Oxidative Conversion Research Articles

Photochemical transformation and immobilization of thallium in the presence of iron and arsenic: Mechanistic insights from the coupled formation of arsenate complexes

Despite the occurrence of thallium (Tl) in the acidic mining-affected areas being highly positively correlated with iron (Fe) and arsenic (As), the effects of the two accompanying elements on Tl redox transformation and immobilization remain largely unknown. Here, we investigated the photochemical redox kinetics and immobilization efficiency of Tl for a wide range of As/Fe and As/Tl ratios under acidic conditions. We provided the first experimental confirmation of the complexation of Tl(III) with As(V) by the spectrophotometric method and revealed the role of Tl(III)-As(V) complexes in decreasing the photoreduction rate of Tl(III) under sunlight. Additionally, the negative impact of colloidal Fe(III)-As(V) and Fe(III)-As(III) complexes formation on decreasing photoactive Fe(III) speciation and thus the apparent quantum yield of •OH was highlighted, which consequently hindered the oxidative conversion of Tl(I) to Tl(III). We rationalize the kinetics results by developing the model which quantitatively describes the photochemistry of Tl. Furthermore, we demonstrated the colloid-facilitated immobilization of Tl(III) through the formation of Tl(III)-As(V) clusters and surface adsorption onto the complexes. This study broadens the mechanistic understanding of redox transformation and immobilization potential of Tl and aids in assessing Tl speciation as well as its coupled transformation with Fe and As species in the sunlit water environment.

Hierarchical molecular sieve-based Ce-Ru oxide for enhanced catalytic oxidation of chlorobenzene: Insight into the synergistic effect of Ce and Ru, the role of molecular sieve

In this work, a series of hierarchical molecular sieve were synthesized via adjusting the ratio of Si/Al. Then, Ce and Ru were supported on the molecular sieve and the loading amount of Ru were optimized. Catalytic evaluation showed that 5Ce0.5Ru/HZ-3 with the value Si/Al ratio of 80 performed the best catalytic activity of chlorobenzene oxidation with T50 and T90 values of 238 ℃ and 278 ℃, respectively and no chlorobenzene conversion can be seen on the 5Ce/HZ-3 and HZ-3, indicating that Ru was the active sites on 5Ce0.5Ru/HZ-3 and Ce played a promoter role in chlorobenzene oxidation. Catalytic stability showed that 5Ce0.5Ru/HZ-3 can maintain the complete conversion of chlorobenzene oxidation at 300°C for 190 h and the CO2 and HCl selectivity kept around 80% and 27%, respectively, while 5Ce0.5Ru performed worse catalytic stability and no HCl was detected. Subsequently, characterization results implied that HZ-3 with the Si/Al ratio of 80 had the biggest mesoporous volume of 0.5193 cm3·g−1 on the basis of micropore volume around 0.1236 cm3·g−1, which was beneficial to the diffusion of reactant molecule; Raman spectra implied that there is a strong interaction between Ce and Ru. H2-TPR and O2-TPD showed that 5Ce0.5Ru/HZ-3 possessed the biggest consumption of hydrogen (0.486 mmol·g−1), surface adsorbed oxygen (0.683 mmol·g−1) and surface lattice oxygen (0.626 mmol·g−1), which was conducive to the adsorption and dissociation of reactant molecule; XPS showed 5Ce0.5Ru/HZ-3 had the biggest molar percentage of Ru4+ species (79.50%) and Ce3+ species (44.14%), which can induce the generation of much more oxygen vacancies. Overall, the introduction of Ce can result in the improvement of physical-chemical properties of 5Ce0.5Ru/HZ-3. Finally, the possible reaction route was given based on the in-situ DRIFTS and TD/GC-MS result.

ZIF-67-derived Co@NC as an efficient catalyst for magnesium sulfite oxidation in the flue gas desulfurization process

Magnesium desulfurization is a wet flue gas desulfurization (WFGD) technology widely used in China, however, the low oxidation rate of magnesium sulfite (MgSO3), a byproduct of WFGD, causes the subsequent oxidation and crystallization process to require amount energy. Here, we prepared a cobalt-based nitrogen-doped porous carbon catalyst (Co@NC) using ZIF-67 as a precursor for the efficient catalytic oxidation of MgSO3 generated during magnesium desulfurization. The performance of Co@NC catalysts obtained at an optimal calcination temperature of 650 °C showed that the catalysts with oxidation rates up to 0.1332 mmol·L−1·s−1 of MgSO3 were considerably better than those previously studied, which outperformed the catalysts described in earlier research by a considerable margin. Further studies revealed that the Co@NC’s exceptional catalytic activity was attributed to both its special porous structure and the exposed active Co sites in the organic skeleton. The uniformly dispersed Co species act as the active sites of the Co@NC that can be fully contacted with the reactant. The presence of 0.5 g·L−1 Co@NC increases the MgSO3 oxidation rate by about 14 times compared to the noncatalytic benchmark. A practical tactic is furnished by this research for energy saving and emission reduction in the WFGD process, especially for the efficient oxidation and resource conversion of the by-product MgSO3.

Efficient Selective Catalytic Fixation of CO2 into Epoxide to Form Cyclic Carbonates Using Sodium Aluminate Engineered Gamma Alumina Catalyst

The anthropogenic carbon dioxide (CO2) fixation and various engineering strategies are gaining very significant attention because of the expansion of the net‐zero carbon environment in the atmosphere. Herein, we designed a sodium aluminate@γ‐alumina (NaAlO2@γ‐Al2O3) catalyst by a simple and facile precipitation and impregnation tactics. A series of different weight percentage NaAlO2@γ‐Al2O3 materials were successfully synthesized and well characterized by using advanced analytical and spectroscopic techniques such as TGA, XRD, FE‐SEM, TEM/HR‐TEM, FT‐IR, Raman, TPD, and XPS analysis. The NaAlO2@γ‐Al2O3 catalyst was employed as a competent catalyst for the CO2 fixation under atmospheric pressure reaction conditions. The catalytic activity results evidently revealed that the cycloaddition reaction successfully achieved 94% styrene oxide conversion and 93% selectivity, along with an 87% yield of the styrene carbonate at 120 °C for 6 h. Furthermore, we comprehensively examined the effect of different reaction parameters such as the effect of sodium aluminate amount, co‐catalyst amount, temperature, and time for CO2 fixation reaction. Additionally, different terminal and internal epoxides were tested under optimized reaction conditions and achieved moderate to excellent yield of the desired cyclic carbonate products. Interestingly, a plausible reaction mechanism was proposed for the styrene carbonate synthesis using NaAlO2@γ‐Al2O3 catalyst surface with the support of characterization and experimental results. Remarkably, the NaAlO2@γ‐Al2O3 catalyst could be easily recoverable and successfully recyclable up to six consecutive cycles without declining its initial catalytic activity along with stable structural and physicochemical properties.

Mechanisms of endogenous and exogenous partial denitrification in response to different carbon/nitrogen ratios: Transcript levels, nitrous oxide production, electron transport

Nitrite as an important substrate for Anammox can be provided by partial denitrification (PD). In this study, endogenous partial denitrification (EdPD) and exogenous partial denitrification (ExPD) sludge were domesticated and their nitrite transformation rate reached 74.4% and 83.4%, respectively. The impact of four carbon/nitrogen (C/N) ratios (1.5, 3.0, 5.0 and 6.0) on nitrous oxide (N2O) emission and denitrification functional genes expression in both PD systems were investigated. Results showed that elevated C/N ratios enhanced most denitrification genes expression, but in EdPD, high nitrite levels suppressed nosZ genes expression (from 9.4% to 1.4%), leading to increased N2O emission (0 to 3.4%). EdPD also exhibited lower electron transfer system activity, resulting in slower nitrogen oxide conversion efficiency and more stable nitrite accumulation compared to ExPD. These findings offer insights for optimizing PD systems under varying water quality conditions.

SIMULATION OF THE KINETICS OF HETEROGENEOUS OXIDATION OF N-HEPTANE BY OXYGEN

The catalytic reaction of n-heptane (n-C7H16) oxidation with molecular oxygen has been studied. Various compositions of the polymer catalyst Mn-P4VP/MBAA (where Mn-P4VP is manganese-immobilised poly-4-vinylpyridine and MBAA is N,N′-methylene-bis-acrylamide) containing 2-5 wt% Mn were prepared and tested. The concentration of manganese in the catalyst based on immobilized metal-polymer complexes is within the range of 2-5 wt% Mn. The oxidation reaction was carried out at a ratio of components n-C7H16/O2/polymer catalyst with Mn = 1 : 3.38 : 0.003 and time 6 h within the temperature range 303-383 K. The data on the yield of the major products of n-heptane oxidation are presented, taking into account the initial components, catalyst composition, temperature and the time of oxygen contact with the reacting components. It has been established that during the oxidation of n-C7H16 (303-383 K), the yield of alcohols is higher than the yield of other oxidation products. The oxidative conversion of n-heptane increases from 45 to 75 mol% with an increase in temperature in the range of 303-383 K. For the multistage oxidation of n-heptane with oxygen, a kinetic model was selected and considered. On the basis of this model, the reaction rate constants were calculated in the range of 303-383 K considering the degree of heptane conversion. The activation energy of n-heptane oxidation was estimated, taking into account the method of choosing the most plausible parameter and experimental data on n-heptane convection.

Simulation Study of Propylene Glycol Formation from Propylene Oxide and Water: Effect of Reactor Type, Reactant Ratio, Temperature, and Reactor Configuration

This study investigates the effect of reactor type, reactor configuration, reactor temperature, and reactant ratio on the formation of propylene glycol from propylene oxide and water using HYSY Simulation Software. The reactor types studied were Continuous Stirred Tank Reactors (CSTR) and Plug Flow Reactors (PFR). The effect of the reactant ratio was investigated by varying the mole ratio of propylene oxide to water. The effect of temperature was studied by varying the reaction temperature from 24 to 40°C. The HYSYS simulation results showed that the PFR resulted in the highest conversion compared to the CSTR. The CSTR configuration in series resulted in the highest conversion compared to the CSTR configuration in parallel. The conversion of propylene oxide to propylene glycol increased with increasing temperature. The reactant ratio of 1:1 (propylene oxide to water) resulted in the highest conversion compared to other reactant ratios. The implication of this study is to provide information on a more efficient and economical propylene glycol process.

Sulfurization of cobalt oxide to cobalt sulfide: A positrode for the high-performance supercapacitor

The conversion of transition metal oxide to sulfide has attracted researchers in the use of electrochemical energy devices due to their unique features, like highly oriented crystalline nanostructure, high electrochemical active sites, and tailored morphology. Herein, we demonstrate the preparation of binder-free cobalt sulfide (Co3S4) nanostructure by converting hydrothermally synthesized cobalt oxide (Co3O4) on nickel foam using the hydrothermal method. X-ray photoelectron and diffraction analysis confirms the chemical state and phase of Co3S4 after sulfurization process. The FE-SEM analysis reveals the synthesized nanostructures are rod-like morphology for both Co3O4 and Co3S4 grown on Ni foam. The electrochemical performance of the synthesized binder-free electrode was investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy analysis, which reveals the charge storage mechanism is like faradaic type intercalation and Co3S4/NF electrode reaches areal capacity of 543.7 μAh cm−2 at scan rate of 1 mV s−1 which is approximately 24-folds higher than the Co3O4/NF electrode (22.7 μAh cm−2). The self-discharge study was carried out to identify the factors behind the energy dissipation in the Co3S4/NF electrode. The experimental outcomes disclose insightful information on electrode material prepared via hydrothermal process, and it could accelerate the development of new high-energy density supercapacitor applications.

Debromination of novel brominated flame retardants using Zn-based additives: A viable thermochemical approach in the mitigation of toxic effects during e-waste recycling

Brominated flame retardants (BFRs) are bromine-bearing additives added to the polymeric fraction in various applications to impede fire ignition. The Stockholm Convention and various other legislations abolished legacy BFRs usage and hence, the so-called novel BFRs (NBFRs) were introduced into the market. Recent studies spotlighted their existence in household dust, aquifers and aquatic/aerial species. Co-pyrolysis of BFRs with metal oxides has emerged as a potent chemical recycling approach that produces a bromine-free stream of hydrocarbon. Herein, we investigate the debromination of two prominent two NBFRs; namely tetrabromobisphenol A 2,3-dibromopropyl ether (TD) and tetrabromobisphenol A diallyl ether (TAE) through their co-pyrolysis with zinc oxide (ZnO) and franklinite (ZnFe2O4). Most of the zinc content in electrical arc furnace dust (EAFD) exists in the form of these two metal oxides. Conversion of these metal oxides into their respective bromides could also assist in the selective extraction of the valuable zinc content in EAFD. The debromination potential of both oxides was unveiled via a multitude of characterization studies to analyze products (char, gas and condensates). The thermogravimetric analysis suggested a pyrolytic run up to 500 °C and the TAE treatment with ZnO produced only a trivial amount of brominated compounds (relative area, 0.83%). Phenol was the sole common compound in condensable products; potentially formed by the β-scission debromination reaction from the parental molecular skeleton. Inorganic compounds and methane were the major constituents in the gaseous products. The pyrochar analyses confirmed the presence of metal bromides retained in the residue, averting the bromine release into the atmosphere. The ion chromatography analysis portrayed <8% of HBr gas release into the atmosphere upon pyrolysis with ZnO. The ZnO dominance herein envisaged further probes into other spinel ferrites in combating brominated polymers.

Catalytic fractionation of Palm Kernel shell with Co and Cu over zeolite HY catalysts

Lignocellulosic biomass has the potential to be transformed valuable chemicals. This study extracted lignin from palm kernel shell with liquid phased oxidative fractionation in the presence of Co and Cu loaded over Zeolite HY catalysts. The oxidative fractionation was conducted at temperatures ranging from 140 °C to 180 °C, with various reaction times of 2–4 h. The GCMS analysis identified various products from the oxidative conversion including phenol derivatives (Butylated hydroxytoluene, 1,2-Benzenediol, etc.), phenolic aldehydes (Vanillin, Syringaldehyde, p-hydroxybenzaldehyde, etc.), and carboxylic acids (p-hydroxybenzoic acid, vanillic acid etc.). At a reaction temperature of 180 °C with a 2 h reaction time, Co/Zeolite HY catalyst yielded 9.81% and Cu/Zeolite HY catalyst yielded 13.53% for phenol derivatives. The optimal yield of lignin-derived compounds was achieved with a 5 wt% catalyst loading in the context of biomass weight, particularly with a 10% metal loading of Co and Cu over Zeolite HY support. Additionally, the total yield of lignin-derived compounds obtained was 32.85% for 10%Co/Zeolite HY and 23.89% for 10%Cu/Zeolite HY, catalysts respectively. This research displays incorporating metals into zeolite support subsequently boosts their catalytic efficiency in lignin oxidation.

Deep Potential Molecular Dynamics Study of Propane Oxidative Dehydrogenation.

Oxidative dehydrogenation (ODH) of light alkanes is a key process in the oxidative conversion of alkanes to alkenes, oxygenated hydrocarbons, and COx (x = 1,2). Understanding the underlying mechanisms extensively is crucial to keep the ODH under control for target products, e.g., alkenes rather than COx, with minimal energy consumption, e.g., during the alkene production or maximal energy release, e.g., during combustion. In this work, deep potential (DP), a neural network atomic potential developed in recent years, was employed to conduct large-scale accurate reactive dynamic simulations. The model was trained on a sufficient data set obtained at the density functional theory level. The intricate reaction network was elucidated and organized in the form of a hierarchical network to demonstrate the key features of the ODH mechanisms, including the activation of propane and oxygen, the influence of propyl reaction pathways on the propene selectivity, and the role of rapid H2O2 decomposition for sustainable and efficient ODH reactions. The results indicate the more complex reaction mechanism of propane ODH than that of ethane ODH and are expected to provide insights in the ODH catalyst optimization. In addition, this work represents the first application of deep potential in the ODH mechanistic study and demonstrates the ample advantages of DP in the study of mechanism and dynamics of complex systems.

Mechanism and thermodynamics of scorodite formation by oxidative precipitation from arsenic-bearing solution

Arsenic pollution is a challenging environmental issue caused by arsenic-bearing wastes from nonferrous metallurgy. Oxidative precipitation via introducing O2 into an ionic Fe(II)–As(V) solution is an advanced method for arsenic immobilization. However, the underlying mechanism is still not well understood. This study proposed a mechanism for scorodite formation by oxidative precipitation, and its thermodynamics were calculated using Gaussian software. Scorodite formation was divided into three stages: precursor formation (3–90 min), oxidative conversion (90–270 min) and crystallization (270–720 min) from the variation in precipitates and solution characterization and parameters such as initial pH, arsenic concentration, and ferrous dosage. In the scorodite formation mechanism, the precursors originate from the coordination polymerization of aqueous Fe(H2O)62+ and H2AsO4−, which contributes to the oxidative conversion of coordinated polymers ([Fe(H2O)4(H2O)]nn+) to basic Fe(H2O)2AsO4 until regular octahedral crystals are formed via nucleation and growth during crystallization. The ΔrGmθ for polymerization varied from −491.96 kJ mol−1 to −33.30 kJ mol−1, and the ΔrGmθ of oxidative conversion changed from −982.16 kJ mol−1 to −224.82 kJ mol−1, demonstrating the feasibility in scorodite formation. This research is significant for understanding scorodite formation in As(V) solutions. It can provide schemes for controlling and modifying the conditions of arsenic-bearing waste immobilization in the laboratories and industries.

Selective Electrocatalytic Conversion of Nitric Oxide to High Value-Added Chemicals.

The artificial disturbance in the nitrogen cycle has necessitated an urgent need for nitric oxide (NO) removal. Electrochemical technologies for NO conversion have gained increasing attention in recent years. This comprehensive review presents the recent advancements in selective electrocatalytic conversion of NO to high value-added chemicals, with specific emphasis on catalyst design, electrolyte composition, mass diffusion, and adsorption energies of key intermediate species. Furthermore, the review explores the synergistic electrochemical co-electrolysis of NO with specific carbon source molecules, enabling the synthesis of a range of valuable chemicals with C─N bonds. It also provides in-depth insights into the intricate reaction pathways and underlying mechanisms, offering valuable perspectives on the challenges and prospects of selective NO electrolysis. By advancing comprehension and fostering awareness of nitrogen cycle balance, this review contributes to the development of efficient and sustainable electrocatalytic systems for the selective synthesis of valuable chemicals from NO.

Enhanced photoelectric performance of ZnFe2O4 catalysts for oxidative carboxylation of styrene by tuning crystal planes and thermal and electrical conductivity

The photocatalytic oxidative carboxylation to yield cyclic carbonates was a promising approach for value-added utilization of olefins. Herein, various ZnFe2O4 (ZFO) based catalysts with different morphologies and supports were successfully prepared. Layered ZFO exposed highly active (422) crystal planes, which endowed the catalyst with narrow band gap and favorable electron transfer and charge separation, thereby promoting photocatalytic styrene epoxidation. Consequently, a 95 % selectivity for styrene oxide along with the complete conversion of styrene was achieved. Graphene with excellent electrical and thermal conductivity was compounded into ZFO based catalysts. On the one hand, ZFO/Graphene hybrids composed of 50 wt% graphene promoted fast charge transport in oxygen evolution reaction (OER), and the OER performance was comparable to the commercial RuO2 electrocatalyst. On the other, it exhibited significant photothermal effect and used into CO2 cycloaddition, delivering 95 % selectivity for styrene carbonate at a styrene oxide conversion of 95 %. As a result, a coupled photo-electro-heterogeneous catalytic system was proposed to yield styrene carbonate over ZFO based catalysts, including OER, styrene epoxidation and CO2 cycloaddition. This study provided an effective avenue for designing and fabricating ZFO based catalysts by crystal plane and support control.

Influence of organic sulfur gas-phase sulfation on the NH3-SCR activity of CeO2 catalyst: The competitive adsorption and conversion of CS2 and COS at a low hydrolysis temperature

In this study, a simplified approach is proposed to realize the gas-phase sulfation of CS2 or/and COS at the hydrolysis temperature for further facilitating the NH3-SCR activity of CeO2 in diverse conditions. A low-temperature oxidation conversion process for the adsorbed CS2 or COS on cubic fluorite CeO2 surface is developed. It is found that the gas-phase sulfation of organic CS2 or/and COS at 50 °C enhances the mobility of lattice oxygen of cubic fluorite CeO2 and the concentration of oxygen defects for the sulfated CeO2 catalyst, but the kinds of organic COS/CS2 can regulate the formed types and quality of sulfur-containing species on the catalyst surfaces during the gas-phase sulfation. and the formed sulfates under the gas-phase sulfation of CS2 are more active than those of COS, and CeO2-CS2-50 °C-3 h presents the best mobility of lattice oxygen, the largest concentration of adsorbed oxygen and the best NH3-SCR activity. Furthermore, the competitive adsorption and conversion of CS2 and COS is disadvantageous for the formation of oxygen vacancies on the catalyst surfaces compared to single CS2 or COS. However, the long-time durability testing coupling re-cycle experiments can optimize the oxygen vacancy defects and increase the concentration of chemisorbed oxygen of the sulfated CeO2-CS2 + COS-50 °C-24 h catalyst via optimizing the oxidization of sulfur element to sulfur oxides or/and sulfates, thereby improves its NH3-SCR activity. And the sulfated CeO2 catalyst by the gas-phase sulfation of organic COS + CS2 presents a good stability for NH3-SCR reaction. This study specifies a novel approach to simplify the gas-phase sulfation process of CeO2 catalyst, which is valuable in promotion of the NH3-SCR activity of CeO2 and reduction of cost in experimental procedures.

Photocatalytic metal‐free oxidation of alcohols with molecular oxygen in supercritical CO2 medium

AbstractNear‐UV‐light‐induced oxidative conversion of cyclic and linear alcohols into corresponding carbonyl compounds was achieved in the supercritical CO2 medium under the action of molecular oxygen in the presence of 2‐fluoroanthraquinone (1 mol %), a simple and available metal‐free photocatalyst. A thorough examination of the impact of various process parameters on the reaction outcome allowed to identify a narrow density area at ~0.3 g/cm3 in the vicinity of the medium critical point and optimal reaction conditions (~45 °C, ~8.4 MPa) where up to 99 % conversions and 65–93 % yields of the oxidation products could be attained. Furthermore, it has been shown that compressed atmospheric air, a far cheaper and safer oxidizer than pure oxygen, can be applied to the reaction. Based on the experimental data, a plausible mechanism of the photocatalytic process has been proposed comprising photocatalyst excitation with near‐UV light followed by the hydrogen atom transfer (HAT) as the key stages.

Nonlinear Predictive Control of Diesel Engine DOC Outlet Temperature

In the regeneration mode, precise control of the Diesel Oxidation Catalyst (DOC) outlet temperature is crucial for the complete combustion of carbon Particulate Matter (PM) in the subsequent Diesel Particulate Filter (DPF) and the effective conversion of Nitrogen Oxides (NOx) in the Selective Catalytic Reduction (SCR). The temperature elevation process of the DOC involves a series of intricate physicochemical reactions characterized by high nonlinearity, substantial time delays, and uncertainties. These factors render effective and stable control of the DOC outlet temperature challenging. To address these issues, this study proposes an approach based on Long Short-Term Memory (LSTM) neural networks for Model Predictive Control (MPC), emphasizing precise control of the Diesel Oxidation Catalyst’s outlet temperature during the regeneration mode. To tackle the system’s nonlinear characteristics, LSTM is employed to construct a predictive model for the outlet temperature of the Diesel Oxidation Catalyst, thereby enhancing prediction accuracy. Simultaneously, model predictive control is applied to mitigate the significant time delays inherent in the system. The gradient descent algorithm is utilized within a rolling optimization cycle to optimize the objective function, enabling the rapid determination of the control law. To validate the performance of the proposed control strategy, tracking performance and disturbance rejection tests are conducted. Simulation results demonstrate that, compared to the traditional Proportional Integral Derivative (PID) controller, this control strategy exhibits superior tracking performance and disturbance rejection capabilities. In the regeneration mode, the adoption of this control strategy enables more effective and precise control of the Diesel Oxidation Catalyst’s outlet temperature.

Stable switching behavior of low-temperature ZrO2 RRAM devices realized by combustion synthesis-assisted photopatterning

We have realized efficient photopatterning and high-quality ZrO2 films through combustion synthesis and manufactured resistive random access memory (RRAM) devices with excellent switching stability at low temperatures (250 °C) using these approaches. Combustion synthesis reduces the energy required for oxide conversion, thus accelerating the decomposition of organic ligands in the UV-exposed area, and promoting the formation of metal-oxygen networks, contributing to patterning. Thermal analysis confirmed a reduction in the conversion temperature of combustion precursors, and the prepared combustion ZrO2 films exhibited a high proportion of metal-oxygen bonding that constitutes the oxide lattice, along with an amorphous phase. Furthermore, the synergistic effect of combustion synthesis and UV/O3-assisted photochemical activation resulted in patterned ZrO2 films forming even more complete metal-oxygen networks. RRAM devices fabricated with patterned ZrO2 films using combustion synthesis exhibited excellent switching characteristics, including a narrow resistance distribution, endurance of 103 cycles, and retention for 105 s at 85 °C, despite low-temperature annealing. Combustion synthesis not only enables the formation of high-quality metal oxide films with low external energy but also facilitates improved photopatterning.

Biochar-based solid-acid catalysts for the selective oxidation of glucose to α,β-unsaturated carboxylic acids in water

H2SO4-modified biochar loaded with TiO2nanoparticles (SBC) was synthesized via anoxic pyrolysis of rice straw biomass. This SBC material was employed for the photo-Fenton-like oxidative conversion of D(+)-glucose intoα,β-unsaturated carboxylic acids (UCAs). Varying catalyst and peroxide loadings generated multiple reactive oxygen species (ROS), including •OH and •O2–, as well as photogenerated electrons and holes. Remarkably, a 90.8 % glucose conversion rate was achieved within 4 h, with an overall carboxylic acid production rate of 463.0μ mol.gcat-1.h-1 and 330.3μ mol.gcat-1.h-1 for UCAs, while maintaining a high selectivity of 71 %. This study elucidated the mechanism through UHPLC-MS/MS analysis, demonstrating the potential of SBC for sustainable glucose valorization and renewable chemicals production.

Selective oxidation of methanol to green oxygenates on vanadium-aluminum phosphate based catalysts

The methanol transformation reaction in the presence of oxygen was carried out in the temperature range of 210–310 ºC, over vanadium catalysts based on vanadium oxide (V2O5) and on vanadium-phosphorus oxide (VPO) calcined at 450 ºC in air. Specifically, the vanadium oxide systems with V2O5 loadings below, above or corresponding to the theoretical monolayer (1–34 wt% of V2O5) were obtained by the impregnation of a mesoporous amorphous aluminum phosphate, AlPO4, calcined at different temperatures (from 350 ºC to 650 ºC) with vanadyl oxalate. Additionally, mechanical mixtures of either VPO or V2O5 with AlPO4 were also employed. Under the experimental conditions employed, with a methanol enriched feed (O2/methanol molar ratio=0.6), formaldehyde and dimethoxymethane were the main products obtained with all the catalysts studied. Vanadyl phosphate (VPO) exhibited slightly lower activity than vanadium oxide, formaldehyde being the main product (SFA ≥ 95%). The conversion of both vanadium oxide and vanadyl phosphate appreciably increased when mixed with the AlPO4, also promoting the formation of dimethoxymethane. The interaction of the vanadium species with the aluminum phosphate surface took place preferentially through the surface Al-OH groups, the vanadium species with less development being the most active in the formation of formaldehyde and dimethoxymethane, per at-g of vanadium.