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Replacing fossil feedstocks for chemicals and polymers in the chemical industry is a key step towards a future circular society. Making use of CO2 as a starting material in Carbon Capture and Utilization (CCU) or Carbon Capture and Storage (CCS) processes presents a great opportunity. Unfortunately, converting CO2 is not easy - due to its stability and inherently low reactivity either high energy inputs or nifty catalytic systems are required for its conversion. An electrochemical cell using a gas-diffusion electrode to convert CO2 into formate is such a promising system. But making formate alone does not allow us to substitute many fossil carbon-fed processes. Oxalic acid on the other hand is a potential new platform chemical for material production as useful monomers such as glycolic acid can be derived from it. Fortunately, formate can be converted into oxalate (and subsequently oxalic acid) by coupling two formates in a formate to oxalate coupling reaction (FOCR). The FOCR is a reaction that has been studied for more than 175 years and has seen widespread industrial use in the past. In this work, we critically discuss the history of the FOCR, present the most recent advances and draw a perspective for its future. We provide an overview of all (side)products obtained in FOCR and examine the various reaction parameters and their ability to influence the reaction. To understand the reaction better and improve it in the future, we critically discuss the many mechanisms proposed for the various catalytic systems in the FOCR. At last, we explore the potential to introduce new catalytic and solvent systems or co-reactants to the FOCR to improve reaction performance and broaden the range of products from CO2 derived formate.

Superbase ionic liquids (ILs) with a trihexyltetradecylphosphonium cation and a benzimidazolide ([P66614][Benzim]) or tetrazolide ([P66614][Tetz]) anion were investigated in a dual-IL system allowing the selective capture and separation of CO2and SO2, respectively, under realistic gas concentrations. The results show that [P66614][Tetz] is capable of efficiently capturing SO2in preference to CO2and thus, in a stepwise separation process, protects [P66614][Benzim] from the negative effects of the highly acidic contaminant. This results in [P66614][Benzim] maintaining >53% of its original CO2uptake capacity after 30 absorption/desorption cycles in comparison to the 89% decrease observed after 11 cycles when [P66614][Tetz] was not present. Characterization of the ILs post exposure revealed that small amounts of SO2were irreversibly absorbed to the [Benzim]-anion responsible for the decrease in CO2capacity. While optimization of this dual-IL system is required, this feasibility study demonstrates that [P66614][Tetz] is a suitable sorbent for reversibly capturing SO2and significantly extending the lifetime of [P66614][Benzim] for CO2uptake.

Catalytic wastewater treatment has rarely been applied to treat high-ionic-strength wastewater (HISWW) as it contains large amounts of catalyst poisons (e.g., Cl–). This work investigates the catalytic wet oxidation (CWO) of phenol over a MnCeOx catalyst in the presence of high NaCl concentrations where the combination of MnCeOx and NaCl promoted the CWO of phenol. Specifically, in the presence of NaCl at a concentration of 200 g L–1 and MnCeOx at a concentration of 1.0 g L–1, phenol (initially 1.0 g L–1) and total organic carbon (TOC) conversions were ∼98 and 85%, respectively, after a 24 h reaction. Conversely, under the same reaction conditions without NaCl, the catalytic system only achieved phenol and TOC conversions of ∼41 and 27%, respectively. In situ Attenuated Total Reflection infrared spectroscopy identified the nature of the strongly adsorbed carbon deposits with quinone/acid species found on Ce sites and phenolate species on Mn sites in the single oxides and on MnCeOx. The presence of high concentrations of NaCl reduced the carbon deposition over the catalyst, promoting surface oxidation of the hydrocarbon and reoxidation of the catalyst, resulting in enhanced mineralization. Moreover, the used MnCeOx catalyst in the salt water system was efficiently regenerated via a salt water wash under the reaction conditions, showing the great potential of MnCeOx in practical HISWW treatment.

Photoreforming of cellulose is a promising route for sustainable H2 production. Herein, ball-milling (BM, with varied treatment times of 0.5–24 h) was employed to pretreat microcrystalline cellulose (MCC) to improve its activity in photoreforming over a Pt/TiO2 catalyst. It was found that BM treatment reduced the particle size, crystallinity index (CrI), and degree of polymerization (DP) of MCC significantly, as well as produced amorphous celluloses (with >2 h treatment time). Amorphous cellulose water-induced recrystallization to cellulose II (as evidenced by X-ray diffraction (XRD) and solid-state NMR analysis) was observed in aqueous media. Findings of the work showed that the BM treatment was a simple and effective pretreatment strategy to improve photoreforming of MCC for H2 production, mainly due to the decreased particle size and, specifically in aqueous media, the formation of the cellulose II phase from the recrystallization of amorphous cellulose, the extent of which correlates well with the activity in photoreforming

Hydrothermal degreening and ageing procedures were applied to a tri-metal (Pt-Pd-Rh) fully formulated lean NOx Trap catalyst to evaluate the effects of thermal stress on the performances and structural properties. X-ray absorption fine structure (XAFS) analysis revealed that the average size of the platinum particles was the same after degreening and ageing treatments. The formation of a new phase of alloyed Pt-Pd was observed to increase with the thermal load. The size of the ceria particles also increased after the ageing treatment. NOx storage capacity experiments revealed a substantial decrease of the concentration of active NOx storage sites which correlated with both ageing and degreening protocols. The performances of the treated catalyst were evaluated through spatially resolved (SpaciMS) lean-rich cycles. During the lean phase, the impact of the decrease in storage sites was significant on the aged sample, where an enlargement of the area required to achieve full storage was observed. On the other hand, the regeneration functionalities did not appear to be particularly affected by ageing. Rather, the aged sample showed a decrease of oxygen storage capacity (OSC), which promoted a lower reductant consumption and therefore a quicker and more efficient reduction process. On the other hand, the different distributions of adsorbed species by the end of the lean phase produced greater spread presence of NH3 and NOx slip along the channels of the aged sample during the reduction.

In situ photoemission and near edge X-ray absorption fine structure (NEXAFS) techniques have been used to study the interaction of CO2 with an ionic liquid thin film. A thin film of the superbasic ionic liquid (SBIL) trihexyltetradecylphosphonium benzimidazolide ([P66614][benzim]) was prepared on a rutile TiO2 (110) surface and exposed to CO2 at near-ambient pressures. NEXAFS measurements combined with density functional theory calculations indicate a realignment of [benzim]- anions from 27° from the surface normal to 54° upon exposure to CO2. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) shows evidence of irreversible CO2 absorption in thin films of [P66614][benzim] and a greater concentration of CO2-reacted anions in the deeper layers. These results give a new perspective on CO2 uptake in ionic liquids and fundamental interactions at the liquid-gas interface. Understanding this interfacial behaviour is important for developing ILs for gas capture applications and may influence the performance of other IL-based technologies.

Herein, catalytic aqueous phase photoreforming of cellulose was carried out over Pt/m-TiO2 (i.e., mixed phase of anatase and rutile) and Pt/anatase catalysts to investigate the effect of the TiO2 support structure and Pt loading on the production of H2. The effect of the TiO2 support on the properties of the resulting Pt/TiO2 catalysts (such as actual Pt loading and BET surface area) was not significant. At low Pt loading of 0.16 wt.%, the TiO2 supports affected the sub-nanometre Pt structures which was confirmed by the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterisation (using CO as the probe). Conversely, the effect of TiO2 supports on larger Pt particles (on 1 wt.% catalysts) was insignificant possibly due to the reduced effect of restructuration of bigger Pt particles on the TiO2 supports. With an increase in Pt loading from 0.16 wt% to 1.00 wt.%, the normalised H2 production rate (with respect to the actual supported Pt amount and specific surface area of the catalysts) showed a decreasing trend over the two types of the catalysts, i.e., from 10.6 to 1.4 μmol h−1 m−2 mgPt−1 for Pt/m-TiO2, and from 8.5 to 1.2 μmol h−1 m−2 mgPt−1 for Pt/anatase. Specifically, large Pt particle sizes reduced the CO2/H2 production from cellulose photoreforming over both Pt/m-TiO2 and Pt/anatase catalysts, indicting an important role played by Pt particle size in photoreforming. Interestingly, in this study, the m-TiO2 supported catalysts only showed the benefits of enhanced charge separation across the phase junction in producing H2 with small Pt particles (at sub-nanometre), whilst, when large Pt particles (at around 1–2 nm) were supported, such a benefit was not significant in cellulose photoreforming. The promoting effect of small, sub-nm particles is attributed to the better capture of photoelectrons from bulk TiO2 and better activity of H+ coupling on small Pt particle. Further fundamental study on such guest-host interactions is devised to optimise Pt/TiO2 catalysts for improving H2 production from photoreforming reactions.

The stability of catalysts in dry reforming of methane (DRM) is a known issue. In this paper an encapsulation strategy has been employed to improve the stability compared with conventional impregnation methods. Herein, nickel nanoparticles encapsulated in silicalite-1 were prepared using a range of methods including post treatment, direct hydrothermal and seed-directed methods to investigate the effect of synthesis protocol on the properties of catalysts, such as degree of encapsulation and Ni dispersion, and anti-coking/-sintering performance in DRM. The Ni@SiO2-S1 catalysts obtained by the seed-directed synthesis presented the full encapsulation of Ni NPs by the zeolite framework with small particle sizes (∼2.9 nm) and strong metal-support interaction, which could sterically hinder the migration/aggregation of Ni NPs and carbon deposition. Therefore, Ni@SiO2-S1 showed stable CO2/CH4 conversions of 80% and 73%, respectively, with negligible metal sintering and coking deposition (∼0.5 wt%) over 28 h, which outperformed the other catalysts prepared. In contrast, the catalysts developed by the post-treatment and ethylenediamine-protected hydrothermal methods showed the co-existence of Ni phase on the internal and external surfaces, i.e. incomplete encapsulation, with large Ni particles, contributing to Ni sintering and coking. The correlation of the synthesis-structure-performance in this study sheds light on the design of coking-/sintering-resistant encapsulated catalysts for DRM.

While methane-powered vehicles produce fewer greenhouse gas emissions in comparison to conventional fuel vehicles, there is a significant amount of methane slip in their exhaust that needs to be treated. This study investigates non-thermal plasma (NTP) assisted catalytic methane oxidation as an alternative method for the low temperature methane slip abatement applicable to the exhaust of biogas methane-powered vehicles. It is concluded that high CH4 conversion and CO2 selectivity can be obtained using NTP-catalysis at low temperature with Pd/Al2O3 found to be the most promising candidate among all catalysts tested. In addition, it was found that CH4 conversion efficiency was dependent on the feed gas components and gas hourly space velocity as well as how the activation energy is introduced. For example, a combination of plasma and external heat supply provides advantages in terms of CH4 conversion along with lower plasma energy consumption. The presence of N2 and O2 in the feed gas during NTP-catalytic methane oxidation results in unfavourable NOX formation which linearly increases with CH4 conversion. These results conclude that the most suitable aftertreatment option involves the combination of an oxidation catalyst with plasma to target the hydrocarbon and CH4 oxidation, followed by an ammonia-SCR system to convert the NOX formed in plasma assisted zone.

Water scarcity and the consequent increase of freshwater prices are a cause for concern in regions where shale gas is being extracted via hydraulic fracturing. Wastewater treatment methods aimed at reuse/recycle of fracking wastewater can help reduce water stress of the fracking process. Accordingly, this study assessed the catalytic performance and life cycle environmental impacts of cerium-based mixed oxide catalysts for catalytic wet oxidation (CWO) of organic contaminants, in order to investigate their potential as catalysts for fracking wastewater treatment. For these purposes, MnCeO

Herein mixtures of cyclohexane and benzene have been investigated in both the bulk liquid phase and when confined in MCM-41 mesopores. The bulk mixtures have been studied using total neutron scattering (TNS), and the confined mixtures have been studied by a new flow-utilising, integrated TNS and NMR system (Flow NeuNMR), all systems have been analysed using empirical potential structure refinement (EPSR). The Flow NeuNMR setup provided precise time-resolved chemical sample composition through NMR, overcoming the difficulties of ensuring compositional consistency for computational simulation of data ordinarily found in TNS experiments of changing chemical composition—such as chemical reactions. Unique to the liquid mixtures, perpendicularly oriented benzene molecules have been found at short distances from the cyclohexane rings in the regions perpendicular to the carbon–carbon bonds. Upon confinement of the hydrocarbon mixtures, a stronger parallel orientational preference of unlike molecular dimers, at short distances, has been found. At longer first coordination shell distances, the like benzene molecular spatial organisation within the mixture has also found to be altered upon confinement.

Thermophysical properties of 1-butyl-3-methylimidazoliumtris(pentafluoroethyl) trifluorophosphate, [C4mim][(C2F5)3PF3] (CAS RN 917762-91-5) ionic liquid, were measured in the temperature range T = ...

Understanding the surface structure of bimetallic nanoparticles is crucial for heterogeneous catalysis. Although surface contraction has been established in monometallic systems, less is known for bimetallic systems, especially of nanoparticles. In this work, the bond length contraction on the surface of bimetallic nanoparticles is revealed by XAS in H2at room temperature on dealloyed Pt-Sn nanoparticles, where most Sn atoms were oxidized and segregated to the surface when measured in air. The average Sn-Pt bond length is found to be ∼0.09 Å shorter than observed in the bulk. To ascertain the effect of the Sn location on the decrease of the average bond length, Pt-Sn samples with lower surface-to-bulk Sn ratios than the dealloyed Pt-Sn were studied. The structural information specifically from the surface was extracted from the averaged XAS results using an improved fitting model combining the data measured in H2and in air. Two samples prepared so as to ensure the absence of Sn in the bulk were also studied in the same fashion. The bond length of surface Sn-Pt and the corresponding coordination number obtained in this study show a nearly linear correlation, the origin of which is discussed and attributed to the poor overlap between the Sn 5p orbitals and the available orbitals of the Pt surface atoms.

Life cycle thinking analysis (LCT) was conducted on the production of vanillin via bamboo wet air oxidation compared to vanillin production from crude oil or Kraft lignin. Synthetic vanillin has been produced from crude oil and paper pulping process “waste” for nearly a century. Bamboo is quick growing, lignin rich biomass with the potential for the generation of aromatic products including vanillin. Wet air oxidation experiments were performed, using CuSO4 and Fe2O3 catalysts in alkaline environments, on raw bamboo with the purpose of determining the aromatic compound yields in order to investigate bamboo as a potential source of fine chemical products. From the LCT approach, production of vanillin from Kraft Lignin compared to crude oil has a lower environmental impact across all categories per kg produced of vanillin. Kraft lignin production of vanillin is shown to reduce smog formation and CO2 emissions from non energy sources to negligible levels while decrease acidification potential by 38 times, toxic inhalation by 18 times and toxic inhalation potential by 346 times compared to crude oil. The proposed bamboo oxidation route has the potential to have the least environmental impact with negligible impact on smog formation potential and ozone depletion potential if a green polar extractive solvent can be utilised in future while also decreasing toxicity by inhalation by a further 10 fold and ingestion by 198 fold. This work has the potential to contribute to the United Nation Sustainable Development Goal for Responsible Consumption and Production, Goal 12

The involvement of water in the selective oxidation of MAL to MAA over a pure Keggin-type H3PMoO12O40 catalyst was investigated using an in situ DRIFTS reactor coupled with a mass spectrometer for the first time to elucidate the reaction pathway associated with water. Comparing the spectra and activity data using D2O instead of H2O during transient switching experiments has allowed us to evaluate the possible active sites where D2O is activated. It has been found that, during the cycling switches of D2O in and out of the MAL + O2 gas feed at 320 °C, the formation of MAA–OD product is increased and decreased when D2O is added and removed, respectively. This suggests that the deuterium from D2O is involved in the production of gas phase MAA–OD. In addition, the in situ DRIFTS-MS results obtained from the isotopic switches between D2O and H2O reveal changes in the characteristic infrared bands of the Keggin unit between 1200 and 600 cm−1. It is found that the isotopic exchange possibly occurs on the bridging oxygen of Mo–O–Mo unit, where water is activated for the formation of MAA. Based on the in situ DRIFTS-MS analysis from the transient switching experiments, the reaction mechanism associated with the effect of water on the selective oxidation of MAL to MAA over Keggin-type H3PMoO12O40 catalyst is proposed.

A range of Pt and Pt–Re catalysts on titania were mechanochemically prepared and compared to conventional catalysts made by wet impregnation for the selective hydrogenation of stearic acid. Mechanochemically prepared catalysts showed superior selectivity toward stearyl alcohol compared to the conventional catalysts. It was possible to achieve 100% selectivity to stearyl alcohol using mechanochemically prepared Pt/TiO2.

Photocatalytic reforming of biomass has emerged as an area of significant interest within the last decade. The number of papers published in the literature has been steadily increasing with keywords such as ‘hydrogen’ and ‘visible’ becoming prominent research topics. There are likely two primary drivers behind this, the first of which is that biomass represents a more sustainable photocatalytic feedstock for reforming to value-added products and energy. The second is the transition towards achieving net zero emission targets, which has increased focus on the development of technologies that could play a role in future energy systems. Therefore, this review provides a perspective on not only the current state of the research but also a future outlook on the potential roadmap for photocatalytic reforming of biomass. Producing energy via photocatalytic biomass reforming is very desirable due to the ambient operating conditions and potential to utilise renewable energy (e.g., solar) with a wide variety of biomass resources. As both interest and development within this field continues to grow, however, there are challenges being identified that are paramount to further advancement. In reviewing both the literature and trajectory of the field, research priorities can be identified and utilised to facilitate fundamental research alongside whole systems evaluation. Moreover, this would underpin the enhancement of photocatalytic technology with a view towards improving the technology readiness level and promoting engagement between academia and industry.

Supported bimetallic nanoparticles (BNPs) are promising catalysts, but study on their compositional and structural changes under reaction conditions remains a challenge. In this work, the structure of PtNi BNPs supported on UiO-67 metal–organic framework (MOF) catalyst (i.e., PtNi@UiO-67) was investigated by in situ by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The results showed differences in the reduction behaviour of Ni species in PtNi BNPs and monometallic Ni supported on UiO-67 catalysts (i.e., PtNi@UiO-67 and Ni@UiO-67), suggesting charge transfer between metallic Pt and Ni oxides in PtNi@UiO-67. Under CO oxidation conditions, Ni oxides segregated to the outer surface of the BNPs forming a thin layer of NiOx on top of the metallic Pt (i.e., a NiOx-on-Pt structure). This resulted in a core-shell structure which was confirmed by high-resolution scanning transmission electron microscopy (HR-STEM). Accordingly, the layer of NiOx on PtNi BNPs, which is stabilised by charge transfer from metallic Pt, was proposed as the possible active phase for CO oxidation, being responsible for the enhanced catalytic activity observed in the bimetallic PtNi@UiO-67 catalyst.

Plasma-catalysis systems are complex and require further understanding to advance the technology. Herein, CO poisoning in CO2 hydrogenation over supported ruthenium (Ru) catalysts in a nonthermal p...

Hydrogen (H2) production from photocatalytic reforming of cellulose is a promising way for sustainable H2 to be generated. Herein, we report a systematic study of the photocatalytic reforming of cellulose over Pt/m-TiO2 (i.e. mixed TiO2, 80% of anatase and 20% of rutile) catalysts in water. The optimum operation condition was established by studying the effect of Pt loading, catalyst concentration, cellulose concentration and reaction temperature on the gas production rate of H2 (rH2) and CO2 (rCO2), suggesting an optimum operation condition at 40 °C with 1.0 g·L−1 of cellulose and 0.75 g·L−1 of 0.16-Pt/m-TiO2 catalyst (with 0.16 wt% Pt loadting) to achieve a relatively sound photocatalytic performance with rH2 = 9.95 μmol·h−1. It is also shown that although the photoreforming of cellulose was operated at a relatively mild condition (i.e. with an UV-A lamp irradiation at 40 °C in the aqueous system), a low loading of Pt at ~ 0.16 wt% on m-TiO2 could promote the H2 production effectively. Additionally, by comparing the reaction order expressed from both rH2 (a1) and rCO2 (a2) with respect to cellulose and water, the possible mechanism of H2 production was proposed.

Carbon dioxide (CO2) capture and utilisation (CCU) plays an important role in abating carbon emissions, mitigating global warming and converting CO2 as feedstock to value-added fuels and chemicals. Herein, a proof-of-concept study of a novel integrated process, consisting of a membrane separator (MS) followed by a non-thermal plasma reactor (NTPR) in tandem, was presented and systematically investigated, as an efficient platform, for potential applications in CCU. Specifically, biogas upgrading via CH4 enrichment was used as the model system to investigate the proposed integrated system (using SAPO-34 zeolite membrane in MS and Ni/NaBETA and Ni/UiO-66 catalyst in NTPR). Upon optimisation, the hybrid MS-NTPR system showed satisfactory carbon capture efficiency (CCE) and carbon utilisation efficiency (CUE) of ca. 91.8% and 71.7%, respectively. In addition, the integrated process also exhibited excellent stability for CCU in upgrading synthetic biogas with a stable performance over a 40-h longevity test. This work, for the first time, showed the feasibility of using the novel integrated process for effective CCU.

The kinetics of the low-temperature forward water gas shift (LT-WGS) reaction have been studied over a 2 wt% Au/CeZrO4 (Au/CZO) catalyst using both thermal and dielectric barrier discharge plasma heterogeneous catalyst systems. Using the energy density (e), the apparent activation energy has been calculated under plasma and thermally activated conditions. A substantially lower apparent activation energy is observed in the plasma activated system (9.5 kJ/mol) compared with the thermal-catalysed reaction (132.9 kJ/mol). Different kinetic isotope effect (KIE) values for water were found in thermal (1.43) and plasma (1.89) activated catalytic systems which infer different mechanisms between the two activation processes and also shows the importance of water activation. Furthermore, negative and positive reaction orders with respect to CO and H2O are found for both conditions which are − 1.30, 0.28 under thermal and − 1.53, 0.35 under plasma processes, respectively. The reaction order with respect to H2O and KIE studies demonstrate that the bond cleavage in H2O molecule is a rate determining step in the plasma-assisted LT-WGS, similar to that in the thermal-assisted reaction.

Techniques employing synchrotron radiation (SR) have had a major and growing impact on catalytic science. They have made key contributions to our understanding of structural properties of catalytic...

A combination of Molecular Dynamics (MD) simulations and Quasielastic Neutron Scattering (QENS) experiments has been used to investigate the dynamics and structure of benzene in MCM-41 based catalysts. QENS experiments of benzene as both an unconfined liquid and confined in the catalyst Pt/MCM-41 find that the mobility of benzene decreases upon confinement as shown by the decreased diffusion coefficients. Complementary MD simulations on benzene in MCM-41 show agreement with the QENS experiments when using a novel fully flexible model of MCM-41. Structural information from the MD simulations show that benzene in MCM-41 has a significantly different structure from that of the bulk liquid; with benzene molecules closer together and no prefered orientation.

PVC is often found in composite materials and dehydrochlorination has been shown to be a viable option to recover valuable carbon forms and HCl from PVC, however, in current processes, the high temperature of operation is still detrimental. Ionic liquids were shown to tackle this issue by reducing the temperature of dehydrochlorination and improving its yield. The aim of this work is to address the separation problems associated with mixed composite materials and provide insight into the use of dehydrochlorination as a potential feedstock recycling process, such as, cracking or hydrocracking. To this end, a multicomponent blisterpack containing PVC/aluminium/oPA was chosen, to study the separation and dehydrochlorination of a mixed waste. Three ionic liquids with different anions were chosen for this purpose, i.e. trihexyl(tetradecyl)phosphonium chloride, bromide and hexanoate. The results showed that ionic liquids are capable of separating the layered components in the blisterpack and improving the dehydrochlorination degree significantly (up to 99%). The recyclability was shown to be reproducible with halide-based ionic liquids, whilst with the hexanoate anion, the recyclability was achieved by washing with sodium hydroxide, with simultaneous separation of the second polymer (namely oPA). Efficient separation of the layers in the blisterpack was observed using ionic liquids which also allows recycling of the PVC through dehydrochlorination.

NMR relaxation has been used to characterise the strength of surface interaction of reducing agent species in Ag/Al2O3 catalysts used for the selective catalytic reduction (SCR) of NOx. Several classes of compounds, including aliphatic and aromatic hydrocarbons, as well as alcohols, were investigated. The results show that the strength of interaction of the reducing agent with the catalyst surface, characterised by the NMR relaxation time ratio T1/T2, plays an important role in determining the catalyst performances, with reducing agents able to compete with water for adsorption over the surface giving better catalytic activities. In particular, a clear trend was observed when comparing the T1/T2 ratio of different reducing agents with the initial activity of the catalyst, in particular with the activation temperature, with species such as alcohols, which showed a higher affinity with the catalyst, showing an easier initial activation. Whilst SCR is a complex reaction, whereby a series of phenomena are responsible for the overall catalytic activity, the strength of surface interaction of the reducing agent is a useful indicator for the initial catalytic activation in such processes.

Photoreforming of cellulose is a promising route for sustainable H

A superbase ionic liquid (IL), trihexyltetradecylphosphonium benzimidazolide ([P66614][Benzim]), is investigated for the capture of CO2 in the presence of NO2 impurities. The effect of the waste gas stream contaminant on the ability of the IL to absorb simultaneously CO2 is demonstrated using novel measurement techniques, including a mass spectrometry breakthrough method and in situ infrared spectroscopy. The findings show that the presence of an industrially relevant concentration of NO2 in a combined feed with CO2 has the effect of reducing the capacity of the IL to absorb CO2 efficiently by ∼60% after 10 absorption–desorption cycles. This finding is supported by physical property analysis (viscosity, 1H and 13C NMR, and X-ray photoelectron spectroscopy) and spectroscopic infrared characterization, in addition to density functional theory (DFT) calculations, to determine the structure of the IL-NO2 complex. The results are presented in comparison with another flue gas component, NO, demonstrating that the absorption of NO2 is more favorable, thereby hindering the ability of the IL to absorb CO2. Significantly, this work aids understanding of the effects that individual components of flue gas have on CO2 capture sorbents, through studying a contaminant that has received limited interest previously.

Water electrolysis is one of the most promising methods to produce H2 and O2 as high potential fuels. Comparing the two half-reactions, the oxygen evolution reaction (OER) is the more difficult to be optimized and still relies on expensive noble metal-based catalysts such as Ru or Ir. In this paper, we prepared nanoparticles of HfN and Hf2 ON2 and tested them for the OER for the first time. The HfN sample, in particular, showed the highest activity, requiring an overpotential of only 358 mV at 10 mA cm-2 in Fe-free electrolyte and, above all, exhibiting long-term stability. This result places this system amongst one of the most promising catalysts for OER tested to date, in terms of sustainability, activity and stability. The prepared nanoparticles are small (less than 15 nm in diameter), well-defined in shape and crystalline, and were characterised before and after electrochemical testing also via electron microscopy (EM), powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopy (XPS).