Showing papers by "Masatake Haruta published in 2016"
TL;DR: Correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeOx catalyst.
Abstract: The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviours after heat treatment of Au/FeOx materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed to reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. Correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeOx catalyst.
60 citations
TL;DR: The interplay between physicochemical analysis, computational studies, and rational experiments for catalysis by supported Au NPs is becoming more and more important and the experiences and progress in such interplay are summarized.
Abstract: When gold is deposited as nanoparticles (NPs) with mean diameters of 2-5 nm or clusters with mean diameters below 2 nm onto a variety of supports such as metal oxides, carbons, polymers, etc., the supported Au NPs exhibit unique catalytic properties, while bulk Au is almost inert as a catalyst. A lot of research works indicate that the key factors of the catalysis by supported Au NPs are the selection of the supports, the control of the Au NP size, the shape of the Au NPs, and the strong junction between Au NPs and the supports, because the perimeter zone around Au NPs acts as the active site for many reactions. In order to elucidate the origin of catalysis by supported Au NPs, the interplay between physicochemical analysis, computational studies, and rational experiments for catalysis by supported Au NPs is becoming more and more important. This article summarizes our experiences and progress in such interplay.
55 citations
TL;DR: In this article, the authors discuss the interplay of theoretical calculations and reasonable experiments in catalysis by supported gold NPs and summarize the recent examples of such interplay, including the selection of the support materials, the control of the size of the gold nanoparticles, and the strong contact of gold particles with the supports.
26 citations
TL;DR: The effect of a wide variety of metal oxide (MO x ) supports has been discussed for CO oxidation on nanoparticulate gold catalysts by using typical co-precipitation and deposition precipitation methods and under identical calcination conditions as discussed by the authors.
22 citations
TL;DR: In this paper, a 1 wt% Au/Nb 2 O 5 catalyst with a mean diameter of about 5 nm was prepared by both the deposition precipitation (DP) and DR method on Nb 2 o 5 (HT) under an optimized condition.
21 citations
TL;DR: In this article, Nanoparticulate gold catalysts (NPGCs) supported on niobium oxides (Nb2O5) were prepared by different deposition methods.
Abstract: Nanoparticulate gold catalysts (NPGCs) supported on niobium oxides (Nb2O5) were prepared by different deposition methods. Au nanoparticles (NPs) with a mean diameter of approximately 5 nm were deposited by conventional deposition methods, which include the deposition-precipitation (DP) and deposition-reduction (DR) methods, on layered-type Nb2O5 that possesses a deformed orthorhombic structure. Moreover, Au NPs with a mean diameter of approximately 2.7 nm could be deposited by the sol immobilization method on several crystalline forms of Nb2O5 (deformed orthorhombic, pseudohexagonal, and orthorhombic). NPGCs deposited on deformed orthorhombic Nb2O5 had a higher catalytic activity for CO oxidation. The temperature for 50 % CO conversion was 11 °C for 1 wt % Au/Nb2O5 (deformed orthorhombic) prepared by the sol immobilization method, and the CO conversion was 91 % at 28 °C. As far as we know, this is the first report of highly active Au NPGCs (smaller than 3 nm in diameter) supported on Nb2O5. NPGCs supported on acidic metal oxides will expand the utilization of gold catalysts for new applications.
18 citations
TL;DR: In the SMSI effect tuned catalyst, Au/TiO 2 -HAP, the Au NPs are located at the TiO 2 /HAP interfaces, forming anchored and partially covered AuNPs which are ultrastable and highly active as discussed by the authors.
2 citations
Patent•
12 Sep 2016TL;DR: In this article, a denitration catalyst is obtained by coating a substrate with a catalyst component, which contains 43 wt % or more of vanadium pentoxide and has a BET specific surface area of 30 m 2 /g or more.
Abstract: There is provided a catalyst that exhibits a high denitration efficiency at a relatively low temperature and does not cause oxidation of SO 2 in a selective catalytic reduction reaction that uses ammonia as a reducing agent. A denitration catalyst is obtained by coating a substrate with a catalyst component. The catalyst component contains 43 wt % or more of vanadium pentoxide and has a BET specific surface area of 30 m 2 /g or more. The denitration catalyst is used for denitration at 200° C. or lower.
2 citations
1 citations
TL;DR: In this article, the authors discuss the key factors of the catalytic properties of supported Au NPs, and discuss the interplay between physicochemical analysis, computational studies, and rational experiments for catalysis by supported AU NPs.
Abstract: When gold is deposited as nanoparticles (NPs) with mean diameters of 2-5 nm or clusters with mean diameters below 2 nm onto a variety of supports such as metal oxides, carbons, polymers, etc., the supported Au NPs exhibit unique catalytic properties, while bulk Au is almost inert as a catalyst. A lot of research works indicate that the key factors of the catalysis by supported Au NPs are the selection of the supports, the control of the Au NP size, the shape of the Au NPs, and the strong junction between Au NPs and the supports, because the perimeter zone around Au NPs acts as the active site for many reactions. In order to elucidate the origin of catalysis by supported Au NPs, the interplay between physicochemical analysis, computational studies, and rational experiments for catalysis by supported Au NPs is becoming more and more important. This article summarizes our experiences and progress in such interplay.