adsorción del naranja de metilo en solución acuosa sobre hidróxidos dobles laminares

2015 ◽  
Vol 25 (3) ◽  
pp. 25-34 ◽  
Author(s):  
Laura Alicia Ramírez Llamas ◽  
Araceli Jacobo Azuara ◽  
J. Merced Martínez Rosales
Keyword(s):  
Methyl Orange ◽  
Adsorption Capacity ◽  
Dye Adsorption ◽  
Temperature Programmed Desorption ◽  
Maximum Adsorption Capacity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Suitable Temperature ◽  
Temperature Programmed ◽  
Double Hydroxides

In this paper, layered double hydroxides (LDH) were synthesized and characterized using techniques of Physisorption of Nitrogen, Infrared, Temperature Programmed Desorption, X-Ray Diffraction, TGA and Immersion Microcalorimetry, in order to determine the basic properties of the adsorbent. The methyl orange (MO) is used as a dye and as a result, it is frequently found in effluents from textile industries. The dye adsorption isotherms on LDH were studied as function of pH and temperature. The maximum adsorption capacity of methyl orange on LDH was carried out at pH 5, and the minimum adsorption capacity at pH 11, being 40.2 mg/g and 22.1 mg/g, respectively. Furthermore, the suitable temperature to promote the adsorption of methyl orange on LDH was at 25 °C, as at 35 °C shows a significant decrease. 

scholarly journals In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 807
Author(s):  
Zen Maeno ◽  
Xiaopeng Wu ◽  
Shunsaku Yasumura ◽  
Takashi Toyao ◽  
Yasuharu Kanda ◽  
...  
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
X Ray ◽  
Catalytic Activities ◽  
Ethane Dehydrogenation ◽  
Temperature Programmed

In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites.

scholarly journals Experimental Investigations of the Interaction of SO2 with MgO

1999 ◽  
Vol 590 ◽  
Author(s):  
Andrea Freitag ◽  
J. A. Rodriguez ◽  
J. Z. Larese
Keyword(s):  
High Resolution ◽  
Film Thickness ◽  
Room Temperature ◽  
Temperature Programmed Desorption ◽  
Experimental Investigations ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Temperature Programmed ◽  
X Ray Absorption

ABSTRACTHigh resolution adsorption isotherms, temperature programmed desorption (TPD), x-ray diffraction (XRD) and x-ray absorption near edge spectroscopy (XANES) methods were used to investigate the interaction of SO2 with high quality MgO powders. The results of these investigations indicate that when SO2 is deposited on MgO in monolayer quantities at temperatures near 100K both SO3 and SO4 species form that are not removed by simply pumping on the pre-dosed samples at room temperature. TPD and XANES studies indicate that heating of pre-dosed MgO samples to temperatures above 350 °C is required for full removal of the SO3/SO4 species. XANES measurements made as a function of film thickness indicate for coverages near monolayer completion that the SO4 species form first.

scholarly journals Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2Methanation

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Wen Yang ◽  
Yanyan Feng ◽  
Wei Chu
Keyword(s):  
Surface Coverage ◽  
Temperature Programmed Desorption ◽  
Impregnation Method ◽  
Nio Nanoparticles ◽  
X Ray Diffraction ◽  
Ni Catalysts ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption ◽  
Supported Ni

The catalysts Ni/Al2O3and CaO modified Ni/Al2O3were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2adsorption/desorption, temperature-programmed reduction of H2(H2-TPR), X-ray diffraction (XRD), and temperature-programmed desorption of CO2and H2(CO2-TPD and H2-TPD) techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2and H2adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3showed high CO2conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4was very close to 1. The high CO2conversion over Ni/CaO-Al2O3was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3surface.

The Effect of Thermal Treatment on the Structure of Palygorskite Used for Flue Gas SO2 Removal

2011 ◽  
Vol 356-360 ◽  
pp. 698-703 ◽  
Author(s):  
Xian Long Zhang ◽  
Wei Ping Jiang ◽  
Xue Ping Wu ◽  
Bo Wen Shi ◽  
Bao Jun Yang ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Structural Properties ◽  
Flue Gas ◽  
Temperature Programmed Desorption ◽  
Flue Gas Desulfurization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Adsorption Sites ◽  
Transmission Electron ◽  
Temperature Programmed

Palygorskite is widely used as industrial adsorbent and also potential for flue gas desulfurization by adsorption of SO2. The effect of thermal treatment on Palygorskite’s structural properties and its performance in SO2adsorption were investigated. The textural and structural properties of the prepared palygorskite adsorbent were characterized by X-ray diffraction, transmission electron microscopy and temperature programmed desorption. The result showed the channel of Palygorskite is partial collapsed and the structure is not changed ultimately when thermally treated below 300 °C. The structure of Palygorskite is Gradually changed when the treating temperature is higher than 300 °C and is damaged entirety till 800 °C. As a result, the adsorption capacity of SO2on Palygorskite decreased drastically. It is suggested that the presences of surface adorbed water and zeolitic water which occupy a large number of adsorption sites are disadvantage for the adsorption of SO2, and dissimilarly the presence of crystal-bonded water is favorable.

Effect of the Addition of In to Co/HMCM-49 Catalyst for the Selective Catalytic Reduction of NO Under Lean-burn Conditions

2010 ◽  
Vol 224 (06) ◽  
pp. 907-920 ◽  
Author(s):  
Fei Li ◽  
Dehai Xiao ◽  
Jing Li ◽  
Xiangguang Yang
Keyword(s):  
Selective Catalytic Reduction ◽  
Wide Temperature Range ◽  
Catalytic Reduction ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
Lean Burn ◽  
Reduction Of No ◽  
X Ray ◽  
Scr Of No ◽  
Temperature Programmed

AbstractSelective catalytic reduction (SCR) of NO with propane using bimetals (3Co2Ce, 3Co2Sr, 3Co2Sn and 3Co2In) loaded on HMCM-49 zeolite was studied under lean-burn condition. Only 3Co2In/HMCM-49 exhibited higher deNOx activity in a wide temperature range. The catalysts were characterized by N2-adsoption, X-ray diffraction (XRD), temperature-programmed surface reactions (TPSR) and temperature-programmed desorption (TPD) of NO. TPSR and TPD results exhibited that the addition of In inhibited the oxidation ability of Co on 3Co2In/HMCM-49 catalyst, but enhanced NOx adsorption.

Effect of Heat Treatments on TiH2: Surface Composition and Hydrogen Release

2016 ◽  
Vol 879 ◽  
pp. 2032-2037 ◽  
Author(s):  
Gabriele Lapi ◽  
Carlo Alvani ◽  
Francesca Varsano ◽  
Saulius Kaciulis ◽  
Roberto Montanari ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Titanium Hydride ◽  
Surface Composition ◽  
Hydrogen Desorption ◽  
Temperature Programmed Desorption ◽  
Heat Treatments ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

The present work investigates the effect of heat treatments in air on the surface and structure of titanium hydride (TiH2) and hydrogen desorption. TiH2 has been heated in air at 440 and 540 °C for increasing time up to 180 min. to obtain the samples representative of 12 different oxidation conditions. The samples have been then examined by Temperature Programmed Desorption (TPD), X-Ray Diffraction (XRD) and Photoelectron Spectroscopy (XPS). Experimental results are presented and discussed.

scholarly journals The Effect of Catalyst Calcination Temperature on Catalytic Decomposition of HFC-134a over γ-Al2O3

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1021
Author(s):  
Mahshab Sheraz ◽  
Ali Anus ◽  
Van Cam Thi Le ◽  
Caroline Mercy Andrew Swamidoss ◽  
Seungdo Kim
Keyword(s):  
Catalytic Activity ◽  
Catalytic Pyrolysis ◽  
Catalytic Decomposition ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hfc 134A ◽  
Acidic Sites ◽  
Temperature Programmed ◽  
Decomposition Efficiency

This paper explores the thermal and catalytic pyrolysis of HFC-134a over γ-Al2O3 calcined at temperatures of 550 °C (A550), 650 °C (A650), 750 °C (A750), and 850 °C (A850). The physicochemical properties of catalysts were studied through thermogravimetric analysis (TGA), Brunauer–Emmett–Teller equation for nitrogen physisorption analysis (BET), X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH3-TPD). The non-catalytic pyrolysis of HFC-134a showed less than 15% decomposition of HFC-134a. Catalysts increased the decomposition as A650 revealed the highest decomposition efficiency by decomposing more than 95% HFC-134a for 8 h followed by A750, A850, and A550. The larger surface area and pore volume paired with a low amount of strong acidic sites were considered as the main contributors to the comparatively longer catalytic activity of A650.

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