48 research outputs found
Pd/CeO2 Methane Abatement Catalysts Prepared by Solvent-free Mechano-chemical Synthesis
No full textAn ecofriendly solventless mechano-chemical synthesis was developed for the preparation of Pd/CeO2 methane oxidation catalysts, which exhibited outstanding results in terms of catalytic activity and stability. Their enhanced reactivity coupled with their peculiar morphology prompted a systematic study of these catalysts in order to gain a better understanding of methane activation and deeper insights into the correlation between methane activation and Pd-Ce interaction, specifically at nanoscale level
Sustainable Alternatives for Tertiary Treatment of Pulp and Paper Wastewater
No full textIn this work, different alternatives to conventional tertiary treatment of pulp and paper (P&P) wastewater (WW), i.e., physicochemical coagulation-flocculation, were investigated to enhance the environmental and economic sustainability of industrial wastewater treatment. In particular, following a preliminary characterization of secondary effluents, cloth filtration and adsorption were studied, the former by pilot-scale tests, while the latter at laboratory scale. An economic analysis was
finally accomplished to verify the full-scale applicability of the most promising technologies. Cloth filtration showed excellent total suspended solids (TSS) removal efficiency (mean 81% removal) but a very limited influence on chemical oxygen demand (COD) (mean 10% removal) due to the prevalence of soluble COD on particulate COD. Adsorption, instead, led to a good COD removal efficiency (50% abatement at powdered activated carbon—PAC—dosage of 400 mg/L). The economic analysis proved that adsorption would be convenient only if a local low-cost (100 /ton) adsorbent supply chain was established. Ultrafiltration was considered as well as a potential alternative: its huge capital cost (19 M ) could be recovered in a relatively short timeframe (pay-back time of 4.7 years) if
the ultrafiltrated effluent could be sold to local industries
Feasibility of green mechanochemical synthesis for dual function materials preparation
No full textDual function materials (DFMs) are key for the integrated capture of CO2 from waste gas streams and its valorisation to valuable chemicals, such as syngas. To be able to function in commercial applications, DFMs require
both high capture capacity and catalytic activity, achieved by optimising the synergistic interactions among the
catalytic metals, support and adsorbent components. To obtain increased interaction, the dry milling process can
be used as a sustainable, solvent free, green synthesis method. In this work, we report the performance of RuNi
bimetallic DFMs supported on CeO2-Al2O3 and promoted with CaO and Na2O, synthesised by a mild-energy
mechanochemical process. The materials show generally comparable, and sometimes superior, capture capacity and increased activity in Reverse Water-Gas Shift (RWGS) reaction for CO production at 650 °C compared to
their counterpart prepared by a conventional impregnation method, underlining the potential of the synthesis
method for highly functional DFMs. Remarkably, high activity and stability are also maintained when O2 is
present in the capture step, indicating potential for real exhaust-gases capture applications. Also, direct air
capture of CO2 is reported, further underlining the benefits of the dry milling approach for creating versatile
DFMs
Mechanochemistry: A Green and Fast Method to Prepare A New Generation of Metal Supported Catalysts
No full textIn this review, we report on recent advances in the use of mechanochemistry to synthesize new catalytic materials. We report recent results obtained by our groups where a rational design of the milling parameters led to the synthesis of advanced materials with novel properties such as unconventional arrangements of metals on the surface of oxide support materials, highly dispersed metals or the stabilization of species in particular oxidation states. These properties resulted in superior catalytic performances of the mechanochemically-synthesized catalysts compared to their counterparts prepared by traditional impregnation methods. To illustrate these advances, we review the progress made in two important fields of catalysis where noble metals are used: (i) emission-control catalysis using Pd-based materials, and (ii) the development of photocatalysts to produce hydrogen based on Au and Pd materials.Peer ReviewedPostprint (author's final draft
Outstanding Methane Oxidation Performance of Palladium-Embedded Ceria Catalysts Prepared by a One-Step Dry Ball-Milling Method
No full textBy carefully mixing Pd metal nanoparticles with CeO2 polycrystalline powder under dry conditions, an unpredicted arrangement of the Pd-O-Ce interface is obtained in which an amorphous shell containing palladium species dissolved in ceria is covering a core of CeO2 particles. The robust contact that is generated at the nanoscale, along with mechanical forces generated during mixing, promotes the redox exchange between Pd and CeO2 and creates highly reactive and stable sites constituted by PdOx embedded into CeO2 surface layers. This specific arrangement outperforms conventional Pd/CeO2 reference catalysts in methane oxidation by lowering light-off temperature by more than 50°C and boosting the reaction rate. The origin of the outstanding activity is traced to the structural properties of the interface, modified at the nanoscale by mechanochemical interaction.Postprint (author's final draft
Integrated carbon capture and dry reforming of methane of mechanochemically synthesised dual-function materials
No full textThis article is part of the themed collections: UN Sustainable Development Goal 13: Climate Action and UN Sustainable Development Goal 12: Responsible consumption and production.[Data availability]
Data supporting this article have been included as part of the SI.
Supplementary information including details of material synthesis, further characterization and time dependent data from DFM activity tests. See DOI: https://doi.org/10.1039/d5su00317b.Herein we report a green mechanochemical synthesis with low energy input of dual-function materials for integrated CO2 capture and dry reforming of methane. The materials produced syngas during the CH4 step (up to 0.6 mmol g−1 CO and 7.7 mmol g−1 H2) and CO during the CO2 step (up to 3.1 mmol g−1) via the reverse Boudouard reaction due to the carbon produced from CH4 cracking.This study was carried out within the Interconnected Nord-Est Innovation Ecosystem (iNEST) and received funding from the European Union Next-GenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.5 – D.D. 1058 23/06/2022, ECS00000043, CUP: G23C22001130006). M. D. is grateful for funding under the REACT EU Italian PON 2014–2020 Program – Action IV.4 – Innovation (DM 1062, 10/08/2021, CUP G51B21006040007). S. C., M. S. D. and T. R. R. acknowledge funding by the European Commission under the framework of C-NET project, HORIZON-MSCA-2023-SE-01, project reference: 101182598. M. S. D. acknowledges support by the Engineering and Physical Sciences Research Council (EPSRC) grant EP/X000753/1. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them. The team of the University of Surrey acknowledge the financial support for this work from the School of Chemistry and Chemical Engineering and the Doctoral College of the University of Surrey. SASOL is kindly acknowledged for providing the CeAl support.Peer reviewe
Maila Talvio and Eliza Orzeszkowa friendship in the field of literature
No full textStraipsnyje nagrinėjami ir plačiai cituojami septyni suomių rašytojos Mailos Talvio laiškai lenkų prozininkei Elizai Orzeszkowai, kuriuos autorė aptiko Lenkijos Mokslų Akademijos Literatūros instituto Elizos Orzeszkowos archyve. Nors tai asmeninė korespondencija, ji teikia daug informacijos apie dviejų kūrėjų literatūrinius ir kultūrinius ryšius, atskleidžia XIX–XX amžių sandūros kultūrinę dvasią, gyvenimo realijas Lenkijoje, Lietuvoje, Suomijoje. Laiškai liudija Mailos Talvio, jos vyro kalbininko Jooseppio Juliaus Mikkolos norą išpopuliarinti lenkų rašytoją Suomijoje, versti ir publikuoti jos veikalus. Straipsnyje panaudojami ir kiti rašytojų bendravimą liudijantys šaltiniai Reikšminiai žodžiai: Archyvai; Biografika; Kultūrų dialogai; Kultūrų dialogas; Laiškai; Lenkų literatūra; Vertimas; Archive; Biography; Culture dialogues; Cultures dialogues; Letters; Polish literature; TranslationThe article includes the results of the investigation work and a lot of quotations taken from the seven letters written by the Finnish writer Maila Talvio to the Polish writer Eliza Orzeszkowa. The author of the article has found the letters in Eliza Orzeszkowa's archive of the Institute of Literature, Polish Science Academy. Although it may seem that the letters are personal, the correspondence provides a lot of information about the literary and cultural links between these two writers, reveal the details of spiritual and everyday life of people in Poland, Lithuania and Finland at the turn of the nineteenth and twentieth centuries. The letters also present the evidence of the efforts of Maila Talvio and her husband and linguist Jooseppi Julius Mikkola to make the Polish writer more popular in Finland by translating and publishing her works. The author of the article also uses some other sources of information reflecting the relationship between the two writer
The effect of milling parameters on the mechanochemical synthesis of Pd-CeO2 methane oxidation catalysts
No full textThe preparation of catalytic materials via mechanochemical routes is a very promising alternative to complex wet chemical syntheses due to its simplicity, versatility and ecological advantages. The mechanical mixing of Pd nanoparticles and CeO2 results in very active methane oxidation catalysts; here we explore the effect of milling parameters on the overall performance of Pd–ceria catalysts. The high methane combustion activity is the result of nanoscale interaction between palladium and cerium oxide and it is shown to be strongly dependent on the intensity of milling. This was investigated through methane combustion tests up to 1173 K and characterized by means of temperature programmed oxidation and reduction experiments. The morphological features of the obtained materials were investigated by HRTEM analysis and correlated to the catalytic behavioPeer ReviewedPostprint (author's final draft
Pd/CeO2 catalysts prepared by solvent-free mechanochemical route for methane abatement in natural gas fueled vehicles
No full textThe increasing diffusion of alternative mobility solutions, ranging from electric technologies to natural gas fueled vehicles (NGVs), has led to a progressive life-cycle analysis approach of their environmental impact in terms of greenhouse gases (GHGs) emissions. This new approach prompted a careful design of the NGVs catalytic aftertreatment system in order to minimize the catalytic converter carbon footprint as well as the unburned methane emissions at tailpipe. Here, a series of Pd/CeO2 methane oxidation catalysts were prepared by an environmentally friendly solvent-free method and compared to the commercial wet-synthesized state-of-the-art catalysts. Their application in NGVs aftertreatment systems was evaluated by testing powder catalysts and coated monolith cores for CH4 oxidation and steam reforming, which are the main methane abatement reactions occurring in a three-way catalyst (TWC) under lean and rich conditions, respectively. Pd/CeO2 catalysts prepared by mechanochemical synthesis initially displayed superior activity compared to their counterpart obtained by conventional wet impregnation, especially under lean oxidation conditions, but appeared less resistant to the industrial aging process after core washcoating. Lambda sweep experiments carried out under full gas composition proved that, despite needing further optimization in the washcoating and aging processes, the developed mild milling synthesis procedure is a viable way for the production of Pd/CeO2 based catalysts for natural gas TWCs.Peer ReviewedPostprint (author's final draft
Structural Evolution of Bimetallic PtPd/CeO2 Methane Oxidation Catalysts Prepared by Dry Milling
No full textBimetallic Pt–Pd catalysts supported on ceria have been prepared by mechanochemical synthesis and tested for lean methane oxidation in dry and wet atmosphere. Results show that the addition of platinum has a negative effect on transient light-off activity, but for Pd/Pt molar ratios between 1:1 and 8:1 an improvement during time-on-stream experiments in wet conditions is observed. The bimetallic samples undergo a complex restructuring during operation, starting from the alloying of Pt and Pd and resulting in the formation of unprecedented “mushroom-like” structures consisting of PdO bases with Pt heads as revealed by high-resolution transmission electron microscopy (HRTEM) analysis. On milled samples, these structures are well-defined and observed at the interface between palladium and ceria, whereas those on the impregnated catalyst appear less ordered and are located randomly on the surface of ceria and of large PdPt clusters. The milled catalyst prepared by first milling Pd metal and ceria followed by the addition of Pt shows better performances compared to a conventional impregnated sample and also to a sample obtained by inverting the Pd–Pt milling order. This has been ascribed to the intimate contact between Pd and CeO2 generated at the nanoscale during the milling process.Postprint (published version
