Formation Of Aluminosilicates Research Articles

Fly Ash and Bottom Ash Utilization as Geopolymer: Correlation on Compressive Strength and Degree of Polymerization Observed using FTIR

Concerning on the dependancy of coal on electric generation wordwidely, study on fly ash, thesolid waste of fired coal electricity generation, has been comprehensively conducting, i.e. geopolymer, cenosphere, soil remediation, and adsorbent. However, only few studies dealing with the utilization of bottom ash. Having of about 53% of coal in the 2050 energy mix, Indonesia will be dealing with more than 200 million tonnes of fly ash and bottom ash (FABA). In this study, FABA was mixed in certain proportion of 50:50, 75:25, dan 100:0. The formation of geopolymer was conducted with sodium hydroxide and sodium silicate in certain concentration. Once the mixture had been homogenized, it was casted and cured in varied temperature of 30, 60, dan 90 oC with curing time of 1, 3, 5, 14, 21, dan 28 days. In each curing time, sample was then analyzed using compresive strength apparatus and FTIR in order to observed the geopolimerization of the FABA mixture. It was found that compressive strength representing the macro characteristic of the geopolymer is in line with the CORR analysis of the FTIR results showing that the formation of aluminosilicate is responsible for the mechanical strength of the geopolymer. The higher the bottom ash ratio in the mixture with decrease the strength of the geopolymer in the order of one per second. Higher temperature results higher compresive strength to the value of 42 Mpa (FABA ratio is 75:25 at temperature of 90 oC) above the Indonesian standard for concrete. From this study, kinetics of FABA geopolymerization can be generated in accordance todiffusion model with R2 of 0.9135. Thus the utilization of FABA for geopolymer is going to be a potential solution to overcome the increasing amount of FABA resulted from fired coal electrical generation in Indonesia.

Effective Materials from Recycled Aluminum Waste for Steel Ladle Treatment

The paper presents the results of research on the use of recycled aluminum waste (RAW) for steel ladle treatment. It has been established that simultaneously with the deoxidation of refining slags before desulfurization of steel, their liquid mobility increases, which eliminates the need for using fluorspar for these purposes. A thermodynamic analysis of possible reactions of formation of aluminates and calcium aluminosilicates in the refining slag has been carried out. The composition of briquettes based on RAW for liquefaction of refining slags is proposed.

Release and migration characteristics of sodium and potassium in high alkali coal under oxy-fuel fluidized bed combustion condition

Zhundong coal is promising to replace inferior coal in fossil-fueled power plants, considering its high abundance, low contents of sulfur and nitrogen. However, the relative high contents of alkalis, especially sodium and potassium, damage the operational economy and safety badly since the release of alkali metals in flue gas can lead to fly ash-related problems such as slagging, ash accumulation and corrosion. Although, oxy-fuel circulating fluidized bed (CFB) combustion is beneficial to reduce the release of sodium and potassium by lowering the operation temperature, the ash formation characteristics of Zhundong coal under the oxy-fuel CFB is still scarce. Our results showed that the residual amounts of sodium and potassium in the ash samples, both tend to decrease with increasing temperature no matter under air combustion or oxy-fuel combustion. However, the sodium content in the cinder obtained under the oxy-fuel combustion atmosphere was higher than that under the air combustion atmosphere, and the insoluble sodium, mainly existed in the form of aluminosilicates, was the main form. In addition, the increase of steam content in both atmospheres reduced the sodium content in the cinder while the residual amount of potassium increased. Density functional theory calculations verified the transformation behavior between sodium and potassium and the inhibiting effect of steam. This study elucidates the release and migration characteristics of sodium and potassium in Zhundong coal both experimentally and theoretically and will benefit the popularity of Zhundong coal.

Direct Synthesis of Aluminosilicate IWR Zeolite from a Strong Interaction between Zeolite Framework and Organic Template.

A large amount of zeolite structures are still not synthetically available or not available in the form of aluminosilicate currently. Despite significant progress in the development of predictive concepts for zeolite synthesis, accessing some of these new materials is still challenging. One example is the IWR structure as well. Despite successful synthesis of Ge-based IWR zeolites, direct synthesis of aluminosilicate IWR zeolite is still not successful. In this report we show how a suitable organic structure directing agent (OSDA), through modeling of an OSDA/zeolite cage interaction, could access directly the aluminum-containing IWR structure (denoted as COE-6), which might allow access to new classes of materials and thus open opportunities in valuable chemical applications. The experimental results reveal that the COE-6 zeolites with a SiO2/Al2O3 ratio as low as 30 could be obtained. Very interestingly, the COE-6 zeolite has much higher hydrothermal and thermal stabilities than those of the conventional Ge-Al-IWR zeolite. In methanol-to-propylene (MTP) reaction, the COE-6 zeolite exhibits excellent selectivity for propylene, offering a potential catalyst for MTP reaction in the future.

Experimental comparative study on ash fusion characteristics of Ningdong coal under oxidizing and reducing atmosphere by means of SiO2-Al2O3-(CaO + MgO + Na2O + K2O) pseudo-ternary diagrams

Concern about the serious slagging during combustion and the troublesome liquid slag tapping during gasification has motivated the study on ash fusion characteristics of Ningdong coal under oxidizing and reducing atmosphere by SiO2-Al2O3-(CaO + MgO + Na2O + K2O) pseudo-ternary diagrams of ash fusion temperatures (AFTs). The AFTs contours in the pseudo-ternary diagrams presented inverted V-shape distributions. Al2O3 showed positive effect on the AFTs; with unchanged Al2O3 content (less than 0.5), the AFTs went down first and then up with increasing SiO2 content; whereas with consistent AAEM (CaO + MgO + Na2O + K2O), the AFTs decreased with increasing SiO2 content. By doping SiO2 and Al2O3 or the mixtures into the coal, the AFTs increased significantly due to the formation of high-melting quartz, corundum, silicates, and aluminosilicates, which impeded melt-induced slagging under both oxidizing and reducing atmosphere. On the contrary, when doping AAEM, the AFTs plunged because of the formation of low-melting akermanite, which favored liquid slag tapping during gasification. The pseudo-ternary diagrams indicated that the AFTs under reducing atmosphere were higher than that under oxidizing atmosphere, with an exception of around the limited region of SiO2:Al2O3:AAEM = 0.25:0.45:0.3. Ningdong coal located in the singularity region, where the existing forms of Fe as low-melting FeS and FeO under reducing atmosphere and high-melting Fe2O3 under oxidizing atmosphere resulted in slightly higher AFTs under oxidizing atmosphere. Besides, the atmosphere difference had more influence on IDT, ST, and HT, and less influence on FT. This research provides valuable practical guidance for the selection and dosage of additives during the combustion and gasification of Ningdong coal.

The impact of aluminosilicate-based additives upon the sintering and melting behaviour of biomass ash

The composition of ash arising from biomass combustion can cause significant slagging and fouling issues in pulverised-fuel boilers, particularly if high concentrations of alkalis are present. Al–Si additives have shown promise in improving the ash deposition characteristics of troublesome biomass, converting volatile potassium to potassium aluminosilicates. This article presents results of lab-scale testing for two high-potassium biomass ashes, olive-cake (OCA) and white-wood (WWA), combined with two promising additives, coal pulverised fuel ash (PFA) and kaolin powder, at 5% mass fraction. Ash fusion testing results show that the use of these additives consistently increases flow temperatures. For WWA, kaolin was observed to reduce deformation temperatures and increase flow temperatures to far above combustion temperatures. Sinter strength testing showed that additive use significantly improves the deposition properties of OCA, preventing the precipitation of KCl and formation of deposits that are highly undesirable for removal via sootblower. Sintering was eliminated at all temperatures measured with the use of kaolin. Both additives had negative effects upon the sintering of WWA, indicating that Al–Si additive use should be restricted to high K, high Cl biomass. High temperature viscometry of OCA, combined with thermodynamic modelling, showed that viscosities at combustion temperatures were far below ideal values due high Mg concentration and silicate formation. Kaolin at 5% mass fraction was predicted to significantly improve this behaviour, with aluminosilicate formation producing favourable viscosities. Results indicate that kaolin addition to high K, high Cl biomass such as OCA shows promise in making the ash compositions viable for pulverised-fuel combustion.

Formation of sylicides of aluminium in the Al-Si-Ti system

Currently used discrete fillers of cast aluminum matrix composite antifriction materials in most cases are characterized by high hardness, leading to increased wear of steel pairs of friction, which makes the search for new fillers urgent. Due to the formation of titanium aluminosilicates in the Al-Ti-Si system and the insignificant solubility of silicon and titanium in aluminum, it was suggested that it is possible to obtain composite materials based on them by the in-situ method or by synthesizing reinforcing materials in a liquid metal matrix. The introduction of titanium in the amount of 10 wt. % into the melts of Al-10÷20 wt. % Si at 700, 800 and 900 °C and subsequent isothermal holding the composite materials are synthesized. By melting in the range of 1000-1100 °C the Al-10÷25 wt. % Si-5÷15 wt. % Ti materials are obtained The phase composition of these materials and the content of elements in the primary phases formed in the aluminum matrix, the hardness of materials obtained by melting is determined. Studies of the formation of phases in the Al-Si-Ti system showed that under the conditions of their synthesis in the liquid phase as a result of reaction-diffusion, a large spectrum of aluminosilicates is formed, which are characterized by a dispersed structure. Under such conditions, since the processes are far from equilibrium, the formation of phases that cannot form during crystallization from the melt under conditions of its cooling is possible. This makes it possible, by varying the synthesis temperature and composition of the charge materials, in wide intervals, to change the properties of the resulting aluminum-matrix composite materials. Similar composite alloys that form during crystallization from the melt are characterized by a more coarse-crystalline structure and a substantially smaller spectrum of silicides, which obviously impairs their properties. The tests of the composite material of composition 85 % Al-15 % Si – 10 % Ti for friction-wear showed that it is characterized by high tribological characteristics. A significant advantage of the materials of the Al-Si-Ti system is the absence of solid phases capable of damaging the surface of the counter body made of steel. This makes promising further studies of the tribotechnical characteristics of the composites of this system.

Co-combustion of industrial coal slurry and sewage sludge: Thermochemical and emission behavior of heavy metals

A combination of thermogravimetric analysis and lab-scale fixed bed combustion experiments was carried out to study the thermochemical, kinetic and heavy metals emission behavior during co-combustion of industrial coal slurry (CS) and sewage sludge (SS). The results found that the blends had integrative combustion profiles which reflected both coal slurry and sewage sludge. During co-combustion, the ignition performance of CS could be significantly improved with the addition of SS. Synergetic effects of the co-combustion were observed at lower temperature, while the high-temperature char combustion of the blends was inhibited because of high ash components of SS or formation of inactive alkali metal aluminosilicates. Kinetic analysis confirmed the improve iginition behavior of blends. Both the comprehensive combustibility index S and the activation energy suggested that the blends with 20% SS may have the best promoting effects. Compared with CS, the higher concentration of Cl in SS increased the volatilization ratios of Cu, Zn, As, and Pb. When added CS into SS, the volatilization ratios of arsenic decreased during combustion. The inhibition effects for arsenic during co-combustion might be associated with the capture of arsenic vapors by the new-formed Ca/Al from CS thermal decomposition.

Experimental study on enrichment of heavy metals by intercalation-exfoliation modified kaolin during coal combustion

ABSTRACT An intercalation-exfoliation method is applied to modify the natural kaolin mineral, so that to improve the enrichment effects on heavy metals (Zn, Pb, Cr & Cd) during coal combustion. The modified kaolin is scanned by electron microscope (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and Brunner-Emmett-Teller (BET), which indicate that the natural kaolin is peeled off to form fine flakes and the interlayer spacing is significantly increased. The coal-kaolin combustion tests were performed in a tube furnace from 900°C to 1300°C. It is found that the enrichment of heavy metals is enhanced obviously during the coal combustion, especially when the raw kaolin has high activity. Besides, the adsorption effects on the above four heavy metals are different. To be specific, the kaolin modified by potassium acetate has a better performance for Zn and Pb, but that intercalated by dimethyl sulfoxide shows better influences on Cd and Cr. The modified kaolin can provide more active sites for the adsorption of heavy metals, enhance chemical adsorption, and fix heavy metals in the form of aluminosilicates, silicates and aluminates. These founding could reduce the pollutant emissions of coal combustion in industrial applications.

Effect of PVA/SiO2 NPs Additive on the Structural, Durability, and Fire Resistance Properties of Geopolymers

This exertion introduces polyvinyl alcohol fiber/silica nanoparticles (poly vinyl alcohol (PVA)/SiO2 NPs) in the fly ash-based geopolymer at ambient curing temperature. The present study aims at investigating the structural properties (compressive, bond strength, fracture parameters (fracture toughness (KIc), crack mouth opening displacement (CMOD)), cyclic compression), durability (freeze-thaw), and fire resistivity of the newly developed PVA/SiO2 NPs mediated geopolymer. The outcomes suggest that geopolymers incorporated with 5% PVA fibers showed improved structural properties and durability as compared to other specimens. Investigation on the fire resistivity of the geopolymers exposed to different heating temperatures (400 °C, 600 °C, 800 °C), showed that geopolymers with PVA/SiO2 NPs significantly prevented the explosive concrete spalling. Microstructural studies confirmed that PVA fibers in the geopolymeric matrixes were well distributed and developed a fiber-bridging texture with improved performance. Addition of the nano-silica particles accelerated the heat evolution during the hydration process and the geopolymeric reaction (formation of sodium aluminosilicate N-A-S-H gel) at ambient curing environment.

Electrocoagulation for the purification of highly concentrated brine produced from reverse osmosis desalination of coal seam gas associated water

The ability of electrocoagulation (EC) at facilitating salt recovery from brine resultant from reverse osmosis (RO) desalination of coal seam gas (CSG) associated water is described. The aim was to reduce the presence of high concentrations of dissolved silicate which inhibit salt recrystallization by forming precipitates on equipment. The hypothesis was that EC could operate effectively in brine solutions and provide high silicate removal; thus facilitating a zero liquid discharge strategy. A benchtop EC unit equipped with either aluminium, iron or mixed iron-aluminium electrodes was used to treat simulated brine from a high recovery RO process. Up to 98.9% of silica was removed when aluminium or aluminium-iron electrodes were used. Significant reduction in concentrations of alkaline earth ions were also recorded (Ba > Sr > Ca > Mg) especially with iron electrodes. It appeared that silicate removal was via aluminosilicate formation. Hydraulic retention time was a key variable with 20 s recommended on the basis of performance/cost trade-off. Polarity reversal did not substantially change removal performance but impacted power consumption. For iron and iron-aluminium electrodes 1 min polarity reversal was preferred whereas for aluminium electrode 5 min was optimal. However, a thick coating was formed on the electrode surface and this may inhibit performance if longer tests are conducted. All flocs formed settled relatively rapidly (<20 min) which was in a time frame suitable for industrial application.

Aluminium leaching from red muds for their complexing reprocessing

Complexing processing of «red muds» (R.M.) - waste of bauxite reprocessing by the Bayer's method, is one of the important tasks of toxic industrial waste utilization. Studied the possibility of aluminum leaching from the R.M. which content reach 14 %, received from Bogoslovsky aluminum plant of JSC «Siberian-Urals Aluminium Company» by aqueous solutions of NaOH. The process was carried out at atmospheric pressure and temperatures near to the boiling point of leaching solutions with the utilization of the residual alkali. The time’s dependence of the aluminum leaching degree from the R.M. by aqueous solutions of NaOH passes through the maximum due to the formation of secondary precipitation of aluminum. The cause of secondary sedimentation is the interaction of silicon with aluminum with formation of insoluble aluminosilicates, for example, Nа2Аl2Si2O8·2Н2O. The conditions of leaching, under which the formation of stable aluminate solutions during the time do not form of secondary precipitations were established. The maximum achieved values of the aluminum leaching degree in autoclave-free conditions was reach 20-25 %. The removal of alkali and part of aluminum under the first stage of complexing processing of R.M. leads to their enrichment in iron. The cakes from aluminum leaching and next carbonate scandium leaching can be used for pyrometallurgical recovery of iron and slag, in which untreated elements are passed, including residual aluminum, scandium, sum of rare earth elements, titanium and zirconium. A significant decrease in the volume of slag opens more opportunities for further isolation their components by acidic methods.

Study on the modes of occurrence of rare earth elements in coal fly ash by statistics and a sequential chemical extraction procedure

Rare earth elements and yttrium (REY) are strategically important materials in the defense, aerospace, automation and electronic industries, and therefore, REY has been referred as the “vitamin of industries.” The recovery of REY from coal fly ash has been recognized as a promising way to expand REY sources, and characterization of REY in coal fly ash will be critical for its subsequent exploitation and utilization. The work reported here investigates the modes of occurrences of REY in fly ash. Coal fly ash samples were collected from Guizhou Province. The results of the particle size classification showed that the content of total REY as well as that of individual components increased with a decrease in the particle size, and REY showed a moderate degree of enrichment in the smaller particles. The REY content was found to be a strongly and positively correlated with the content of silicon and aluminum through Pearson correlation and regression correlation analysis. A mathematical model between REY and Si/Al was established and this can be used to predict the content of REY with known Si and Al content. A sequential chemical extraction procedure for REY in coal fly ash was designed, and results from these tests showed that the silicate & aluminosilicate form was the dominant mode of occurrence of REY; this form accounted for 80% of the material. Hence the silicate & aluminosilicate form, which contains the most REY, must be the focus of subsequent recovery processes.

Evolution of PM2.5 from biomass high-temperature pyrolysis in an entrained flow reactor

In this study, wheat straw pyrolysis was conducted in an entrained flow reactor at 900–1300 °C, and PM2.5 were sampled from the flue gas through a heated sampling system. Multi-phase PM2.5 including carbonaceous matter, potassium-containing particles, and ash particles, was separated and quantified using a thermogravimetric analyzer (TGA). The micro-morphologies and chemical compositions of these three phases were characterized by scanning electron microscopy (SEM), scanning transmission electron microscope (STEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). Results show that PM2.5 yields during biomass pyrolysis are in the range of 7–34 g/kg (dry-basis biomass) and increase with the increase of pyrolysis temperature. At low pyrolysis temperatures (900–1000 °C), the carbonaceous matter is dominated by char-carbon. When the pyrolysis temperature increase from 1000 °C to 1100 °C, the production of soot is greatly enhanced and soot becomes dominant in PM2.5, and the amorphous morphologies of soot are replaced by the concentric graphitic layers. With the further increasing in pyrolysis temperature, soot particles become more spherical and onion-like. Above 1100 °C, the KCl content in PM2.5 declines, which is because of the capture of KCl and the formation of low-melting potassium aluminosilicates in large char particles. At 1300 °C, the fragmentation of char particles is significantly strengthened, resulting in more ash in PM2.5.

Release and transformation of potassium in co-combustion of coal and wheat straw in a BFB reactor

Potassium transformation and migration characteristic during wheat straw-coal co-combustion was investigated in a lab-scale BFB reactor, with the emission of SO2 also discussed. Results indicated that the reaction of sulfation mainly took place below 900 °C in co-combustion. At higher combustion temperatures, K mainly existed in the form of aluminosilicates. In addition, reaction between bed material and wheat straw was promoted as the temperature increased, causing the enrichment of K in the bottom phase. Ash deposition during the co-combustion at 900 °C can be divided into three stages: (1) deposition of coal ash stuck to the probe, (2) deposition of WS ash adhered to the coal ash, (3) sulfation on the surface of the WS ash. Fluidized air velocity also made a difference to alkali distribution by changing heat and mass release of K into gas phase by improving the combustion. When the velocity was even higher, K content in the flue gas decreased due to the shorter residence time of fuel particles.

Impacts of CO2 on the pyrite–kaolinite interaction and the product sintering strength

Interactions between pyrite and silicates are very critical to ash slagging in coal-fired boilers. However, no work has been reported regarding the impacts on such interactions of CO2, the dominant component in the oxy–fuel combustion gas. This was investigated in the present work by using mixtures of pyrite and kaolinite, a prevailing silicate mineral in coal. Furthermore, the sintering strength of the generated products was also evaluated. The pyrite–kaolinite mixtures were treated on a fixed bed reactor in both N2 and CO2 for comparison. The treating temperature was 1050, 1150 and 1250 °C while the reaction time was 3, 6 and 12 min, respectively. The solid products were characterized by techniques such as X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Sintering tests of these products were carried out as well. It was found that some interactions between pyrite and kaolinite took place in the N2 atmosphere. This was evidenced by the formation of iron aluminosilicate and attributed to the effects of water vapor released from kaolinite dehydroxylation. Nevertheless, pyrite–kaolinite interactions in N2 were limited and had insignificant effects on product sintering strength development. In CO2, pyrite–kaolinite interactions were significantly enhanced, compared with those in N2. Although the kaolinite-derived water vapor had some effects, CO2 was found to play a dominant role. Enhanced pyrite–kaolinite interactions resulted in an increase of eutectic phases. Consequently, the product sintering strength development was greatly elevated. It was further found that, under the conditions investigated, the interactions between pyrite and kaolinite were actually through reactions between FeO, rather than other intermediates, and aluminosilicate. This new finding enabled us to develop the mechanisms for pyrite–kaolinite interactions in N2 and CO2.

Tea Garden Lateritic Soil as a High-Temperature Desulfurization Sorbent: Effect of Oxygen on Regeneration Process

The lateritic soils collected from a tea garden were used to explore the regeneration process using different O2 contents for high-temperature desulfurization. The desulfurization and regeneration experiments were carried out using a fixed-bed reactor at 500°C and the gaseous mixture composed of 1% H2S, 25% CO, 15% H2, and balance N2 for the desulfurization process. Experimental results showed that the regenerability is better when the air was used as a regeneration gas and the regeneration time is shortened. Multiple regeneration experiments indicated that lateritic soils can be regenerated by passing air and can thus be reused many times and its regeneration efficiency is slightly better than that regenerated by 1% O2. The sulfur capacity after air desulfurization/regeneration cycles was examined by elemental analysis with a value ranging from 1.40% to 1.49%, and residual sulfur was detected with a value of 0.12% after the diluted 1% O2 regeneration. No sulfur was detected for the regenerated lateritic soil after air regeneration. From NMR structural identification, the 6-coordinated octahedral structure of Al and trioctahedral coordinated Si are the major Al-containing and Si-containing compounds. Broad shoulder peaks were detected after regeneration process that may be associated with the formation of aluminosilicate and further reduces the dispersion of iron on the surface of lateritic soils.

Improved catalyst recovery combined with extracting alumina from Na2CO3-catalyzed gasification ash of a high-aluminium coal char

The catalyst recovery from Na2CO3-catalyzed steam gasification ash of Sunjiahao (SJH) high-aluminium coal char was investigated using water leaching method combined with extracting alumina by means of Ca(OH)2 thermal activation. The recovery efficiency of sodium catalyst from Na2CO3-catalyzed gasification ash (NCGA) with single water leaching method was as low as 39.5 wt%, which resulted from the formation of water insoluble sodium aluminosilicate during Na2CO3-catalyzed gasification. In order to improve sodium recovery, the water-washed NCGA was activated by means of Ca(OH)2 thermal activation for simultaneous recovery of sodium and alumina. The recovery efficiency of sodium from the water insoluble sodium aluminosilicate is 63.6 wt%, thus the total sodium recovery can be remarkably improved and reach 72 wt%. Meanwhile, the extraction efficiency of alumina from NCGA can reach 88.46 wt%. The low sodium recovery with Ca(OH)2 thermal activation is attributed to the formation of Na2CaSiO4 during Ca(OH)2 calcination. Extracting alumina process from NCGA of SJH high-aluminium coal can effectively promote the recovery of sodium catalyst and the process economy.

Thermodynamic analysis and reaction behaviors of alkali metal elements during iron ore sintering

Reaction thermodynamics and behaviors of alkali metal compounds were studied by FactSage7.1 and sinter pot trials. Main transformation behavior of alkali metal compounds was divided into three parts: part of alkali metal chloride was gasified and emitted into the flue gas, and most of alkali metal chloride turned into sulfate, which was remained in the finished sinter, through reacting with sulfur oxide; KAlSi3O8 and NaAlSi3O8 were transformed into KAlSi2O6, NaAlSi2O6 and alkali metal oxides by reacting with calcium oxide. Moreover, newly formed alkali metal oxides turned into sulfate and silicate, entering finished sinter finally. Only a small amount of KAlSi3O8 and NaAlSi3O8 were reduced into gaseous alkali metals in ambient strong reduction atmosphere and removed into the flue gas. 21.67% of potassium and 14.56% of sodium entered flue gas. In finished sinter, alkali metal elements existed in the form of alkali metal sulfate, silicate and aluminosilicate. The influences on alkali metal elements distribution, basicity (mass ratio of CaO to SiO2 in sinter), sulfur content, chloride content and coal ratio of raw materials indicated that increasing basicity level, rising coal ratio and adding CaCl2 promoted the removal of alkali metal elements into the flue gas. However, with sulfur content increasing in raw materials, alkali metal elements distribution ratio in the finished sinter rose.

Mesoporous Shell@Macroporous Core Aluminosilicates as Sustainable Nanocatalysts for Direct N‐alkylation of Amines

AbstractAluminosilicate spheres with a macroporous core and mesoporous shell (Si/Al ratio of 11) is synthesised by a sol‐gel method utilizing cetyltrimethyl ammonium bromide (CTAB) as a structure directing agent in basic medium. The selective incorporation of aluminium in the silica matrix results in the formation of aluminosilicates with an overall acidity of 0.32 mmol/g with interconnected pores. Direct N‐alkylation reaction is a prototype of C−N bond formation reaction and meso‐ macroporous aluminosilicate is shown to catalyze this reaction with excellent yield. The catalyst is tested and found sustainable for five catalytic cycles even without any high temperature regeneration step.