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Films formed by the heterojunction of CuWO₄ and TiO₂ on conductive transparent substrate (fluorine-doped tin oxide - FTO) were utilized in moxifloxacin (MOX) degradation under polychromatic irradiation. The individual materials and the heterojunctions were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), confirming the formation of heterojunctions from pure materials. Compared to the other configuration, the electrochemical characterizations showed higher photocurrent for FTO|CuWO₄|TiO₂ heterojunction, associated with better charge transport in the film. Thus, the photocatalytic activity of the FTO|CuWO₄|TiO₂ heterojunction was investigated for MOX degradation, which achieved an oxidation of 54.4 % of the drug in 150 min, employing the configuration electrochemically assisted heterogeneous photocatalysis (EHP). The efficiency of the heterojunction is about 2.5 times greater than that shown by electrodes formed from their individual materials. Radical scavenger studies showed that •OH radicals are the main species responsible for MOX oxidation process. The results of XPS, radical scavenging, photoelectrochemical, and photoelectrocatalytic activity show a charge transfer mechanism associated with a direct Z-scheme and that the FTO|CuWO₄|TiO₂ film is promising for the degradation of organic pollutants.

Hydroformylation is an important industrial process that produces aldehydes from alkenes and syngas in accordance with the atom economy principle. Hydroaminomethylation, on the other hand, allows the direct conversion of alkenes into valuable tertiary amines in a sequential one-pot reaction involving hydroformylation followed by hydrogenation of the imine or enamine produced by condensation of the amine with the aldehyde formed by the first hydroformylation step. Recycling of the expensive organometallic catalyst could be achieved by working in aqueous biphasic conditions, with the catalyst immobilised in the aqueous phase by water-soluble ligands, while the reactants and products are in the organic phase. However, for highly hydrophobic substrates like long chain olefins, a mass transfer additive is mandatory in order to obtain high productivity. With this in mind, the use of native and chemically modified cyclodextrins and more sophisticated cyclodextrin-based systems in the aqueous biphasic hydroformylation and hydroaminomethylation are reviewed. The early first results, their developments and the recent advances are discussed. The promotor effect of these cyclodextrins is highlighted by key examples. The main examples have been designed in batch mode, but perspectives in continuous flow are also presented.

This work studied the effect of adding Fe to an Ir/γ-Al₂O₃ catalyst in different Fe/Ir molar ratios (0.5, 1.0, and 2.0) on the conversion and selectivity of the glycerol hydrogenolysis reaction. Additionally, the effect of the calcination of the solids was evaluated. The catalysts were prepared by incipient wetness impregnation of the Ir and Fe salts on the support and were characterized by textural analysis, XRD, TPR, XPS, and TEM-EDS techniques. The interaction between Ir and Fe was evidenced in the characterization of the catalysts. The addition of Fe to the Ir catalyst led to an increase in activity; however, this effect was better observed for the non-calcined catalyst series. The calcined catalyst series did not present a significant increase in glycerol conversion and selectivity to 1,2-PDO, probably due to the sintering of Ir occasioned by the catalyst's calcination, as observed in the characterization. For non-calcined bimetallic catalysts, the conversion increased from 7 % to 21.5 % for IrFe_2.0/γ-Al₂O₃ catalyst, probably due to the synergic effect between both metals and the formation of Ir-Fe bimetallic particles, as evidenced in EDS mapping and XPS analysis. In the presence of this catalyst, selectivity to 1,2-PDO remained high (90.1 %).

This work describes the investigation of the photoelectrochemical response and photocatalytic activity of homojunction NiWO₄|CoWO₄ films as a photoanode for progesterone removal in wastewater. The junction of semiconductor films is a strategy that aims to reduce charge recombination and favor the photocatalytic activity of the material. The bare and coupled films were deposited by drop-casting from polymeric resin. The structural, morphological, and optical properties were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy, respectively. The bare and coupled nanostructured films showed irregular morphological, monoclinic structure and optical properties in the visible region in the spectrum. Compared with NiWO₄ and CoWO₄|NiWO₄ films, NiWO₄|CoWO₄ film showed enhanced photoelectrochemical response (27μA cm⁻² at 0.7 V vs. Ag/AgCl) and efficient photoelectrocatalytic performance for progesterone degradation under polychromatic light irradiation. The favorable position of the edge of the conduction and valence bands helps in the charge transfer process, increasing the lifetime charge recombination to 19.7 s. According to the results, after applying the polarization potential in the photoelectrocatalytic process, the photodegradation efficiency of the drug progesterone was verified for approximately 150 minutes, showing that 92 % of progesterone was photodegraded on NiWO₄|CoWO₄ homojunction film. Furthermore, the film remained active for 3 reuse cycles.

Furfural is a biomass-derived chemical that can be converted into different valuable chemicals using green processes. The current study deals with a highly efficient, robust, and selective solid catalyst for the aldol condensation of furfural and 3-pentanone to synthesize 1-furan-2-yl-2-methylpent-1-en-3-one under environmentally benign conditions. CaZr (different molar ratios of Ca and Zr) mixed oxide (MO) catalysts along with reference CaO and ZrO₂ catalysts were prepared by the hydrothermal technique and investigated for the current reaction. Among all, CaZr (1:2) MO catalyst was found to be the best for the conversion of furfural due to its desirable basic strength with good surface area and reusability characteristics. Furfural conversion and 1-furan-2-yl-2-methylpent-1-en-3-one selectivity were found to be 94 % and 98 %, respectively, under optimized reaction conditions. Effect of various reaction parameters was studied carefully to achieve the maximum yield of the required product. Reaction mechanism and kinetics were developed. The reaction aligns with the LHHW mechanism, and the activation energy was determined to be 10.40 kcal/mol.

This contribution reports the impact of the reaction pressure (1, 10, 20 and 30 bar) on the deactivation of the commercial catalyst Cu/ZnO/Al₂O₃ during the CO₂ hydrogenation to CH₃OH. The best performance was obtained at 30 bar with ≈ 30 % of initial CO₂ conversion (X_CO2) and CH₃OH space-time-yield (STY_MEOH) of 255 mg_MeOH/g_cat.h. Although the initial conversion decreased drastically the activity was kept along all the reaction time, ≈ 5 %. The analysis of fresh and post-reaction samples using X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Electron Microscopy (SEM-FEG, STEM, HRTEM), and Raman Spectroscopy demonstrated profound microstructural changes, characterized by phase sintering, formation of Cu-aluminate, segregation of phases, an imbalance among Cu-species, as well as the presence of coke. As the catalyst Cu/ZnO/Al₂O₃ has a particular microstructure, these modifications provoked the loss of the geometric configuration of the active sites, which might also originate a disturbance in the electronic interactions, resulting in activity loss. HRTEM and STEM image (dark field) of the passivated sample showed the presence of crystalline nanostructures (d < 4 nm) attributed to Cu⁰, surrounded by amorphous phases. STEM images of spent samples also reveals the development of hierarchical and elongated nanostructures spread on all the spent catalysts. This result foresees the co-existence of small nanoparticles (< 5 nm) with large ones in all the catalyst surface, corroborating XRD results. It is noteworthy that the hydrothermal environmental developed inside the reactor originated from the high pressure and the continuous H₂O production, both which may favor the phase sintering and aluminate formation.

Stringent environmental regulations require reducing fuel sulfur content for adequate operation of vehicle emission control systems. Deep hydrodesulfurization (HDS) removes over 99 % of sulfur compounds, including the less reactive ones like 4,6-dimethyldibenzothiophene (4,6-DMDBT). However, HDS kinetics is inhibited by compounds like H₂S, nitrogenous compounds, and aromatics. This article delves into kinetic modeling of concurrent hydrodesulfurization (HDS) of 4,6-DMDBT and hydrodenitrogenation (HDN) of quinoline (Q) reactions. It explored the use of stacked beds of CoMoP and NiMoP catalysts in two configurations. The effects of temperature and weight hourly space velocity (WHSV) on conversions and product yields were investigated. Higher reaction temperatures, in addition to the expected increase of 4,6-DMDBT and quinoline overall conversions, also led to an increased in hydrogenation selectivity. Kinetic models were developed for these reactions and catalysts, and kinetic parameters were estimated using a hybrid numerical procedure. The configuration where CoMoP was the first catalyst to encounter the reaction feedstock exhibited higher conversions for both reactions. The apparent activation energies for 4,6-DMDBT HDS were 99 and 41 kJ mol⁻¹ for NiMoP and CoMoP, respectively while for HDN, values of 62 and 68 kJ mol⁻¹ were estimated. For the adsorption enthalpy of nitrogenous compounds, values of −59 and −40 kJ mol⁻¹ were observed for NiMoP and CoMoP, respectively.

Innovative and sustainable approaches are being pursued to convert plastic waste into high-value fuels, particularly without using noble metal catalysts or external hydrogen sources. In this scenario, we explored the utilization of a spent fluid catalytic cracking (FCC) catalyst (ECAT), aiming to enhance the yield and quality of products through catalytic cracking of Polypropylene (PP) under different reaction conditions. Under a 20 bar H₂ atmosphere, ECAT efficiently cracked PP into alkanes (71.6 %) and aromatics (25.5 %), with minimal alkenes (2.2 %) production. Similarly, under a 20 bar N₂ atmosphere, ECAT achieved comparable conversion levels, producing mainly saturated hydrocarbons, which was intriguing. However, tests conducted at 1 bar N₂ pressure showed that PP conversion remains unaffected but presents higher olefins’ yield and lower aromatics than ECAT. Thus, pressure seems to favor aromatization and in situ hydrogen transfer. By comparing the performance of ECAT with commercial CBV 712 zeolite, we propose that PP acts as an internal hydrogen source, eliminating the need for external supply improving efficiency and selectivity. Interestingly, mechanistic insights suggested that dehydroaromatization and hydrogen transfer within zeolite pores were dominant, and pressure (H₂ or N₂) could have helped it. In addition, contrary to previous studies that claim that metal contaminants in ECAT are essential for the hydrogenation process, our findings suggest that for this particular ECAT composition, we do not observe any boost in alkane yield due to the presence of these metals. Hence, our study comprehensively evaluates different strategies that can be employed to promote PP upcycling promoted by ECAT.

The conversion of glycerol into value-added products is crucial for reducing waste generation in the biodiesel industry. In this context, glycerol carbonate has emerged as a promising molecule, capable of being produced through various processes, with glycerol transesterification being considered the most environmentally friendly method. In order to investigate the transesterification process comprehensively, this work focused on reactions between glycerol and different carbonic acid esters (dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate), utilizing calcium oxide (CaO) as a basic catalyst. The catalyst was obtained commercially and characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The catalyst characterizations showed that it consisted of nano and micrometric particles with high purity, making it suitable for use without prior pretreatment. The reactions were conducted in a batch reactor using dimethylformamide as a solvent, and the products were analyzed by gas chromatography (GC-FID and GC-MS). Experiments were performed to investigate the effects of different reaction parameters on the formation process of glycerol carbonate and potential co-products. CaO showed moderate catalytic activity in glycerol conversion, which occurred in three steps, forming glycerol carbonate with high selectivity, along with small amounts of co-products, glycidol and glycerol tricarbonate. Thus, considering the results obtained in this and other studies, it was possible to identify that moderately strong basic catalysts favor simple reaction mechanisms, predominantly yielding glycerol carbonate. Conversely, highly basic catalysts induce more complex reaction mechanisms, resulting in significant formation of co-products.

Owing to their metallic-like surface electronic properties and their capacity to act as reservoirs and solid transfer agents for active nitrogen, transition metal nitrides are interesting as solid catalysts for C-C and C-N coupling reactions for the bottom-up production of higher (C₂₊) nitrogenated chemicals from unconventional carbon resources. The catalytically active state and reaction mechanism for the direct synthesis of acetonitrile from syngas/ammonia mixtures are studied on an unsupported Mo catalyst from complementary experimental and computational approaches. Temperature resolved X-ray diffraction and X-ray photoemission spectroscopy verify that an oxidic MoO₃ catalyst precursor undergoes in situ (near-surface) nitridation, upon exposure to reaction conditions at 723 K, rendering Mo₂N the actual working catalyst. Density Functional Theory mechanistic investigations on a γ-Mo₂N(100) model surface point to a hydrogen-assisted CO dissociation on the nitride surface. Moreover, surface oxygen, evolved from CO dissociation, is predicted to play a central role as hydrogen acceptor, to enable the dehydrogenative NH₃ dissociation. Direct condensation of CH and N adspecies proceeds with a low energy barrier of 33 kJ mol⁻¹, which makes C-N coupling preferred over full hydrogenation of CH_x species, in agreement with the experimental modest selectivity to methane (ca. 10 %). Both experimental and computational results indicate that HCN is a major intermediate product along the reaction pathway to acetonitrile. No energetically feasible associative reaction pathways could be identified for C-C coupling from HCN. The dissociation of the latter intermediate product is predicted to precede the reaction of CN adspecies to CH_x. Similarly to NH₃ dissociation, dehydrogenative HCN activation on the Mo₂N surface is predicted to be facilitated through hydrogen abstraction by surface oxygen species, yet subjected to a comparatively higher energy barrier (>120 kJ mol⁻¹), therefore likely to control the overall kinetics. These findings suggest that the enhancement of HCN dissociation is a central design objective towards Mo₂N-based catalysts with advanced performance.