Copper phosphinate complexes as molecular precursors for ethanol dehydrogenation catalysts

Nowadays, the production of acetaldehyde heavily relies on the petroleum industry. Developing new catalysts for the ethanol dehydrogenation process that could sustainably substitute current acetaldehyde production methods is highly desired. Among the ethanol dehydrogenation catalysts, copper-based materials have been intensively studied. Unfortunately, the Cu-based catalysts suffer from sintering and coking, which lead to rapid deactivation with time-on-stream. Phosphorus doping has been demonstrated to diminish coking in methanol dehydrogenation, fluid catalytic cracking, and ethanol-to-olefin reactions. This work reports a pioneering application of the well-characterized copper phosphinate complexes as molecular precursors for copper-based ethanol dehydrogenation catalysts enriched with phosphate groups (Cu-phosphate/SiO2). Three new catalysts (CuP-1, CuP-2, and CuP-3), prepared by the deposition of complexes {Cu(SAAP)}n (1), [Cu6(BSAAP)6] (2), and [Cu3(NAAP)3] (3) on the surface of commercial SiO2, calcination at 500 °C, and reduction in the stream of the forming gas 5% H2/N2 at 400 °C, exhibited unusual properties. First, the catalysts showed a rapid increase in catalytic activity. After reaching the maximum conversion, the catalyst started to deactivate. The unusual behavior could be explained by the presence of the phosphate phase, which made Cu2+ reduction more difficult. The phosphorus content gradually decreased during time-on-stream, copper was reduced, and the activity increased. The deactivation of the catalyst could be related to the copper diffusion processes. The most active CuP-1 catalyst reaches a maximum of 73% ethanol conversion and over 98% acetaldehyde selectivity at 325 °C and WHSV = 2.37 h-1CF BIC; European Regional Development Fund-Project “UP CIISB, (CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110); Grant Agency of Masaryk University, (CZ.02.01.01/00/22_008/0004572, MUNI/A/1298/2022, MUNI/J/0007/2021, QM4ST); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (LM2018127, LM2023042, LM2023056, RP/CPS/2022/007); Grantová Agentura České Republiky, GA ČR, (GJ20-03636Y); Central European Institute of Technology, CEITECMEYS CR [LM2023042, LM2018127, CZ.02.1.01/0.0/0.0/18_046/0015974]; European Regional Development Fund-Project "UP CIISB" [LM2018110]; Czech Science Foundation [GJ20-03636Y]; Grant Agency of Masaryk University [MUNI/J/0007/2021, MUNI/A/1298/2022]; Quantum Materials for Applications in Sustainable Technologies (QM4ST) [CZ.02.01.01/00/22_008/0004572]; Ministry of Education, Youth and Sports of the Czech Republic [LM2023056]; Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/007

Propylene metathesis over molybdenum silicate microspheres with dispersed active sites

In this work, we demonstrate that amorphous and porous molybdenum silicate microspheres are highly active catalysts for heterogeneous propylene metathesis. Homogeneous molybdenum silicate microspheres and aluminum-doped molybdenum silicate microspheres were synthesized via a nonaqueous condensation of a hybrid molybdenum biphenyldicarboxylate-based precursor solution with (3-aminopropyl)triethoxysilane. The as-prepared hybrid metallosilicate products were calcined at 500 °C to obtain amorphous and porous molybdenum silicate and aluminum-doped molybdenum silicate microspheres with highly dispersed molybdate species inserted into the silicate matrix. These catalysts contain mainly highly dispersed MoOx species, which possess high catalytic activity in heterogeneous propylene metathesis to ethylene and butene. Compared to conventional silica-supported MoOx catalysts prepared via incipient wetness impregnation (MoIWI), the microspheres with low Mo content (1.5-3.6 wt %) exhibited nearly 2 orders of magnitude higher steady-state propylene metathesis rates at 200 °C, approaching site time yields of 0.11 s-1CF CryoE; European Regional Development Fund-Project “UP CIISB, (CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110); Francqui Foundation; Grant Agency of Masaryk University, (MUNI/A/1298/2022, MUNI/J/0007/2021); U.S. Department of Energy, USDOE; Basic Energy Sciences, BES, (DE-SC0016214); Massachusetts Institute of Technology, MIT; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (LM2023042, RP/CPS/2022/007); Grantová Agentura České Republiky, GA ČR, (GJ20-03636Y); Central European Institute of Technology, CEITECMinistry of Education, Youth, and Sports of the Czech Republic within the INTER-EXCELLENCE II program; Ministry of Education, Youth, and Sports of the Czech Republic [RP/CPS/2022/007]; U.S. Department of Energy, Office of Basic Energy Sciences [DE-SC0016214]; European Regional Development Fund-Project "UP CIISB" [CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110]; MEYS CR [GJ20-03636Y, LM2023042]; Czech Science Foundation; Grant Agency of Masaryk University [MUNI/J/0007/2021, MUNI/A/1298/2022]; Francqui Foundation for the Francqui Research Professor chai

Late Carboniferous palaeodepositional changes recorded by inorganic proxies and REE data from the coal-bearing strata: An example on the Czech part of the Upper Silesian Coal basin (USCB)

In the Czech Republic, coal-bearing siliciclastic sediments have been deposited during the Serpukhovian and Bashkirian (Carboniferous). Until now, no attention has been paid to inorganic geochemical assessment of the coals and associated non-coal rocks from the mixed shallow-marine to continental sediments (Ostrava Formation), and continental non-marine settings (Karviná Formation). Samples were collected from a 750 m deep coal exploration borehole at the ČSM Mine. The bulk parameters, total organic carbon TOC, total inorganic carbon TIC, total sulphur TS, major elements, trace elements, and REEs were measured on these samples, and their mineral associations have been investigated using microscopy combined with the principal component analysis (PCA). Common redox proxies V/Cr, U/Th, Ni/Co, Mo/U, and the ratio S/TOC have been tested on the samples to investigate their usefulness for studying anoxia. Research concludes that redox proxies such as U/Th, Ni/Co and V/Cr have been strongly influenced by the clastic input and carbonates, which it hinders for them to be reliable indicators of anoxia. On the basis of Eu anomaly and REEs distribution, the primary source of detrital elements comes from the parent rock, being governed more by physical than redox processes.The Dominik Vöröš' Postdoctoral Fellowship at INCAR, Spain was financially supported by a grant (Project No. MSM100462001), provided by the Czech Academy of Science within the Research and Mobility Support of Starting Researchers Programme.Peer reviewe

Highly efficient affinity anchoring of gold nanoparticles on chitosan nanofibers via dialdehyde cellulose for reusable catalytic devices

Polysaccharides are often utilized as reducing and stabilizing agents and as support in the synthesis of gold nanoparticles (AuNPs). However, using approaches like spin coating or dip coating, AuNPs are generally bound to the support only by weak interactions, which can lead to decreased stability of the composite. Here, a two-stage approach for the preparation of composites with covalently anchored AuNPs is proposed. First, 5 nm AuNPs with high catalytic activity for the reduction of 4-nitrophenol (TOF = 15.8 min−1) were synthesized and stabilized using fully oxidized and solubilized 2,3-dialdehyde cellulose (DAC). Next, the carbonyl groups in the shell of prepared nanoparticles were used to tether AuNPs to chitosan nanofibers with quantitative efficacy in a process that we termed “affinity anchoring”. Schiff bases formed during this process were subsequently reduced to secondary amines by borohydride, which greatly improved the stability of the composite in the broad pH range from 3 to 9. The catalytic efficacy of the resulting composite is demonstrated using a model catalytic device, showing high stability, fast conversion rates, and direct reusability. © 2023 Elsevier LtdDKRVO, (RP/CPS/2022/007); Tomas Bata University in Zlin, TBU, (IGA/CPS/2023/006); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR, (23-07361S); Masarykova Univerzita, MU, (MUNI/A/1298/2022

Non-aqueous synthesis of homogeneous molybdenum silicate microspheres and their application as heterogeneous catalysts in olefin epoxidation and selective aniline oxidation

In this work, a novel synthesis of homogeneous molybdenum silicate spheres under non-aqueous conditions is presented. A preparation method is based on the condensation of molybdenum metal–organic framework-based precursor solution prepared via a microwave-assisted approach from bis(acetylacetonato)dioxomolybdenum and biphenyl-4,4′-dicarboxylic acid with 3-aminopropyltriethoxysilane under non-aqueous conditions. The as-prepared product was calcined at 500 °C to obtain amorphous and porous molybdenum silicate microspheres with homogeneously distributed molybdenum species within silicate matrix. The microspheres exhibit an average size of about 480 nm. This material was further studied as a heterogeneous catalyst for the epoxidation of olefins via the model catalytic epoxidation of cyclohexene with cumylhydroperoxide. High catalytic activity at the moderate temperature (65 °C) with the conversion of 86% after 2 h and the high selectivity to cyclohexene oxide has been achieved. In addition, molybdenum silicate microspheres exhibit catalytic activity and high selectivity in the oxidation of aniline to nitrosobenzene. © 2021 The Korean Society of Industrial and Engineering ChemistryRP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018110, LM2018127; Grantová Agentura České Republiky, GA ČR: GJ20-03636Y; Central European Institute of Technology, CEITEC; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

Nickel nanoparticle-decorated reduced graphene oxide via one-step microwave-assisted synthesis and its lightweight and flexible composite with Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene polymer for electromagnetic wave shielding application

Nickel nanoparticle–decorated reduced graphene oxide nanocomposites (NiG) were prepared by a one-step microwave-assisted solvothermal method. The as-prepared NiG nanocomposite systems were further heated up to 800 °C under an inert atmosphere (named NiG-800) to modify their structural and electromagnetic properties. Thereafter, these developed NiG-800 nanocomposite systems of rGO and nickel nanoparticles (25 wt.%) were applied as nanofillers (50 wt.% and 70 wt.%) in a SEBS (Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene) polymer matrix to create NiG-800(50)-SEBS and NiG-800(70)-SEBS nanocomposites. The addition of NiG-800 to SEBS led to an increase of Young’s modulus from 16 (SEBS) to 35 MPa (NiG-800(70)-SEBS) while the maximum elongation is still around 300%. The developed NiG-800(70)-SEBS nanocomposite exhibited high-performance electromagnetic wave absorption (minimum reflection loss RLmin ≈ –48.2 dB at 9.29 GHz) at a low thickness of 2.3 mm in the frequency range of 8.2−12.4 GHz. The prepared NiG-800(70)-SEBS nanocomposite has the potential of an electromagnetic wave absorber. The NiG-800(70)-SEBS nanocomposite reported here has total shielding efficiency > 10 dB at a thickness of 1 mm in the whole frequency range (X-band) with reflection ≈ 50% and absorption ≈ 40% which has the potential for electromagnetic wave absorber applications. © 2023, The Author(s).RP/CPS/2022/005, RP/CPS/2022/007; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018110; Univerzita Tomáše Bati ve Zlíně; Masarykova Univerzita, MU: MUNI/A/1298/2022; Lékařská fakulta, Masarykova univerzita, LF MU, LF MUNational Technical Library in Prague; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/007, RP/CPS/2022/005]; MEYS CR [LM2018110

Microwave-assisted synthesis of platelet-like cobalt metal-organic framework, its transformation to porous layered cobalt-carbon nanocomposite discs and their utilization as anode materials in sodium-ion batteries

In this work a facile microwave-assisted synthesis of a platelet-like cobalt-based metal-organic framework (MOF) material is presented. This material was synthesized from cobalt(II) acetylacetonate and biphenyl-4,4′-dicarboxylic acid (Bpdc) in N,N’-dimethylformamide at 160°C. As-prepared Co-Bpdc MOF product with a platelet-like disc architecture was transformed by heat treatment in a nitrogen atmosphere at 800°C to porous cobalt-carbon nanocomposite discs. It is demonstrated that this synthetic strategy allows for obtaining magnetic microporous carbon layered discs with homogeneously incorporated metallic cobalt nanoparticles with a size of ca. 4 nm. The Co-C nanocomposite material was characterized by a variety of physico-chemical methods. It is shown that both Co-Bpdc MOF and Co-C nanocomposite were electrochemically active in sodium battery system as a material for the negative electrode. The high capacity retention over 80% and capacities over 200 mAh g–1 in the sodium-ion battery systems have been achieved. © 2019 Elsevier LtdMinistry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504, LTT19001]; Operational Program Research and Development for Innovations; European Regional Development Fund (ERDF) within the framework of project CPS - strengthening research capacityEuropean Union (EU) [CZ.1.05/2.1.00/19.0409]; national budget of Czech Republic within the framework of project CPS - strengthening research capacity [CZ.1.05/2.1.00/19.0409]; BUT specific research programme [FEKT-S-17-4595