Catalytic Process Research Articles

Synergistic electronic regulation and piezocatalytic effect in CoTiO3-BaTiO3 heterojunction for boosting fenton-like oxidation toward pollutants degradation

Water flow is a sustainable mechanical energy source. Utilizing such energy for promoting Fenton-like oxidation toward water remediation is anticipated, yet rarely reported. Herein, CoTiO3-BaTiO3 (CT-BT) nanorod was constructed as piezocatalysis for triggering Fenton-like oxidation toward pollutant degradation via peroxymonosulfate (PMS) activation. The CT-BT was synthesized by coprecipitation method, and its physicochemical property was comparatively analyzed by a series of characterizations, including SEM, TEM, XRD, PFM, FT-IR, N2 adsorption/desorption, and XPS. The p-n heterojunction formed by CT-BT provided a built-in electric field induced charge redistribution, thereby enhancing affinity toward PMS and facilitating electron transfer. Furthermore, a rectangular tubular reactor was designed to utilize water flow to trigger piezoelectric effect of CT-BT, boosting the generation of reactive oxygen species. High-speed turbulence (turbulent kinetic energy > 50 m2/s2) was generated as the water flowed through the slits inside the tubular reactor. The water flow greatly promoted PMS activation on CT-BT for berberine degradation (100 % removal within 30 min), with a kinetic constant of 0.1206 min−1, which was 4.7 times that of the non-piezoelectric catalytic process. Practical application experiments demonstrated decent anti-interference capability and stability (Co leaching < 20 μg/L) of the piezocatalytic system. This work is hoped to advance piezocatalysis in promoting Fenton-like oxidation through utilizing hydrokinetic energy.

Mimicomes: Mimicking Multienzyme System by ArtificialDesign.

Enzymes are widely distributed in organelles of cells, which are capable of carrying out specific catalytic reactions. In general, several enzymes collaborate to facilitate complex reactions and engage in vital biochemical processes within cells, which are also called cascade systems. The cascade systems are highly efficient, and their dysfunction is associated with a multitude of endogenous diseases. The advent of nanotechnology makes it possible to mimic these cascade systems in nature and realize partial functions of natural biological processes both in vitro and in vivo. To emphasize the significance of artificial cascade systems, mimicomes is first proposed, a new concept that refers to the artificial cascade catalytic systems. Typically, mimicomes are able to mimic specific natural biochemical catalytic processes or facilitate the overall catalytic efficiency of cascade systems. Subsequently, the evolution and development of different types of mimicomes in recent decades are elucidated exhaustedly, from the natural enzyme-based mimicomes (immobilized enzyme and vesicle mimicomes) to the nanozyme-based mimicomes and enzyme-nanozyme hybrid mimicomes. In conclusion, the remaining challenges in the design of multifunctional mimicomes and their potential applications are summarized, offering insights into their future prospects.

Effect of Residual Cuts on Deactivation of Hierarchical Y Zeolite-Based Catalysts during Co-Processing of Vacuum Gas Oil (VGO) with Atmospheric Residue (ATR)

The influence of residual cuts on the deactivation of hierarchical Y zeolite-based catalysts during the co-processing of vacuum gas oil (VGO) with atmospheric residue (ATR) was investigated. The experiments were conducted in a laboratory-scale MAT-type reactor. The conversion of VGO, ATR, and their 70:30 (mass basis) mixture was examined using two composite catalysts: Cat.Y.0.00 and Cat.Y.0.20. The operating conditions closely resembled those of the commercial catalytic cracking process (550 °C and contact times of 10 to 50 s). When ATR was processed individually, the conversion remained below 50 wt%. However, significant improvements in conversion rates were achieved and catalyst deactivation was mitigated when ATR was co-processed with VGO. Notably, the BET surface area and average mesopore volume were adversely impacted by ATR, which also led to the accumulation of high levels of metals and nitrogen on the spent catalyst, detrimentally affecting its acidic and structural properties. Moreover, substantial coke deposition occurred during ATR cracking. The soluble and insoluble coke analysis revealed H/C ratio values of up to 0.36, indicative of polycondensed coke structures with more than ten aromatic rings. The nature of the coke was confirmed through TPO and FTIR analyses. Interestingly, the CatY.0.20 catalyst exhibited less activity loss, retaining superior acid and structural properties. Co-processing Colombian atmospheric residue with ATR loadings of 30 wt% (higher than the typical 20 wt%) in catalysts formulated with hierarchical zeolites presents a promising alternative for commercial applications. This research opens avenues for optimizing catalytic cracking processes.

Surface plasmons on silver gratings transform pyrolytic carbon into luminescent graphitized carbon dots.

Plasmonic catalysis holds the promise of opening new reaction pathways that are inaccessible thermally or via direct UV-vis electronic transitions. Here, energetic carriers produced via the decay of surface plasmons excited by visible light at 532nm (2.33eV, green) on a Ag-grating-bearing pyrolytic carbon residue drive its transformation into light-emitting graphitized carbon dots. The pyrolytic carbon residue is detectable via high-magnification surface-enhanced Raman scattering but cannot be directly observed using optical, electron, atomic force, or helium ion microscopy. When a Ag-grating-bearing pyrolyzed residue is introduced into a high-purity O2-depleted gas environment (Ar, N2, and CO2) and excited with 532nm light, bright yellow luminescence emerges and is readily observed. Light emission is not observed without the pyrolytic carbon, without the excitation of plasmons, or in air or an Ar/O2 gas mixture. This process, driven by visible light and a nanostructured Ag surface bearing pyrolytic carbon, will be of interest to researchers involved in plasmonic catalysis, catalytic processes involving carbon, and luminescent plasmonic surfaces.

Magnetic Nanoparticles and Radio Frequency Induction: From Specific Heating to Magnetically Induced Catalysis

AbstractThis comprehensive review explores the potential of radio frequency (RF) induction heating in chemical reactions, explicitly focusing on magnetically induced catalysis using magnetic nanoparticles (NPs). We trace the recent historical progress of induction heating and highlight the advancements in liquid and gas‐phase reactions, particularly in its integration with heterogeneous catalysis. The review finds that induction heating profoundly impacts reaction kinetics, and selectivity, and can even reduce overpotentials in electrocatalytic processes. A final outlook unveils the challenges and opportunities associated with aspects such as fundamental research and reactor design, with a particular focus on expanding its use to higher pressures and necessary optimizations to improve energy efficiency. Moreover, it highlights the pressing need for standardized reporting in induction‐heated catalysis. The study underscores the significance of this brand‐new field in developing efficient and sustainable catalytic processes, which are essential for meeting the growing demand for clean energy and sustainable chemical production.

Electrocatalytic Hydrogenation of Pyridines and Other Nitrogen-Containing Aromatic Compounds.

The production of cyclic amines, which are vital to the pharmaceutical industry, relies on energy-intensive thermochemical hydrogenation. Herein, we demonstrate the electrocatalytic hydrogenation of nitrogen-containing aromatic compounds, specifically pyridine, at ambient temperature and pressure via a membrane electrode assembly with an anion-exchange membrane. We synthesized piperidine using a carbon-supported rhodium catalyst, achieving a current density of 25 mA cm-2 and a current efficiency of 99% under a circular flow until 5 F mol-1. Quantitative conversion of pyridine into piperidine with 98% yield was observed after passing 9 F mol-1, corresponding to 65% of current efficiency. The reduction of Rh oxides on the catalyst surface was crucial for catalysis. The Rh(0) surface interacts moderately with piperidine, decreasing the energy required for the rate-determining desorption step. The proposed process is applicable to other nitrogen-containing aromatic compounds and could be efficiently scaled up. This method presents clear advantages over traditional high-temperature and high-pressure thermochemical catalytic processes.

Enhanced synergistic catalysis of bisphenol A in river water using an anti-aging photocatalytic membrane

Bisphenol A (BPA), as an endocrine disruptor, poses a potential threat to ecosystems and human health in aquatic environments. Membrane catalytic systems can accelerate the degradation of BPA and facilitate its conversion into harmless compounds. Nevertheless, the complex nature of the water environments and the limited stability of catalysts often result in challenges such as catalyst aging and deactivation. Herein, an anti-aging multifunctional AgFeO2 catalytic material with electron transfer membrane support was prepared for synergistic catalysis of low-energy LED light (12 W) excitation and peroxydisulfate (PDS) activation. The anti-aging photocatalytic membrane completely degraded 10 ppm of BPA within 30 min, and did not show significant aging after the long-term synergistic catalytic process. In addition, actual river water was employed to assess the aging process and catalytic efficiency in a practical environment. A 60.79 cm2 photocatalytic membrane completely purified 10 L of BPA polluted river water, while the total organic carbon content decreased by 50 %. This was mainly due to the synergistic catalytic effect of the membrane, which boosted photoelectron transfer through electron transfer shortcuts, thereby enhancing persulfate activation. Overall, the multifunctional membrane provides an effective strategy for achieving a long-lasting catalytic effect and controlling photocatalyst aging in practice.

A Critical Review of the Synthesis and Applications of Spinel-Derived Catalysts to Bio-Oil Upgrading.

The transformation of renewable bio-oil into platform chemicals and bio-oil through catalytic processes embodies an efficient approach within the realm of advancing sustainable energy. Spinel-based catalysts have garnered significant attention owing to their ability to precisely tune metals within the framework, facilitating adjustments to structural, physical, and electronic properties, coupled with their remarkable thermal stability. This review aims to provide a comprehensive overview of recent advancements in spinel-based catalysts for upgrading bio-oil. Its objective is to shed light on their potential to address the limitations of conventional catalysts. Initially, a comprehensive analysis is conducted on different metal oxide composites in terms of their similarity and dissimilarity on properties. Subsequently, the synthesis methodologies are scrutinised and potential avenues for their modification are explored. Following this, an in-depth discussion ensues regarding the spinels ascatalysts or catalyst precursors for catalytic cracking, ketonisation, catalytic hydrodeoxygenation, steam and aqueous-phase reforming, andelectrocatalytic upgrading of bio-oil. Finally, the challenges and potential prospectsare addressed, with a specific focus on the machine learning - based approaches to optimise the structure and activity of spinel catalysts. This review aims to provide specific directions for further exploration and maximisation of the spinel catalysts in the bio-oil upgrading field.

Distinct Adjacent Substrate Binding Pocket Regulates the Activity of a Decameric Feruloyl Esterase from Bacteroides thetaiotaomicron.

Understanding how the human gut microbiota contribute to the metabolism of dietary carbohydrates is of great interest, particularly those with ferulic acid (FA) decorations that have manifold health benefits. Here, we report the crystal structure of a decameric feruloyl esterase (BtFae) from Bacteroides thetaiotaomicron in complex with methyl ferulate (MFA), revealing that MFA is situated in a noncatalytic substrate binding pocket adjacent to the catalytic pocket. Molecular docking and mutagenesis studies further demonstrated that the adjacent pocket affects substrate binding in the active site and negatively regulates the BtFae activity on both synthetic and natural xylan substrates. Additionally, quantum mechanics (QM) calculations were employed to investigate the catalytic process of BtFae from substrate binding to product release, and identified TS_2 in the acylation step is rate-limiting. Collectively, this study unmasks a novel regulatory mechanism of FAE activity, which may contribute to further investigation of FA-conjugated polysaccharides metabolism in the human gut.

Microwave-assisted catalytic dry reforming of methane with CO2 over nitrogen-doped catalysts derived from metal-organic frameworks

Dry reforming of methane (DRM) can convert CO2 into syngas for the production of fuels and chemicals, offering both environmental and energetic benefits. However, its large-scale industrial applications face challenges such as harsh reaction conditions and catalyst deactivation. In this study, metal–organic frameworks (MOFs) derived N-doped Ni-based bifunctional nanomaterials (Ni-Co/NC) were meticulously synthesized to function as microwave absorbers and catalysts. Efficient syngas production was achieved through the microwave-enhanced DRM process over Ni-Co/NC. The results showed that the Ni-Co/NC catalyst significantly increased the conversion of CH4 (∼93.2 %) and CO2 (∼94.8 %). By comparing the changes in the surface properties of the catalysts before and after N-doping, it was found that N-doping enhanced the interaction between the carrier and metal particles, improved the specific surface area and surface basicity, and inhibited the aggregation of metal particles, thereby enhancing catalytic activity. The reaction mechanism was investigated using in-situ infrared spectroscopy, revealing that the formation of intermediates such as carbonates, formates, O-H groups was crucial to improving catalytic activity and stability. Compared to conventional catalytic processes, the catalysts prepared in this study demonstrated stronger catalytic activity and stability in the microwave catalytic process.

New insights into the catalyzed ozonation mechanism of a hydroxyl riched goethite: Contributions of H2O2 and surface Fe2+

Fe-based catalysts have been widely used to catalyze ozonation during water treatment. Among these catalysts, goethite (α-FeOOH) is of concern for the properties of low cost, easy availability, and excellent performance. In general, the surface hydroxyl groups of goethite are believed to be crucial catalytic sites. However, the contributions of Fe2+ on the goethite surface and H2O2 produced from pollutant degradation have rarely been mentioned. In this study, a goethite with rich surface hydroxyl was fabricated to remove aromatics by O3 catalysis. Probe and quenching experiments together proved that although the •OH was produced less than the O2•⁻ and 1O2 in the catalytic system, it contributed about 95 % of the target removal. EDTA complexation and heating experiments suggested that when the surface Fe2+ of the catalyst was destroyed, although the Fe-site hydroxyl or the vacancy hydroxyl of the catalyst was retained, its catalytic activity was reduced greatly. The outcomes of degradation kinetics of acetic acid further confirmed that, in the catalytic process, most of •OH originated from the reaction of Fe2+ reducing HO2• and Fe2+ ozonation, while the surface hydroxyl contributed less than 44.7 %. Moreover, as the main source of HO2•, the role of H2O2 produced from aromatics degradation cannot be ignored. The detection of H2O2 precursors in the degradation byproducts further confirmed this opinion. Finally, an efficient circular route for •OH production was proposed. This may be beneficial for the development of efficient Fe-based catalysts.

Visible light mediated decarboxylative difluoroalkylations of cyclic N-sulfonyl ketimines: Efficient synthesis of difluoroalkylated Cα-tetrasubstituted α-amino acid derivatives

An efficient decarboxylative difluoroalkylation method of cyclic N-sulfonyl ketimines with difluoroalkyl carboxylates has been developed through visible light-mediated photoredox catalysis process. This protocol provides a straightforward route for the synthesis of difluoroalkylated Cα-tetrasubstituted α-amino acid derivatives in moderate to good yields with excellent functional group tolerance under mild and simple conditions.

Enhancing catalytic oxidation of benzene with Cu-Doped MnO2: Insights into structural defects and electronic modifications

The present research focuses on the role of copper (Cu) doping in enhancing the catalytic efficacy of manganese dioxide (α-MnO2) for benzene oxidation, a representative volatile organic compound (VOC). Despite the abundance and low cost of MnO2, its pristine form requires improvement for industrial VOC oxidation processes. Utilizing a range of characterization methods, the study reveals that Cu doping generates oxygen vacancies and increases the Mn3+ content within the catalyst structure, which are crucial for enhancing the adsorption and activation of reactants. The findings indicate that Cu-doped α-MnO2 exhibits superior catalytic activity and lower activation energy for benzene oxidation compared to the undoped counterpart. The electronic interactions induced by the doping of Cu and the effect on the catalytic process are demonstrated and discussed in depth. This work emphasizes the strategic importance of dopant optimization and contributes to the advancement of MnO2-based catalysts for environmental remediation, aligning with goals of environmental protection and human health safety.

Advancements in Green Chemical Engineering: Developing Sustainable Catalysts for Carbon Capture and Utilization

The development of sustainable catalysts for carbon capture and utilization (CCU) represents a pivotal advancement in green chemical engineering, addressing both climate change and resource scarcity. This study utilizes a qualitative approach, specifically employing literature review and library research methods, to analyze recent advancements in catalyst development for CCU technologies. The analysis highlights the growing emphasis on designing catalysts that are not only efficient but also eco-friendly, with a focus on minimizing environmental impact. By examining various catalytic processes, including chemical absorption, photocatalysis, and electrochemical reduction, this research identifies key strategies for enhancing the effectiveness and sustainability of CCU systems. The findings reveal that while significant progress has been made in improving catalyst performance, challenges remain in scaling up these technologies for industrial applications. Moreover, this study underscores the role of green chemical engineering in fostering a circular economy by converting captured carbon dioxide into valuable products such as fuels and chemicals. Future research should focus on overcoming existing limitations, including catalyst stability and cost-effectiveness, to ensure broader adoption of sustainable CCU technologies. This review contributes to the growing body of knowledge on sustainable chemical processes and offers a roadmap for advancing green engineering practices.

Stable Silica-Based Zeolites with Three-Dimensional Systems of Extra-Large Pores.

Zeolites are microporous crystalline materials that find a very wide range of applications, which, however, are limited by the size and dimensionality of their pores. Stable silica zeolites with a three-dimensional (3D) system of extra-large pores (ELP, i.e., pores with minimum windows along the diffusion path consisting of more than 12 SiO4/2 tetrahedra, 12R) are in demand for processing larger molecules than zeolites can currently handle. However, they have challenged worldwide synthetic capabilities for more than eight decades. In this review we first present a brief history of the discovery of ELP zeolites. Next, we show that earlier successes of zeolites with 3D ELP were not actually zeolites, but rather interrupted structures with, in addition, a composition that severely detracted from their stability. Finally, we present three new fully connected stable silica-based 3D ELP zeolites ZEO-1, ZEO-3 and ZEO-5, discuss their preparation methods and stability as well as the clear advantage of their increased porosity in catalysis and adsorption processes involving large molecules. We will discuss peculiar characteristics of their preparation and present two new reaction types giving rise to zeolites (1D-to-3D topotactic condensation and interchain expansion), highlighting how new synthesis methods can provide materials that would otherwise be unfeasible.

Stable Silica‐Based Zeolites with Three‐Dimensional Systems of Extra‐Large Pores

AbstractZeolites are microporous crystalline materials that find a very wide range of applications, which, however, are limited by the size and dimensionality of their pores. Stable silica zeolites with a three‐dimensional (3D) system of extra‐large pores (ELP, i.e., pores with minimum windows along the diffusion path consisting of more than 12 SiO4/2 tetrahedra, 12R) are in demand for processing larger molecules than zeolites can currently handle. However, they have challenged worldwide synthetic capabilities for more than eight decades. In this review we first present a brief history of the discovery of ELP zeolites. Next, we show that earlier successes of zeolites with 3D ELP were not actually zeolites, but rather interrupted structures with, in addition, a composition that severely detracted from their stability. Finally, we present three new fully connected stable silica‐based 3D ELP zeolites ZEO‐1, ZEO‐3 and ZEO‐5, discuss their preparation methods and stability as well as the clear advantage of their increased porosity in catalysis and adsorption processes involving large molecules. We will discuss peculiar characteristics of their preparation and present two new reaction types giving rise to zeolites (1D‐to‐3D topotactic condensation and interchain expansion), highlighting how new synthesis methods can provide materials that would otherwise be unfeasible.

Catalytic activity insight into sustainable Fe-hydroxyapatite application using an experimental design approach

Combining experimental design with advanced characterisation methods provides a valuable opportunity to deepen our understanding of catalytic processes and their underlying mechanisms. Here, a series of hydroxyapatite doped with Fe2+ at different molar loadings noted HAP-FeX% (X = 1; 5.5 and 10; Ca/Fe molar ratio) were elaborated using a one-pot synthesis method. Characterization of these catalysts by various techniques such as ICP, BET/BJH, TGA/DSC, XRD, Raman, UV–visible, TPD-NH3, SEM, and TEM revealed substantial Fe2+ oxidation during synthesis, inducing changes in the morphological and physical-chemical characteristics of HAP caused by Fe3+/Ca2+ substitution. Furthermore, the synthesis produced nanoparticles (approximately 0.30 nm in size) on the hydroxyapatite surface, resulting from the precipitation of Fe/O phases. The catalysts exhibited good catalytic performance in methylene blue (MB) degradation through the photo-Fenton process (95 %). The Ca/Fe molar ratio = 8.8 %, [H2O2] = 2.8 mmol L−1, and pH = 8.8 were optimized using the design of experiments (DOE) via response surface methodology (RSM). A mathematical model was developed to determine the influence of the Ca2+/Fe3+ substitution and the Fe/O phase on the catalytic activity. The results revealed the role of the Fe/O phase in the reaction initiation and the surface modification induced by Ca2+/Fe3+ substitution to facilitate the reaction chain.

Optimized Furfural Production Using the Acid Catalytic Conversion of Xylan Liquor from Organosolv-Fractionated Rice Husk

This study determined the optimal production of furfural (FuR) from liquid hydrolysate xylan liquor obtained through a two-stage pretreatment process using NaOH for de-ashing and EtOH for the delignification of raw rice husk (RH). The de-ashing pretreatment was conducted at 150 °C, with 6.0% (w/v) NaOH and a reaction time of 40 min. The optimal conditions for delignification pretreatment, performed using an organosolv fractionation method with EtOH, were a reaction temperature of 150 °C, 60% (v/v) EtOH, 0.25% (w/v) H2SO4, and a reaction time of 90 min. Through a two-stage pretreatment process, a liquid hydrolysate in the form of xylan liquor was obtained, which was subjected to an acid catalytic conversion process to produce FuR. The process conditions were varied, with reaction temperatures of 130–170 °C, H2SO4 catalyst concentrations of 1.0–3.0 wt.%, and reaction times of 0–90 min. The Response Surface Methodology tool was used to identify the optimal FuR yield from xylan liquor. Ultimately, the optimal process conditions for the acid catalytic conversion were found to be a substrate-to-catalyst ratio of 2:8, a reaction temperature of 168.9 °C, a catalyst concentration of 1.9 wt.%, and a reaction time of 41.24 min, achieving an FuR yield of 67.31%.

Predicting Methanol Space-Time Yield from CO? Hydrogenation Using Machine Learning: Statistical Evaluation of Penalized Regression Techniques

This study investigates the effectiveness of machine learning techniques, specifically penalized regression models Ridge Regression, Lasso Regression, and Elastic Net Regression in predicting methanol space-time yield (STY) from CO? hydrogenation data. Using a dataset derived from Cu-based catalyst research, the study implemented a comprehensive preprocessing approach, including data cleaning, imputation, outlier removal, and normalization. The models were rigorously evaluated through 10-fold cross-validation and tested on unseen data. Ridge Regression outperformed the other models, achieving the lowest Root Mean Squared Error (RMSE) of 0.7706, Mean Absolute Error (MAE) of 0.5627, and Mean Squared Error (MSE) of 0.5938. In comparison, Lasso and Elastic Net Regression models exhibited higher error metrics. Feature importance analysis revealed that Gas Hourly Space Velocity (GHSV) and Molar Masses of Support significantly influence catalytic activity. These findings suggest that Ridge Regression is a promising tool for accurately predicting methanol production, providing valuable insights for optimizing catalytic processes and advancing sustainable practices in chemical engineering.

Novel Lewis Acid‐Base Interactions in Polymer‐Derived Sodium‐Doped Amorphous Si−B−N Ceramic: Towards Main‐Group‐Mediated Hydrogen Activation

AbstractInterest is growing in transition metal‐free compounds for small molecule activation and catalysis. We discuss the opportunities arising from synthesizing sodium‐doped amorphous silicon‐boron‐nitride (Na‐doped a‐SiBN). Na+ cations and 3‐fold coordinated BIII moieties were incorporated into an amorphous silicon nitride network via chemical modification of a polysilazane followed by pyrolysis in ammonia (NH3) at 1000 °C. Emphasis is placed on the mechanisms of hydrogen (H2) activation within Na‐doped a‐SiBN structure. This material design approach allows the homogeneous distribution of Na+ and BIII moieties surrounded by SiN4 units contributing to the transformation of the BIII moieties into 4‐fold coordinated geometry upon encountering H2, potentially serving as frustrated Lewis acid (FLA) sites. Exposure to H2 induced formation of frustrated Lewis base (FLB) N−= sites with Na+ as a charge‐compensating cation, resulting in the in situ formation of a frustrated Lewis pair (FLP) motif (≡BFLA⋅⋅⋅Hδ−⋅⋅⋅Hδ+⋅⋅⋅:N−(Na+)=). Reversible H2 adsorption‐desorption behavior with high activation energy for H2 desorption (124 kJ mol−1) suggested the H2 chemisorption on Na‐doped a‐SiBN. These findings highlight a future landscape full of possibilities within our reach, where we anticipate main‐group‐mediated small molecule activation will have an important impact on the design of more efficient catalytic processes and the discovery of new catalytic transformations.