Effect of Calcinations Temperature on Crystallography and Nanoparticles in ZnO Disk

We proposed a good calcinations condition of the ZnO disk to control the crystallography and nanoparticles in ZnO disk. The crystallography of precursor powder and disk powder were analyzed by the X-ray diffraction (XRD). The mean nanoparticles of ZnO disk was determinate by XRD results and observed by scanning electron microscope. The temperature ranges of 400℃ to 650℃ in air for 30 minutes were used calcinations ZnO disk. These temperature can be controlled the single phase, lattice parameters, unit cell volume, crystalline size, d-value, texture coefficient and bond lengths of Zn–Zn, Zn–O and O–O which correspond significantly the hexagonal crystal structure. The nanoparticles were small changed mean of 76.59 nm at the calcinations temperature range.

Effects of precursor moisture and inert N_2 atmosphere calcinations on structure and properties of alumina modified CeZrLaNd mixed oxides

CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of cerium zirconium mixed oxides are the key properties for the automotive catalysts so as to meet the strict emission regulations. In this work, alumina modified CeZrLaNd mixed oxides were prepared by a co-precipitation method. The effects of moisture in precursor and inert N2 atmosphere during calcinations on the structure and properties were investigated by Brunauer-Emmett-Teller(BET) surface area measurements, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), hydrogen temperature-programmed reduction(H_2-TPR), oxygen storage capacity(OSC), Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). The results show that the moisture in precursor during calcinations increases the crystal grain size of the cerium zirconium mixed oxides, improving the thermal stability. And the aged surface area of sample after being calcined at1000 ℃ for 4 h reaches 68.8 m^2/g(5.7% increase compared with the common sample). The inert N2 atmosphere endows a great pore-enlarging effect, which leads to high fresh surface area of 148.9 m2/g(13.5% increase compared with the common sample) and big pore volume of 0.5705 mL/g. The redox and oxygen storage capacity are also improved by inert N2 atmosphere with high OSC value of 241.06μmolO_2/g(41.3% increase compared with the common calcination), due to the abundant formation of the crystal defects and oxygen vacancies.

Effect of calcinations temperature on the luminescence intensity and fluorescent lifetime of Tb^(3+)-doped hydroxyapatite(Tb-HA)nanocrystallines

Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.

Recycling arsenic-containing bio-leaching residue after thermal treatment in cemented paste backfill:Structure modification,binder properties and environmental assessment

The substantial arsenic(As)content present in arsenic-containing bio-leaching residue(ABR)presents noteworthy environ-mental challenges attributable to its inherent instability and susceptibility to leaching.Given its elevated calcium sulfate content,ABR exhibits considerable promise for industrial applications.This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement(SSC),offering an innovative binder for cemented paste backfill(CPB).Thermal treatment at varying temperatures of 150,350,600,and 800℃ was employed to modify ABR’s performance.The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR.Subsequently,the hydration characteristics of SSC utilizing ABR,with or without thermal treatment,were studied,encompassing reaction kinetics,setting time,strength development,and microstructure.The findings revealed that thermal treatment changed the calcium sulfate structure in ABR,consequently impacting the resultant sample performance.Notably,calcination at 600℃ demonstrated optimal modification effects on both early and long-term strength attributes.This enhanced performance can be attributed to the augmented formation of reaction products and a densified micro-structure.Furthermore,the thermal treatment elicited modifications in the chemical As fractions within ABR,with limited impact on the As immobilization capacity of the prepared binders.

A thermodynamic view on the in-situ carbon dioxide reduction by biomass-derived hydrogen during calcium carbonate decomposition

In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.

Controllable synthesis of CuAlO_(2) via solid-phase method and its catalytic performance for methanol steam reforming to hydrogen

This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investigation in methanol steam reforming(MSR).Various catalysts were prepared under different conditions,such as calcination temperature,calcination atmosphere,and heating rate.Characterization techniques including BET,XRD,XPS,SEM and H2-TPR were employed to analyze the samples.The results revealed significant effects of calcination temperature on the phase compositions,specific surface area,reduction performance,and surface properties of the CA-T catalysts.Based on the findings,a synthesis route of CuAlO_(2) via the solid-phase method was proposed,highlighting the importance of high calcination temperature,nitrogen atmosphere,and low heating rate for CuAlO_(2) formation.Catalytic evaluation data demonstrated that CuAlO_(2) could catalyze MSR without pre-reduction,with the catalytic performance of CA-T catalysts being notably influenced by calcination temperature.Among the prepared catalysts,the CA-1100 catalyst exhibited the highest catalytic activity and stability.The findings of this study might be useful for the further study of the catalytic material for sustained release catalysis,including the synthesis of catalytic materials and the regulation of sustained release catalytic performance.

Preparation and Characterization of Activated Carbons from Palm Nut Shells: Effects of Calcination Temperature on Porosity and Chemical Properties

Activated carbons (ACs) calcined at 400˚C, 500˚C, and 600˚C (AC-400, AC-500, and AC-600) were prepared using palm nut shells from Gabon as raw material and zinc chloride (ZnCl2) as a chemical activating agent. Prepared ACs were characterized by physisorption of nitrogen (N2), determination of diode and methylene blue numbers for studies of porosity and by quantification and determination of surface functional groups and pH at point of zero charge (pHpzc) respectively, for studies of chemical properties of prepared ACs. Then, effects of calcination temperature (Tcal) on porosity and chemical properties of prepared ACs were studied. The results obtained showed that when the calcination temperature increases from 500˚C to 600˚C, the porosity and chemical properties of prepared ACs are modified. Indeed, the methylene blue and iodine numbers determined for activated carbons AC-400 (460 and 7.94 mg·g−1, respectively) and AC-500 (680 and 8.90 mg·g−1, respectively) are higher than those obtained for AC-600 (360 and 5.75 mg·g−1, respectively). Compared to the AC-500 adsorbent, specific surface areas (SBET) and microporous volume losses for AC-600 were estimated to 44.7% and 45.8%, respectively. Moreover, in our experimental conditions, the effect of Tcal on the quantities of acidic and basic functional groups on the surface of the ACs appears negligible. In addition, results of the pHpzc of prepared ACs showed that as Tcal increases, the pH of the adsorbents increases and tends towards neutrality. Indeed, a stronger acidity was determined on AC-400 (pHpzc = 5.60) compared to those on AC-500 and AC-600 (pHpzc = 6.85 and 6.70, respectively). Also according to the results of porosity and chemical characterizations, adsorption being a surface phenomenon, 500˚C appears to be the optimal calcination temperature for the preparation of activated carbons from palm nut shells in our experimental conditions.

Highly active Cu/SiO_2 catalysts for hydrogenation of diethyl malonate to 1,3-propanediol

Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3‐propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO2 catalysts, which were systematically characterized by N2 adsorption‐desorption, inductively coupled plasma‐atomic emission spectros‐copy, N2O chemisorption, X‐ray diffraction, Fourier transform infrared spectroscopy, H2 tempera‐ture‐programmed reduction, transmission electron microscopy, and X‐ray photoelectron spectros‐copy. When the Cu/SiO2 catalyst was calcined at 723 K, 90.7%conversion of diethyl malonate and 32.3%selectivity of 1,3‐propanediol were achieved. Compared with Cu/SiO2 catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO2 catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu＋/Cu0. The synergetic effect of Cu0 and Cu＋is suggested to be responsible for the optimum activity.

Optimization of preparing V_2O_5 by calcination from ammonium metavanadate using response surface methodology

Parameters of technique to prepare vanadium pentoxide by calcination from ammonium metavanadate were optimized using central composite design of response surface methodology. A quadratic equation model for decomposition rate was built and effects of main factors and their corresponding relationships were obtained. The results of the statistical analysis show that the decomposition rate of ammonium metavanadate is significantly affected by calcination temperature and calcination time. The optimized calcination conditions are as follows： calcination temperature 669.71 K, calcination time 35.9 min and sample mass 4.25 g. The decomposition rate of ammonium metavanadate is 99.71%,which coincides well with experimental value of 99.27% under the optimized conditions, suggesting that regressive equation fits the decomposition rates perfectly. XRD reveals that it is feasible to prepare the V2O5 by calcination from ammonium metavanadate using response surface methodology.

Element distribution of high iron-bearing zinc calcine in high gradient magnetic field

High gradient magnetic separation was conducted in order to separate insoluble zinc ferrite from zinc calcine before acid leaching of hydrometallurgical process. Chemical composition and structural characterization of zinc calcine were studied via inductively coupled plasma （ICP）, X-ray diffraction （XRD）, Mossbauer spectra, scanning electron microscopy （SEM） and laser particle analysis （LPA）. The parameters of magnetic separation which affect the distribution of zinc ferrite and undesired elements, such as calcium, sulfur and lead in magnetic concentrate were investigated. The results of high gradient magnetic separation indicate that more than 85% of zinc ferrite is distributed into magnetic concentrate from the zinc calcine under the magnetic induction of 0.70 T. In addition, about 60% of calcium and 40% of sulfur distribute in non magnetic phases of tailings during magnetic separation process. Most of lead distributes uniformly along the zinc calcine in superfine particle size.

Effect of Calcination Temperature on Catalytic Activity and Textual Property of Cu/HMOR Catalysts in Dimethyl Ether Carbonylation Reaction

The effect of calcination temperature on the catalytic activity for the dimethyl ether （DME） carbonylation into methyl acetate （MA） was investigated over mordenite supported copper （Cu/HMOR） prepared by ion-exchange process. The results showed that the catalytic activity was obviously affected by the calcination temperature. The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ℃ under conditions of 210 ℃, 1.5 MPa, and GSHV of 4883 h^-1. The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction, N2 absorption, NH3 temperature program desorption, CO temperature program desorption, and Raman techniques. Proper calcination temperature was effective to promote copper ions migration and diffusion, and led the support HMOR to possess more acid activity sites, which exhibited the complete decomposing of copper nitrate, large surface area and optimum micropore structure, more amount of CO adsorption site and proper amount of weak acid centers.

Effect of Calcination Temperature on La-Modified Al2O3 Catalysts for Vapor Phase Hydrofluorination of Acetylene to Vinyl Fluoride

A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts calcined at different temperatures were characterized using NH3-TPD, pyridine-FTIR, X-ray diffraction, and Raman techniques. It was found that the calcination process could not only change the structure of these catalysts but also modify the amount of surface acidity on the catalysts. The catalyst calcined at 400 ℃ exhibited the highest conversion of acetylene （94.6%） and highest selectivity to vinyl fluoride （83.4%） and lower coke deposition selectivity （0.72%）. The highest activity was related to the largest amount of surface acidity on the catalyst, and the coke deposition was also related to the total amount of surface acidic sites.

Low temperature molten salt synthesis of porous La_(1-x)Sr_xMn_(0.8)Fe_(0.2)O_3(0≤x≤0.6) microspheres with high catalytic activity for CO oxidation

A molten salt method was developed to prepare porous La1‐xSrxMn0.8Fe0.2O3 （0≤ x ≤ 0.6） micro‐spheres using hierarchical porous δ‐MnO2 microspheres as a template in eutectic NaNO3‐KNO3. X‐ray diffraction patterns showed that single phase LaMn0.8Fe0.2O3 with good crystallinity was syn‐thesized at 450℃ after 4 h. Transmission electron microscope images exhibited that the LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h possessed a porous spherical morphology com‐posed of aggregated nanocrystallites. Field emission scanning electron microscope images indicated that the growth of the porous LaMn0.8Fe0.2O3 microspheres has two stages. SEM pictures showed that a higher calcination temperature than 450？？ had an adverse effect on the formation of a po‐rous spherical structure. The LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h displayed a high BET surface area of 55.73 m2/g with a pore size of 9.38 nm. Fourier transform infrared spectra suggested that Sr2＋ions entered the A sites and induced a decrease of the binding energy between Mn and O. The CO conversion with the La1‐xSrxMn0.8Fe0.2O3 （0≤x≤0.6） samples indicated that the La0.4Sr0.6Mn0.8Fe0.2O3 sample had the best catalytic activity and stability. Further analysis by X‐ray photoelectron spectroscopy demonstrated that Sr2＋doping altered the content of Mn4＋ions, oxygen vacancies and adsorbed oxygen species on the surface, which affected the catalytic performance for CO oxidation.

Adsorption of glutamic acid from aqueous solution with calcined layered double Mg-Fe-CO_3 hydroxide

Layered double Mg-Fe-CO3 hydroxide （Mg-Fe-LDH） with a mole ratio of Mg to Fe of 3 was synthesized by coprecipitation method and calcined product Mg-Fe-CLDH was obtained by heating Mg-Fe-LDH at 500 ℃ for 6 h. The as prepared Mg-Fe-LDH and calcined Mg-Fe-CLDH were used for removal of glutamic acid （Glu） from aqueous solution, respectively. Batch studies were carried out to address various experimental parameters such as contact time, pH, initial glutamic acid （Glu） concentration, co-existing anions and temperature. Glu was removed effectively （99.9%） under the optimized experimental conditions with Mg-Fe-CLDH. The adsorption kinetics follows the Ho’s pseudo second-order model. Isotherms for adsorption with Mg-Fe-CLDH at different solution temperatures were well described using the Langmuir model with a good correlation coefficient. The intraparticle diffusion model fitted the data well, which suggests that the intraparticle diffusion is not only the rate-limiting step.

The Mechanical Properties and Hydration Characteristics of Cement Pastes Containing Added-calcium Coal Gangue

The mechanical properties of several kinds of coal gangue calcined with limestone were Researched so as to find the optimum way of calcinations with limestone. Microstructure and property of hydration process of cement pastes containing added-calcium coal gangue were analyzed by means of scanning electron microscope （SEM） and method of mercury in trusion poremeasurement （MIP）, etc. The experiment can approve those results： when proper amounst of gypsum and fluorite were taken as mineralizers in the course of calcinations of added-calcium coal gangue, activity of coal gangue can be effectively improved. The results of mechanical property and structural characteristic such as hydration process, hydration product and microstructure etc. of cement pastes containing added-calcium coal gangue are consistent.

Preparation of Highly Active Pt-K/γ-Al_2O_3 Catalyst for o-Phenylphenol Synthesis from o-Cyclohexenyl-cyclohexanone Dehydrogenation

0.5%Pt-K/γ-Al2O3 catalysts for the synthesis of o-phenylphenol（OPP） from o-cyclohexenyl-cyclohexanone （dimer） dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K2SO4 to Pt/γ-Al2O3 catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. The higher activity was obtained when Pt/γ-Al2O3 catalyst was calcined in nitrogen atmosphere at 400--500 ℃ and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h.

Study on melting available silicone from coal gangue

Available silicone was melted from coal gangue samples from Hancheng dig- gings through calcination, digestion, and other means. The best calcination temperature was determined from a range of 550-1 150 ℃; and the best time, from a range of 0.5-5 h by colorimetry method. The proper ratio of coal gangue, limestone, sodium carbonate, and caustic soda was then determined through orthogonal experiment. The results show that the proper extraction condition for available silicone is the ratio of coal gangue, limestone, sodium carbonate, and caustic soda at 1：0.5：0.1：0.05, calcination temperature at 700 ℃, and calcination time at 2 h. In this condition, the available silicone content can be more than 19.65%.

Magnetic α-Fe_2O_3,γ-Fe_2O_3 and Fe_3O_4 Prepared by Facile Calcination from K_4[Fe(CN)_6]

Magnetic a-Fe2O3, γ-Fe2O3 and Fe3O4 were prepared by facile calcination under different temperature from K4[Fe（CN）6] as raw materials, in which the calcined products are a-Fe2O3, Fe3O4 and y-Fe203 at 400 or 700, 500, and 600 ℃, respectively. The as-prepared compounds were characterized by X-ray powder diffraction and scanning electron microscopy, and their magnetic behavior at room temperature was also studied. This method provided a simple approach to prepare different polymorphic forms of magnetic iron oxides, which may have potential applications in magnetic science, magnetic composite materials, magnetic core, magnetic separation and medical diagnostics.

Synthesis and Characterization of Nanoscale Mullite Powder

Nanoscale mullite powder were synthesized via Sol-gel-SCFD and middle temperature treatment by using AIP( aluminum-isopropoxde) and TEOS ( tetraethyl orthosili-cate) as starting materials. Both of the binary aerogel of alumina-silica and calcined nanoscale materials were investigated by using TG-DSC ( thermogravimetry-differentialscanning calorimeter) , TEM( transmission electron microscope) , XRD(X-Ray diffractometer ) and specific surfacearea and porosimetry. TG-DSC indicated the removal of most of the volatiles, i.e. 15.98% up to about 700℃ ,and in the DSC curve , existence of two exothermic peak atabout 445℃ and 1015℃ may be due to the crystallizationof Si-O-Al-O in diphasic gels and mullitization and a small endothermic peak at about 805℃ indicated the decomposition of structural water molecules . On the colligation of the results of TG-DSC, XRD and TEM, the beginning temperature of mullitization in Al2O3-SiO2 aerogel system can be confirmed at about 1015℃. XRD results also showed the formation of mullite at the range 1100-1200℃. TEM and surface area and porosimetry results showed that the nanosized mullite were calcinated at 1100and 1200℃ exhibited size 30 nm and 50 nm, specific surface area 138.91 m2/g and 95.81 m2/g.

Model of limestone calcination / sulfation under oxy-fuel fluidized bed combustion

The characteristics of the simultaneous calcination/ sulfation of limestone under oxy-fuel fluidized bed combustion were studied and compared with those of the sulfation of precalcined CaO. During the calcination stage, SO2 can react with product CaO and slow down the CaCO3 decomposition rate by the covering effect of the CaSO4 product. The sulfation rate of simultaneous calcinatiort/sulfation is slower than that of precalcined CaO, but with a long enough sulfation time, the calcium conversion of simultaneous calcination/sulfation is higher than that of the precalcined CaO. A grain-micrograin model is established to describe the simultaneous calcination, sintering and sulfation of limestone. The graln-micrograln model can reflect the true reaction process of the calcination and sulfation of limestone in oxy-fuel fluidized bed combustion.