Halloysite (Hal) hybridized ceria-zirconia solid solution material (CZ-Hal) for three way catalysis was synthesized through co-precipitation method. X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), X-ray energy dispersion spectrum (EDS), and temperature-programmed H2 reduction (H2-TPR) were used to characterize the crystalline, textural, morphological, and reducibility of the products. The three way catalytic performances of the supported products was tested in stoichiometric air/fuel condition. The modified Hal hybridized cerium- zirconium solid solutions showed a rod-like morphology consisted of agglomerated nanoparticles with sizes of about 100 nm. The adaption of PEG-4000 has guided the formation of the nano-rods in the products. The Hal mineral in the composites retained their tubular morphology. The CZ-Hal composite showed larger BET surface area (130 m2/g compared to 71 m2/g), concentrated pore size distribution, as well as lower reduction temperature, compared with the pure CZ solid solutions. The supported Pd-Rh/CZ-Hal showed optimized catalytic performances for CO, NOx (conversion up to 98%), and CnHm (70%) at light-off temperatures.Download high-res image (202KB)Download full-size image

•Fully stabilized ZrO2 can be obtained through doping 8mol% Sm2O3.•No luminescent from Sm3+ is detected on optical spectra of the products.•Oxygen vacancies in the SDZ play as 3 interesting roles.This work reports the synthesis and characterization of samaria doped zirconia (SDZ) nanoparticles by solvothermal method. The samples were characterized by XRD, SEM, UV–vis and PL spectra. Effect of oxygen vacancies on the phase and optical properties were carefully discussed. The as-prepared products showed cubic structured nanoparticles with average size of 1.1 nm. Fully stabilized cubic ZrO2 could be obtained via doping 8mol % of Sm2O3 into its lattice. UV-blue absorption spectra of ZrO2 host showed obscure absorption edge, while those doped by Sm3+ showed distinguished spectra. No luminescence from Sm3+ center could be observed on PL spectra of all of the samples. Nine different Gaussian-Lorentz amplitude bands should be used to fully deconvolve the acquired PL spectra, and all of them were proven to be originated from oxygen vacancies. The oxygen vacancies in SDZ played as the roles of phase stabilizer, quencher of Sm3+ fluorescence, and PL center of UV-blue emission.

Form-stable composite phase change materials (PCMs) for use in wallboards were prepared by absorbing stearic acid (SA) and lauric acid (LA) eutectic mixtures into the pores of expanded perlite (EP) via vacuum impregnation. The microstructure, thermal properties and the thermal reliability of the composite PCMs were characterized by thermogravimetric and differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results indicate that the maximum SA–LA absorption of the EP was as high as 65 wt% without any melted SA–LA leakage. The latent heat of the composite PCMs was 119.0 J g−1 at its melting temperature of 31.69 °C and 117.4 J g−1 at its freezing temperature of 30.01 °C. A thermal cycling test showed that the composite PCMs have excellent structural stability and thermal reliability after 100 melt–freeze cycles. A gypsum-based building wallboard containing 6 wt% SA–LA/EP had a low density (0.924 g cm−3), high mechanical strength (2.19 MPa), and remarkable heating preservation performance. These properties indicate that the composite PCMs that we used for wallboards can be considered an efficient heating preservation material for practical applications in building energy conservation.

The feasibility of mineral carbonation of a desulfurization residue for sequestering CO2 was evaluated both through theoretical and experimental approaches. The carbonation reaction, including carbonation of Ca(OH)2 and CaSO4, occurred through a kinetically controlled stage with an activation energy of 20.21 kJ mol−1. The concentration of ammonia, CO2 flow rate, liquid to solid ratio and temperature impacted on the carbonation ratio of the desulfurization residue through their direct and definite influence on the rate constant. Concentration of ammonia and liquid to solid ratio were the most important factors influencing the desulfurization residue carbonation in terms of both the carbonation ratio and reaction rate. Under optimized conditions the carbonation ratio could reach approximately 98% when using industry-grade CO2. The crystalline phases of the carbonated desulfurization residue were calcite and vaterite with spherical and granular morphology. CO2/O2/N2 mixed gas was also used as the simulated desulfurization fuel gas in the carbonation reaction and it had a relatively minor effect on the carbonation ratio. However, it slowed the carbonation reaction and produced a carbonation product with a smaller average particle size, which included high purity (≥99%) white calcite. The carbonated desulfurization residue reported herein showed a rapid CO2 sequestration ratio, high CO2 sequestration amount, low cost, and a large potential for in situ CO2 sequestration in the electricity and steel industry.

•Tungsten tailing powders were mechanically and chemically activated.•Mechanical activation made the tailing particles amorphous.•Chemical activation provided the available elements for cement application.•Activated tungsten tailing powders were suitable for qualified Portland cement.Tungsten tailing powders were activated by mechanical and chemical methods for use as cementitious material in mortar. The composition, microstructure and properties of tungsten tailing were characterized with X-ray fluorescence, X-ray diffraction, scanning electron microscopy, Fourier transformation infrared spectroscopy, differential scanning calorimetry and thermogravimetry. The results showed that garnet was the major mineral in the tailing, which possessed excellent chemical and structural stability but poor cementitious property. Mechanical milling and chemical activator were used to activate the tailing. The activation effects and structural evolution of activated tungsten tailing were assessed, and the possible mechanism was discussed. A series of cement mortar samples was prepared to evaluate the cementitious property of the activated tailing. Effects of activation condition and mixture proportion on mechanical strength of cement mortar were investigated. The mechanical and chemical activations could synergistically improve the cementitious property. The properties of cement mixed with 20% of the activated tailing were well comparable with those of 42.5 ordinary Portland cement. The activated tailing as cementitious material could be used to solve the tailings pollution and reduce cost in cement industry.Download full-size image

•Multi-scale porous CeO2 can be synthesized by EISA method using P123 as the template.•Step-by-step reduction is found through deconvolving the TPR curves.•Calcinations the precursor to at least 600 °C can obtain CeO2 with clean surface.Ceria (CeO2) powder with multi-scale porosity was synthesized by evaporation induced self-assembly (EISA) strategy using tri-block copolymer (P123) as the template. The product was characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), and N2 adsorption–desorption isotherms. Reducing property and repeatability were tested by temperature programmed H2 reduction (TPR). Oxygen storage capacity (OSC) was calculated according to the Gaussian–Lorentz deconvolving to the TPR curves. The results showed that the product possessed multi-scale porosity, sizes of the pores were in the ranges of ∼40 μm, ∼2 μm and <0.3 μm, respectively. Specific surface area of the porous CeO2 was 32.5 m2/g. Mechanism in the reduction of surface, near surface and inner parts of porous CeO2 were discussed. Carbonate groups remained on the surface when CeO2 were calcined below 600 °C. The initial H2-TPR yielded an OSC of 383 mol O2/g, which was attributed to oxygen release from the surface nanocrystals, (near) surface sites as well as the inner parts. While the repeated tests showed an OSC of 418 mol O2/g, which was associated with the diminished reaction before 620 °C and the enhanced reduction around 782 °C. A schematic was proposed for the preparation of CeO2 with multi-scale porosity in the amended EISA strategy, based on the characterization results, and the strategy may provide a candidate to obtain catalyst with excellent properties.Graphical abstract

•Highly ordered mesoporous Ce0.5Zr0.5O2 was prepared in an aqueous solution.•The complex plus de-complex strategy was adapted into preparing mesostructures.•The product show fairly good pilot scale TWC performances.•A tentative mechanism of the strategy was proposed based on the experimental results.Synthesis of ordered mesoporous ceria-zirconia (CeO2–ZrO2, M-CZ) solid solution in water-based conditions have challenged scientists for a long time due to the extremely different chemical properties of cerium and zirconium cations. This study discuss the synthesis of highly ordered mesoporous Ce0.5Zr0.5O2 solid solution in aqueous solution through a new complex and de-complex method using di-cationic Gemini as the template. The method takes advantage of the coordinative capability of citric acid (CA) to allow the coexistence of inorganic resources in mild basic solutions and uses the strong oxidic capability of H2O2 to precipitate Ce and Zr cations homogeneously. Through this strategy, the combination between inorganic–organic groups in aqueous solution was avoided, whereas coordination between inorganic–organic species was realized. Mechanisms show that the formation of peroxycarboxylic groups (–COOOH) from the reaction between metal-CA molecular and hydroxyl radical (OH) was the key process. Meso-scale micelles were formed during hydrothermal treatment, while hexagonally arranged pores with narrow size distribution were obtained in the calcination procedure. The surface area of the calcined product was 228 m2 g−1 with a pore volume of 0.7 cm3 g−1, whereas oxygen storage capacity was 652 μmol g−1. The M-CZ product illustrated fairly good pilot-scale three-way catalytic (TWC) performances thanks to the thin pore walls in the mesostructures. A complete (100%) conversion of CO and NOy at 340 °C was detected in the engine pedestal tests. The complex and de-complex strategy may provide a new route for the preparation of ordered mesoporous composite oxides.

•Gemini was successfully used to synthesis mesoporous Ce0.5Zr0.5O2 materials.•A OSC up to 0.58 mol O2/mol Ce was obtained without any structural changes.•Step by step redox circles in the sample were detected.Mesostructured Ce0.5Zr0.5O2 solid solutions (M-CZ) were hydrothermally synthesized using Gemini surfactant as the template. X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), N2 adsorption–desorption isotherms and high-resolution transmission electronic microscopy (HRTEM) were adopted to characterize the samples. The product had a surface area of 123.5 m2 g−1 with maximum oxygen storage capacity (OSC) of 0.58 mol O2/mol Ce. Oxygen anions in the M-CZ can be repeatedly released and resumed during the redox recycles. Reduction of Ce4+ to Ce3+ or lower valence and Zr4+ to Zr3+ were fulfilled with an obvious color change during the temperature programmed reduction (TPR) process, while the crystal structure of the product remained unchanged even after severe reduction. The mesostructure of the product can improve the reductive ability of Ce4+ and Zr4+ cations, which was beneficial to the enhancement of OSC.