Hydrothermally stable mesoporous aluminosilicates as superior FCC catalyst:From laboratory to refinery

Well-ordered aluminosilicates(MAs)were prepared by in-situ assembly of pre-crystallized units of zeolite Y precursors at a commercial scale,and applied in an industrial fluid catalytic cracking unit for the first time.Compared with incumbent equilibrium catalyst,the surface area of trial equilibrium catalysts(30%inventory ratio)increased from 110 m^(2)g^(-1)to 120m^(2)g^(-1).Moreover,a significant increase of the mesoporous surfaceareaof trial equlibrium catalysts(30%inventoryrati)from 33 m g/to 40magi(22%increase).Furthermore,the equilibrium catalyst that contain 80%LPC-65 yields significantly lower heavy oil(0.23%)and higher total liquids(0.53%)compared with LDO-70.The industrial results demonstrated excellent hydrothermal stability and superior catalytic cracking properties,showing the promising futurein the industrial units.

Iron Activation of Natural Aluminosilicates to Remove Arsenic from Groundwater

Low-cost adsorbents constituted by Fe-modified-aluminosilicates （laminar and zeolite type minerals） were developed and characterized to be used in the arsenic removal from groundwater. Iron activation was carried out ＂in situ＂ by the synthesis and deposition of mesoporous ferrihydrite. Natural iron-rich aluminosilicate was used as reference. All samples were characterized by X-ray diffraction, Raman spectroscopy, BET N2-adsorption, SEM-EDS microscopy and ICP chemical analysis. Experimental results of arsenic sorption showed that iron-poor raw materials were not active, unlike iron activated samples. The iron loading in all activated samples was below 5% （expressed as Fe203）, whereas the removal capacity of these samples reaches between 200-700 gg of As by g of adsorbent, after reusing between 17 cycles and 70 cycles up to adsorbent saturation. Differences can be associated to mineral structure and to the surface charge modification by iron deposition, affecting the attraction of the As-oxoanion. On the basis of low-cost raw materials, the easy chemical process for activation shows that these materials are potentially attractive for As（V） removal. Likewise, the activation of clay minerals, with natural high content of iron, seems to be a good strategy to enhance the arsenic adsorption ability and consequently the useful life of the adsorbent.

Synthesis and Characterization of Mesoporous Aluminosilicates for Copper Removal from Aqueous Medium

In this study the characterization of an aluminosilicate synthesized from commercial Al2(SO4)3 and colloidal SiO2 is presented, as well as its capacity for the removal of copper from aqueous solution. Characterization of the synthesized material was performed using X-ray diffraction, BET nitrogen adsorption-desorption, mass titration and the Boehm method. In order to obtain stable agglomeration and enhance its surface area (165 - 243 m2/g) and solid adsorbing capabilities, the molar ratio SiO2:Al2O3 (1:3, 1:1 and 3:1) was studied, the solubility of the preparation material, synthesis-procedure time and solution pH function were also examined. The maximum capacity to remove copper ions from an aqueous solution by synthesized aluminosilicate was 16 mg/g at pH 4 and 25℃. The Langmuir model fitted better to the copper adsorption experimental data.

Effect of inorganic salt impurities on seeded precipitation of silica hydrate from sodium silicate solution

To clarify the precipitation of silica hydrate from the real desilication solutions of aluminosilicate solid wastes by adding seeds and improve integrated waste utilization,the seeded precipitation was studied using synthesized sodium silicate solution containing different inorganic salt impurities.The results show that sodium chloride,sodium sulfate,sodium carbonate,or calcium chloride can change the siloxy group structure.The number of high-polymeric siloxy groups decreases with increasing sodium chloride or sodium sulfate concentration,which is detrimental to seeded precipitation.Calcium chloride favors the polymerization of silicate ions,and even the chain groups precipitate with the precipitation of high-polymeric sheet and cage-like siloxy groups.The introduced sodium cations in sodium carbonate render a more open network structure of high-polymeric siloxy groups,although the carbonate ions favor the polymerization of siloxy groups.No matter how the four impurities affect the siloxy group structure,the precipitates are always amorphous opal-A silica hydrate.

Effect of Fe_(2)O_(3)on the Structure,Physical Properties and Crystallization of CaO-Al_(2)O_(3)-SiO_(2)Glass

The calcium aluminosilicate-based glasses(CaO-Al_(2)O_(3)-SiO_(2),CAS)with different Fe_(2)O_(3)content(0.10wt%,0.50wt%,0.90wt%,and 1.30wt%)were prepared by traditional melt-quenching method.The glass network structure,thermal and mechanical properties,and crystallization behavior changes were investigated by nuclear magnetic resonance spectrometer,Fourier-transform infrared spectro-photometer,X-ray diffractometer,differential scanning calorimetry and field emission scanning electron microscope measurements.The change of Q^(n)in glass structures reveals the glass network connectivity decreases due to the increasing content of Fe_(2)O_(3)addition,resulting in the increasing of non-bridging number in glass structure.The glass densities slightly rise from 2.644 to 2.681 g/cm^(3),while Vickers’s hardness increases at first,from 6.469 to 6.901 GPa,then slightly drops to 6.745 GPa,with Fe_(2)O_(3)content increase.There is almost no thermal expansion coefficient change from different Fe_(2)O_(3)content.The glass transmittance in visible range gradually decreases with higher Fe_(2)O_(3)content,resulting from the strong absorption of Fe^(2+)and Fe^(3+)ions.The calculated activation energy from thermal analysis results first decreases from 282.70 to 231.18 kJ/mol,and then increases to 244.02 kJ/mol,with the Fe_(2)O_(3)content increasing from 0.10wt%to 1.30wt%.Meanwhile,the maximum Avrami constant of 2.33 means the CAS glasses exhibit two-dimensional crystallization.All of the CAS glass-ceramics samples contain main crystal phase of anorthite,the microstructure appears lamellar and columnar crystals.

Influence of Al_(2)O_(3)/SiO_(2) Ratio on the Structure and Properties of Na^(+)/K^(+)Ion Exchange Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) Glasses

In this work,the structure,viscosity and ion-exchange process of Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) glasses with different Al_(2)O_(3)/SiO_(2) molar ratios were investigated.The results showed that,with increasing Al_(2)O_(3)/SiO_(2) ratio,the simple structural units Q_(1) and Q_(2) transformed into highly aggregated structural units Q_(3) and Q_(4),indicating the increase of polymerization degree of glass network.Meanwhile,the coefficient of thermal expansion decreased from 9.23×10^(-6)℃^(-1) to 8.88×10^(-6)℃^(-1).The characteristic temperatures such as melting,forming,softening and glass transition temperatures increased with the increase of Al_(2)O_(3)/SiO_(2) ratio,while the glasses working temperature range became narrow.The increasing Al_(2)O_(3)/SiO_(2) ratio and prolonging ion-exchange time enhanced the surface compressive stress(CS)and depth of stress layer(DOL).However,the increase of ion exchange temperature increased the DOL and decreased the CS affected by stress relaxation.There was a good linear relationship between stress relaxation and surface compressive stress.Chemical strengthening significantly improved the hardness of glasses,which reached the maximum value of(622.1±10)MPa for sample with Al_(2)O_(3)/SiO_(2) ratio of 0.27 after heat treated at 410℃for 2 h.

Adsorptive desulfurization of diesel with mesoporous aluminosilicates

Mesoporous aluminosilicates (MAS) bearing microporous zeolite units and mesoporous structures were synthesized by the hydrothermal method. Adsorptive desulfurization ability of model oil and hy-drotreated diesel was studied. The effects of template concentration, crystalization time and calcination time were investigated. The desulfurization ability of adsorbents was improved by transitional metal ion-exchanging. The adsorptive desulfurization of diesel was carried out on a fixed-bed system. The results show that the adsorptive capacity is MAS>MCM-41>NaY. The improvement of desulfurization ability of MAS by Cu+ is more significant than that of Ag+.

Stable Tetrahedral Aluminum Sites in Hexagonal Mesoporous Aluminosilicates

A unique templating approach for the synthesis of hexagonal mesoporous aluminosilicates via self assembly of pre formed aluminosilcate nanoclusters with the templating micella formed by cetyltrimethylammonium bromide (CTAB) is described. The obtained materials of MAS 5 are hydrothermally stable, which is shown by X ray diffraction (XRD) analysis. Furthermore, as characterized by NMR technique, MAS 5 has stable tetrahedral aluminum sites that is the major contributions to the acidity of aluminosilicate molecular sieve, and on non framework aluminium species in the samples was observed.

Tailor and Control of Acidic Strength in Ordered Mesoporous Aluminosilicates by Using Preformed Zeolite Precursors

The acidic strength of ordered mesoporous aluminosilicates of MAS-2, MAS-3, MAS-7 and MAS-9 and mi-croporous crystals of Y, L, beta, and ZSM-5 zeolites was systemically investigated by temperature-programmed desorption of ammonia (NH3-TPD). Due to the use of preformed zeolite precursors of Y, L, beta and ZSM-5, the ordered mesoporous aluminosilicates with distinguished acidic strength were obtained, being dependent on the type of preformed zeolite precursors. Therefore, the acidic strength of these mesoporous aluminosilicates could be tai-lored and controlled.

n-Dodecane Hydroconversion over Nickel Supported on Different Mesoporous Aluminosilicates

Several 2.0 wt% nickel catalysts supported on nanometer bimodal mesoporous aluminosilicate (NBMAS), AlHMS and AlMCM-41 were prepared by means of the wetness impregnation method. The characterization tech-niques such as Py-FTIR and H2 chemisorption showed that the amount of Br鰊sted acid sites decreased in the order of Ni/AlHMS>Ni/AlMCM-41>Ni/NBMAS, while the nickel dispersion differed a little. In the catalytic n-dodecane hydroconversion, the highest conversion was obtained over Ni/NBMAS, and the lowest isomerization selectivity occurred over Ni/AlHMS. For the cracked products, the symmetrical carbon number distribution cen-tered at C6 was obtained on the Ni/AlMCM-41 catalyst due to the well balanced metal/acid functions, whereas the Ni/AlHMS and Ni/NBMAS catalysts led to more C3-C5 and C1+C11 products, respectively.

Effect of ZnO,La_(2)O_(3),and YF_(3)on Crystallization and Rehological Behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)Glass

The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass was studied.La_(2)O_(3)and YF_(3)substitution for Y_(2)O_(3)decreases the melting temperature of studied glass from 1402 to 1346 and 1379℃,and the activation energy of viscous flow decreases from 340 to 250 and 265 kJ/mol.Meanwhile,ZnO substitution for Al_(2)O_(3)decreases the melting temperature to 1379℃while increases the activation energy of viscous flow to 542 kJ/mol,due to their different role in glass structure.Substitution ZnO for Al_(2)O_(3)refines and homogenizes the crystals size and lowers crystallinity because the nucleation and crystal growth are depressed by higher activation energy of crystallization and change of crystallization mechanism from bulk crystallization to surface crystallization.Replacement of Y_(2)O_(3)by La_(2)O_(3)and YF_(3)respectively also decreases the crystallinity of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass ceramic due to competitive and hindering effect on the rearranged atoms,structural units and groups required by precipitated two crystals.Besides,y-Y2Si2O7,precipitation of Y4.67(SiO4)3O,ZnAl_(2)O_(4),and Y3Si3O10F were observed respectively due to incorporation of La_(2)O_(3),ZnO,and YF_(3).

Comparative studies on flotation of aluminosilicate minerals with Gemini cationic surfactants BDDA and EDDA

Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.

Quantifying aluminosilicate manganese release and dissolution rates across organic ligand treatments for rocks, minerals,and soils

Manganese is ubiquitous in terrestrial environments and most studies have focused on dissolution of Mn oxides,but aluminosilicates also release Mn.Here,we evaluated oxic Mn dissolution from six rocks and minerals(amphibolite,anorthosite,kaolinite,kyanite,muscovite,orthoclase feldspar) and soils from four Critical Zone Observatories(CZOs) under four LMWOLs treatments(catechol,citric acid,oxalic acid,control).Overall rock and mineral Mn mass-normalized release was 1.4 ± 0.5 nM μM^(-1) 14 d^(-1) and dissolution rate was 2403 ± 935 nM m^(-2) d^(-1) x 10^(3).Overall CZO soil Mn release was 16.7±5.1 nM μM^(-1) 14 d^(-1) and dissolution rate was 7010 ± 2570 nM m^(-2) d^(-1) × 10^(3).Anorthosite and kyanite had the highest Mn dissolution rates but kaolinite and kyanite had the highest Mn mass-normalized release rates.We hypothesize the structural location of Mn,surface area,and potential inclusions of highly-weatherable-phases control Mn dissolution for rocks and minerals.CZO soils with the highest solid phase Mn had the highest Mn release and dissolution rates.Citric acid and catechol had higher Mn release and dissolution rates than the control while oxalic acid did not.For rocks and minerals,we found pH 4 had higher Mn release and dissolution rates than pH6,but not for control treatments without LMWOL.Our study highlights that the abundance of Mn drove Mn release in soils but not rocks and minerals.Moreover,LMWOLs are important for Mn dissolution,even under acidic pH conditions.

Green Cementitious Paste Based on Recycled Materials

Cementitious alkali activated aluminosilicates pastes were produced from recycled and locally obtainable materials in Iraq. The compositions were based on recycled bricks, water glass, commercial caustic soda flakes, and nano silica. The nano silica was prepared from the abundant local ＂Iraqi anber＂ rice husks and added to the prepared pastes in different weight percentages. Another set of pastes was prepared via adding 5w% of＂A1-Najaf＇ fly ash at the expense of the recycled bricks powders. The pastes were cured for 1-28 days under ambient conditions. The compressive strengths for the cured pastes were measured. In addition, the cured pastes were characterized via X-ray diffraction, FTIR, and optical microscopy. The addition of the nano silica and longer curing times improve the microstructure packing and thus increases the compressive strengths. The added fly ash impregnates the microstructure with extra gel phase and further improves the compressive strengths of the cured pastes.

Mineralogical and sink-float studies of Jajarm low-grade bauxite

Jajarm＇s bauxite deposits are mainly diasporic, and they have a low mass ratio of Al2O3/SiO2. It is necessary to increase the run-of-mine mass ratio before feeding the material to the Bayer process. Chemical analysis indicated that the low-grade bauxite sample from Jajarm contained 43.9wt% Al2O3 and 13.35wt% SiO2, resulting in a mass ratio of 3.29. According to mineralogical studies, the presence of aluminosilicate minerals such as kaolinite, illite, and quartz was the main reason for the decrease of the mass ratio. Microscopic observations revealed that, with the size reduction from -1000＋710 to -38 μm, the liberation degree of diaspore increased from 10% to 60%, and that of aluminosilicates increased from 20% to 85%. Heavy liquids with the densities of 2.8, 3.0, 3.2, and 3.4 g/cm3 were used to evaluate the heavy media separation in three sizes, i.e., -3350＋710, -710＋212, and -212＋125 μm. Laboratory studies confirm that the density of 3.2 g/cm3 can produce the concentrates （in sunk fractions） with recoveries of 89.09%, 91.24%, and 84.68% with the Al2O3/SiO2 mass ratios of 5.03, 5.16, and 5.15 for the -3350＋710, -710＋212, and -212＋ 125 μ m sizes, respectively.

Mechanical properties of gangue-containing aluminosilicate based cementitious materials

High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent. The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM. The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt. For 28-day curing time, the compressive strength of the sample with a mass proportion of 2：1：1 （gangue： slag： fly ash） is 58.9 MPa, while the compressive strength of the sample containing 80wt% gangue can still be up to 52.3 MPa. The larger K^＋ favors the formation of large silicate oligomers with which AI（OH）4- prefers to bind. Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator. The reasons for this were found through IR and NMR analysis. Glauber＇s salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.

Occurrence mechanism of silicate and aluminosilicate minerals in Sarcheshmeh copper flotation concentrate

The Sarcheshmeh copper flotation circuit is producing 5× 10^4 t copper concentrate per month with an averaging grade of 28% Cu in rougher, cleaner and recleaner stages. In recent years, with the increase in the open pit depth, the content of aluminosilicate minerals increased in plant feed and subsequently in flotation concentrate. It can motivate some problems, such as unwanted consumption of reagents, decreasing of the copper concentrate grade, increasing of Al2O3 and SiO2 in the copper concentrate, and needing a higher temperature in the smelting process. The evaluation of the composite samples related to the most critical working period of the plant shows that quartz, illite, biotite, chlorite, orthoclase, albeit, muscovite, and kaolinite are the major Al2O3 and SiO2 beating minerals that accompany chalcopyrite, chalcocite, and covellite minerals in the plant feed. The severe alteration to clay minerals was a general rule in all thin sections that were prepared from the plant feed. Sieve analysis of the flotation concentrate shows that Al2O3 and SiO2 bearing minerals in the flotation concentrate can be decreased by promoting the size reduction from 53 to 38 μm. Interlocking of the Al2O3 and SiO2 bearing minerals with chalcopyrite and chalcocite is the occurrence mechanism of silicate and aluminosilicate minerals in the flotation concentrate. The dispersed form of interlocking is predominant.

Interactions between bubble and particles of key minerals of diasporic bauxite through the extended DLVO theory

The flotation of diasporic bauxite is to separate diaspore(valuable mineral)from aluminosilicate minerals(gangue minerals,mainly including kaolinite,illite and pyrophyllite),and the microscopic interaction force between the two types of minerals and air bubbles determines the separation efficiency.In this paper,based on the extended Derjaguin-Landau-Verwey-Overbeek(DLVO)theory,the van der Waals,electrostatic and hydrophobic interaction between particles of the four minerals mentioned above and air bubbles in collectorless solution were calculated first,and then diaspore and kaolinite were taken as examples to analyze the influence of various factors such as electrolyte concentration,mineral particle size,air bubble size,collector type(dodecylamine hydrochloride(DAH)and sodium oleate(NaOL))and concentration,and pulp pH on the interactions between the particles of valuable mineral and gangue minerals and air bubbles.The results showed that the total extended DLVO interactions between the four minerals and air bubbles were repulsive in most cases in collectorless solution.The increase in electrolyte concentration reduced the interaction force or even changed the direction of the force under certain circumstances.The addition of DAH and NaOL can reduce the adhesion energy barrier of kaolinitebubble and diaspore-bubble respectively.Each type of minerals exhibited a specific interface interaction response with air bubbles in each collector with different pH values.The research results have theoretical guiding significance for the optimization and directional control of diasporic bauxite flotation conditions.

Synthesis of γ-alkoxy-propylamines and their collecting properties on aluminosilicate minerals

alkoxy-propylamines, C12H25O（CH2）3NH2, C14H29O（CH2）3NH2, C16H33O（CH2）3NH2, C18H37O-（CH2）3NH2 were synthesized from aliphatic alcohol and acrylonitrile. The flotation tests of kaolinite, pyrophyllite and illite were conducted. The flotation mechanisms were explained in view of the structures of reagents and aluminium silicate minerals, zeta potential and Fourier transform infrared spectrum measurements. The results show that the synthesized r-alkoxy-propylamines are more effective than dodecyl amine for flotation of kaolinite, pyrophyllite and illite. For flotation kaolinite and illite, the collecting ability is in the order of C18H37O（CH2）3NH2>C16H33O-（CH2）3NH2>C14H29O（CH2）3NH2>C12H25O（CH2）3NH2, but the r-alkoxy-propylamines types of collectors have almost the same collecting ability on pyrophyllite, which demonstrating that γ-alkoxy-propylamines are new selective collectors for reverse floatation to remove aluminium silicate minerals from bauxite.

Effect of quaternary ammonium salts on flotation behavior of aluminosilicate minerals

The electrokinetic properties and flotation of diaspore, kaolinite, pyrophyllite and illite with quaternary ammonium salts collectors were studied. The results of flotation tests show that the collecting ability of quaternary ammonium salts for the four minerals is in the order（from strong to weak） ofoctadecyl dimethyl benzyl ammonium chloride（ODBA）, cetyl trimethyl ammonium bromide（CTAB）, dodecyl trimethyl ammonium chloride（DTAC）. Under the condition of alkalescence, it is possible to separate the diaspore from the silicate minerals such as kaolinite, illite and pyrophyllite using quaternary ammonium salts as collector. Isoelectric points （IEP） of diaspore, kaolinite, pyrophyllite and illite are pH=6.0, 3.4, 2.3 and 3.2, respectively. Quaternary ammonium salts can change ζ-potential of the aluminosilicate minerals obviously. The flotation mechanisms were explained by ζ-potential and Fourier transform infrared spectrum （FT-IR） measurements. The results demonstrate that only electrostatic interaction takes place between aluminosilicate minerals （diaspore, kaolinite, pyrophyllite and illite） and quaternary ammonium salts.