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•The MPV reduction of aromatic aldehydes with methanol was catalyzed by MgO.•The mechanism of the reaction was elucidated by means of DFT calculations.•The mechanism was fully ...consistent with results of catalytic experiments.•The reaction was of general validity for the reduction of aromatic aldehydes.•Furfural was reduced to furfuryl alcohol with 100% yield.
The previously unexplored use of methanol as a H-transfer agent for the Meerwein–Ponndorf–Verley reduction of aromatic aldehydes and aryl ketones is described. Furfural, 5-hydroxymethylfurfural, benzaldehyde, and acetophenone were selectively reduced to the corresponding alcohols in mild conditions. The reaction mechanism was elucidated by means of reactivity tests and DFT calculations. It was found to include the highly efficient H-transfer with the formation of formaldehyde, which further reacted with excess methanol to generate the adsorbed hemiacetal. In turn, the latter reduced carbonyl, with the formation of methylformate, which further decomposed into CO, CH4, and CO2. Compared to the alcohols typically used for carbonyl reductions, methanol showed the advantage of producing gaseous components as the only co-products, which are easily separated from the reaction medium. In the case of furfural, a 100% yield to furfuryl alcohol was obtained, using the high-surface area MgO as the easily recoverable and reusable catalyst.
The oxidation of 5-hydroxymethyl-2-furfural was studied under mild reaction conditions using TiO2-supported Au and Au-Cu catalysts synthesized from pre-formed nanoparticles. Bimetallic gold-copper ...catalysts display superior activity as compared to monometallic gold. Moreover, after reaction, the bimetallic Au-Cu catalysts can be recovered by filtration and reused without significant loss of activity and selectivity whereas gold materials are not stable. STEM-HAADF imagining and XEDS spectra obtained from bimetallic materials show that particles are homogeneous AuCu alloys. No AuCu ordering or segregation effects were noted from these analyses, and the Au:Cu ratio was quite consistent from particle-to-particle irrespective of its absolute size, proving the efficiency of the original method of synthesis utilized. Isolation effects of gold by copper in the alloy nanoparticles is imagined to play a pivotal role in the reaction. The effect of oxygen pressure, metal loading, reaction time, amount of base and temperature were studied in detail and a 99% yield of furandicarboxylic acid was achieved under optimized reaction conditions.
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► Preparation of Au and Au–Cu TiO2 supported catalysts from pre-formed nanoparticles. ► Cu presence allowed a remarkable increase of the catalytic behavior. ► Stability of Au–Cu ...catalysts was much higher than that shown by the Au material.
5-Hydroxymethyl-2-furfural (HMF) oxidation to furandicarboxylic acid (FDCA) was performed under mild reaction conditions using TiO2-supported Au and Au–Cu catalysts synthesized from pre-formed nanoparticles of different composition. Catalysts were characterized by BET, XRD and XPS. The Au3Cu1/TiO2 catalyst exhibited the best catalytic performance for FDCA yield. Moreover, after reaction, bimetallic Au–Cu catalysts with high gold content can be recovered by filtration and reused without significant loss of activity and selectivity; whereas, the monometallic gold materials are not stable.
The bio-based substrate and target product 2,5-bishydroxymethylfuran (BHMF) demonstrated to influence the reaction kinetics in the homogeneous reduction of 5-hydroxymethylfurfural (HMF) catalyzed by ...the Ru-based Shvo's catalyst. A combined experimental and computational study supports an important role of the -CH2OH moiety which may be involved in the catalytic cycle toward the formation of different intermediates from HMF and BHMF. The reaction is selective and leads to quantitative formation of BHMF working under mild conditions. Furthermore, an optimized recycling procedure which avoids the use of water, allows recover and reuse of the catalyst without loss of activity. The mechanistic insights from this work may be extended to provide a general description of the chemistry of the Shvo's catalyst feeding further bio-based molecules.
We present the discovery of a very extended (550 kpc) and low-surface-brightness (3.3 at 144 MHz) radio emission region in Abell 1318. These properties are consistent with its characterisation as an ...active galactic nucleus (AGN) remnant radio plasma, based on its morphology and radio spectral properties. We performed a broad-band (54 - 1400 MHz) radio spectral index and curvature analysis using LOFAR, uGMRT, and WSRT-APERTIF data. We also derived the radiative age of the detected emission, estimating a maximum age of 250 Myr. The morphology of the source is remarkably intriguing, with two larger, oval-shaped components and a thinner, elongated, and filamentary structure in between, plausibly reminiscent of two aged lobes and a jet. Based on archival Swift as well as SDSS data we performed an X-ray and optical characterisation of the system, whose virial mass was estimated to be $ This places A1318 in the galaxy group regime. Interestingly, the radio source does not have a clear optical counterpart embedded in it, thus, we propose that it is most likely an unusual AGN remnant of previous episode(s) of activity of the AGN hosted by the brightest group galaxy ($ which is located at a projected distance of sim 170 kpc in the current epoch. This relatively high offset may be a result of IGrM sloshing sourced by a minor merger. The filamentary morphology of the source may suggest that the remnant plasma has been perturbed by the system dynamics, however, only future deeper X-ray observations will be able to address this question.
The recovery and use of oil crops' byproducts is becoming essential to assure the sustainability of biodiesel production. This work aims to study oil cakes obtained from three second-generation oil ...feedstocks, i.e., Brassica juncea, Brassica carinata, and Camelina sativa, to be used as animal feed. To do so oil cakes were characterized for crude protein content, fibre fractions, macro- and micro-nutrient composition. Fatty acids and amino acid profiles and energy contents were also determined. Results indicated good nutritional properties for the oil cakes, particularly for AA and FA. A preliminary study to evaluate the effect of cakes' recovery on biodiesel production sustainability indicated a GHG reduction vs. petroleum diesel of 70 %, 67 %, 65 % for B. carinata, B. juncea, C. sativa, respectively. These data may be compared with the Renewable Energy Directive (RED II, 2021) of the EU that asks for a GHG reduction of 65 %.
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•Second generation oil crops can be used producing biodiesel.•Oil by-products recovery improves biodiesel production sustainability.•Oil by-products have good nutritional profile suggesting their used as feed.•Oil by-products can be used as animal feed to the dose of 10 g 100 g−1 diet.•Biodiesel GHG reductions of 70 % can be achieved recovering by-products as feed.
The bio-based substrate and target product 2,5-bishydroxymethylfuran (BHMF) demonstrated to influence the reaction kinetics in the homogeneous reduction of 5-hydroxymethylfurfural (HMF) catalyzed by ...the Ru-based Shvo's catalyst. A combined experimental and computational study supports an important role of the -CH
2
OH moiety which may be involved in the catalytic cycle toward the formation of different intermediates from HMF and BHMF. The reaction is selective and leads to quantitative formation of BHMF working under mild conditions. Furthermore, an optimized recycling procedure which avoids the use of water, allows recover and reuse of the catalyst without loss of activity. The mechanistic insights from this work may be extended to provide a general description of the chemistry of the Shvo's catalyst feeding further bio-based molecules.
The Shvo's catalyzed selective hydrogenation of HMF to BHMF showed substrate and product effects on the reaction rate. DFT calculation suggested the formation of several intermediates influencing the catalytic cycle.
We present the analysis of new, deep \(Chandra\) observations (130~ks) of the galaxy cluster Abell~2495. This object is known for the presence of a triple offset between the peaks of the intracluster ...medium (ICM), the brightest cluster galaxy (BCG), and the warm gas glowing in H\(\alpha\) line. The new \(Chandra\) data confirm that the X-ray emission peak is located at a distance of \(\sim\)6.2 kpc from the BCG, and at \(\sim\)3.9 kpc from the H\(\alpha\) emission peak. Moreover, we identify two generations of X-ray cavities in the ICM, likely inflated by the central radio galaxy activity. Through a detailed morphological and spectral analysis we determine that the power of the AGN outbursts (\(P_{cav} = 4.7\pm1.3\times10^{43}\)~erg~s\(^{-1}\)) is enough to counterbalance the radiative losses from ICM cooling (\(L_{cool} = 5.7\pm0.1\times10^{43}\)~erg~s\(^{-1}\)). This indicates that, despite a fragmented cooling core, Abell~2495 still harbors an effective feedback cycle. We argue that the offsets are most likely caused by sloshing of the ICM, supported by the presence of spiral structures and a probable cold front in the gas at \(\sim\)58 kpc east of the center. Ultimately, we find that the outburst interval between the two generations of X-ray cavities is of the order of the dynamical sloshing timescale, as already hinted from the previous \(Chandra\) snapshot. We thus speculate that sloshing may be able to regulate the timescales of AGN feedback in Abell~2495, by periodically fuelling the central AGN.
We present a multi-wavelength analysis of the galaxy cluster A1668, performed by means of new EVLA and Chandra observations and archival H\(\alpha\) data. The radio images exhibit a small central ...source (\(\sim\)14 kpc at 1.4 GHz) with L\(_{\text{1.4 GHz}}\) \(\sim\)6 \(\cdot\) 10\(^{23}\) W Hz\(^{-1}\). The mean spectral index between 1.4 GHz and 5 GHz is \(\sim\) -1, consistent with the usual indices found in BCGs. The cooling region extends for 40 kpc, with bolometric X-ray luminosity L\(_{\text{cool}} = 1.9\pm 0.1 \cdot\) 10\(^{43}\) erg s\(^{-1}\). We detect an offset of \(\sim\) 6 kpc between the cluster BCG and the X-ray peak, and another offset of \(\sim\) 7.6 kpc between the H\(\alpha\) and the X-ray peaks. We discuss possible causes for these offsets, which suggest that the coolest gas is not condensing directly from the lowest-entropy gas. In particular, we argue that the cool ICM was drawn out from the core by sloshing, whereas the H\(\alpha\) filaments were pushed aside from the expanding radio galaxy lobes. We detect two putative X-ray cavities, spatially associated to the west radio lobe (cavity A) and to the east radio lobe (cavity B). The cavity power and age of the system are P\(_{\text{cav}} \sim\) 9 \(\times\)10\(^{42}\) erg s\(^{-1}\) and t\(_{\text{age}} \sim\)5.2 Myr, respectively. Evaluating the position of A1668 in the cooling luminosity-cavity power parameter space, we find that the AGN energy injection is currently consistent within the scatter of the relationship, suggesting that offset cooling is likely not breaking the AGN feedback cycle.
The demand of energy, fuels and chemicals is increasing due to the strong growth of some countries in the developing world and the development of the world economy. Unfortunately, the general picture ...derived sparked an exponential increase in crude oil prices with a consequent increase of the chemical, by-products and energy, depleting the global market. Nowadays biomass are the most promising alternative to fossil fuels for the production of chemicals and fuels.
In this work, the development of three different catalytic processes for the valorization of biomass-derived has been investigated.
5-hydroxymethylfurfural oxidation was studied under mild reaction condition using gold and gold/copper based catalysts synthetized from pre-formed nanoparticles and supported onto TiO2 and CeO2.
The analysis conducted on catalysts showed the formation of alloys gold/copper and a strong synergistic effect between the two metals. For this reason the bimetallic catalysts supported on titania showed a higher catalytic activity respect to the monometallic catalysts.
The process for the production of 2,5-bishydroxymethyl furan (BHMF) was also optimized by means the 5-hydroxymethylfurfural hydrogenation using the Shvo complex. Complete conversion of HMF was achieved working at 90 °C and 10 bar of hydrogen. The complex was found to be re-usable for at least three catalytic cycles without suffering any type of deactivation.
Finally, the hydrogenation of furfural and HMF was carried out, developing the process of hydrogen transfer by using MgO as a catalyst and methanol as a hydrogen donor. Quantitative yields to alcohols have been achieved in a few hours working in mild condition: 160 °C and at autogenous pressure. The only by-products formed were light products such as CO, CO2 and CH4 (products derived from methanol transformation), easily separable from the reaction solution depressurizing the reactor.
