Catalytic Conversion Research Articles

Turning on Low-Temperature Catalytic Conversion of Biomass Derivatives through Teaming Pd1 and Mo1 Single-Atom Sites.

On-purpose atomic scale design of catalytic sites, specifically active and selective at low temperature for a target reaction, is a key challenge. Here, we report teamed Pd1 and Mo1 single-atom sites that exhibit high activity and selectivity for anisole hydrodeoxygenation to benzene at low temperatures, 100-150 °C, where a Pd metal nanoparticle catalyst or a MoO3 nanoparticle catalyst is individually inactive. The catalysts built from Pd1 or Mo1 single-atom sites alone are much less effective, although the catalyst with Pd1 sites shows some activity but low selectivity. Similarly, less dispersed nanoparticle catalysts are much less effective. Computational studies show that the Pd1 and Mo1 single-atom sites activate H2 and anisole, respectively, and their combination triggers the hydrodeoxygenation of anisole in this low-temperature range. The Co3O4 support is inactive for anisole hydrodeoxygenation by itself but participates in the chemistry by transferring H atoms from Pd1 to the Mo1 site. This finding opens an avenue for designing catalysts active for a target reaction channel such as conversion of biomass derivatives at a low temperature where neither metal nor oxide nanoparticles are.

Better Together: Synergic Effect of Gallium‐Based Catalyst and Porous Support for Reduction Reactions

Liquid metal solutions are a new class of catalysts with outstanding properties in terms of catalytic conversion and resistance to coking. Finding the perfect combination of catalytic particles with homogeneous size distribution and support material able to stabilize them during catalysis is key for preparing model systems to gain understanding of these complex catalytic processes. In this work, we present a method for the preparation of small and narrowly distributed gallium‐palladium particles supported on inverse opals, interconnected 3‐dimensional porous networks with a very narrow pore size distribution. Our platform is a promising candidate as supported liquid metal catalytic system thanks to its permeability to fluids and its confined pore environment, which prevents the coalescence of the metal alloy, thus maximizing the surface area available for the catalytic reaction. We demonstrate their enhanced performance when compared to other state of the art systems giving a proof of concept of their application as catalysts for a simple model reaction, the reduction of methylene blue.

High‐Throughput Screening of Dual‐Atom Catalysts for Methane Combustion: A Combined Density Functional Theory and Machine‐Learning Study

AbstractCeria‐supported precious metal catalysts have undergone extensive investigation for the catalytic methane combustion. However, it remains a significant challenge to achieve both highly synergistic oxidation activity and efficient atom utilization remains a challenge for commonly used supported nanoparticles and single‐atom catalysts. Dual‐atom catalysts (DACs) emerges as a frontier of advanced catalysts, presenting unique catalytic properties that benefit from the synergy of neighboring metal sites. In this study, 361 ceria‐supported DACs (M1M2/CeO2) encompassing combinations of 19 transition metals are systematically explored. Using high‐throughput density functional theory calculations, the structures, stability as well as activity of M1M2/CeO2 are assessed. Notably, Au1Ga1/CeO2 is identified as a promising DAC exhibiting high activity for methane total oxidation, substantiated by comprehensive DFT‐calculated reaction pathways. Furthermore, employing six machine‐learning algorithms, the structure‐properties relationship is explored within ceria‐based DACs and highlight the importance of oxidation states and atomic radii of doped metals as the descriptors. The trained model by computational dataset exhibits high accuracy and predict a more active Mn1Au1/CeO2 than those screened using only DFT datasets. The high‐throughput strategy demonstrated in this work not only provides insights into the rational design of methane oxidation catalysts, but also paves the way for exploring DACs for diverse applications.

Spinel-Based Catalysts That Enable Catalytic Oxidation of Volatile Organic Compounds.

Volatile organic compounds (VOCs) have caused serious harm to human health and ecological environment, and have received much attention in recent years. Despite the successful applications of catalytic combustion of VOCs as the core technology of VOCs removal in industry, the development of efficient catalysts that can mineralize VOCs into nontoxic CO2 and H2O at low temperatures remains a great challenge. Recent studies show that spinel-based materials as efficient catalysts were extensively used in the catalytic oxidation VOCs field due to their synergistic effect, manifold compositions, and electron configurations. However, most of the pollutants are complex, consisting of multiple VOCs, water vapor, CO2, SO2 and other substances, which presents a significant challenge in constructing highly active and stable catalysts. To meet the future demand for efficient catalysts capable of removing various types of VOCs, it is urgent to rationally design and scientifically prepare spinel catalysts based on existing knowledge. This work reviews the research and development of various spinel catalysts with an emphasis on their catalytic performance in VOCs oxidation. The catalytic performance of spinel-based catalysts for different sorts of VOCs was summarized and compared. Moreover, the effects of the reaction conditions on the catalytic performance of spinel-based catalysts were examined to accommodate complicated operating conditions. Subsequently, the regulation of spinel oxides in structure and defect was coherently reviewed to guide the development and design of efficient catalysts. Especially, the research techniques for the reaction mechanism over spinel catalysts were displayed to better deepen the understanding of catalytic oxidation of VOCs. Finally, the current development and challenges were proposed and put forward for future research. This review provided a systematic understanding of the VOCs oxidation over spinel-based catalysts and offered guidance for the development of high-performance catalysts for VOCs elimination.

First direct measurements of the nitrogen isotopic composition of vehicle tailpipe-emitted NH3 and implications for the source apportionment of NH3 in urban atmosphere.

The introduction of three-way catalytic converter (TWC) to meet stringent vehicular NOx emission standards worldwide has led to an unintended consequence of vehicle-derived ammonia (NH3) emission, which might degrade air quality and affect human health, especially in urban areas. The nitrogen stable isotope composition of NH3 (δ15N-NH3) may be a useful tool to trace NH3 sources, but the isotopic signature of vehicle-emitted NH3 is lacking. Here we report the δ15N-NH3 measured from tailpipe exhausts collected directly from 19 different vehicles equipped with TWC using "grab" sample technique optimized to avoid isotopic fractionation. We found a large of range of NH3 concentration (from 1 to 37 ppm, x̄ ± 1σ = 10 ± 8 ppm) and δ15N value (from -38.1 ‰ to 49.0 ‰, x̄ ± 1σ = 1.2 ± 20.9 ‰) for our samples (n = 57). Our results indicate a correlation between δ15N-NH3 and NH3 concentrations (i.e. δ15N-NH3 (‰) = 16.9(± 2.2)In(NH3 concentration; ppm) - 31.7(± 4.7) (R2 = 0.53, P < 0.01) that is associated with the catalyst temperature, which is generally agree with the results of theoretical calculation. After consideration of the vehicle emission evolution, dominant driving condition and tunnel δ15N-NH3 variation, a representative δ15N-NH3 value (meanminmax) of vehicle source is identified as 0.8000-2.20005.2000, which is distinct from (larger than) other NH3 volatilization-related emission sources. Using our newly measured δ15N values and Bayesian mixing model, we approximate the overall contribution of vehicles to ambient NH3 before, during, and after an international event in Beijing was 14.1 %, 7.9 %, and 21.5 %, respectively, which agree well with the course of traffic restriction. Collectively, our findings demonstrate the importance of using vehicle-emitted δ15N-NH3 to quantify vehicular NH3 contribution in urban atmospheres.

Sustainable production of BioAIE materials from biomass

The research of aggregation‐induced emission (AIE) materials has aroused extensive interests during the past 20 years. Until recently, biomass‐inspired AIE (BioAIE) materials have become highly attractive owing to the advantages of natural structural diversity, renewability, biocompatibility, and biodegradability of the biomass. In this concept, we focus on the sustainable production of BioAIE materials from biomass resources (biomacromolecules and small natural products) through extraction, chemical conversion, and physical conversion. Chemical conversion is especially stated, including catalytic conversion, Schiff base reaction, “in water” reaction, and other chemical modifications. The luminescence mechanism of AIE behaviors along with their structure‐property relationships is emphasized, and the applications are addressed as well. An outlook is provided to highlight the challenges and opportunities associated with the future development trend in this field.

Feedstock recycling of polycarbonate waste via thermochemical conversion supported by municipal solid waste incinerator bottom ash.

The rising demand for plastics has driven up its production, causing severe environmental challenges like CO2 emissions and microplastic pollution. Furthermore, improper disposal of incinerator bottom ash (IBA), a byproduct of municipal solid waste (MSW) treatment, poses additional environmental risks. This study explores a method for recovering non-petroleum-based monomers from plastic products. A smartphone case waste (SCW) is used as feedstock in this study and it is made of polycarbonate (PC), confirmed by thermogravimetric analysis and Fourier transform infrared spectroscopy. The MSW incinerator bottom ash (MSW-IBA) is used as a catalyst for thermochemical conversion of SCW. To determine the optimal pyrolysis conditions for BPA recovery, experiments were conducted under different atmosphere (N₂ and CO₂) and catalyst configurations (in situ and ex situ). The MSW-IBA leads to 127% higher yield of bisphenol A (BPA), the monomer of PC, at 600 °C under a N2 atmosphere, compared to non-catalytic conversion. In situ configuration of the catalyst loading leads to up to 147% higher BPA yield than ex situ configuration. The increased BPA production from SCW is most likely because metal oxides (e.g., CaO) present on the MSW-IBA catalyst promotes the cleavage of and C-O bonds, dissociation of CO (or CO2) and hydrogen extraction from C1-C3 hydrocarbon and H2. For the catalytic conversion of SCW under a CO2 atmosphere, CO2 adsorbs onto CaO in the MSW-IBA, decreasing the number of active sites. It deactivates the catalyst, resulting in a lower BPA yield (22.96 wt%) than the BPA yield obtained under the N2 atmosphere (25.86 wt%).

Influence of Channel, Construction and Brønsted Acid Sites on the Catalytic Conversion Pathways of Isobutane Over MFI, TON and RFE Zeolites

Influence of Channel, Construction and Brønsted Acid Sites on the Catalytic Conversion Pathways of Isobutane Over MFI, TON and RFE Zeolites

Nickel and Molybdenum-Containing Perovskites as Efficient Heterogeneous Catalysts for the Conversion of Biobased Furfural to a Fuel Additive Intermediate

AbstractIn this work, the catalytic conversion of furfural was found to follow both CTHs and etherification pathways in one-pot over multicationic inorganic perovskites (LaNi1-xMoxO3±δ) as heterogeneous catalysts. The conversion of furfural (FA) into alcohols and ether functionalities using the as-synthesized perovskite catalysts showed good conversions that are above 80% and excellent selectivity towards the desired product. The LaMoO3 catalyst was found to achieve the highest percentage conversion of 83%. Simple and multicationic inorganic perovskites were successfully employed in the transformation of furfural to produce β-methoxy-2-furanethanol. Furthermore, we postulate the hydrogenation of the keto-group to be the first step in the mechanism of the formation of β-methoxy-2-furanethanol and that its formation is characterized by rearrangement of the intermediate over the surface of the catalyst. Graphical abstract

β-Cyclodextrin Functionalized Au@Ag Core-Shell Nanoparticles: Plasmonic Sensors for Cysteamine and Efficient Nanocatalysts for Nitrobenzene-to-Aniline Conversion

We reported the gold/silver core-shell nanoparticles (Aucore@Agshell NPs) functionalized with β-cyclodextrin (β-CD) as versatile nano-agents demonstrated for human urine-based biosensing of cysteamine and catalytic conversion from nitrobenzene (NB) to aniline. First, the hybrid bimetallic nanoparticles, i.e., β-CD-Aucore@Agshell NPs, constituted a colorimetric sensing platform based on localized surface plasmons, enabling cysteamine (Cyst) to be detected in a remarkably rapid manner, i.e., within 2 min, which was greatly shortened in comparison with that of our previous report. This was due largely to use of β-CD being effectively replaceable by Cyst. The detection of Cyst was demonstrated using human urine specimens in the linear range of 25–750 nM with a limit of detection of 1.83 nM. Excellent specificity in detecting Cyst was also demonstrated against potential interfering molecules. Meanwhile, the β-CD-Aucore@Agshell NPs were demonstrated as nanocatalysts for converting NB to aniline with efficiency enhanced by more than three-fold over the pure gold nanoparticles previously reported, due to the dual functions of the structural core-shell. The demonstrated versatile features of the hybrid nanoparticles can find applications in human urine-based biosensors for Cyst detection, and in the screening of Cyst-containing drugs, while detoxicating NB for ecological protection in aqueous media.

A comprehensive investigation of the impact of carbon-supported metal complexes of triaminoguanidine on the characteristics of a double-base propellant

ABSTRACT In this study, triaminoguanidine complexes grafted onto activated carbon (AC-TAG-Fe and AC-TAG-Co) were designed and investigated for their catalytic effect on the thermolysis of a double base propellant consisting of nitrocellulose (NC) and diethylene glycol dinitrate (DEGDN). The successful synthesis of transition metal complexes with triaminoguanidine and their subsequent grafting onto activated carbon were confirmed using various analytical techniques, including Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray Diffraction, and Scanning Electron Microscopy. Thermal characterization using Thermogravimetric Analysis and Differential Scanning Calorimetry provided valuable insights into the thermal properties and reactivity of the elaborated NC/DEGDN-based composites. Importantly, the addition of various additives resulted in notable improvements in both the enthalpy of reaction and density. Isoconversional kinetic studies revealed that the incorporation of TAG-Fe and TAG-Co complexes reduced the apparent activation energy of the NC/DEGDN composite from 137.4 kJ/mol to 135.4 kJ/mol and 114.8 kJ/mol, respectively, suggesting their catalytic effect. Furthermore, it is found that the addition of activated carbon (AC) resulted in an increase in activation energy to 154 kJ/mol, whereas grafting TAG-Fe and TAG-Co complexes onto AC as a catalytic support subsequently reduced activation energy to 119 kJ/mol and 112 kJ/mol, respectively. Overall, this research serves as a valuable reference for future studies focusing on investigating the catalytic combustion characteristics of double-base solid propellants.

Advances in Carbon Dioxide Catalytic Conversion and Applications

To achieve the global climate goals set out in the Paris Agreement, reducing carbon dioxide (CO2) emissions and utilizing resources have become key areas of focus within international energy technology research and development. CO2 can be converted into high-value chemicals, including hydrocarbons, alcohols and hydrocarbons, through the catalytic technology. This process can potentially address environmental issues while generating economic benefits. This paper presents a review of the principal products resulting from the catalytic conversion of CO2, together with an examination of their practical applications. These include hydrogenation of olefins, light aromatics, methanol, polyols, and synthetic bioconversion technologies. The development of catalysts with high conversion and selectivity represents a key area of current research. In the future, it will be necessary to combine physical, chemical, and biological technologies to establish an engineered heterogeneous carbon sequestration technology system to achieve the efficient conversion and utilization of CO2.

Enhancing catalytic converter performance: effects of noble metals and rare earth washcoating on CO and NOx conversion

Enhancing catalytic converter performance: effects of noble metals and rare earth washcoating on CO and NOx conversion

Regulating the electronic modulation configuration of MnxFeCoNiCu high entropy alloy for reliable sulfur redox kinetics

Current research on sulfur redox catalysis primarily focuses on the adsorption and catalytic conversion of lithium polysulfides (LiPSs). However, it often neglecting the modulation of the catalysts' electronic structure, which includes charge transfer and orbital interactions that significantly affect adsorption and catalytic properties. In this work, multi-channel carbon nanotubes modified with high entropy alloy nanoparticles (MnxFeCoNiCu/MCCFs) are elaborately synthesized as hosts to reveal the relationship between the catalytic activity and surface electronic configuration for reliable sulfur electrochemistry. Combining density functional theory (DFT) calculations with detailed experimental investigations, we demonstrate that modulating the electron consumption center of this intrinsic electron transfer-replenishment mechanism, the surface charge distribution is reestablished, thereby improving the performance of multi-electron reactions. Achieving a balance between adsorption and desorption significantly enhance the catalytic efficiency for LiPSs conversion. Consequently, the as-prepared Mn1.00/MCCFs with an optimized electronic structure as sulfur host can deliver a high capacity of 938 mAh g−1, corresponding to an ultralow capacity decay of 0.013 % per cycle over 500 cycles at 1.0 C.

Efficient paddle-wheel copper cluster-based metal-organic framework for catalytic conversion of CO2 to oxazolidinones under mild conditions

Efficient utilization of CO2 and its conversion into high-value-added products contribute to mitigating environmental issues such as the greenhouse effect. Among these methods, the carboxylation cyclization of CO2 with propargylic amine represents a green and atom-economical approach. Developing cost-effective catalyst that can promote this reaction under mild condition is desirable but challenging. Herein, a unique two-dimensional (2D) metal–organic framework (MOF) {[Cu(QCA)2]∙0.5DMF∙0.5H2O}n (1) (QCA =6-quinolinecarboxylic acid, DMF = N,N-dimethylformamide) have been synthesized and thoroughly characterized. Compound 1 was constructed from paddle-wheel dinuclear copper clusters [Cu2(COO)4] and carboxylate ligands, presenting a two-dimensional framework with new topology. Stability tests indicate that compound 1 undergoes reversible structural changes in different solvents and exhibits good thermal stability. 1 as heterogeneous catalyst enabled the transformation of CO2 and propargylic amine into oxazolidinones under mild conditions with broad substrate generality. In addition, 1 could maintain its catalytic performance with five continuous reactions. This work presents an infrequent example of a 2D noble metal free MOF-based catalyst that shows high catalytic efficiency under mild conditions.

Conversion of CO2 into Synthetic Motor Fuels

The process of CO2 conversion into synthetic hydrocarbons including the stages of synthesis gas production on the catalyst NIAP 06-06 and hydrocarbon synthesis by the Fischer-Tropsch method on a bifunctional zeolite-containing catalyst has been investigated. Experimental studies of the process of catalytic conversion of CO2 into synthesis gas were carried out in order to obtain gas with the ratio of H2/CO close to the required ratio for Fischer-Tropsch synthesis. The possibility of obtaining gasoline and diesel fractions of hydrocarbons with a high content of isomeric structures that increase the performance characteristics of motor fuels has been shown. The yield of hydrocarbons C5+ with 1 m3 of initial CO2 and H2 at the synthesis temperature of 220 °C is found to be 44.5 g.

Incorporation of Fe/FeOx Nanoparticles into Interlinked N-Doped Porous Carbon Nanofiber Networks to Realizing Sequential Catalytic Conversion of Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries (LSBs) with energy density (2600 Wh/kg) much higher than typical Li-ion batteries (150-300 Wh/kg) have received considerable attention. However, the insulation nature of solid sulfur species and the high activation barrier of lithium polysulfides (LiPSs) lead to slow sulfur redox kinetics. By the introduction of catalytic materials, the effective adsorption of LiPSs, and significantly reduced conversion, energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing these challenges. In this work, a multifunctional catalyst consisting of highly dispersed heterostructure Fe-Fe2O3 nanoparticles was synthesized and introduced to the LSB. Experimental and theoretical analyses revealed that the spontaneous interfacial charge redistribution, resulting in moderate polysulfide adsorption, facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. This catalyst achieves sequential catalytic processes on polysulfides with different components. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe/Fe2O3-NG for expediting LiPS conversion. Consequently, the battery exhibited long-term stability for 300 cycles with 0.03% capacity decay per cycle at 5C. This work provides in-depth insight into the fundamental design principles of effective catalysts for LSBs.

D‐Band Center Modulation of Metallic Co‐Incorporated Co7Fe3 Alloy Heterostructure for Regulating Polysulfides in Highly Efficient Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li‐S) batteries, with their high theoretical energy density and cost‐effectiveness, have become one of the most promising next‐generation energy storage devices. However, they still face challenges such as the “shuttle effect” caused by the dissolution of polysulfide intermediates and the slow sulfur conversion kinetics. In this study, based on the Co7Fe3 alloy catalyst, additional Co metal is introduced to form a Co7Fe3Co catalyst with a heterostructure through a simple heat treatment process. This catalyst is incorporated into Ketjenblack (KB) to form a sulfur‐infused cathode material (designated as S/KB/Co7Fe3Co). Li‐S batteries using S/KB/Co7Fe3Co as the cathode demonstrate outstanding electrochemical performance, maintaining a reversible specific capacity of over 500 mAh g−1 after 1000 cycles at a current density of 1 C, with a capacity decay rate of 0.046% per cycle. DFT theoretical calculations and experimental results both reveal that the introduction of additional Co effectively regulates the d‐band center of the material, enhancing the adsorption of polysulfide intermediates by Co7Fe3Co and promoting bidirectional catalytic sulfur conversion. This work highlights the importance of the simple construction of heterostructured catalytic materials and their role in improving the performance of Li‐S batteries.

Synergistic degradation of refractory organic pollutant by underwater bubbling plasma combined with heterogeneous Fenton process

Excessive discharge of the refractory organic pollutants endangers the development of the society and economy, thus seeking an efficient wastewater abatement method is an urgent need. Herein, Iron (Ⅱ) sulfide (FeS) was employed as the heterogeneous catalyst and coupled with underwater bubbling plasma (UBP) for the elimination of the refractory organic pollutant, malachite green (MG). FeS catalyst was synthesized using the solvothermal method and subsequently characterized comprehensively, focusing on its microstructure, specific surface area, chemical bonds and elements valence states. The UBP system combined with FeS (UBP/FeS) exhibited the robust synergism with a maximum synergistic factor of 1.89. The MG degradation percentage and rate constant were up to 94.7% and 0.237 min−1 within 12 min. The parameter experiments revealed that FeS dosage, pulse frequency, initial MG concentration and solution conductivity of 150 mg/L, 56 Hz, 5 mg/L and 21.8 μS/cm, respective, were more conducive for MG elimination. The MG removal efficiency reached 86.2% after five consecutive applications of FeS. Reactive substances including ·OH, ·O2−, eaq, O3 and H2O2 were confirmed to contribute to MG elimination. Additionally, the conversion circle between ≡ Fe(Ⅱ) and ≡ Fe(Ⅲ) promoted the catalytic conversion of H2O2 and O3 into ∙OH. The comparison of UV–vis spectra and total organic carbon of MG solution before and after reaction revealed the superior degradation of MG in the UBP/FeS system. Hypotheses regarding to the decomposition pathways of MG were formulated based on the identified intermediates. The toxicity level of MG solution was lightened after reaction. The above results indicate that UBP/FeS has the advantages of quick degradation and high efficiency, representing a promising approach for refractory pollutants treatment.

Single-Pass Demonstration of Integrated Capture and Catalytic Conversion of CO2 from Simulated Flue Gas to Methanol in a Water-Lean Carbon Capture Solvent

Single-Pass Demonstration of Integrated Capture and Catalytic Conversion of CO₂ from Simulated Flue Gas to Methanol in a Water-Lean Carbon Capture Solvent