Reaction Chemistry & Engineering最新文献

The reaction network of higher alcohol synthesis over a pyrolised Prussian blue analogue-based catalyst was investigated by performing transient as well as steady-state kinetic experiments using a Mn-promoted Co catalyst with a molar Mn : Co ratio of 1 : 11 (Mn₁Co₁₁) at 260 °C. While the temperature variation revealed an apparent activation energy of 88 kJ mol⁻¹, the partial pressure variations of CO and H₂ resulted in reaction orders of −0.3 and +0.7 for CO and H₂, respectively. The reaction order for H₂ was similar to the value of +0.8 derived for the previously established 2CoCu catalyst (Co : Cu = 2 : 1) synthesized by co-precipitation, but the activation energy of the Mn₁Co₁₁ catalyst was lower by 52 kJ mol⁻¹ amounting to only 88 kJ mol⁻¹. While ethylene co-feeding showed that reductive hydroformylation takes place yielding 1-propanol presumably at the Co₂C/Co⁰ interface similar to the 2CoCu catalyst, high-pressure pulse experiments using methanol as probe molecule demonstrated the presence of an additional Co-based active site catalyzing the reductive carbonylation of primary alcohols over the Mn₁Co₁₁ catalyst. Correspondingly, the presence of Co–N–C sites anchored in the highly nitrogen- and oxygen-functionalized carbon matrix is assumed to result in the intertwined reaction network, comprising the carbide-based mechanism and reductive olefin hydroformylation over Co₂C/Co⁰, reductive alcohol carbonylation over the molecular sites and olefin hydration over acidic sites.

This study focuses on the design and evaluation of lanthanum (La)-modified boehmite (AlOOH)-derived catalysts synthesized by a urea homogeneous precipitation (hp-) method (non-calcined), with performance compared to catalysts prepared by a conventional impregnation (imp-) method (calcined). These catalysts were applied in the intramolecular aldol condensation of 2,5-hexanedione (HD) to produce 3-methyl-2-cyclopentenone (MCP). A range of La loadings and calcination temperatures were investigated. Structural characterization by XRD and N₂ physisorption was conducted to correlate physical properties with catalytic performance. The hp-La–Al–(OH) catalyst exhibited high activity even without calcination with 54% yield and 82% selectivity, which was comparable to the imp-La/AlOOH catalyst requiring thermal treatment to become active with 60% yield and 71% selectivity, in 3.0 mmol scale of the reaction. These differences were attributed to distinct surface characteristics and active site distributions arising from the preparation method. Poisoning experiments using benzoic acid, 2,6-dimethylpyridine and 3,5-dimethylpyridine reagent indicated that the reaction proceeds via a base mechanism over the non-calcined hp-La–Al–(OH) catalyst, and via an acid–base cooperative mechanism over the calcined imp-La/AlOOH catalyst.

The textile industry is one of the most harmful to the environment due to the large amount of waste it generates, which usually ends up in landfills or is incinerated, as happened in 2015, when 73% of the textiles produced worldwide were disposed of in these ways. This study evaluates the feasibility of energetically valorizing textile waste through catalytic combustion with zeolite in fluidized bed and carbon capture, using Aspen Plus® software. The simulation shows that textile waste can be combusted, ultimately reducing NO_x to N₂ and capturing about 40% of CO₂. Furthermore, catalytic combustion has an overall efficiency of 40%, and oxy-combustion has an efficiency of only 18%, attributable to the energy consumption of the N₂ air separation stage. This study is a starting point for the energetic valorization of textile waste in an environmentally responsible manner.

This study demonstrates the enhanced photocatalytic decolorization of methylene blue (MB) dye using silver nanoparticle-decorated CeCoO₃ (Ag/CeCoO₃) perovskite under UV light irradiation. The Ag/CeCoO₃ photocatalyst was synthesized through a ligand-assisted deposition method and comprehensively characterized using XRD, FTIR, SEM, EDS, PL, and UV-DRS. The incorporation of Ag nanoparticles significantly improved light absorption and charge carrier separation, resulting in a six-fold enhancement in photocatalytic activity compared to pristine CeCoO₃. Under optimized operating conditions (pH 5, 50 °C, catalyst dosage 0.003 g L⁻¹, initial MB concentration 10 ppm), the Ag/CeCoO₃ composite achieved 97% MB decolorization within 25 minutes, exhibiting a reaction rate constant (k) of 0.13 min⁻¹ through pseudo-first-order kinetics. Radical scavenging experiments elucidated the predominant role of photogenerated electrons (e⁻, 71% contribution), hydroxyl radicals (˙OH, 59%), and holes (h⁺, 47%) in the decolorization mechanism. Furthermore, the catalyst maintained exceptional stability and reusability, retaining over 88% of its initial efficiency after four consecutive cycles. These results highlight Ag/CeCoO₃ as a highly efficient and durable photocatalyst for advanced wastewater treatment applications, demonstrating superior performance in organic dye remediation.

Methylene blue (MB⁺) was mechanochemically immobilized on pure silica particles derived from industrial waste by hydrogen bonding and electrostatic interactions. The concentration of singlet oxygen (¹O₂) generated from MB⁺ on the particles increased with increasing concentration of immobilized MB⁺ monomers.

Chemical recycling of industrial fiber-reinforced polycarbonate (PC) to produce bisphenol-A (BPA) is carried out in the present study using water and an alkali catalyst (KOH) via hydrothermal processing (HTP). The operating window for the conversion of PC was determined using differential scanning calorimetry (DSC), and batch HTP reactions were carried out under two conditions: neutral sub-critical conditions (260–300 °C) with water and alkaline mild conditions (130–150 °C) with 1 M KOH. Sub-critical conditions led to the formation of a mixture of BPA, phenol and alkylphenols, whereas mild alkaline conditions mainly led to the formation of BPA with >90% recovery. The kinetic parameters for the alkaline conversion of PC to BPA were investigated using high pressure DSC, and six different kinetic models were compared with the experimental data and assessed for their accuracy. The first-order kinetic model was found to be the best to describe the decomposition of PC to BPA, with an average activation energy of 162.1 kJ mol⁻¹. Glass fibers after HTP were recovered and their structural integrity was analyzed using scanning electron microscopy (SEM). Nearly 100% recovery of glass fibers was achieved with neutral water, while more than 10 wt% of glass fibers were lost due to leaching when 1 M KOH was used. Process intensification via recirculation of the aqueous phase proved to be detrimental to the monomer yield.

The selective oxidation of natural alcohols into carbonyl derivatives is a pivotal transformation in synthetic organic chemistry and industrial applications. This study focuses on the oxidation of borneol, a bicyclic secondary terpenic alcohol, into camphor using a tungsten-exchanged hydroxyapatite (W/HAP) catalyst and hydrogen peroxide as a green oxidant. Hydroxyapatite was synthesized via co-precipitation and functionalized with sodium tungstate to create the W/HAP catalyst, which was characterized using techniques such as SEM, EDS, TPD, XPS, and N₂ adsorption–desorption to evaluate its surface morphology, porosity, and chemical composition. Oxidation reactions were conducted under optimized conditions, employing dimethylacetamide (DMA) as a solvent to achieve maximum conversion and selectivity. The W/HAP catalyst demonstrated superior performance, achieving nearly 99% conversion of borneol with 100% selectivity for camphor. Reaction parameters, including temperature, reactant stoichiometry, solvent choice, and catalyst loading, were systematically investigated. Higher reaction temperatures and oxidant concentrations favoured rapid conversion while maintaining high selectivity. Solvent effects revealed that DMA stabilized peroxo-tungstate intermediates, enhancing reaction efficiency compared to other solvents. Kinetic studies confirmed a first-order reaction mechanism with respect to borneol, and the activation energy was determined to be 44.23 kJ mol⁻¹, highlighting the catalytic efficiency of W/HAP. Reusability tests confirmed the stability of the W/HAP catalyst over multiple cycles with minimal tungsten leaching. The methodology was extended to other terpenic alcohols, with varying degrees of success, emphasizing the substrate-specific activity of the catalyst. This work underscores the potential of tungsten-based heterogeneous catalysts in sustainable alcohol oxidation and highlights the industrial relevance of camphor synthesis as a renewable and eco-friendly approach to produce fine chemicals, fragrances, and pharmaceuticals.

In this report, we detail direct inject mass spectrometry via a robotically automated vacuum enabled (RAVE) interface that utilizes commercially available capillary electrophoresis hardware to directly inject samples for mass spectrometry (MS) at a sampling rate of approximately 12 s per sample. This system enables direct electrospray ionization from standard 48, 96 or 384-well plates with minimal investment in hardware and utlilizes custom developed open source software that provides both autosampler control and analysis of raw extracted data from the mass spectrometer. We show a high level of correlation among results obtained with RAVE coupled MS, acoustic ejection (Echo) MS, and liquid chromatography coupled MS (LCMS) on 384 biocatalytically driven reactions. We additionally utilize RAVE MS on an array of 96 chemocatalytic reaction conditions to show that, while direct MS analysis can be challenging in complex mixtures, simple dilution followed by direct injection is often sufficient for analysis. With these results, we demonstrate the potential for RAVE MS to be utilized as a low-cost, low barrier to entry tool for rapid direct-inject MS analysis.

Direct bioethanol conversion into renewable 1,3-butadiene (1,3-BD) is an attractive approach toward biorefineries. The dependency on fossil-based chemicals will be minimized by using bioethanol as an alternative source. Here, the Zn-La-De-β catalyst composed of Zn and La grafted into dealuminated zeolite beta is reported for ethanol conversion to 1,3-BD. Zn and La sites were grafted into silanol nests created by the dealumination of beta zeolite to produce Zn-De-β, La-De-β, and Zn-La-De-β. These prepared catalysts were then evaluated for the conversion of bioethanol to 1,3-BD. Zn-De-β was more active for the dehydrogenation of ethanol to acetaldehyde; in contrast, La-De-β was active for 1,3-BD formation. The catalyst Zn-La-De-β, having both active sites, was most active for 1,3-BD formation and resulted in 50% C-mol selectivity for 1,3-BD at an optimized reaction temperature of 325 °C. Various characterization techniques, including XRD, XPS, CO₂-TPD, and Py-IR, realized the location and nature of active centers. This study highlights the role of each metal site in the selective production of renewable 1,3-BD. 1.38 g_1,3-BD g_cat⁻¹ h⁻¹ was the highest productivity of 1,3-BD observed at a temperature of 325 °C and WHSV of 9.7 h⁻¹.

Energy storage technologies are critical to supporting modern applications, ranging from portable electronics to large-scale renewable energy systems. Among the prominent solutions, nickel–cadmium (NiCd), nickel–metal hydride (NiMH), and sodium-ion (Na-ion) batteries exhibit distinct characteristics, advantages, and limitations. NiCd batteries, known for their robustness and reliability, are suited for demanding applications but face environmental concerns due to cadmium toxicity. NiMH batteries, with improved energy density and reduced environmental impact, are pivotal in hybrid vehicles and renewable energy storage. Emerging Na-ion batteries leverage abundant sodium resources to offer cost-effective and scalable alternatives to lithium-ion systems, addressing resource scarcity and supply chain challenges. This review compares these technologies, exploring their mechanisms, performance metrics, and future prospects. Research directions include advancing electrode materials, enhancing recycling techniques, and developing solid-state and hybrid systems. By highlighting their unique roles and innovation pathways, this work underscores the potential of these battery technologies to shape a sustainable energy future.