Hierarchical SAPO-34 Catalysts as Host for Cu Active Sites.

Cu-containing hierarchical SAPO-34 catalysts were synthesized by the bottom-up method using different mesoporogen templates: CTAB encapsulated within ordered mesoporous silica nanoparticles (MSNs) and sucrose. A high fraction of the Cu centers exchanged in the hierarchical SAPO-34 architecture with high mesopore surface area and volume was achieved when CTAB was embedded within ordered mesoporous silica nanoparticles. Physicochemical characterization was performed by using structural and spectroscopic techniques to elucidate the properties of hierarchical SAPO-34 before and after Cu introduction.

Pinpointing basic sites formed upon incorporation of iron in hierarchical SAPO-11 using catalytic model reactions.

By utilizing previously established catalytic model reactions, a method for probing the topological location of transition metal sites incorporated in hierarchical silicoaluminophosphates (SAPOs) is presented. For the first time, iron(III)-incorporated hierarchical SAPO-11 (FeCTAB-11) was prepared and thoroughly characterized with conventional iron(III)-incorporated SAPO-11 (FeSAPO-11) as a reference. Initially, inductively coupled plasma - mass spectrometry (ICP-MS) indicated that the FeSAPOs contained similar amounts of metal (∼2.

Improved lifetime and stability of copper species in hierarchical, copper-incorporated CuSAPO-34 verified by catalytic model reactions.

The first successful synthesis of hierarchical CuSAPO-34 (3.9 wt% Cu) is reported using the polymer Pluronic F127 as a mesoporous structure directing agent (SDA). X-Ray absorption spectroscopy (XAS) revealed single site Cu2+ with 4 nearest oxygen neighbours at 1.

XAS investigation of silica aerogel supported cobalt rhenium catalysts for ammonia decomposition.

The implementation of ammonia as a hydrogen vector relies on the development of active catalysts to release hydrogen on-demand at low temperatures. As an alternative to ruthenium-based catalysts, herein we report the high activity of silica aerogel supported cobalt rhenium catalysts. XANES/EXAFS studies undertaken at reaction conditions in the presence of the ammonia feed reveal that the cobalt and rhenium components of the catalyst which had been pre-reduced are initially re-oxidised prior to their subsequent reduction to metallic and bimetallic species before catalytic activity is observed.

An in situ XAS study of high surface-area IrO produced by the polymeric precursor synthesis.

Iridium oxide powders with a surface area of more than 1 m g (4 m g from the H-UPD charge) and iridium-oxide crystallites less than 10 nm across were synthesized by heat treating gels formed from citric acid, ethylene glycol and dihydrogen hexachloroiridate(iv) in air. The characteristics of the resulting material was found to be strongly dependent on the heat-treatment step in the synthesis. A single heat-treatment of the gel resulted in a material with a substantial fraction of elemental iridium metal, i.

Strategies for the analysis of the elemental metal fraction of Ir and Ru oxides via XRD, XANES, and EXAFS.

Iridium and ruthenium oxide are active electrocatalysts for oxygen evolution. The relation between preparation method, structure, and behavior of mixed oxides of iridium and ruthenium are of interest in order to obtain active and stable catalysts. In this work the structure of mixed Ru-Ir oxides synthesized by the polymeric precursor method, which involves the formation of a gel containing the metal precursors and subsequent heat-treatment in air, was studied for the IrRuO system.

An In Situ XAS Study of the Cobalt Rhenium Catalyst for Ammonia Synthesis.

A cobalt rhenium catalyst active for ammonia synthesis at 400 °C and ambient pressure was studied using in situ XAS to elucidate the reducibility and local environment of the two metals during reaction conditions. The ammonia reactivity is greatly affected by the gas mixture used in the pre-treatment step. Following H/Ar pre-treatment, a subsequent 20 min induction period is also observed before ammonia production occurs whereas ammonia production commences immediately following comparable H/N pre-treatment.

Identification of synergistic Cu/V redox pair in VCu:AlPO-5; a comparison with VCu:ZSM-5.

Vanadium(V) and copper(II) were co-deposited into AlPO-5 and H-ZSM-5 three-dimensional microporous carriers to yield VCu:AlPO-5 and VCu:ZSM-5. The materials, along with copper analogues were tested for the selective oxidation of propene, and the catalysts perform in the following order: VCu:AlPO-5 > Cu:AlPO-5 > VCu:ZSM-5 > Cu:ZSM-5. Acrolein was selectively formed over VCu:AlPO-5 and Cu:AlPO-5 over a very wide range from 300 to 450 °C, whereas VCu:ZSM-5 displays a limited temperature window for acrolein formation (300-350 °C).

The Methylococcus capsulatus (Bath) secreted protein, MopE*, binds both reduced and oxidized copper.

Under copper limiting growth conditions the methanotrophic bacterium Methylococcus capsulatus (Bath) secrets essentially only one protein, MopE*, to the medium. MopE* is a copper-binding protein whose structure has been determined by X-ray crystallography. The structure of MopE* revealed a unique high affinity copper binding site consisting of two histidine imidazoles and one kynurenine, the latter an oxidation product of Trp130.

In situ XAS and IR studies on Cu:SAPO-5 and Cu:SAPO-11: the contributory role of monomeric linear copper(i) species in the selective catalytic reduction of NOx by propene.

Cu:SAPO-5 and Cu:SAPO-11 were prepared by conventional and hydrothermal ion exchange. Copper incorporation is increased six-fold by hydrothermal ion exchange relative to conventional methods. In all cases, the amount of copper taken up by SAPO-11 is superior to uptake in SAPO-5.