scholarly journals Effect of H2O Activity on Zeolite Formation

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4780
Author(s):  
Claudia Belviso ◽  
Francesco Cavalcante
Keyword(s):  
Liquid Nitrogen ◽  
Sodium Aluminate ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Zeolite Formation ◽  
Silica Alumina ◽  
Over Time ◽  
Scanning Electron

In an effort to understand the effects of H2O activity on zeolite formation, we have synthesized LTA zeolite using a combination of freezing processes and varying drying temperatures. Sodium aluminate and sodium silicate were used to form LTA zeolite, according to the IZA (International Zeolite Association) protocol. The synthesis steps were modified by adding the precursor frozen process by a rapid liquid nitrogen (−196 °C) treatment or slow conventional freezer treatment (−20 °C). The samples were subsequently sonicated and then dried at 80 °C or 40 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed on the samples immediately after the drying process as well as after 2 weeks and 1 month of aging the solid products. The results indicated that LTA zeolite does not form. The silica-alumina precursor after both freezing processes and after being dried at 80 °C showed the presence of sodalite displaying stable behavior over time. Both sets of samples dried at 40 °C and did not show the presence of zeolite immediately after the drying process. However, after 2 weeks, the liquid nitrogen–frozen precursor was characterized by the presence of EMT whereas zeolites never formed in the −20 °C samples. These results suggest that freezing processes differently control the H2O activity during the drying and aging processes in the solid state. Thus, although the precursor chemical composition is the same, the type of zeolite formed is different.

Corrosion Behavior of Q235A Steel under Wet-Dry Cyclic Condition

2012 ◽  
Vol 557-559 ◽  
pp. 139-142
Author(s):  
Jian Guo Liu ◽  
Yan Tao Li ◽  
Bao Rong Hou
Keyword(s):  
Electron Microscopy ◽  
Chloride Concentration ◽  
Corrosion Products ◽  
Drying Process ◽  
X Ray Diffraction ◽  
Cathodic Process ◽  
X Ray ◽  
Reduction Processes ◽  
Cyclic Condition ◽  
Scanning Electron

The corrosion processes and mechanisms of Q235A steel under wet-dry cyclic condition were studied using polarization curve compared with immersion samples, while, the corrosion morphologies and corrosion products of the steel samples were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The cathodic process of wet-dry samples was likely to be controlled not by the oxygen reduction, but rather by the reduction of corrosion products. During the drying process of the wet-dry sample, the electrolyte thickness decreased and chloride concentration increased. Oxygen would be much easier to diffuse into the interface of electrolyte/metal, which improved the cathodic reduction processes. Except for this, the rust itself took part in the reduction processes and hence increased the corrosion rate of the steel samples.

scholarly journals Preparation of BaZrO3 powders by a spray-drying process

2003 ◽  
Vol 18 (6) ◽  
pp. 1325-1332 ◽  
Author(s):  
B. Robertz ◽  
F. Boschini ◽  
A. Rulmont ◽  
R. Cloots ◽  
I. Vandriessche ◽  
...  
Keyword(s):  
Spray Drying ◽  
Precursor Solution ◽  
Barium Zirconate ◽  
Drying Process ◽  
X Ray Diffraction ◽  
High Quality ◽  
Corrosion Resistant ◽  
X Ray ◽  
Potential Use ◽  
Scanning Electron

The potential use of barium zirconate for the manufacture of corrosion-resistant substrates emphasizes the need for a simple, inexpensive, and easily scalable process to produce high-quality powders with well-controlled composition and properties. However, the classical solid-state preparation of barium zirconate leads to an inhomogeneous powder unsuitable for applications in highly corrosive environment. For this paper, the possibility to use the spray-drying technique for the preparation of BaZrO3 powders with a controlled size distribution and morphology was investigated. The influence of the nature and concentration of the precursor solution and the influence of the spray-drying step are discussed on the basis of x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dilatometric measurements.

scholarly journals Membran Reaktor untuk Pembuatan dan Pemurnian Isomer Xylene

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Wahyudin Wahyudin ◽  
Hens Saputra
Keyword(s):  
Pore Size Distribution ◽  
Zeolite Membrane ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Alumina Catalyst ◽  
Mfi Zeolite ◽  
Entire Surface ◽  
X Ray ◽  
Silica Alumina ◽  
Scanning Electron

Abstrak Membran reaktor merupakan konsep perpaduan dari sistem reaksi dan proses pemisahan/pemurnian. Membran ini disebut juga sebagai membran katalis atau sistem katalis-membran. Dengan membran reaktor ini diharapkan konversi suatu reaksi dapat ditingkatkan dan diperoleh suatu produk yang memiliki tingkat kemurnian lebih tinggi. Sebagai katalis digunakan silica alumina yang berukuran 1,0 mm. Membran anorganik  zeolit MFI dilapiskan menutupi seluruh permukaan katalis. Bahan baku yang digunakan antara lain tetraethylortosilicate (TEOS) sebagai sumber silikat dan template organik tetraprophyl ammonium bromide (TPABr). Proses kristalisasi dilakukan pada temperatur 453 K di dalam autogeneous autoclave, dilanjutkan dengan kalsinasi pada temperatur 873 K selama 1 jam. Karakterisasi membran zeolit yang dihasilkan dilakukan dengan X-ray diffraction (XRD) dan pengamatan dengan Scanning Electron Mycroscope (SEM). Karakteristik pori dipelajari menggunakan metode physisorption dan BJH pore size distribution. Selain itu dilakukan pula uji selektifitas dan alkilasi toluena dan xylene. Berdasarkan pengamatan menggunakan XRD mengindikasikan adanya struktur zeolit MFI pada sampel membrane katalis yang dihasilkan. Diperkuat dengan obserbasi SEM menunjukkan bahwa membran zeolit MFI melapisi seluruh permukaan pelet silika alumina dan terdapat indikasi terjadinya komposit terhadap silika alumina pada daerah perbatasan antara membran zeolit atau lapisan bagian luar dengan katalis silika alumina. Hasil pengujian menunjukkan hasil bahwa membran reaktor zeolit MFI berpotensi untuk diaplikasikan sebagai membran katalis yang bersifat sangat selektif terhadap bentuk suatu molekul. Kata kunci: membran reaktor, isomer, xylene, zeolit, silika alumina, hidrotermal   Abstract Membrane fusion reactor is the concept of system reactions and separation processes of purification. These membranes are called also catalyst membrane or catalyst-membrane system. With the reactor membrane is expected conversion of a reaction can be increased and obtained a product having a higher purity. As the silica alumina catalyst used measuring 1.0 mm. MFI zeolite coated inorganic membranes covering the entire surface of the catalyst. The raw materials used include tetraethylortosilicate (TEOS) as the source of silicates and organic template tetrapropyl ammonium bromide (TPABr). Crystallization process carried out at a temperature of 453 K in the autogeneous autoclave, followed by calcination at a temperature of 873 K for 1 hour. Characterization of zeolite membranes produced performed by X-ray diffraction (XRD) and scanning electron observations with Mycroscope (SEM). Pore ​​characteristics were studied using physisorption method and BJH pore size distribution. In addition, the selectivity of the test is also conducted and alkylation of toluene and xylene. Based on observations using XRD indicates a structure of MFI zeolite membrane on the resulting catalyst samples. Reinforced with SEM showed that the MFI zeolite membrane coating the entire surface of the silica alumina pellets and there are indications of the silica alumina composites in the border area between zeolite membrane or outer coating with silica alumina catalyst. The results show that the results of MFI zeolite reactor  membrane has the potential to be applied as a catalyst membrane that is highly selective to form a molecule. Keywords : reactor membrane, isomers, xylene, zeolite, silica alumina, hydrothermal

scholarly journals Influence of Strong Acid Hydrolysis Processing on the Thermal Stability and Crystallinity of Cellulose Isolated from Wheat Straw

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Chemar J. Huntley ◽  
Kristy D. Crews ◽  
Mohamed A. Abdalla ◽  
Albert E. Russell ◽  
Michael L. Curry
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Scanning Electron Microscopy ◽  
Acid Hydrolysis ◽  
Wheat Straw ◽  
Cellulose Fibers ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Cellulose extractions from wheat straw via hydrochloric, nitric, and sulfuric acid hydrolysis methods were carried out. X-ray diffraction spectral analyses reveal that depending on the acid conditions used the structure of the cellulose exhibited a mixture of polymorphs (i.e., CI and CIII cellulose phases). In addition, the percent crystallinity, diameter, and length of the cellulose fibers varied tremendously as determined by X-ray diffraction and scanning electron microscopy. Thermal gravimetric analysis measurements revealed that the thermal stability of the extracted cellulose varied as a function of the acid strength and conditions used. Scanning electron microscopy analysis revealed that the aggregation of cellulose fibers during the drying process is strongly dependent upon the drying process and strength of the acids used.

Study and Properties of a Steel Microalloyed Hardened Superficially

2015 ◽  
Vol 365 ◽  
pp. 122-127 ◽  
Author(s):  
N. López-Perrusquia ◽  
M.A. Doñu Ruiz ◽  
C. R. Torres San-Miguel ◽  
M. Flores-Báez ◽  
I. Flores-Báez
Keyword(s):  
Growth Process ◽  
Energy Dispersive Spectrometry ◽  
Boride Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Controlled ◽  
Boriding Process ◽  
Kinetics Of ◽  
Over Time ◽  
Scanning Electron

In this study, we present a boronizing treatment on a steel microalloy that was performed according to dehydrated paste-pack boriding. The temperatures conducted were at 1173, 1223 and 1273 K; at various exposure times of 1, 3, 6 and 9 h. As a result of the boriding process, diffusion-controlled growth of the FeB/Fe2B layers was obtained at the surface of the micro-alloy steel, and the kinetics of the growth process changed parabolically over time. The results of these examination properties of the boride layer as revealed by Optical Microscopy (OP) showed the morphology of the boride layer as a saw-tooth with a thickness ranging from 33 μm to 220 μm depending on the boronizing time. The analysis of Scanning Electron Microscopy (SEM-EDS); showed a distribution of the alloying elements that were detected by Energy Dispersive Spectrometry. The X-ray diffraction (XRD) technique indicated that the surface was a mixture of FeB and Fe2B borides. The evaluation of adhesion of the layers was determined by the technique of Rockwell-C hardness. Young’s modulus and hardness of the layer were evaluated by a nanoindentation technique with a load of 250 mN. The paste dehydrate boriding of micro-alloy reveal a change of properties on the surface; also the coatings FeB and Fe2B, to make a sacrificial function in the steels micro alloyed as widely used in pipelines transporting oil.

scholarly journals Interzeolitic Transformation of Clinoptilolite into GIS and LTA Zeolite

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1313
Author(s):  
Renata C. F. de Lima ◽  
Daniele da Silva Oliveira ◽  
Sibele B. C. Pergher
Keyword(s):  
Electron Microscopy ◽  
X Ray Diffraction ◽  
Synthesis Time ◽  
X Ray ◽  
Synthesis Conditions ◽  
Environmentally Sustainable ◽  
Lta Zeolite ◽  
Clinoptilolite Zeolite ◽  
Natural Clinoptilolite ◽  
Scanning Electron

A natural clinoptilolite zeolite was transformed into other zeolites of greater industrial interest, such as zeolites with GIS and LTA structures. The synthesis conditions were studied, and the interzeolitic transformation was characterized by X-ray diffraction (XRD), X-ray fluorescence (FRX), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). From the results, it was possible to observe that the GIS and LTA zeolites were successfully synthesized. Furthermore, the results revealed that a synthesis time of 4 days was enough to obtain the GIS structure, and 4 h was sufficient to obtain LTA. The interzeolitic transformation can be explained by the RBU (Ring Building Unit) approach using C4 units from the HEU topology. The use of clinoptilolite in the synthesis of other zeolites is an innovative, economically viable, and environmentally sustainable process that exploits a material that exists in large quantities and is still little explored by industry.

scholarly journals Microencapsulation of guava pulp using prebiotic wall material

2021 ◽  
Vol 24 ◽  
Author(s):  
Jéssica Chaves Rivas ◽  
Lourdes Maria Correa Cabral ◽  
Maria Helena Miguez da Rocha-Leão
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Antioxidant Activity ◽  
Spray Drying ◽  
Carotenoid Content ◽  
Wall Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Over Time ◽  
Scanning Electron

Abstract Important functional compounds present in fruits are often lost in technological processes and during storage. Microencapsulation technique allows maintaining the compounds of interest and adding value to the product using functional encapsulating materials. This work aimed to produce microencapsulated guava pulp using the spray-drying technique and a functional encapsulant material, i.e., a mix of inulin and maltodextrin. The guava pulp was analyzed for centesimal composition, carotenoid content, and antioxidant activity. The microspheres were analyzed for retention of carotenoids, antioxidant activity over time, and morphology by Scanning Electron Microscopy (SEM) and X-ray diffraction. Two proportions of coating material could maintain the antioxidant activity of guava pulp. The microencapsulation with a higher percentage of inulin is a preferred option due to the good results of retention and stability regarding antioxidant activity over time, relevant retention of the carotenoid content, and a more stable microstructure. In addition, inulin can add value to powders owing to its inherent functional properties. The product obtained in the study is innovative and interesting, as well as may provide a capable use of these materials as encapsulated agents. In fact, it can be considered a potential functional ingredient.

scholarly journals Influence of Synthesis Method on LTA Time-Dependent Stability

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2122 ◽  
Author(s):  
Claudia Belviso ◽  
Antonio Lettino ◽  
Francesco Cavalcante
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
Synthesis Method ◽  
Synthetic Zeolite ◽  
Time Dependent ◽  
Time Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Scanning Electron

Time-stability of LTA zeolite formed by hydrothermal method with or without the action of ultrasonic irradiation was investigated by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The results show that 6 months after the synthesis by hydrothermal process with continuous sonication, LTA evolves into a more stable sodalite, whereas no differences are detected 12 months after LTA synthesis by conventional pre-fused hydrothermal process. These data confirm that using the two approaches, different mechanisms control both zeolite crystallization and time-stability of the newly-formed mineral at solid state. The results are particularly important in the light of the synthetic zeolite application.

scholarly journals Hydrophobic and Flame-Retardant Foam Based on Cellulose

2021 ◽  
Author(s):  
Amal H. Abdel Kader ◽  
sawsan Dacrory ◽  
Tawfik A. Khattab ◽  
samir kamel ◽  
Hussein Abou-Yousef
Keyword(s):  
Chemical Structure ◽  
Freeze Drying ◽  
Fire Retardant ◽  
Spray Coating ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flammability Test ◽  
Flammability Characteristics ◽  
Scanning Electron

Abstract A series of lightweight, hydrophobic, and fire retardant foams were fabricated through activation of cellulose by phosphoric acid as a primarily step. Dolomite clay was embedded onto the cellulosic suspensions with gelatin/ tannin as adhesive followed by freeze drying process. A solution of the environmentally friendly silicone rubber (RTV) was applied onto foam samples via spray-coating to improve their water repealing performance, which was explored by investigating both of water contacting angle and wettability time of the coated foam samples. Flammability characteristics, thermal decomposition, surface morphology, and chemical structure of treated and untreated foams were investigated by flammability test, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared, respectively. Results showed that the foams loaded dolomite and coated RTV have high hydrophobicity as well as anti-inflammability.

Study on Coal Seam Damage Caused by Liquid Nitrogen Under Different Ground Temperature Conditions

2021 ◽  
Vol 144 (7) ◽  
Author(s):  
Zekai Wang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Shanjie Su ◽  
Menglin Du
Keyword(s):  
Coal Seam ◽  
Liquid Nitrogen ◽  
Wave Velocity ◽  
Coal Sample ◽  
Initial Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Nitrogen Treatment ◽  
Scanning Electron

Abstract The thermal stress caused by the ultra-low temperature of liquid nitrogen (LN2) can seriously affect the porosity of the coalbed. In this paper, the effects of various temperature differences on the LN2 damage were studied by changing the initial temperature, so as to explore the effect of LN2 on coal seam with different buried depth. The X-ray diffraction (XRD), scanning electron microscope (SEM), wave velocity, acoustic emission (AE), and uniaxial compression experiments were used in the experiments. The experimental results show that LN2 causes a lot of damage to coal and the LN2 effect increase at first and then decrease with the increase of the initial temperature. When the initial temperature is 293 K, before and after liquid nitrogen treatment, the wave velocity damage of the coal sample reaches 0.2207 and the compressive strength decreases by 27.92%. These two values are 0.3697 and 47.37% at the initial temperature of 323 K, and 0.2727 and 28.27% at the initial temperature of 353 K. This is because if the temperature exceeds 353 K, it will cause a 3.17% drop in water content, thus reducing the damage caused by LN2, resulting in the overall effect slightly lower than that at 323 K.

Sign in / Sign up

Export Citation Format

Share Document