scholarly journals Influence of alumina addition on structural and catalytic properties of sulphated zirconia in isomerization of n-hexane

2021 ◽  
Vol 15 (2) ◽  
pp. 111-119
Author(s):  
Aleksandra Zarubica ◽  
Jugoslav Krstic ◽  
Dejan Popovic ◽  
Aleksandra Krstic ◽  
Radomir Ljupkovic ◽  
...  
Keyword(s):  
Calcination Temperature ◽  
Tetragonal Zirconia ◽  
Chemical Properties ◽  
Acid Sites ◽  
Catalytic Systems ◽  
Organic Precursor ◽  
Sulphated Zirconia ◽  
Calcination Temperatures ◽  
Physico Chemical ◽  
Catalytic Material

New binary catalytic systems based on sulphated zirconia-alumina were synthesized by controlled hydrolysis of alkoxides using relative molar ratios of constituents 1:1, 1:2 and 1:3 in favour of zirconia. The obtained differences in the final catalytic material?s properties may be related to organic precursor memory effect, the applied calcinations temperatures and used alumina contents. The addition of alumina to zirconia affected the structural and surface properties stabilizing bare zirconia by means of slower phase transformation of tetragonal zirconia crystal phase into monoclinic one, further resulting in smaller crystallites sizes and higher surface density of acidic function (sulphates). The best alumina impact on physico-chemical properties was achieved when the highest amount of alumina (e.g. 50%) and lower calcination temperature (500?C) were used, causing relatively high steady-state activity in isomerization of n-hexane at reaction temperature 250 ?C. On the other hand, higher calcination temperature (600 ?C) played a role in the genesis of greater sulphate density. Catalytic activity and selectivity are expressed as a complex synergistic function of relative density of acid sites together with positive status of other optimized physico-chemical properties of the catalytic material (by activation and calcination temperatures).

scholarly journals Influence of the Calcination Temperature on the properties of The Alumina as Catalyst Support for Catalysis

Paliva ◽  
2020 ◽  
pp. 155-161
Author(s):  
Tomáš Hlinčík ◽  
Veronika Šnajdrová ◽  
Veronika Kyselová
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Temperature Range ◽  
Calcination Temperatures ◽  
Physical And Chemical

Alumina is commonly used in industrial practice as a catalyst support and it is made from boehmite. Depending on the calcination temperature, this mineral is transformed into various crystalline modifications which have different physical and chemical properties. For this reason, the following parameters were determined at different calcination temperatures: length, width, material hardness, specific surface area and total pore volume. The results show that with increasing calcination temperature there have been significant changes which may be important when using the material as a catalyst support, e.g. in the preparation of catalysts or in the design of cat-alytic reactors. The specific surface area, which decreases in the temperature range 450–800 °C, is an important parameter for the preparation of catalysts, so it is appropriate to choose a temperature of 600 °C, when the specific surface area is above 200 m2·g-1. The effect of calcination temperature on the structural transitions of boehmite was also monitored. The results showed that γ-Al2O3 has the most suitable properties as a catalyst sup-port in the temperature range 450–800 °C.

scholarly journals Morphology and Mechanical Properties of 3Y-TZP Nanofiber Mats

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2097
Author(s):  
Alexander I. Tyurin ◽  
Vyacheslav V. Rodaev ◽  
Svetlana S. Razlivalova ◽  
Viktor V. Korenkov ◽  
Andrey O. Zhigachev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Phase Composition ◽  
Calcination Temperature ◽  
Tetragonal Zirconia ◽  
Calcination Temperatures ◽  
Nanoindentation Testing ◽  
Average Grain Size ◽  
Nanofiber Mats ◽  
Morphology And Mechanical Properties

The mats of yttria-stabilized tetragonal zirconia nanofibers were prepared using electrospinning. The effect of calcination temperature in the range of 600–1200 °C on their microstructure, phase composition and mechanical properties was investigated. Phase composition of the nanofibers did not change in all ranges of the calcination temperatures, while the average grain size increased from 8 to 39 nm. Nanoindentation testing of the mats showed a decrease in the hysteresis loop energy in samples with higher calcination temperature. Hardness and the elastic modulus measured with the indentation technique were the highest for the mats calcined at 900 °C.

scholarly journals Decolorization of crystal violet over TiO2 and TiO2 doped with zirconia photocatalysts

2017 ◽  
Vol 71 (3) ◽  
pp. 259-269 ◽  
Author(s):  
Marija Vasic ◽  
Marjan Randjelovic ◽  
Jelena Mitrovic ◽  
Nikola Stojkovic ◽  
Branko Matovic ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Uv Light ◽  
Sol Gel ◽  
Chemical Properties ◽  
Dye Decolorization ◽  
Operational Parameters ◽  
Physico Chemical ◽  
Irradiation Treatment ◽  
Catalytic Material ◽  
Reaction Cycles

Titania based catalyst and TiO2 doped with zirconia were prepared by modified sol?gel method. The synthesized catalysts samples were characterized by BET, XRD, SEM and FTIR techniques. Photocatalytic activity was tested in the reaction of crystal violet (CV) dye decolorization/decomposition under UV light irradiation. The effect of several operational parameters, such as catalyst dosage, initial dye concentrations, duration of UV irradiation treatment and number of reaction cycles were also considered. The obtained results indicated faster dye decolorization with the increase of the catalyst amount and a decrease of initial CV concentrations. An influence of doping with zirconia on the physico-chemical properties of bare titania was studied. The doping procedure had affected photocatalytic properties of the final catalytic material, and had improved photocatalytic performances of doped catalyst on crystal violet decolorization/degradation in comparison to bare titania.

scholarly journals Physico-Chemical Properties of Nickel Promoted Sulfated Zirconia Powder Prepared using Different Procedures

2020 ◽  
Vol 32 (3) ◽  
pp. 555-560
Author(s):  
Amalia Kurnia Amin ◽  
Karna Wijaya ◽  
Wega Trisunaryanti
Keyword(s):  
Crystallite Size ◽  
Sulfated Zirconia ◽  
Pore Volume ◽  
Chemical Properties ◽  
Acid Sites ◽  
Impregnation Method ◽  
Zirconia Powder ◽  
Ammonia Adsorption ◽  
Physico Chemical ◽  
Zirconia Support

In this work, nickel promoted sulfated zirconia (Ni/SZ) as catalyst was prepared by either by reflux (Ni/SZ-R) or hydrothermal Ni impregnation (Ni/SZ-H) routes. The aim of this study was to evaluate the influences of two preparative methods on the physico-chemical properties of prepared catalysts. Both the catalysts were characterized by XRD, FTIR, ammonia adsorption, SEM-EDX, TEM-SAED, AAS and BET. It was found that the presence of sulfate and nickel could enhance the Brønsted and Lewis active acid sites. In relation to the effect of Ni impregnation method, acidity, amount of sulfate and Ni found in Ni/SZ-R were higher than those in Ni/SZ-H. Unfortunately, higher impregnated sulfate and nickel on zirconia support led to a decrease in surface area and pore volume and an increase in crystallite size of grainy aggregated mesoporous nickel promoted sulfated zirconia (Ni/SZ).

Nitrogen-Incorporated NaY Zeolite as Promising Basic Microporous Catalytic Material

2010 ◽  
Vol 148-149 ◽  
pp. 957-962
Author(s):  
Tao Wang ◽  
Lan Dong Li ◽  
Guang Jun Wu ◽  
Nai Jia Guan
Keyword(s):  
Condensation Reaction ◽  
Co Adsorption ◽  
Chemical Properties ◽  
Nay Zeolite ◽  
Characterization Methods ◽  
Surface Areas ◽  
Physico Chemical ◽  
Catalytic Material ◽  
Base Strength ◽  
Knoevenagel Condensation Reaction

A promising basic microporous catalytic material is prepared by nitridation of dehydrated NaY zeolite. The base strength of zeolite framework is enhanced due to the replacement of oxygen by nitrogen with lower electronegativity. Various characterization methods, including XRD, CHN elemental analysis, SEM and FTIR spectra of CO adsorption, are employed to analyze the physico-chemical properties of the nitrogen-incorporated NaY zeolite. High crystallinity and high specific surface areas of NaY are well preserved in nitrogen-incorporated NaY. Compared to parent NaY zeolite, the nitridized materials exhibit improved basic catalytic performances in Knoevenagel condensation reaction and side-chain monomethylation reaction of phenylacetonitrile.

The Effect of the Method of Gallium Introduction into a Zeolite on its Physico-Chemical Properties and Reactivity in the Course of Propane Aromatization

2015 ◽  
Vol 670 ◽  
pp. 15-20 ◽  
Author(s):  
Ludmila N. Vosmerikova ◽  
Aleksandra N. Volynkina ◽  
Vladimir I. Zaikovskii ◽  
Aleksandr V. Vosmerikov
Keyword(s):  
Catalytic Activity ◽  
Aromatic Hydrocarbons ◽  
Pore Volume ◽  
Structural Characteristics ◽  
Chemical Properties ◽  
Acid Sites ◽  
Efficient Catalyst ◽  
Propane Aromatization ◽  
Physico Chemical ◽  
The Relationship

Different methods are used to prepare gallium-containing zeolites of a ZSM-5 structure. Their acidic and structural characteristics are investigated and the effect of the method of gallium introduction into a zeolite on distribution and ratio of acid sites of different strengths, as well as on pore volume and diameter is determined. The relationship between the localization of gallium introduced into a zeolite by different methods and its electronic state and the catalytic activity and selectivity of the resulting contacts in the course of propane aromatization is established. The Ga-containing zeolite prepared by impregnation is found to be the most efficient catalyst for conversion of propane into aromatic hydrocarbons.

scholarly journals Investigation the effects of Al-grafting and calcination temperature on acidity and physicochemical properties of silica SBA-15

2020 ◽  
Vol 85 (10) ◽  
pp. 1345-1356
Author(s):  
Reza Orouj ◽  
Mehdi Rashidzadeh ◽  
Akbar Irandoukht ◽  
Sepehr Sadighi
Keyword(s):  
Physicochemical Properties ◽  
Calcination Temperature ◽  
Mesoporous Structure ◽  
Acid Sites ◽  
Weak Acid ◽  
N2 Adsorption ◽  
Calcination Temperatures ◽  
Post Synthesis ◽  
Adsorption Desorption ◽  
High Aluminum

In this study, the effect of calcination temperature and Si/Al mole ratio on acidity and physicochemical properties of silica SBA-15 were investigated. Silica SBA-15 samples were calcined at 350, 450 and 550?C, and then post-synthesis, the Al-grafting method was applied to incorporate aluminum species into their framework with Si/Al mole ratio of 10 and 30. Characterizations using small angle XRD and N2 adsorption?desorption techniques indicated that the hexagonal mesoporous structure was retained after performing Al-grafting even at the high aluminum loading. Moreover, FTIR results implied that the aluminum species were incorporated into the SBA-15 framework. NH3-TPD results showed that by decreasing Si/Al mole ratio at all calcination temperatures, the number of weak acid sites increased in comparison to those of the pure SBA-15 samples. Additionally, the maximum total acidity of synthesized samples was observed at the calcination temperature of 450?C with Si/Al mole ratio of 30.

SHS Oxide Catalysts: Synthesis, Properties and Applications

2006 ◽  
Vol 45 ◽  
pp. 1058-1066 ◽  
Author(s):  
Galina Xanthopoulou ◽  
George Vekinis
Keyword(s):  
Chemical Properties ◽  
Oxidation Of Co ◽  
Commercial Catalyst ◽  
Catalytic Systems ◽  
Physico Chemical ◽  
Synthesis Properties ◽  
Catalyst Systems ◽  
Oxidative Dehydrodimerization ◽  
Better Than ◽  
Shs Method

Over the last 30 years, the SHS method has been used to produce a range of very active catalysts with a range of compositions (borides, carbides, nitrides, oxides, intermetallides, metals on carriers) for various chemical processes. Physico-chemical properties of each composition were regulated by control of the SHS process parameters. Such SHS catalysts have been examined over a range of compositions and reaction temperatures and the processing conditions were optimised for each particular process, which included: oxidation of CO, H2, soot, hydrocarbons, organic acids, aldehides, alcoholes, deep methane oxidation, dehydrogenation, pyrolysis of diesel, naphta and petrol, oxidative dehydrodimerization of methane, hydrogenation, isomerization, cracking, production of synthesis gas, synthesis ammonia and other processes. The activity of many of the materials developed is substantially better than many of commercial catalyst systems and SHS catalysts used in industry. We herein present a review of some of the most important SHS oxide catalytic systems produced worldwide with particular emphasis on the optimization of properties via control of SHS processing and discuss important industrial and environmental applications.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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