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Abstract: CeO2–ZrO2 (CZ) doped with different transition metals was prepared through a co-precipitation and supercritical drying method and the corresponding Pd-only TWCs were characterized. Pd/CZFe and Pd/CZCo exhibit the best catalytic activity and the widest operation window, in accordance with the decrease of the light-off and full-conversion temperature. However, Pd/CZCr restrains the catalytic property. It may be due to the different effect of transition metals on the property of CZ. The introduction of Fe and Co promotes the surface atom ratios of Ce/Zr, makes part of Ce4+ transferred into Ce3+ in order to maintain the electrical neutrality and seems to facilitate the reduction of Ce4+ →Ce3+ or the formation of oxygen vacancies of CZ. The increasing concentration of oxygen vacancies for CZFe leads to the enhancement of DOSC. Moreover, the introduction of Fe favors the transfer of oxygen in different atmospheres. [Copyright &y& Elsevier]

Abstract: CZ doped by nickel oxide with different loadings was prepared through a co-precipitation and supercritical dried method and the corresponding Pd-only TWCs were prepared and characterized. The results demonstrate that Pd/CZNi(3%) catalyst exhibits the best catalytic activity and the widest operation window before and after aging, compared with that of other catalysts. Moreover, the introduction of nickel oxide with 3% loading increases the average pore diameter and broadens the range of pore size distribution of sample, which is propitious to the formation of accumulative pore favoring the adsorption/desorption of reaction species. The introduction of nickel oxide with suitable loading (3%) promotes the thermal stability of CZ corresponding to the better surface composition and more concentration of Ce3+ or oxygen vacancy. Furthermore, the introduction of nickel oxide with 3% loading exhibits the best DOSC compared with other content doping, possibly due to the better structure and better surface composition and better thermal stability of CZNi(3%). [Copyright &y& Elsevier]

Abstract: In this paper, five types of ceria–zirconia modified alumina (CZA) were prepared by co-precipitation with supercritical drying (CPS), co-precipitation with common drying (CPC), sol–gel (SG), micro-emulsion (ME) and impregnation (IM) methods, respectively. The corresponding supported Pd-only three-way catalysts (TWC) were also prepared and evaluated in the simulative gasoline engine exhaust. The influence of different preparation methods on the physicochemical properties of CZA mixed oxide and its supported TWC was characterized by X-ray diffraction (XRD), N2 adsorption/desorption and transmission electron microscopy (TEM) techniques. The redox behavior was investigated with H2 temperature-programmed reduction (H2-TPR) experiments. The results reveal that the CZA mixed oxides derived from CPS and ME methods exhibit the relatively higher textural and structural properties as well as better redox behavior, which lead to the better catalytic activity and wider air-to-fuel operation window of the corresponding Pd-only three-way catalysts. [Copyright &y& Elsevier]

Abstract: CeO2-ZrO2 doped by nickel oxide (CZN) with different method and Pd-only three-way catalysts (Pd/CZN) were prepared and characterized. The catalyst prepared by co-precipitation and supercritical drying process (Pd/CZN-s) exhibits the best catalytic activity and the widest operation working window before and after aging. Compared with other samples, CZN-s shows the formation of more homogeneous ternary solid solution with the smallest lattice parameter and crystallite size. Moreover, CZN-s maintains the high thermal and structural stability with higher surface area and larger pore volume after aging. Pd/CZN-s exhibits higher relative concentration of Ce3+ associated with the formation of more oxygen vacancies before and after aging, confirmed by X-ray photoelectron spectroscopy and Raman results. The more concentration of Ce3+ or oxygen vacancies leads to the enhancement of oxygen storage complete capacity of CZN-s. Moreover, the higher the oxygen storage capacity, the wider the working ranges of air/fuel variations. [Copyright &y& Elsevier]

Abstract: The role of La doping with different content in the structure of Ce0.2Zr0.8O2 solid solution (CZ) and the effect of modification on the catalytic activity of supported Pd-only three-way catalysts (TWCs) are clarified. The characterization results reveal that the introduction of La into the lattice of CZ is facile. Zr is replaced by the doped La firstly at low doping content and then Ce is substituted further with increasing La content. The substitution occurs in the bulk preferentially, and then in the surface. The addition of La results in preferable thermal stability, higher BET surface area and enhanced oxygen storage capacity (OSC) compared with CZ, due to the structure modification. La doped fresh samples are beneficial to the conversion of NO and the corresponding aged samples exhibit higher activity for the conversion of all the target pollutants. [ABSTRACT FROM AUTHOR]

Abstract: In this work, supercritical drying technology is investigated as a new method contrast with the conventional drying techniques to obtain La modified ceria–zirconia solid solution (CZL) with advanced textural/structural properties, and its supported Pd-only three-way catalysts (TWCs) were also prepared and studied. The results demonstrate that the CZL sample prepared by supercritical drying method shows relatively larger specific surface area, better thermal stability and higher redox properties, as well as the prominent oxygen storage capacity compared with samples prepared by conventional drying method. Moreover, it also exhibits remarkable porosity and wide pore size distribution due to the elimination of vapor–liquid interface in the process of supercritical drying, which is beneficial to the adsorption/desorption of pollutant in TWCs. The excellent structural/textural properties of the forenamed CZL support lead to the outstanding catalytic activity, wide air-to-fuel operation window of the corresponding three-way catalyst, indicating its tremendous potential possibilities. [ABSTRACT FROM AUTHOR]

Abstract: The promotional effect of cobalt oxide on the catalytic performance and the physicochemical properties of Pd only three-way catalysts and Ce0.67Zr0.33O2 mixed oxides (CZ) prepared by co-precipitation and impregnation methods have been investigated. It is worthwhile to note that the role of Co significantly depends on the method of Co doping in the CZ. The introduction of cobalt oxide by co-precipitation exhibits significant influence on the catalytic activity of Pd only three-way catalyst with enhancing textural and structural properties, compared to the introduction of cobalt oxide by impregnation method. Furthermore, CZ doped with cobalt oxide by co-precipitation results in the formation of more homogeneous ternary solid solution, which promotes the metal–support interaction between CZ and cobalt metal and improves oxygen storage capacity (OSC) of samples. It also proves that the textural and structural properties of supports can affect the reducibility and oxygen storage capacity of samples at low temperature. [Copyright &y& Elsevier]

Enantioselective C–P cross-coupling of diarylphosphine oxides with ortho -substituted aryl iodides has been achieved via kinetic resolution strategy, affording chiral triarylphosphine oxides in high yields and with moderate to high enantioselectivity. [ABSTRACT FROM AUTHOR]

Abstract: Ce0.67Zr0.33O2 (CZ) doped by nickel oxide with different content and the corresponding Pd-only three-way catalysts before and after aging has been prepared and characterized. The investigations show that CZ doped with nickel oxide obviously results in more active fresh catalysts with enhanced textural properties, but suffers from a net loss of activity after aging. The introduction of Ni promotes the reducibility of samples, causing the enhancement of oxygen storage capacity (OSC) of fresh samples. CZNi(3%) exhibits better textural and structural properties because of the formation of more homogeneous Ce–Zr–Ni–O ternary solid solution, which promotes the interaction between Ce–Zr and Ni. However, the thermal aging leads to a loss of surface area and a significant decrease of the reducibility and OSC, except for CZNi(3%). Only Pd/CZNi(3%) represents better catalytic activity after aging. It reveals that the catalytic behavior of these bimetallic systems is strongly affected by the nature of support. [Copyright &y& Elsevier]

Abstract: CeO2–ZrO2–Al2O3 (CZA) mixed oxides were synthesized using sol–gel and supercritical drying methods, and their physicochemical properties were characterized by BET surface area (BET), X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and O2-temperature-programmed desorption (O2-TPD) techniques. The catalytic performances of Pd/CZA catalysts with different thermal treatment were also investigated. The results indicate that catalytic activities are affected by thermal treatment of support or catalyst and Pd/CZA catalysts exhibit good thermal stability. H2-TPR results show that the effect of thermal treatment on the dispersion state of PdO is different between catalyst and support after calcination. However, O2-TPD results show that the influence of thermal treatment on the desorption performance of oxygen is similar in both cases. Desorption of surface oxygen is closely related to surface area of the support. During the calcination of the supports or the catalysts at high temperature, the surface oxygen desorption capacity and the mobility of lattice oxygen decrease due to the sintering of supports, which is harmful to the dispersion of active species, corresponding to the decrease of three-way catalytic activities. [Copyright &y& Elsevier]

Abstract: Four types of Ce0.67Zr0.33O2 (CZCP, CZH, CZHP and CZM) mixed oxides as supports were prepared by coprecipitation, hydrothermal, homogeneous precipitation and microemulsion methods, respectively. The results show that both the preparation methods and the aging procedures have significant influences on the physicochemical properties of Ce0.67Zr0.33O2 mixed oxides. All these fresh Ce0.67Zr0.33O2 samples develop mesopore structure, especially that, CZCP obtains the largest diameter (20.87nm) and volume (0.455cm3/g). The XRD results indicate that fresh CZHP and CZCP samples contain cubic and tetragonal phases, while only cubic solid solution is found in fresh CZH and CZM samples, which show better low-temperature reducibility. Moreover, higher oxygen storage capacity complete (OSCC) values and faster O2 uptake are observed in CZH and CZM samples compared with those of fresh CZCP and CZHP. After calcination at 1100°C, it is found that the OSCC values and the kinetics of the O2 uptake for CZM and CZHP samples are deteriorated due to the coexistence of cubic and tetragonal phases as well as strong sintering of samples. On the contrary, the aged CZCP and CZH samples keep satisfactory low-temperature reducibility and oxygen storage capacity. For fresh catalysts, the pore-size distribution of mixed oxides seems to be important for catalytic activities. In contrast, for aged catalysts, their activities are related to both the redox properties and the textural properties of aged mixed oxides. Therefore, the Pd-only three-way catalyst supported on the CZCP exhibits the most promising amplified amplitude of stoichiometric window. [Copyright &y& Elsevier]