Johnson Matthey Technology Review - Volume 70, Issue 2, 2026

The oscillatory baffled reactor (OBR) is one of the most promising reactor types for oxidative desulfurisation (ODS) due to high proven sulfur removal efficiency and improved mass and heat transport steps through the oxidation reaction. In Part III of this literature review, we review OBR design, scale-up, industrial application and economic considerations. Practical application of OBR for ODS process is described, catalytic systems are presented and the remaining challenges are outlined.

This study investigates the comparative performance and emission characteristics of four fuels: diesel, liquefied petroleum gas (LPG), neat biodiesel (mustard-based) and gasoline, using a single-cylinder, four-stroke engine operated at a constant speed of 1500 rpm under eight load conditions (0.25 kW to 2.00 kW). Experiments were conducted both on the stock diesel engine and on the same engine modified for spark ignition (SI) operation. Key performance indicators such as thermal efficiency (TE), fuel consumption and emissions (hydrocarbons, carbon monoxide and nitrogen oxides (NOx)) were measured under steady-state conditions. Outcome indicated that LPG produced the lowest hydrocarbon and carbon monoxide emissions, highlighting its potential as a clean-burning fuel. Biodiesel exhibited moderate emissions but recorded the highest NOx levels, likely due to its higher oxygen content. Diesel demonstrated the best fuel economy (lowest specific fuel consumption (SFC)) but higher emissions compared to LPG and biodiesel. Gasoline achieved the highest TE but exhibited the highest hydrocarbon and carbon monoxide emissions, making it the least environmentally favourable option. The findings support the viability of LPG and biodiesel as cleaner alternatives to conventional diesel and gasoline, with trade-offs in fuel economy and NOx requiring further optimisation.

The utility of molecular organoplatinum complexes in catalytic transformations has long driven major industrial advancements, most notably in the hydrosilylation reaction, a process that is critical to the global, multibillion-dollar silicones industry. One of the most important breakthroughs in this field was the introduction of platinum-N-heterocyclic carbene (NHC) pre-catalysts. Apart from their significance in hydrosilylation processes, these unique complexes have also contributed to developments in other research areas, including cancer therapy and photophysics. This two-part review highlights the evolving role of platinum in homogeneous catalysis, with an emphasis on NHC complexes, providing both historical context and the latest findings. Part I introduces platinum-NHC complexes, covering their synthetic accessibility, properties and role in homogeneous catalysis, along with other notable applications. Part II (1) will discuss the fundamentals and recent developments in the catalytic hydrosilylation of alkenes and alkynes, centred around platinum-NHC pre-catalysts.

Catalyst layers, with commercial PtNi/TKK (TECNiE52; platinum 46.5 wt%), PtCo/TKK (TEC36E52; platinum 45.8 wt%) catalysts, and an in-house catalyst PtNi-NC (platinum 38.4 wt%), synthesised using acoustic mixer and a tube furnace, are prepared using three different ionomers: 20 wt% Nafion^®, 60 wt% polytetrafluoroethylene (PTFE), and an in-house 5 wt% ionomer (‘Ionomer X’). These inks are bar-coated onto carbon paper gas diffusion layers (GDLs), which are cut into 3 cm × 5 cm pieces. The coated layers are tested for oxygen reduction in a commercial gas diffusion electrode (GDE) test cell, FlexCell^® (Gaskatel GmbH, Germany), using 85 wt% phosphoric acid at both room temperature and at 155°C. This study evaluates the polynorbornene (PNB)-based in-house ionomer performance as binder and in-house catalyst oxygen reduction reaction (ORR) activity in comparison to commercial products. The catalyst layers are characterised using X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Among the catalyst layers prepared with PTFE ionomer and tested at 155°C, the in-house catalyst demonstrates the highest ORR activity. Ionomer X proves to be a good candidate to be used as a per- and polyfluoroalkyl-free binder for high-temperature (HT) proton exchange membrane fuel cell (PEMFC) applications.

Single-atom catalysts (SACs) and single-atom alloy (SAA) catalysts are emerging as promising catalysts that allow maximising atom efficiency whilst improving catalyst performance. This literature review focuses on the evaluation of SACs and SAAs for thermocatalytic carbon dioxide methanation, providing mechanistic insights into carbon dioxide methanation on SACs and SAAs. The key findings from this review demonstrate that metal clusters (for example nickel and ruthenium) in many cases provide a greater catalytic efficiency on a metal loading basis for carbon dioxide methanation compared to SACs. In contrast, SAAs have demonstrated a notable positive effect on catalyst activity or selectivity for carbon dioxide methanation, with studies having identified the benefit of a SAA structure in providing these enhancements. Therefore, the use of either supported metal clusters (rather than single atoms) or SAAs shows the most potential in maximising metal atom efficiency in thermocatalytic carbon dioxide methanation.

Single-atom alloy (SAA) catalysts, with advantages of particular geometric and electronic structures, have great potential to improve catalyst performance and maximise atom efficiency for a range of industrially relevant reactions. The use of SAAs for carbon dioxide hydrogenation is of particular interest, since captured carbon dioxide can be converted into valuable chemicals and fuels, such as methane and methanol. This literature review focuses on the use of SAAs for carbon dioxide hydrogenation to methane and methanol. It has been found that SAAs could provide an improved catalytic activity and selectivity over the respective monometallic catalysts for carbon dioxide hydrogenation to methane and methanol. A variety of mechanisms have been proposed to explain the effect of the SAA structure on catalyst performance. Primarily, these proposals involve changes in energetics associated with alloy formation, such as changes in intermediate energies facilitating a faster reaction, or changes in adsorption energies leading to improved selectivity.

This work offers a methodical examination of the hydrogenation of taramira oil using gamma alumina-assisted nickel molybdenum catalyst at pressure and temperature of 400°C and 4 MPa respectively. It was observed that the conversion of fatty acids and triglycerides into hydrocarbons is significantly influenced by temperature and pressure. The resulting mixture of gases and other substances is subjected to fractional distillation, wherein it is separated at various boiling points. The chemical composition of the obtained taramira hydrogenated renewable diesel (HRD) was carried out using gas chromatography flame ionisation detector (GC-FID) chemical composition testing. The paraffin chain C15–C18 i.e., diesel fuel ranges accounted for the final product’s major composition; miscellaneous components include paraffin and lubricating oils. A hydrogenated renewable paraffinic fuel’s physicochemical characteristics were evaluated and contrasted with those of biodiesel and conventional diesel. When comparing HRD (also known as green diesel), biodiesel and diesel, it is determined that green diesel has the finest physical-chemical qualities. With its high cetane index and favourable cold flow characteristics, HRD is used as a ‘drop-in’ fuel. Conversely, oxidation stability and kinematic viscosity for both diesel and HRD were almost identical. The obtained HRD shows a calorific value (CV) higher than the biodiesel. The elemental analysis for the obtained HRD uses a CHNS elemental analyser. The analysis results show that the carbon-hydrogen content of HRD is comparable to that of diesel and higher than that of biodiesel.

In order to systematically sort out the current research status, application areas and development direction of ozone in environmental catalysis, a bibliometric analysis of the relevant literature published in the Web of Science database from 2005 to 2025 was carried out. VOSviewer 1.6.20 and CiteSpace 6.4.R1 software were utilised to view data from 1379 journal articles. Data visualisation and analysis identified 5330 authors, 249 journals and 1276 institutions. The results show that the number of publications in the field of ozone-related environmental catalysis is on an increasing trend, especially after 2017. China, Spain, the USA, Iran and India are the main driving forces, with China being the most active country. The Chemical Engineering Journal and the Journal of Hazardous Materials are the journals that publish the most relevant research. Harbin Institute of Technology, China, University of Engineering and Technology Lahore, Pakistan and Beijing Forestry University, China are the three institutions that publish the most literature. Currently, a more complete theoretical framework and research methodology on ozone environmental catalysis is being developed worldwide. However, the research network is too centralised, with fewer frontier peripheral branches. The research focus has gradually shifted from the early direct oxidation of ozone to the design of catalytic materials, radical modulation and multi-technology coupling (photocatalysis, plasma), and in recent years, more attention has been paid to the synergistic degradation of complex pollutants (antibiotics, volatile organic compounds (VOCs)) and the optimisation of the green and sustainable processes. It is necessary to overcome the bottlenecks of catalyst stability, energy consumption and byproduct control, and promote the scale-up of ozone catalysis technology in water treatment and air purification. The present study is of great importance for a better understanding and further supporting the research of ozone environmental catalytic processes.