Desired properties in catalysts include a nanosize and homogeneity of the particles that form the catalyst and/or its carrier. The creation of catalysts with the finest particles has been a hot topic of scientific research in recent decades. The particle sizes of catalytic oxides are set at the initial stage of forming; in wet-chemistry, this is a precursor to precipitation. It is possible ot create optimal conditions by using homogeneous precipitation when the precipitant is formed in the solution itself due to a hydrolysis reaction. To solve this problem, urea was used in our work, and the hydrolysis products were ammonia and carbon dioxide. As a result of precipitation, hydroxides, carbonates, or hydroxy carbonates of metals can be obtained.

All precipitates were obtained from solutions of metal nitrates. The obtained hydroxides aluminum, indium, and iron, and the hydroxy carbonates nickel, cobalt, and zinc, were studied. The oxides obtained from these materials by calcination were also studied. They form the structure of the catalyst.

The following was found: metal hydroxides were obtained from aluminum, indium, and iron nitrate solutions. According to the XRD patterns, it was established that the crystallite sizes of the obtained hydroxides were, respectively, 1.5, 10, and 35 nm. The oxides obtained by the calcination of these hydroxides have similar sizes, from 0.6 to 15 nm.

Metal hydroxycarbonates were obtained from nickel, cobalt, and zinc nitrate solutions. The crystallite sizes of these compounds are quite large and exceed 100 nm. However, their thermal decomposition allows us to obtain oxides with crystallite sizes less than 15 nm.

The specific surface area and porosity of several of the obtained samples were also measured. It was found that the obtained oxides have a specific surface area that is significantly higher than similar samples obtained by other methods. Most of the porous volume and surface area is located in the mesopores.

Introduction: Chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile, TPN, CAS: 1897-45-6) is a halogenated fungicide currently widely applied to a large variety of crops.¹ The Environmental Protection Agency has classified TPN as a likely human carcinogen, as has the International Agency for Research on Cancers. As of 2022, TPN has been banned in 34 countries around the world, but it is still widely applied in the United States.² Its carcinogenicity, embryo lethality, and high chronic oral toxicity in mammals, among other effects on a variety of organisms, have made its biodegradation of great interest. Chlorothalonil dehalogenase (Chd) from the bacterium Pseudomonas sp. CTN-3 offers a potential solution by catalyzing the first step in the degradation of chlorothalonil.³

Methods: The Chd pET28a+ plasmid was transformed into competent BL21(DE3) Escherichia coli cells, expressed and purified as previously reported.⁴ Tetramethyl othosiliciate (TMOS) (Sigma-Aldrich) (813 µL), 181.4 µL of nanopure water, and 5.6 µL of 0.04 M HCl were combined to make 1 mL of sol material as previously described. Alginate beads were prepared and coated in chitosan as previously described.⁵

Results: Reported herein are the active biomaterials of Chd when encapsulated in tetramethylorthosilicate (TMOS) gels using the sol–gel method (Chd/sol), alginate beads (Chd/alginate), and chitosan-coated alginate beads (Chd/chitosan). Both Chd/sol and Chd/chitosan increased protection from the endopeptidase trypsin as well as imparted stability over a pH range from 5 to 9. Chd/sol outperformed Chd/alginate and Chd/chitosan in long-term storage and reuse experiments, retaining similar activity to soluble Chd stored under similar conditions.

Conclusions: All three materials showed a level of increased thermostability, with Chd/sol retaining >60% activity up to 70 °C. All materials showed activity in 40% methanol, suggesting the possibility for organic solvents to improve TPN solubility. Overall, Chd/sol offers the best potential for the bioremediation of TPN using Chd.

The dry reforming of methane (DRM) is one method by which carbon dioxide and methane can be utilized for value-added products. DRM results in the formation of syngas, which is a combination of hydrogen and carbon monoxide. Syngas, in turn, can be used for energy or as a precursor for the production of liquid fuels, such as methanol. While the required energy input for the DRM reaction is quite high, the utilization of methane and carbon dioxide is enticing for environmental benefit.

Supported nickel (Ni)-based catalysts are often researched as DRM catalysts because they are active and less expensive than precious-metal-based catalysts. A major hurdle to DRM, however, is the deactivation of the catalysts due to carbon build-up during the reaction. The structure of the catalyst support material and its interaction with the active metal is thought to reduce coke deposition and catalyst deactivation during the DRM reaction.

In this study, novel polymer-inspired catalysts for DRM were prepared by pyrolyzing Ni-containing polydimethylsiloxane (PDMS). The pyrolyzed catalysts were found to be largely microporous Ni-based silica-supported catalysts, and the active nickel particles were nano-sized but did not disperse evenly in or on the catalysts. Even so, the catalysts demonstrated significant activity in the DRM reaction and had comparable performance to other catalysts reported in the published literature. The catalyst prepared with nominally 10 wt% Ni in PDMS (before calcination) displayed the highest methane conversion and lowest degradation of performance of the catalysts in this study. This research was successful in exploring polymer-inspired catalysts as novel catalysts for the DRM reaction.

Hydrogels derived from hyaluronic acid (HA) are renowned for their biocompatibility, biodegradability, and extensive biomedical applications. However, conventional crosslinking methods often lack precision, resulting in limited control over the polymer’s properties. This patent evaluation analyzes US8512752, which presents an innovative approach to synthesizing crosslinked derivatives of polycarboxylated polysaccharides, primarily HA, through “click chemistry”. The process leverages copper-based catalytic materials, such as CuCl and CuSO₄.5H₂O, to enable efficient, regioselective Huisgen 1,3-dipolar cycloaddition reactions. These catalysts play a critical role in enhancing reaction yields, ensuring structural uniformity and avoiding undesirable side reactions.

The resulting hydrogels are distinguished by their modifiable viscoelastic properties, making them suitable for a variety of medical applications, including viscosupplementation, controlled drug delivery, and oncologic reconstruction. Notably, the incorporation of bioactive molecules during synthesis allows for the development of advanced drug release systems with improved efficacy.

The invention through the patent demonstrates the pivotal role of catalytic materials in enabling the efficient and regioselective crosslinking of HA derivatives. Copper catalysts not only accelerate the reaction but also preserve the functional integrity of incorporated bioactive molecules. The resulting hydrogels exhibit excellent mechanical properties and extended degradation times, making them suitable for advanced biomedical applications. Future studies may explore alternative catalysts to further enhance biocompatibility and reduce costs.

This analysis-based study highlights the patent’s technical innovations and its significance in advancing hydrogel technology, addressing the limitations of traditional methods and opening pathways for further development in biomedical engineering and regenerative medicine.

Electronic waste (e-waste) has emerged as a growing environmental concern due to inadequate recycling practices and mismanagement, leading to significant consequences. Repurposing e-waste as an efficient nanocatalyst can be a strategy to mitigate such waste with profound implications. Waste printed circuit boards (WPCBs) may be employed for the recovery of various commercial and precious metals due to the presence of rich elemental compositions. This study explores the potential of WPCBs as a source of metal precursor for the synthesis of nanoparticles (NPs) using a biological approach wherein cell-free culture supernatant (CFCS) is employed.

The main objective of this work was to biosynthesize metal NPs using WPCBs and to evaluate the catalytic activity of the NPs. The biosynthesized NPs were characterized by X-ray diffraction analysis, FESEM, FTIR, TEM, and SAED and fringe patterns, which suggested the formation of Cu_xO NPs. FESEM and TEM analyses revealed that the NPs are spherical in shape. FTIR analysis identified the presence of copper oxide and organic functional groups of biological origin, which indicated the action of metabolites present in the CFS as capping agents to stabilize the NPs. The catalytic activity of the Cu_xO NPs was evaluated using a model reaction involving the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH₄) as a reducing agent. The synthesized NPs exhibited excellent catalytic activity, and the reduction reaction was found to follow the pseudo-first-order kinetics.

Heteropolyanions containing molybdenum and/or tungsten are an important class of compounds with properties such as high reactivity, selectivity, and structural diversity. In the present study, the heteropolymolybdate Waugh type containing Mn(II) as a heteroatom, (NH₄)₆MnMo₉O₃₂ (MnMo₉), was studied as a supported catalyst, using diatomaceous earth from northwestern Argentina as the support. The diatomaceous earths are highly adsorbent porous materials. Also, they are inexpensive and widely available in the pre-Cordillera region of Argentina. The HPOM and supported systems were characterised by DRX, FTIR, SEM-EDS, and RTP, among other physicochemical techniques. Given the chemical and structural properties of this phase, the clean oxidation of diphenyl sulfide (DFS) was chosen as the catalytic reaction for system evaluation. The reaction products, diphenyl sulfoxides (DPSOs) and diphenyl sulfones (DPSO₂), are of great interest as intermediates in the fine chemical and pharmaceutical industries. Diphenyl dulphide also acts as a test molecule for the study of processes to obtain ultra-low-sulphur fuels.
The MnMo₉ system was evaluated as a bulk and a support in the oxidation of DPS with H₂O₂, as a clean oxidant, at 80 °C. The results for the supported phase showed high reactivity, and a conversion of 100% of DPS was achieved at longer reaction times, with good selectivity for diphenyl sulfone at short reaction times.

In the field of catalysis, the use of heteropolyacids is widespread, since they operate under mild conditions, favoring selectivity in reactions and reducing environmental pollution by not producing large volumes of waste. Heterogeneous catalysis is preferred because allows for easy recovery and re-use. This work shows the preparation of mixed silica--titania materials to immobilize a Keggin-type heteropolyacid doped with niobium and to use as a heterogeneous catalysts in sulfoxidation reactions under eco-friendly conditions.

Niobium-doped heteropolyacid (PMoNb) was synthesized by way of a hydrothermal synthesis method from orthophosphoric acid, molybdenum trioxide, and niobium pentoxide. Subsequently, PMoNb was included in different silica and titania supports using the sol--gel method from the precursors, i.e., tetraethyl orthosilicate and titanium isopropoxide. The prepared catalysts were characterized by XRD, FT-IR, Raman, and potentiometric titration, and tested in the selective oxidation of diphenyl sulfide to diphenyl sulfoxide.

The characteristic bands of both supports were found in the FT-IR and Raman spectra, with no appreciable differences due to the presence of PMoNb. Similar results were observed from XRD patterns. All the solids obtained present high acidity.

Regarding catalytic performance, bulk PMo and PMoNb catalysts were tested in the reaction, and it was observed that the incorporation of Nb improved the catalytic behaviour: 94% conversion and 94% selectivity (PMoNb) vs. 36% conversion and 100% selectivity (PMo) after 7 h. Moreover, the activity improved when the heteropolyacids were included in the support. However, the presence of Nb did not enhance the activity of the heterogeneous catalysts.

On the other hand, the high activity of TiO₂, undesired since it reduces selectivity, could be controlled when silica is incorporated into the structure. In this way, the best result was obtained using PMo, which was included in a support of silica--titania 1:1, with a conversion of 99% and a selectivity towards diphenyl sulfoxide of 88% after one hour of reaction.

High levels of CO₂ emissions in the atmosphere cause global warming and an associated increase in Earth’s temperature. To meet the target set by the United Nations for 2050, a new strategy must be found to reduce and reuse thisCO₂¹. One promising strategy is CO₂ hydrogenation to methane using renewable hydrogen. This reaction is generally carried out with Ni/Al₂O₃ due to its low cost compared to noble metals and its natural abundance, but it has shown low catalytic performances at low temperatures and deactivation due to carbon deposition and particle sintering^2,3. A possible strategy to reduce these problems is the addition of lanthanides as promoters⁴. In fact, it is well known that lanthanum is a thermal stabilizer used for alumina support, and tailors acido-base properties as well. For these reasons, the aim of this work is to study the effect of preparation techniques and the lanthanide loading of Ni-based catalyst for CO₂ hydrogenation. Catalysts were prepared by co- or sequential incipient wetness impregnation, maintaining the Ni loading constant and varying the lanthanide one. Fresh and spent catalysts were characterized by BET, XRD, FE-SEM, IR, and UV-vis-NIR. The catalytic tests were carried out at atmospheric pressure and temperature range of 523-773 K in both ascending and descending mode to evaluate possible catalyst deactivation in line with our previous work [2,3]. In addition, kinetic, surface, and on-demand studies were performed on the most promising catalysts. The main finding of this work is related to the effect of catalyst preparation that strongly influences the obtained performances. All tested catalysts displayed remarkable activity in the CO₂ hydrogenation reaction, achieving high CO₂ conversion with high methane selectivity at low temperatures and approaching thermodynamic equilibrium at temperatures above 673 K. The best methane yield (92% at 623 K) was achieved in Ce-containing materials.

Molybdenum, a transition metal, is widely recognized for its ability to exhibit multiple oxidation states and form diverse complexes, including molybdenum Schiff base complexes. These complexes, formed by coordinating molybdenum with Schiff base ligands derived from primary amines and carbonyl compounds, possess unique properties and have garnered attention for their roles in biological and industrial applications. They are particularly important in catalytic processes, such as petroleum refining and chemical manufacturing. A key application of molybdenum Schiff base complexes is in the catalytic oxidation of benzyl alcohol to benzaldehyde, an essential industrial chemical. Benzaldehyde is valued for its almond-like aroma, making it a key ingredient in fragrances and cosmetics. It also serves as a precursor in the synthesis of pharmaceuticals, dyes, and agrochemicals, and its reactivity supports its role as an intermediate in organic synthesis. This highlights the industrial significance of molybdenum-based catalysts.

In this study, a Schiff base ligand was synthesized via the condensation of salicylaldehyde or 2-hydroxy-5-nitrobenzaldehyde with 2-furoic hydrazide and subsequently coordinated to the [MoO₂]²⁺ core. Reactions in methanol yielded the complex [MoO₂(L^1or2)(MeOH)], whereas reactions in acetonitrile produced [MoO₂(L^1or2)(H₂O)]. Characterization was performed using IR-ATR spectroscopy and thermogravimetric analysis, while molecular and crystal structures were determined by X-ray diffraction. These complexes were evaluated as catalysts for the oxidation of benzyl alcohol, demonstrating significant potential for catalytic applications, while the effect of varying oxidant quantities on selectivity and conversion was also investigated.

In recent years, water pollution has become one of the most predominant environmental problems. Organic refractory pollutants such as dyes and antibiotics are difficult to degrade in nature and thus cause water pollution. To solve this water pollution problem, the efficient removal of pollutants in wastewater is extremely important. Cobalt is the best metal element for activating peroxymonosulfate (PMS). In this study, we aimed to prepare transition metal-doped CoOOH catalysts to improve the activity of PMS.

The M-doped CoOOH catalyst was prepared as follows (M = Cu, Ni, Fe, Zn, and Mn). To 50 mL of 84 g/L of NaOH, 0.45 M Co(NO₃)₂·6H₂O and 0.05 M metal nitrates were added in a volume of 25 mL. The mixture was stirred for 30 min. Then, 60 mL of 30% H₂O₂ was added, and the mixture was stirred at 60 ℃ for 24 h with a hot stirrer. The product was washed with distilled water and vacuum-dried. Dye decolorization was performed in the presence of peroxymonosulfate using the prepared CoOOH catalyst.

XRD measurements confirmed that CoOOH was prepared, as the characteristic peaks of CoOOH were observed. Some peak positions were shifted to the lower angle side in CoOOH doped with Cu, Ni, Fe, and Zn compared to CoOOH. In the decolorization experiments, RhB was decolorized by 15.2% after 10 min of reaction, when PMS solution was added alone, and by 26.3% in the CoOOH/PMS system. The decolorization rate of the M-doped CoOOH/PMS system was faster than that of the CoOOH/PMS system. Especially in the Ni-doped CoOOH/PMS system, RhB was decolorized by 77.8%. Therefore, X% Ni-doped CoOOH with different Ni doping was prepared and decolorization experiments were performed (X = 5, 10, 20, and 30). As a result, 87.2% of RhB was decolorized in the 20% Ni-doped CoOOH/PMS system.