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14 items found (0 items not approved), displaying 11 to 14.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Identification of single-site gold catalysis in acetylene hydrochlorination Grazia Malta , Simon A. Kondrat , Simon J. Freakley , Catherine J. Davies , Li Lu , Simon Dawson , Adam Thetford , Emma K. Gibson , David J. Morgan , Wilm Jones , Peter Wells , Peter Johnston , C. Richard A. Catlow , Christopher J. Kiely , Graham J. Hutchings Science 355, 1399 - 1403 DOI: 10.1126/science.aal3439 Diamond Proposal Number(s): [10306, 11398, 15214] Show Abstract ▼ Abstract: There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species.	Mar 2017
I15-Extreme Conditions	A new class of Cu/ZnO catalysts derived from zincian georgeite precursors prepared by co-precipitation Paul J. Smith , Simon A. Kondrat , Philip A. Chater , Benjamin R. Yeo , Greg M. Shaw , Li Lu , Jonathan K. Bartley , Stuart H. Taylor , Michael S. Spencer , Christopher J. Kiely , Gordon Kelly , Colin W. Park , Graham J. Hutchings Chem. Sci. DOI: 10.1039/C6SC04130B Open Access Show Abstract ▼ Abstract: Zincian georgeite, an amorphous copper–zinc hydroxycarbonate, has been prepared by co-precipitation using acetate salts and ammonium carbonate. Incorporation of zinc into the georgeite phase and mild ageing conditions inhibits crystallisation into zincian malachite or aurichalcite. This zincian georgeite precursor was used to prepare a Cu/ZnO catalyst, which exhibits a superior performance to a zincian malachite derived catalyst for methanol synthesis and the low temperature water–gas shift (LTS) reaction. Furthermore, the enhanced LTS activity and stability in comparison to that of a commercial Cu/ZnO/Al2O3 catalyst, indicates that the addition of alumina as a stabiliser may not be required for the zincian georgeite derived Cu/ZnO catalyst. The enhanced performance is partly attributed to the exclusion of alkali metals from the synthesis procedure, which are known to act as catalyst poisons. The effect of residual sodium on the microstructural properties of the catalyst precursor was investigated further from preparations using sodium carbonate.	Jan 2017
B18-Core EXAFS I15-Extreme Conditions	Stable amorphous georgeite as a precursor to a high-activity catalyst Simon Kondrat , Paul J. Smith , Peter Wells , Philip Chater , James H. Carter , David J Morgan , Elisabetta M. Fiordaliso , Jakob B. Wagner , Tom Davies , Li Lu , Jonathan K. Bartley , Stuart H. Taylor , Michael S. Spencer , Christopher J. Kiely , Gordon J. Kelly , Colin W. Park , Matthew Rosseinsky , Graham J. Hutchings Nature DOI: 10.1038/nature16935 PMID: 26878237 Diamond Proposal Number(s): [8071] Show Abstract ▼ Abstract: Copper and zinc form an important group of hydroxycarbonate minerals that include zincian malachite, aurichalcite, rosasite and the exceptionally rare and unstable—and hence little known and largely ignored1—georgeite. The first three of these minerals are widely used as catalyst precursors2, 3, 4 for the industrially important methanol-synthesis and low-temperature water–gas shift (LTS) reactions5, 6, 7, with the choice of precursor phase strongly influencing the activity of the final catalyst. The preferred phase2, 3, 8, 9, 10 is usually zincian malachite. This is prepared by a co-precipitation method that involves the transient formation of georgeite11; with few exceptions12 it uses sodium carbonate as the carbonate source, but this also introduces sodium ions—a potential catalyst poison. Here we show that supercritical antisolvent (SAS) precipitation using carbon dioxide (refs 13, 14), a process that exploits the high diffusion rates and solvation power of supercritical carbon dioxide to rapidly expand and supersaturate solutions, can be used to prepare copper/zinc hydroxycarbonate precursors with low sodium content. These include stable georgeite, which we find to be a precursor to highly active methanol-synthesis and superior LTS catalysts. Our findings highlight the value of advanced synthesis methods in accessing unusual mineral phases, and show that there is room for exploring improvements to established industrial catalysts.	Feb 2016
B18-Core EXAFS	Ruthenium nanoparticles supported on carbon: an active catalyst for the hydrogenation of lactic acid to 1,2-propanediol Sarwat Iqbal , Simon Kondrat , Daniel R. Jones , Daniel C. Schoenmakers , Jennifer K. Edwards , Li Lu , Benjamin R. Yeo , Peter Wells , Emma Gibson , David J. Morgan , Christopher J. Kiely , Graham J. Hutchings Acs Catalysis 5 (9), 5047 - 5059 DOI: 10.1021/acscatal.5b00625 Diamond Proposal Number(s): [8071] Show Abstract ▼ Abstract: The hydrogenation of lactic acid to form 1,2-propanediol has been investigated using Ru nanoparticles supported on carbon as a catalyst. Two series of catalysts which were prepared by wet impregnation and sol-immobilization were investigated. Their activity was contrasted with that of a standard commercial Ru/C catalyst (all catalysts comprise 5 wt % Ru). The catalyst prepared using sol-immobilization was found to be more active than the wet impregnation materials. In addition, the catalyst made by sol-immobilization was initially more active than the standard commercial catalyst. However, when reacted for an extended time or with successive reuse cycles, the sol-immobilized catalyst became less active, whereas the standard commercial catalyst became steadily more active. Furthermore, both catalysts exhibited an induction period during the first 1000 s of reaction. Detailed scanning transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption fine structure analysis data, when correlated with the catalytic performance results, showed that the high activity can be ascribed to highly dispersed Ru nanoparticles. Although the sol-immobilization method achieved these optimal discrete Ru nanoparticles immediately, as can be expected from this preparation methodology, the materials were unstable upon reuse. In addition, surface lactide species were detected on these particles using X-ray photoelectron spectroscopy, which could contribute to their deactivation. The commercial Ru/C catalysts, on the other hand, required treatment under reaction conditions to change from raft-like morphologies to the desired small nanoparticle morphology, during which time the catalytic performance progressively improved.	Sep 2015

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