Topic
Mixed oxide
About: Mixed oxide is a research topic. Over the lifetime, 5224 publications have been published within this topic receiving 115567 citations.
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TL;DR: The main reactions involved in this NHSG process and the characteristics of the resulting mixed oxides are described in the first part of this review, underlining the decisive advantages in terms of simplicity and of control (in terms of composition, homogeneity or texture) offered by this process as mentioned in this paper.
Abstract: Despite the enormous amount of research dedicated to this topic in the last 20 years or so, there is still a need for a general, cost-effective methodology allowing the synthesis of mesoporous mixed oxide catalysts. This review deals with the synthesis and catalytic applications of mixed oxides prepared by the nonhydrolytic sol–gel (NHSG) process based on the reaction of chloride precursors with ether or alkoxide oxygen donors. This NHSG process offers simple, one-step syntheses of mixed oxides with well-controlled compositions and non-ordered mesoporous textures, avoiding the use of supercritical drying or templates. Over the last decade, this process has been used to prepare various mesoporous mixed oxide catalysts, which showed real potential in major reactions such as partial and total oxidation, reduction of NOx, alkene metathesis, or alkylation. The main reactions involved in this NHSG process and the characteristics of the resulting mixed oxides are described in the first part of this review, underlining the decisive advantages in terms of simplicity and of control (in terms of composition, homogeneity or texture) offered by this process. In a second part, the literature dealing with mixed oxide catalysts prepared by this NHSG method is exhaustively reviewed and the catalytic performance of NHSG catalysts is compared, whenever possible, to that of catalysts with similar compositions prepared by other methods. The excellent catalytic performances of NHSG-catalysts (notably Si Ti, Ti V and Si Al Mo catalysts) compared to state-of-the art aerogels or ordered mesoporous materials evidences the potential of this sol–gel method, which should open the door to the synthesis of improved catalysts and to the discovery of new catalysts.
142 citations
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TL;DR: A series of CexTi1-xO2 mixed oxide materials was synthesized by a sol−gel method with x varying from 0.1 to 0.9 and characterized by XRD, Raman, and TPR techniques.
Abstract: A series of CexTi1-xO2 mixed oxide materials was synthesized by a sol−gel method with x varying from 0.1 to 0.9 and characterized by XRD, Raman, and TPR techniques. The structure of the mixed oxide...
141 citations
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TL;DR: In this paper, solid phase crystallization (spc) method was used for the preparation of Ni supported catalysts for CO2 reforming of CH4 to synthesis gas, and the precursors were prepared by the co-precipitation method from nitrates of the metal components, and then thermally decomposed, in situ reduced to form Ni-supported catalysts.
Abstract: Ni supported catalysts were prepared by the solid phase crystallization (spc) method starting from hydrotalcite (HT) anionic clay based on [Mg6Al2(OH)16CO3
2−]⋅H2O as the precursor. The precursors were prepared by the co-precipitation method from nitrates of the metal components, and then thermally decomposed, in situ reduced to form Ni supported catalysts (spc-Ni/Mg–Al) and used for the CO2 reforming of CH4 to synthesis gas. Ni2+ can well replace the Mg2+ site in the hydrotalcite, resulting in the formation of highly dispersed Ni metal particles on spc-Ni/Mg–Al. The spc-catalyst thus prepared showed higher activity than those prepared by the conventional impregnation (imp) method such as Ni/α-Al2O3 and Ni/MgO. When Ni was supported by impregnation of Mg–Al mixed oxide prepared from Mg–Al HT, the activity of imp-Ni/Mg–Al thus prepared was not so low as those of Ni/α-Al2O3 and Ni/MgO but close to that of spc-Ni/Mg–Al. The relatively high activity of imp-Ni/Mg–Al may be due to the regeneration of the Mg–Al HT phase from the mixed oxide during the preparation, resulting in an occurring of the incorporation of Ni2+ in the Mg2+ site in the HT as seen in the spc-method. Such an effect may give rise to the formation of highly dispersed Ni metal species and afford high activity on the imp-Ni/Mg–Al.
141 citations
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TL;DR: In this paper, three series of samples having the stoichiometry A′xA1 − xBO3 − λ (x = 0 − 1, B = Mn, Fe, Co) were prepared and used as catalysts for NH3 oxidation.
140 citations
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TL;DR: In this article, a mixed oxide consisting of TiO 2 as the major phase and CeO 2− y (0 y i -OC 3 H 7 ) 3 in an aqueous solution of Ce(NO 3 ) 3.
139 citations