Ce Mn mixed oxides for low temperature emission control catalysts

Manganese oxides molecular sieves (OMS) materials have a mixed valency of Mn3+ and Mn4+ cations that contributes to its highly active redox properties, which make it particularly interesting for emission control applications. Cryptomelane is an OMS-2 material which has a microporous, nano-tunnel structure composed of edge shared MnO6 octahedra that form a 2 x 2 arrangement, with a K+ cation positioned within the framework. The structural incorporation of various dopants and tunnel cations can further enhance the functionality of OMS-2. Other synthesis routes can be used for the incorporation of a high concentration of dopants, can also lead to the inhibition of the crystalline. In this work we have synthesized a range of manganese oxide based supports doped with Ce and tested for applications in automotive emission abatement. Due to the high emissions of lean burn diesel engines operating at low temperatures and during cold start, and issues with catalyst deactivation, the requirement for a catalyst which is active at low temperature is one of the main challenges in automotive emission control. In particular, we have investigated the use of manganese oxide hybrid catalyst supports for their applicable use in automotive after treatment. We have studied their activity in the oxidation reactions of CO and C3H6, before comparing their activity with a commercial diesel oxidation catalyst

Nanocatalysts from Ionic Liquid Precursors for CO2 Valorisation to Hydrocarbons

The conversion of CO2 into lower olefins (C3-C5) is a highly desirable process as a sustainable production route. Thereby, the use of hydrogen from renewable energies and the conversion of CO2 into lower olefins via Fischer-Tropsch synthesis (FTS) offers an attractive route for efficient utilisation of biogas as a renewable feedstock to replace petroleum for the synthesis of key building-block chemicals. Lower olefins, i.e., ethylene, propylene and butene (C2-C4) are key building blocks in the current chemical industry. Iron-based catalysts are of interest due to their ability to catalyse both FTS and Reverse Water Gas Shift (RGS). These are also of interest as they are able to produce high olefin hydrocarbons. The main reason for the iron catalyst effectiveness in such process is its formation of iron carbides (χ-Fe5C2) formed after reaction gas treatment. It has also been reported that the iron catalysts require alkali metal promotion in order to obtain desired activity and selectivity. The further upgrading to gasoline range hydrocarbons can be done by having zeolites in close proximity to the iron catalysts. It has been proposed that the zeolites crack lower chain olefins, and able to facilitate chain growth.However, for such catalysts, controlling the size and the particle distribution remains a major challenge. Thus, in order to obtain monodispersed catalysts, a novel approach is developed, utilising ionic liquids which can dissolve precursors while itself containing dense and tuneable network of hydrogen bonds. Such synthetic methods have been demonstrated by Wang et al. Nanoparticles produced through this method have been shown to produce higher surface areas. We report here on a novel methodology for the controlled synthesis of a Na–Fe3O4/HZSM-5 multifunctional catalyst for the direct hydrogenation of CO2 to gasoline. The catalytic testing under industrially relevant conditions resulted in improved selectivity to C5–C11 as well as low CH4 and CO2 selectivity. Furthermore, the product composition can be tuned by the zeolite properties (i.e. Si/Al ratio, H form, alkaline exchange) and by the choice of ionic liquid in the synthetic method. This study provides a new pathway for the synthesis of nanocatalysts for the production of liquid fuels by utilising CO2 and H2

Mechanism and Site Requirements for NO Oxidation Catalysis and NOx Adsorption on Dispersed Metal and Oxide Substrates

NO oxidation catalysts and NO2 adsorbents based on BaO are used to remove NOx from combustion effluents that lack CO or CxHy reductants. NOx trapping materials, however, inefficiently use costly active components because of persistent ambiguities about fundamental processes responsible for NOx storage. We address such matters by combining NO oxidation and NOx adsorption rate data with infrared spectra of adsorbed species to identify elementary steps and active site requirements for NO oxidation and NOx adsorption

"SOLID CATALYST WITH IONIC LIQUID LAYER (SCILL) FOR THE DIRECT HYDROGENATION OF CO2 TO METHANOL"

The potential of converting CO2 into valuable products, such as methane, dimethyl ether, methanol, and gasoline-range hydrocarbons, offers a promising solution for reducing CO2 emissions and addressing fossil fuel depletion. This study aimed to pioneer a novel approach by developing a Solid Catalyst with Ionic Liquid Layer (SCILL) for the direct hydrogenation of CO2 into methanol. This was achieved by applying an ionic liquid (IL) layer to a commercial Cu/ZnO/Al2O3 catalyst. Initially, a thorough assessment of the thermal stabilities of various ILs was carried out using both static and dynamic thermogravimetric analysis (TGA). The ILs demonstrating exceptional thermal stability were chosen to create SCILL catalysts with a 10% IL loading. During reaction testing, the SCILL catalysts exhibited superior CO2 conversion, outperforming the commercial catalyst's activity under similar conditions. Furthermore, the introduction of Li[NTf2] in the SCILL systems effectively stabilized the system, countering the negative effects of water deactivation observed in the undoped SCILL

α-Alkylation of Aliphatic Ketones with Alcohols: Base Type as an Influential Descriptor

Current global challenges associated with energy security and climate emergency, caused by the combustion of fossil fuels (e.g., jet fuel and diesel), necessitate the accelerated development and deployment of sustainable fuels derived from renewable biomass-based chemical feedstocks. This study focuses on the production of long-chain (straight and branched) ketones by direct α-alkylation of short chain ketones using both homogenous and solid base catalysts in water. Thus, produced long-chain ketones are fuel precursors and can subsequently be hydrogenated to long-chain alkanes suitable for blending in aviation and liquid transportation fuels. Herein, we report a thorough investigation of the catalytic activity of Pd in combination with, (i) homogenous and solid base additives; (ii) screening of different supports using NaOH as a base additive, and (iii) a comparative study of the Ni and Pd metals supported on layered double oxides (LDOs) in α-alkylation of 2-butanone with 1-propanol as an exemplar process. Among these systems, 5%Pd/BaSO4 with NaOH as a base showed the best results, giving 94% 2-butanone conversion and 84% selectivity to alkylated ketones. These results demonstrated that both metal and base sites are necessary for the selective conversion of 2-butanone to alkylated ketones. Additionally, amongst the solid base additives, Pd/C with 5% Ba/hydrotalcite showed the best result with 51% 2-butanone conversion and 36% selectivity to the alkylated ketones. Further, the screening of heterogenous acid-base catalysts 2.5%Ni/Ba1.2Mg3Al1 exhibited an adequate catalytic activity (21%) and ketone selectivity (47%)

Mechanism Understanding for NOx storage, release and reduction on Pt doped Ceria based Catalysts

The introduction of increasingly more stringent regulations for tailpipe emissions of lean-burn gasoline and diesel engines presents the need for further optimisation of existing aftertreatment technologies. These legislations focus primarily on the reduction of NOx at low temperature, i.e., during the cold start period of engine operation. High surface area ceria is successfully employed as an excellent support of PGMs in commercial catalytic LNT (Lean NOx Trap) systems for automotive emission control. Platinum supported on ceria shows enhanced NOx storage at low temperatures (150-300 ̊C), together with improved hydrocarbons light-offs. The OSC (Oxygen Storage Capacity) of ceria can be further enhanced using dopants. Their main function is to allow the catalyst to function outside of the normal working temperature range and widen the operating conditions to increase catalyst efficiency. To this end, Samarium was selected as the doping element because of its reported effect on Pt reducibility and the Pt-ceria interaction, which allow for higher storage capacity during lean operation as well as enhanced activation during rich purge. Sm doped catalysts (10 wt.%) were synthesised on a range of ceriabased catalysts with increasing loadings of Pt (0-1 wt.%). The objective of this study was to investigate the effect of the dopant on the performance of the different catalysts, and, to correlate their reactivity with the morphological changes observed on the surface

Novel synthesis approaches for CO2 Hydrogenation catalysts using Ionic Liquids

The conversion of carbon dioxide into lower olefins (C2-C4) represents a highly desirable process for establishing a sustainable production pathway. These lower olefins, including ethylene, propylene, and butenes, play pivotal roles in the chemical industry and the production of Liquefied Petroleum Gas (LPG). The reaction unfolds through two consecutive primary processes: Reverse Water Gas Shift (RWGS), generating CO, followed by the subsequent transformation of CO into hydrocarbons through the Fischer−Tropsch reaction. Recent research has underscored the cost-effectiveness and satisfactory performance of Febased catalysts in both reaction steps, with an exploration of bimetallic catalysts, particularly combinations of Ru and Fe, aimed at enhancing olefin selectivity. Precise synthesis of multinanoparticle (MNP) becomes a critical factor for performance control in this context. The study introduces an innovative approach to synthesize iron-ruthenium bimetallic catalysts, utilizing ionic liquids as solvents. This method ensures the precise and uniform distribution of active metal phases. Advanced characterizations and extensive tests reveal that this technique outperforms traditional colloid-based methods, resulting in superior selectivity for the desired hydrocarbons

Ionic Liquid Synthesis of Catalysts for Direct CO2 Hydrogenation to shortchain hydrocarbons

The direct conversion of carbon dioxide into lower olefins (C2-C4) is a highly desirable process as a sustainable production route1,2. These lower olefins, such as ethylene, propylene, and butenes, are crucial components in the chemical industry and for Liquefied Petroleum Gas (LPG). The reaction proceeds via two main consecutive reactions: Reverse Water Gas Shift (RWGS) to produce CO followed by the further conversion of CO to hydrocarbons via the Fischer−Tropsch reaction3. Recent studies 45highlight the cost-effectiveness and satisfactory performance of Fe-based catalysts in both reaction steps, while exploring bimetallic catalysts, particularly Ru and Fe combinations, to enhance olefin selectivity6., with precise MNP synthesis as a crucial factor for performance control.The study introduces a novel approach for synthesizing iron-ruthenium bimetallic catalysts that utilizes ionic liquids as solvents7, ensuring precise and uniform distribution of active metal phases. Advanced characterizations and extensive tests reveal that this method surpasses traditional colloid-based techniques, resulting in superior selectivity for target hydrocarbons

Exploring the Viability of Utilizing TreatedWastewater as a Sustainable Water Resource for Green Hydrogen Generation Using Solid Oxide Electrolysis Cells (SOECs)

The European Union aims to achieve carbon neutrality by 2050, prompting substantial investments in sustainable energy research, particularly in the realm of renewable sources (RESs). Italy, anticipating an energy demand of 366 TWh by 2030, is obligated by the EU to fulfill 75% to 84% of this demand through RESs1. A promising solution to meet this requirement is the production of green hydrogen through water electrolysis, specifically employing Solid Oxide Electrolysis Cells (SOECs). SOECs offer advantages over Alkaline Electrolyzers (AEs) and Proton Exchange Membranes (PEMs) since they can utilize treated wastewaters, eliminating the necessity for pure water, which is already scarce. This study centers on exploring the potential of SOECs to operate effectively in high-temperature conditions and utilize water in its gaseous form as the inlet source, commencing with treated wastewaters derived from municipal wastewater treatment plants