Microwave Pyrolysis of Emulsified Ceramic Precursor Ocompounds

1994 ◽  
Vol 347 ◽  
Author(s):  
M. Willert-Porada ◽  
S. Dennhöfer ◽  
D. Hachmeister
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Processing Route ◽  
Nanosized Powders ◽  
Pyrolysis Products ◽  
Microwave Pyrolysis ◽  
Grain Sizes ◽  
Conventional Pyrolysis ◽  
Metalorganic Compounds

ABSTRACTApplication of paraffin as a MW-transparent matrix for microwave pyrolysis of metalorganic compounds enables synthesis of large quantities of nanosized powders with excellent storability and packing behavior. Fully crystalline, nanosized t-ZrO2 powders with specific surface area > 200 m 2 g -1 are obtained from Zr-alcoholate, and alumina powders with > 500 m2g-1 from Al-alcoholates. Some differences exist between microwave pyrolysis and conventional pyrolysis of such mixtures. Powders from microwave pyrolysis transform at lower calcination temperature to α-A12O3 and exhibit after calcination a more homogeneous morphology as compared to powders from conventional pyrolysis. Furthermore, a different composition of the volatile pyrolysis products is found. t-ZrO2 powder from the microwave processing route exhibits an increased stability towards transformation to monoclinic ZrO2 as well as smaller initial grain sizes than a conventionally synthesized powder.

Analysis of Fractional Composition and Specific Surface of Silicone Dioxide Nanopowders

2020 ◽  
Vol 992 ◽  
pp. 551-555
Author(s):  
O.N. Kravtsova ◽  
G.G. Vinokurov ◽  
N.F. Struchkov
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Fractional Composition ◽  
Nanosized Powder ◽  
Nanosized Powders ◽  
Powder Mixtures ◽  
Angle Scattering ◽  
Intermediate Value ◽  
Particle Shapes

For the development of new compositions of modified powder mixtures a comprehensive analysis of the technical characteristics of powder additives is required. The specific surfaces of nanosized powders of "Tarkosil" silicone dioxide were determined by the experimental method. Therefore, at present, the estimating relationships of sizes, particles shapes and specific surface area of nanosized powder is relevant scientific and practical task. And the particles shape was evaluated by the values of these surfaces. Using the method of small-angle scattering the functions of distribution of the modifying powders particles on their sizes were estimated, and the average values of particles size of "Tarkosil" powder were specified The particle shape of the modifying powders has been estimated according to the specific surface values. The particle shapes of T50 powders are close to isometric (a ball, a cube); particle shapes of T150 powders correspond to a tetrahedron, the particle size T80 and T110 corresponds to the intermediate value of the specific surface area.

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.

Effect of Anatase/Rutile Phase Ratio on the Photodegradation of Methylene Blue under UV Irradiation

2020 ◽  
Vol 998 ◽  
pp. 78-83
Author(s):  
Yi Yi Zaw ◽  
Du Ang Dao Channei ◽  
Thotsaphon Threrujirapapong ◽  
Wilawan Khanitchaidecha ◽  
Auppatham Nakaruk
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Band Gap ◽  
Surface Area ◽  
Calcination Temperature ◽  
Organic Compounds ◽  
Specific Surface Area ◽  
Uv Irradiation ◽  
Rutile Phase

Titanium dioxide (TiO2) is known as one of the widely used catalysts in photocatalysis process. Recently, the photocatalysis of TiO2 has been implied in water purification and treatment, particularly dyes and organic compounds degradations. Naturally, the TiO2 can be found in three phases including anatase, rutile and brookite; each phase has its own specific properties such as grain size, stability and band gap energy. In this work, the effect of calcination temperature on the structure, morphology and photocatalytic activity were investigated. The data suggested that the anatase/rutile ratio of TiO2 can be controlled through the calcination process. The phase transformation data strongly indicated the liner function between percentage of rutile phase and calcination temperature. The BET analysis provided the consistent data with XRD patterns by showing that the specific surface area was decreased by increasing calcination temperature. The photodegradation of methylene blue under UV irradiation proved that the mixed phase of anatase/rutile ratio at 78.5/21.5 provided the highest photocatalytic activity. The phase composition ratio can influence the nanoparticles properties including band gap, specific surface area and energy band structure. Therefore, the control of anatase/rutile ratio was an alternative to enhance the photocatalytic activity of TiO2 nanoparticles for dyes and organic compounds degradations.

Influence of Preparation Parameters on the New NSR Catalyst Support Material

2011 ◽  
Vol 412 ◽  
pp. 361-364
Author(s):  
Wei Jun Zhang ◽  
Yuan Feng Huang ◽  
Li Shen ◽  
Jun Liu ◽  
Xiao Qing Luo ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Atomic Ratio ◽  
High Specific Surface Area ◽  
Support Material ◽  
Co Precipitation

A series of Ba-Al-O/NSR supports were prepared by co-precipitation in this work. The effect of Al/Ba atomic ratio and calcination temperature on the structure and texture of the supports was investigated carefully. The XRD spectra show that Ba is mainly exist in the form of BaAl2O4, and Al exists in Al2O3. The results of SBET indicate that the supports possess relative high specific surface area (70~150 m2/g). The effect of different parameters on the process of supports synthesized was investigated carefully. The results show that the structure and specific surface area of support is significantly depended on calcination temperature.

Effect of pH, Molar Ratio of Fuel to Nitrates and Calcination Temperature on the Glycine-Nitrate Synthesis of Nano CoAl2O4

2010 ◽  
Vol 68 ◽  
pp. 176-181 ◽  
Author(s):  
Seyyed Hamid Jazayeri ◽  
Federica Bondioli ◽  
Shiva Salem ◽  
Ali Allahverdi ◽  
Mansoor Shirvani ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Precursor Solution ◽  
Molar Ratio ◽  
Effect Of Ph ◽  
Molar Ratios ◽  
Metal Nitrates ◽  
Powder Characteristics

In this research, solution-based combustion synthesis is applied to prepare the spinel CoAl2O4 pigment from precursor solution of Al(NO3)3 .9H2O, Co(NO3)2 .6H2O and glycine. Effect of pH values (2.5, 7, 10.5), molar ratio of fuel to metal nitrates in the precursor solutions (1.5, 2) and subsequent calcination temperature (800, 1000, 1200 °C) on the powder characteristics are described. Gel formation, morphologies, specific surface area and colour of the powder are characterized using DTA/TG, XRD, TEM, BET and UV-Vis. The results indicate that the crystalline spinel CoAl2O4 is formed at all different Gl/(metal nitrates) molar ratios, pH and temperatures and higher temperature promote the increase of the crystallite size. According to TEM figures most of the particles calcined at 800 and 1000 °C has sizes less than 50 and 100 nm, respectively. Corresponding to results of BET experiment, specific surface area has its maximum values at pH 7 and decreases with increasing of temperature. Finally, colorability test indicates the complete stability of the synthesized powder in the glass matrix.

scholarly journals Carbon Dioxide Absorption and Release Properties of Pyrolysis Products of Dolomite Calcined in Vacuum Atmosphere

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Fei Wang ◽  
Toshihiro Kuzuya ◽  
Shinji Hirai ◽  
Jihua Li ◽  
Te Li
Keyword(s):  
Carbon Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Micropore Volume ◽  
Carbon Dioxide Absorption ◽  
Pyrolysis Products ◽  
Vacuum Atmosphere

The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2absorption and release cycles leading to a decrease in the degree of absorption of CO2.

A Research on Microwave and Conventional Pyrolysis for Low Rank Coal

2014 ◽  
Vol 1044-1045 ◽  
pp. 209-214
Author(s):  
Yong Hui Song ◽  
Xin Li ◽  
Jun Wei Shi ◽  
Xin Zhe Lan
Keyword(s):  
Aromatic Hydrocarbon ◽  
Phenolic Compound ◽  
Gas Analysis ◽  
Low Rank ◽  
Western China ◽  
Low Rank Coal ◽  
Pyrolysis Products ◽  
Microwave Pyrolysis ◽  
Pyrolysis Tar ◽  
Conventional Pyrolysis

In this paper, conventional pyrolysis (CP) and microwave pyrolysis (MWP) for three types of low rank coal in western China was studied. The effects of pyrolysis methods and temperature etc on product yields were also discussed. Pyrolysis products were characterized by IR, Gas analysis meter and GC-MS. Results showed that the tar and gas yields in microwave pyrolysis is about 3%-5% higher than those in the conventional pyrolysis. H2 and CO proportions in gas are above 55%. The contents of benzene, aromatic hydrocarbon and phenolic compound in microwave pyrolysis tar are higher than those in the conventional pyrolysis, in addition, C5~C10 substance content in tar is about 5 times as that in the conventional, so the microwave pyrolysis can prompt tar converting to light fraction.

Preparation of Activated Alumina Admixture

2011 ◽  
Vol 84-85 ◽  
pp. 489-493
Author(s):  
Xiao Yan Wang ◽  
Hong Jian Wang ◽  
Gui Qin Hou ◽  
Zhao Xia Lv
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Crystalline State ◽  
Activated Alumina ◽  
Calcination Process ◽  
X Ray ◽  
Active Alumina ◽  
Alkali Aggregate Reaction

Through calcining bauxite, the preparation of active alumina (Al2O3) admixture was investigated. The effect of calcination temperature and time on the activity of alumina was studied. Calcination production species and crystalline state were determined by X-ray diffractometer, and the specific surface area referred as an important parameter was also determined. The results showed that the best calcination process of acquiring activated alumina admixture was 500°C1.0h. Alkali-aggregate reaction was inhibited effectively by the active alumina admixture.

scholarly journals Enhanced Photocatalytic Activity for Degradation of Methyl Orange over Silica-Titania

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Yaping Guo ◽  
Shaogui Yang ◽  
Xuefei Zhou ◽  
Chunmian Lin ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Anatase Phase ◽  
Solution Treatment ◽  
X Ray

Silica-modified titania (SMT) powders with different atomic ratios of silica to titanium (Rx) were successfully synthesized by a simple ultrasonic irradiation technique. The prepared samples were characterized by X-ray diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible spectroscopy. The specific surface area was measured according to BET theory. Results indicate that the addition of silica to titania can suppress the crystalline size growth and the transformation of anatase phase to rutile phase of titania, enlarge specific surface area of the titania particles, and result in a blue shift of absorption edge compared to pure titania. The photocatalytic activity of the SMT samples was evaluated by decolorizing methyl orange aqueous solutions under UV-visible light irradiation. It was found in our study that this activity was affected by silica content, calcination temperature, H2SO4, and oxidants such as KIO4, (NH4)2S2O8and H2O2. The results reveal that the photocatalytic activity of 0.1-SMT catalyst is the best among all samples calcined at550°C for 1 h and it is 1.56 times higher than that of Degussa P-25 titania, which is a widely used commercial TiO2made by Germany Degussa company and has been most widely used in industry as photocatalyst, antiultraviolet product, and thermal stabilizer. The optimal calcination temperature for preparation was550°C. The photocatalytic activity of SMT samples is significantly enhanced by H2SO4solution treatment and oxidants.

scholarly journals Structure-Activity Relationship of Manganese Oxide Catalysts for the Catalytic Oxidation of (chloro)-VOCs

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 726 ◽  
Author(s):  
Jian Wang ◽  
Hainan Zhao ◽  
Jianfei Song ◽  
Tingyu Zhu ◽  
Wenqing Xu
Keyword(s):  
Specific Surface ◽  
Manganese Oxide ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Oxide Catalysts ◽  
Precipitation Method ◽  
Catalytic Oxidations ◽  
Calcination Temperatures ◽  
Manganese Oxide Catalysts

Manganese oxide catalysts, including γ-MnO2, Mn2O3 and Mn3O4, were synthesized by a precipitation method using different precipitants and calcination temperatures. The catalytic oxidations of benzene and 1,2-dichloroethane (1,2-DCE) were then carried out. The effects of the calcination temperature on the catalyst morphology and activity were investigated. It was found that the specific surface area and reducibility of the catalysts decreased with the increase in the calcination temperature, and both the γ-MnO2 and Mn3O4 were converted to Mn2O3. These catalysts showed good activity and selectivity for the benzene and 1,2-DCE oxidation. The γ-MnO2 exhibited the highest activity, followed by the Mn2O3 and Mn3O4. The high activity could be associated with the large specific surface area, abundant surface oxygen species and excellent low-temperature reducibility. Additionally, the catalysts were inevitably chlorinated during the 1,2-DCE oxidation, and a decrease in the catalytic activity was observed. It suggested that a higher reaction temperature could facilitate the removal of the chlorine species. However, the reduction of the catalytic reaction interface was irreversible.

Sign in / Sign up

Export Citation Format

Share Document