Identifying key mononuclear Fe species for low-temperature methane oxidation.

The direct functionalization of methane into platform chemicals is arguably one of the holy grails in chemistry. The actual active sites for methane activation are intensively debated. By correlating a wide variety of characterization results with catalytic performance data we have been able to identify mononuclear Fe species as the active site in the Fe/ZSM-5 zeolites for the mild oxidation of methane with HO at 50 °C.

The role of surface oxidation and Fe-Ni synergy in Fe-Ni-S catalysts for CO hydrogenation.

Increasing carbon dioxide (CO) emissions, resulting in climate change, have driven the motivation to achieve the effective and sustainable conversion of CO into useful chemicals and fuels. Taking inspiration from biological processes, synthetic iron-nickel-sulfides have been proposed as suitable catalysts for the hydrogenation of CO. In order to experimentally validate this hypothesis, here we report violarite (Fe,Ni)S as a cheap and economically viable catalyst for the hydrogenation of CO into formate under mild, alkaline conditions at 125 °C and 20 bar (CO : H = 1 : 1).

Octane isomer dynamics in H-ZSM-5 as a function of Si/Al ratio: a quasi-elastic neutron scattering study.

Dynamical behaviour of octane and 2,5-dimethylhexane in H-ZSM-5 zeolite catalysts of differing Si/Al ratios (15 and 140) was probed using quasi-elastic neutron scattering, to understand molecular shape and Brønsted acid site density effects on the behaviour of common species in the fluid catalytic cracking (FCC) process, where H-ZSM-5 is an additive catalyst. Between 300 and 400 K, -octane displayed uniaxial rotation around its long axis. However, the population of mobile molecules was larger in H-ZSM-5(140), suggesting that the lower acid site concentration allows for more molecules to undergo rotation.

Solvent Free Synthesis of PdZn/TiO Catalysts for the Hydrogenation of CO to Methanol.

Catalytic upgrading of CO to value-added chemicals is an important challenge within the chemical sciences. Of particular interest are catalysts which are both active and selective for the hydrogenation of CO to methanol. PdZn alloy nanoparticles supported on TiO via a solvent-free chemical vapour impregnation method are shown to be effective for this reaction.

Probing the Role of a Non-Thermal Plasma (NTP) in the Hybrid NTP Catalytic Oxidation of Methane.

Three recurring hypotheses are often used to explain the effect of non-thermal plasmas (NTPs) on NTP catalytic hybrid reactions; namely, modification or heating of the catalyst or creation of new reaction pathways by plasma-produced species. NTP-assisted methane (CH ) oxidation over Pd/Al O was investigated by direct monitoring of the X-ray absorption fine structure of the catalyst, coupled with end-of-pipe mass spectrometry. This in situ study revealed that the catalyst did not undergo any significant structural changes under NTP conditions.

Identification of single-site gold catalysis in acetylene hydrochlorination.

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.

The adsorbed state of a thiol on palladium nanoparticles.

In the present work, a combination of imaging, spectroscopic and computational methods shows that 1-dodecanethiol undergoes S-deprotonation to form 1-dodecanethiolate on the surface of palladium nanoparticles, which then self-assembles into a structure that shows a high degree of order. The alkyl chain is largely in the all-trans conformation, which occurs despite the small size of the nanoparticle, (mean diameter = 3.9 nm).

Optimised photocatalytic hydrogen production using core-shell AuPd promoters with controlled shell thickness.

The development of efficient photocatalytic routines for producing hydrogen is of great importance as society moves away from energy sources derived from fossil fuels. Recent studies have identified that the addition of metal nanoparticles to TiO2 greatly enhances the photocatalytic performance of these materials towards the reforming of alcohols for hydrogen production. The core-shell structured Au-Pd bimetallic nanoparticle supported on TiO2 has being of interest as it exhibited extremely high quantum efficiencies for hydrogen production.