4A-Molecular Sieve Synthesis by Microwave Heating with Silicon and Aluminum Materials Produced from the Coal Fly Ash

2011 ◽  
Vol 675-677 ◽  
pp. 219-222 ◽  
Author(s):  
Guang Hui Bai ◽  
Peng Cheng Li ◽  
Peng Xu ◽  
Shuang Li Chen
Keyword(s):  
Fly Ash ◽  
Pore Size ◽  
Sodium Silicate ◽  
Molecular Sieve ◽  
Coal Fly Ash ◽  
Sodium Aluminate ◽  
Raw Material ◽  
Crystallization Time ◽  
Microwave Technology ◽  
Practical Applications

A new method, using sodium silicate and sodium aluminate synthesize 4A-molecular sieve, was developed by using microwave technology. The sodium silicate was a high modulus liquor by-product of nano-silica production from coal fly ash. Meanwhile, the sodium aluminate was a process by-product of alumina extraction from coal fly ash. Reaction mixture composition was defined as follow:SiO2/Al2O3 ratio in 2.0, Na2O/SiO2 ratio in 1.5, and H2O/Na2O ratio in 65. The gelation process was completed in 1 hr. Microwave crystallization power was (800w) 30%. Microwave crystallization period can last 25 mins. The 4A-molecular sieve was obtained by collecting crystals from the reaction mixture through filtration after washing with water to pH 11-12 and drying inside isotherm oven. The calcium exchange capacity and effective pore size of the product were 316mg/g and 0.4nm respectively. Over 90% of surface pore size reached in sizes of less than or equal to 8μm. Purity of 4A-molecular sieve up to 99%. This method significantly reduced the raw material costs for sodium silicate and sodium aluminate. In addition, the adoption of microwave technology also lowered the energy usage and shortened crystallization time. All these contributed final low costs of 4A-molecular sieve product, which made it possible for many practical applications.

Parameters Affecting the Synthesis of X and A Zeolites from Coal Fly Ash

2021 ◽  
Vol 2 (1) ◽  
pp. 53-59
Author(s):  
A. Korpa ◽  
V. Teneqja ◽  
S. Gjyli ◽  
A. Andoni
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Acid Treatment ◽  
Coal Fly Ash ◽  
Exchange Capacity ◽  
Raw Material ◽  
Crystallization Time ◽  
Zeolite Synthesis ◽  
Different Types ◽  
Type Zeolite

This paper summarizes the investigation results on the main parameters affecting the synthesis of type X and A zeolites using coal silicious fly ash (FA) as raw material. The synthesis was performed by dissolution of alkali-fused alumino-silicates, followed by hydrothermal treatment. The experimental data confirm that fly ash SiO2/Al2O3 ratio, NaOH/FA ratio, acid treatment of pre-fused fly ash, salinity of solution have a significant effect on type and properties of newly formed zeolites. In summary, the results show that A and X-type zeolite form with FA SiO2/Al2O3 ratio < 1.12 and > 1.86, respectively. Moreover, FA characterized by SiO2/Al2O3 mole ratio of 3.15 is suitable for X-type zeolite synthesis while A-type zeolite does not form without NaAlO2 addition. The crystallization occurs faster at higher temperatures although above 90°C X-type zeolite evolves into more stable phases whereas increasing the crystallization time from 1 to 72 hours, the yield of the synthetic products enhances from 60 to 75%. The use of seawater is responsible for the synthesis of X-type showing both lower purity and specific surface area. However, the synthetic products are characterized by high exchange capacity (> 320 meq/100 g), thus suggesting their successful application as adsorbents and catalysts in different types of wastewater and industrial waste treatments.

Effect of Fly Ash Pre-Sintering Temperature on Adiabatic Foam Fabricated by Sodium Silicate

2019 ◽  
Vol 295 ◽  
pp. 105-109
Author(s):  
Ye Li ◽  
Heng Ze Zhao ◽  
Xu Dong Cheng
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Pore Structure ◽  
Pore Size ◽  
Sodium Silicate ◽  
Sintering Temperature ◽  
Raw Material ◽  
Sintering Process ◽  
Spherical Pore

Adiabatic foam was fabricated successfully using sodium silicate as the raw material with pre-sintered fly ash as additive. Fly ash was pre-sintered at 500 to 900 oC and the effect of the pre-sintering temperature on the performance, including the thermal conductivity, density, compressive strength and microstructure, was researched. The results show that the pre-sintering process effectively reduces the density of the samples while the thermal conductivity and compressive strength are higher than those of the samples fabricated by the fly ash without being pre-sintered. Moreover, the samples exhibit tri-modal spherical pore structure with macropores and mesopores. The pore size remains unchanged until the pre-sintering temperature exceeds 700 oC, and then starts to increase.

Study on Using Chenghe Fly Ash to Prepare 4A Molecular Sieve

2015 ◽  
Vol 1120-1121 ◽  
pp. 137-140
Author(s):  
Jian Li Yang ◽  
Mei Li Du ◽  
Tian Qin Zang
Keyword(s):  
Fly Ash ◽  
Molecular Sieve ◽  
Coal Fly Ash ◽  
Rapid Development ◽  
Mining Area ◽  
Coal Industry ◽  
Shanxi Province ◽  
Recycling Rate ◽  
Crystallization Time ◽  
Waste Reclamation

In recent years, with the rapid development of coal industry, a large number of coal fly ash has been produced, while the recycling rate of the ash is rather low. It is not only a waste of the precious land resources, but also makes environment suffering severe pollution. As an important kind of new material in the national economy, the demand for molecular sieve is growing. It is possible to synthesis molecular sieve using fly ash. The way is not only energy conservation and environmental protection, but also waste reclamation, according with the theme of the sustainable development.This study is to synthesize the molecular sieve with guide agent by the method of hydrothermal synthesis using Cheng He mining area in Shanxi province, which is on the basis of the analysis of chemical composition of fly ash. It is also to find a approach for the use of fly ash with subtly. Through XRD expert zing phase, SEM observing appearance, the characterizing results show that excellent performance molecular sieve of 4A can be synthesized at conditions: Calcined at 850°C and for 2 hours, then hydrothermal reacted with composition of reaction mixture 3Na2O:1Al2O3:2SiO2: 185H2O at temperature 90°C, crystallization time 6h with 5% guide agent.

A New Method of Producing High Purity 4A-Molecular Sieve from High Modulus Sodium Silicate Liquor Purified by Carbonization

2010 ◽  
Vol 105-106 ◽  
pp. 736-738 ◽  
Author(s):  
Guang Hui Bai ◽  
Peng Xu ◽  
Wei Teng ◽  
Xiang Gang Wang
Keyword(s):  
Carbon Dioxide ◽  
Sodium Silicate ◽  
High Purity ◽  
Molecular Sieve ◽  
Calcium Absorption ◽  
Ph Value ◽  
Coal Fly Ash ◽  
Sodium Aluminate ◽  
Absorption Capacity ◽  
High Modulus

A new technology for producing high purity 4A-molecular sieve was developed with high modulus sodium silicate liquor and sodium aluminate liquor extracted from coal fly ash as starting materials. The sodium silicate liquor extract was purified by precipitating ferrous, titanium, and other impurities by carbon dioxide injection. Concentration of carbon dioxide in the extract was maintained at 48%, and the pH value of the extract controlled in the range of 11 and 11.2. After that, the purified sodium silicate liquor was mixed with sodium aluminate liquor in the ratios of SiO2/Al2O3=2.0, Na2O/SiO2=1.6 and H2O/Na2O=60. The mixture was then heated to 90°C and kept for 2 h. A high purity 4A-molecular sieve product was obtained after washing and drying the crystals obtained from the reaction mixture. The molecular sieve product has a purity of 99% and aperture of 0.4nm. Its calcium absorption capacity is about 290mg/g. The product was also characterized by SEM, BET, XRD and IR analysis.

scholarly journals Siliceous Fly Ash Utilization Conditions for Zeolite Synthesis

2021 ◽  
Vol 6 (1) ◽  
pp. 24
Author(s):  
Silvana Gjyli ◽  
Arjan Korpa ◽  
Valdet Teneqja ◽  
Dritan Siliqi ◽  
Claudia Belviso
Keyword(s):  
Fly Ash ◽  
Large Scale ◽  
Three Dimensional ◽  
Mineralogical Composition ◽  
Sodium Aluminate ◽  
Raw Material ◽  
Crystallization Time ◽  
Zeolite X ◽  
Pre Treatment ◽  
Novel Catalyst

Fly ash is a coal combustion product partly disposed of in landfills since it finds no other application. Recycling this solid is of great benefit in terms of quality, cost effectiveness and the environment. The chemical and mineralogical composition of siliceous fly ash makes it an attractive and economic raw material for the synthesis of zeolites. Zeolites are microporous, aluminosilicate minerals characterized by a three-dimensional network of tetrahedral units produced industrially on a large scale. In this work, synthetic X and A-type zeolite with high crystallinity and high value of surface area were synthesized by a pre-fusion method followed by a hydrothermal treatment under various conditions. The data indicate that zeolitic products were obtained using NaOH while no zeolitic material was crystallized using KOH and LiOH. Pre-treatment of fly ash with acid before being used in the synthesis of artificial zeolites is considered an important parameter for the purity phase of zeolites. Without sodium aluminate additions, synthetic zeolite A was not formed. The results confirm that temperature, crystallization time, SiO2/Al2O3 ratio and type of water (distilled water and seawater) are also important parameters influencing type of zeolite synthesized. Zeolite X was used as a novel catalyst for the alkylation of phenol using diethyl carbonate.

scholarly journals Coal Fly Ash Derived Silica Nanomaterial for MMMs—Application in CO2/CH4 Separation

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 78
Author(s):  
Marius Gheorghe Miricioiu ◽  
Violeta-Carolina Niculescu ◽  
Constantin Filote ◽  
Maria Simona Raboaca ◽  
Gheorghe Nechifor
Keyword(s):  
Fly Ash ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Coal Fly Ash ◽  
High Surface ◽  
Industrial Applications ◽  
Mixed Matrix Membranes ◽  
Co2 Removal ◽  
Mcm 41

In order to obtained high selective membrane for industrial applications (such as natural gas purification), mixed matrix membranes (MMMs) were developed based on polysulfone as matrix and MCM-41-type silica material (obtained from coal fly ash) as filler. As a consequence, various quantities of filler were used to determine the membranes efficiency on CO2/CH4 separation. The coal fly ash derived silica nanomaterial and the membranes were characterized in terms of thermal stability, homogeneity, and pore size distribution. There were observed similar properties of the obtained nanomaterial with a typical MCM-41 (obtained from commercial silicates), such as high surface area and pore size distribution. The permeability tests highlighted that the synthesized membranes can be applicable for CO2 removal from CH4, due to unnoticeable differences between real and ideal selectivity. Additionally, the membranes showed high resistance to CO2 plasticization, due to permeability decrease even at high feed pressure, up to 16 bar.

scholarly journals Recovery of Cenospheres and Fine Fraction from Coal Fly Ash by a Novel Dry Separation Method

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3576
Author(s):  
Jan Wrona ◽  
Witold Żukowski ◽  
Dariusz Bradło ◽  
Piotr Czupryński
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Fine Fraction ◽  
Free Fall ◽  
Raw Material ◽  
Fluidised Bed ◽  
Air Chamber ◽  
Pneumatic Separation ◽  
Bed Separation ◽  
Separation Product

Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage of a combination of dry methods allowed for maintaining almost 83 wt.% of the raw material in its dry form. Furthermore, the produced fly ash grain fractions could be used for different industrial purposes.

Thermal Behavior of Celsian Ceramics Synthesized from Coal Fly Ash

2012 ◽  
Vol 1373 ◽  
Author(s):  
Jorge López-Cuevas ◽  
David Long-González ◽  
Carlos A. Gutiérrez-Chavarría
Keyword(s):  
Fly Ash ◽  
Thermal Behavior ◽  
Coal Fly Ash ◽  
Thermal Analyses ◽  
Linear Thermal Expansion ◽  
Raw Material ◽  
Synthesis Conditions ◽  
Calcination Step ◽  
Heating Microscopy ◽  
The Mean

ABSTRACTCelsian with a chemical composition of Ba0.75Sr0.25Al2Si2O8, is synthesized by using coal fly ash (byproduct of a Mexican coal-burning power plant, composed mainly by SiO2 and Al2O3) as main raw material. The thermal behavior of the synthesized material is evaluated by differential (DTA) and gravimetric (TGA) thermal analyses as well as by heating microscopy; its coefficient of linear thermal expansion (CTE) is also determined. Heating microscopy shows that cylinders of compacted powdered Celsian start sintering at ∼1140 ºC, which is associated with a considerable contraction occurring up to 1500 ºC. The mean CTE value of the material in the temperature range of 30-1100ºC is slightly affected by the synthesis conditions employed. Synthesis at 1400 or 1300 ºC during 10 h, with a pre-calcination step at 900 ºC/5h in both cases, produce mean CTE values of 5.15 x 10-6 and 5.43 x 10-6 ºC-1, respectively. On the other hand, Celsian synthesized at 1400 ºC/10 h, without the pre-calcination step, has a mean CTE value of 5.25 x 10-6 ºC-1. Lastly, the DTA/TGA analysis of the synthesized material shows that a slight weight gain takes place from room temperature to 1100ºC, which is followed by a slight weight loss up to 1300ºC. This is attributed to oxidation and evaporation of some of the impurities present in the material.

Effect of Borax on Lightweight Material from Cullet and Fly Ash

2016 ◽  
Vol 690 ◽  
pp. 109-113 ◽  
Author(s):  
Sutthima Sriprasertsuk ◽  
Phatthiya Suwannason ◽  
Wanna T. Saengchantara
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Silicate ◽  
Raw Materials ◽  
Raw Material ◽  
Test Results ◽  
Heat Process ◽  
Lightweight Material

This work investigated the recycling of fly ash waste and cullet as the raw materials for lightweight bodies produced by heat treatment and using sodium silicate as the binder. Borax was mixed with fly ash and cullet, and put into the block in dimension 10x10x2 cm3. The lightweight materials thus produced were then sintered at temperature of 800 °C. Density, compressive strength and thermal conductivity were determined. Borax showed a positive sintering effect on the porosity of lightweight material during the heat process. The compressive strength of lightweight material diminished with the reduction of density and thermal conductivity. Lightweight material manufactured with borax showed the lower density and thermal conductivity accompanied by the higher compressive strength. The test results indicated that using fly ash and cullet as the raw material with borax could obtain the lightweight material, thus enhancing the possibility of its reuse in a sustainable way.

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