Low-temperature Reaction Research Articles

Effect of inorganic salts / lignin on the combustion performance of torrefied biochar

In this study, inorganic salts (KMnO4, Ba(NO3)2) and enzymolysis lignin were added into torrefied biochar to improve the drawback of high ignition temperature during combustion when biomass underwent torrefaction. Weight loss characteristics, gas products, combustion kinetics of torrefied biochar with different additives were investigated. The addition of KMnO4, Ba(NO3)2, enzymolysis lignin, and their blends can reduce the ignition point of torrefied biochar, and the addition of Ba(NO3)2 can also extent the burnout time. When KMnO4, Ba(NO3)2 and lignin were added at the same time, the first weight loss peak temperature was reduced, and the reaction rate was accelerated. The combustion kinetics of torrefied biochar with different inorganic salts/lignin can be described by a simple first-order reaction. The addition of different inorganic salts/lignin additives is beneficial to reduce the activation energy of the low temperature reaction stage, and the activation energy of torrefied biochar with lignin addition decreases the most.

Development of Rapid Isothermal Detection Methods Real-Time Fluorescence and Lateral Flow Reverse Transcription Recombinase-Aided Amplification Assay for Bovine Coronavirus

Bovine coronavirus (BCoV) is a notable pathogen affecting newly born calves and adult cattle, increasing mortality rates among calves and reducing productivity in meat and dairy industries, thereby causing substantial economic losses. Current primary laboratory methods for detecting BCoV include RT-PCR assay, real-time RT-PCR assay, and ELISA. However, these methods are time-consuming, require specialized technicians, and necessitate a laboratory environment. Consequently, there is an urgent need for a rapid, sensitive, and easy to use diagnostic method to detect BCoV. This study introduces two innovative protocols: the real-time fluorescent reverse transcription recombinase-aided amplification (RT-RAA) and the test strip RT-RAA (RT-RAA-LFD). Our results indicate that real-time RT-RAA can complete the reaction in 20 min at 39°C, while RT-RAA-LFD can achieve detection in just 17.5 min at 35°C. These new approaches offer higher specificity, with no cross-reactivity to other viruses, and significantly enhanced sensitivity compared to existing methods (1.46 × 101 and 1.46 × 102 copies/μL, respectively). We evaluated the performance of our methods using 242 clinical samples, and compared with RT-PCR and RT-qPCR. Both real-time RT-RAA and RT-qPCR yielded similar detection rates, the detection rate of RT-RAA-LFD was better than RT-PCR. The RT-RAA methods developed in this study effectively overcome the limitations associated with both RT-PCR and RT-qPCR by offering advantages including a single, low reaction temperature that allows for room temperature operation. Both methods boast shorter reaction times, simpler and more portable instrumentation, as well as reduced technical and environmental demands. Generally, both RT-RAA methods established in this study offer new avenues for the rapid detection of BCoV, contributing significantly to the monitoring, prevention, and control of the disease in global bovine industry.

Understanding the Nonlinear Reactivity Promoting Effect of n-Heptane Addition on the Binary Mixture From Low to Intermediate Temperature: A Case of Methane/n-Heptane Mixtures

Abstract To understand the effect of n-heptane (NC7H16) addition on the auto-ignition of methane (CH4) at low to intermediate temperatures, the ignition delay times (IDTs) of stoichiometric CH4/NC7H16 blends with varying NC7H16 concentrations were measured at temperatures from 600 to 1000 K, pressures of 20 and 40 bar. Detailed chemical kinetic mechanisms were validated against the newly measured IDTs. Adding NC7H16 in the binary mixture shows a nonlinear promoting effect on the IDTs: micro-addition of NC7H16 can significantly reduce the IDTs of the binary mixture when the NC7H16 is lower than 20%. However, the decrease of the IDTs becomes much slower when further increasing the NC7H16 addition. Affected by the negative temperature coefficient (NTC) behavior of NC7H16, this nonlinear effect is particularly notable at around 795 K, the low boundary of the NTC region. To reveal the nonlinear reactivity-promoting effect of NC7H16 addition on the binary mixture, reaction flux, ignition sensitivity, rate of production of the key radicals along heat production analyses were conducted. Apart from contributing more O˙H production through the low-temperature chain-branching reaction pathways of NC7H16, adding NC7H16 also promotes the pre-ignition heat release of the binary mixture. The heat release raises the system temperature and further promotes the mixture ignition, enhancing the nonlinear effect at low temperatures.

Autonomous execution of highly reactive chemical transformations in the Schlenkputer

We design a modular programmable inert-atmosphere Schlenkputer (Schlenk-line computer) for the synthesis and manipulation of highly reactive compounds, including those that are air and moisture sensitive or pyrophoric. Here, to do this, we constructed a programmable Schlenk line using the Chemputer architecture for the inertization of glassware that can achieve a vacuum line pressure of 1.5 × 10−3 mbar, and integrated a range of automated Schlenk glassware for the handling, storage and isolation of reactive compounds at sub-ppm levels of O2 and H2O. This has enabled automation of a range of common organometallic reaction types for the synthesis of four highly reactive compounds: [Cp2TiIII(MeCN)2]+, CeIII{N(SiMe3)2}3, B(C6F5)3 and {DippNacNacMgI}2, which are variously sensitive to temperature, pressure, water and oxygen. Automated crystallization, filtration and sublimation are demonstrated, along with analysis using inline nuclear magnetic resonance or reaction sampling for ultraviolet–visible spectroscopy. Finally, we demonstrate low-temperature reactivity down to −90 °C as well as safe handling and quenching of alkali metal reagents using dynamic feedback from an in situ temperature probe.

Unlocking the Potential of Garnet Ferrites: A Comprehensive Review on Properties, Preparation Methods, and Applications

Abstract This review paper provides a comprehensive overview of the recent advances in garnet ferrites, a class of complex magnetic oxides with promising properties for various applications. The paper covers the crystal structure and different properties of garnet ferrites as well as their synthesis methods, including sol-gel auto-combustion, low-temperature liquid phase epitaxy, pulsed laser deposition, coprecipitation method, sol-gel, hydrothermal, ball billing method, and low-temperature solid-state reactions. The functional properties of garnet ferrites, such as permeability, hysteresis loop, loss mechanics, and saturation magnetization, are also discussed in detail, along with their potential applications in microwave devices, antennas, Faraday lasers, and cancer treatment. Finally, the challenges and future directions for the development of garnet ferrites are outlined, highlighting the need for further research to optimize their properties and improve their performance in real-world applications.

Elucidating the low temperature chemistry of o-xylene enhanced by the reaction pool of dimethyl ether

The branched aromatic hydrocarbon with short side chains, such as o-xylene, has weak low temperature oxidation reactivity, while it could proceed low temperature chain recycling reactions by blending a fuel component with higher oxidation reactivity. However, the study of low temperature oxidation kinetics of o-xylene is very scarce. Therefore, this work investigated the low temperature oxidation process of o-xylene in an atmospheric jet stirred reactor by adding a biofuel with higher low temperature oxidation reactivity, i.e. dimethyl ether (DME). A series of characteristic low temperature intermediates, such as phenyl hydroperoxides and ketohydroperoxide from the oxidation of o-xylene, were detected by using the synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The chemical structures of representative low temperature intermediates were determined by comparing the ionization thresholds from measured photoionization efficiency curves with calculated ionization energies. A kinetic model for o-xylene and DME mixture was developed and verified by literature and present experimental data. Rate of production (ROP) and sensitivity analyses were performed, which indicate that the low temperature oxidation chemistry of o-xylene, such as the negative temperature coefficient behavior, is enhanced by the reaction pool of DME. According to the classical low temperature oxidation mechanism of n-alkanes, the low temperature reactions of o-xylene were proposed. In particular, phenyl hydroperoxides and ketohydroperoxides were revealed to be key indicators for the occurrence of first and second O2 addition reactions during the oxidation of o-xylene, respectively. In addition, the sensitivity analysis uncovers the interaction kinetics between the reaction pools of o-xylene and DME, as well as their effects on fuel consumption and products formation. In summary, present evidence elucidates the low temperature chemistry of a representative branched aromatic, which could contribute to the development of future engines and control of combustion pollutants.

Computational Screening of Pt1@Ti3C2T2 (T = O, S) MXene Catalysts for Water-Gas Shift Reaction.

Single-atom catalysts (SACs) provide an opportunity to elucidate the catalytic mechanism of complex reactions in heterogeneous catalysis. The low-temperature water-gas shift (WGS) reaction is an important industrial technology to obtain high purity hydrogen. Herein, we study the catalytic activity of Pt1@Ti3C2T2 (T = O, S) SACs, where one subsurface Ti atom with three T vacancies in the functionalized Ti3C2T2 (T = O, S) MXene is substituted by one Pt atom, for the low-temperature WGS reaction, using density functional theory (DFT). The results show that Pt1@Ti3C2T2 provides an excellent platform for the WGS reaction by its bowl-shaped vacancy derived from the Pt1 single atom and three T defects surrounding it. Especially, Pt1@Ti3C2S2 SAC has higher catalytic performance for the WGS reaction, due to the weaker electronegativity of the S atom than the O atom, which significantly reduces the energy barrier of H* migration in the WGS reaction, which is often the rate-determining step. In the most favorable redox mechanism of the WGS reaction on Pt1@Ti3C2S2, the rate-determining step is the dissociation of OH* into O* and H* with the energy barrier as low as 1.12 eV. These results demonstrate that Pt1@Ti3C2S2 is promising in the application of MXenes for low-temperature WGS reactions.

Immobilization of Ni on MOF-derived CeO2 for promoting low-temperature dry reforming of methane

The development of highly active catalysts for low-temperature dry reforming of methane (DRM) is of great importance for the utilization of CO2 and CH4. Herein, the MOF-derived CeO2-supported Ni (Ni/CeO2-M) catalyst was facilely and mildly prepared, and its catalytic performance for DRM reactions at 400–600 °C was explored and compared with commercial CeO2-supported Ni (Ni/CeO2-C). At 550 °C, the CO2 and CH4 conversions of Ni/CeO2-M are 40.1 % and 30.8 %, respectively, which are significantly higher than those of Ni/CeO2-C (27.3 % and 15.5 %, respectively). The analysis of covariance also shows that the conversions of CO2 and CH4 of Ni/CeO2-M are 8.90 % and 11.65 % higher than those of Ni/CeO2-C after eliminating the effect of temperature, respectively. After 10 h of DRM reaction, Ni/CeO2-M exhibits better resistance to carbon deposition and sintering than Ni/CeO2-C, and carbon deposition is related to the reaction temperature rather than the catalyst. Morphological analysis suggests that, unlike the serious Ni accumulation on Ni/CeO2-C, metallic Ni is uniformly immobilized on Ni/CeO2-M. The highly dispersed metallic Ni0 on Ni/CeO2-M facilitates the dissociation of CH4, and more oxygen vacancies facilitate the dissociation of CO2 into CO and active O. Therefore, Ni/CeO2-M exhibits better catalytic performance and is very promising for low-temperature DRM reactions.

Biocrude extraction from human-excreta-derived hydrochar for sustainable energy and agricultural applications

Hydrothermal carbonization may be a sustainable sanitary treatment for wet organic waste including human excreta. Human-excreta-derived hydrochar properties differ from those of typical wet biomass due to the formation of a biocrude-like phase at low reaction temperatures. This study characterized the importance of this phase in terms of hydrochar combustion properties and potential agricultural use. Hydrothermal carbonization of raw human excreta was undertaken at 180, 210, and 240 °C, after which the biocrude phase was extracted with dichloromethane. Physicochemical properties, surface-area parameters, combustion profiles, and gas emissions of non-extracted hydrochar, biocrude, and extracted hydrochar were compared. The potential agricultural use of extracted hydrochar was assessed in germination experiments. Biocrude comprised up to 49.5% of hydrochar mass with a calorific value of >60% that of extracted hydrochar. Biocrude combustion properties were better than those of hydrochar, before and after extraction as demonstrated by higher combustion index value (Si). The extracted hydrochar surface area (34.7 m2 g−1) was greater than that of non-extracted hydrochar (<2 m2 g−1), and seeds germinated more readily due to the lower phytotoxin content. Most macro and micronutrients required for plant growth were retained in the extracted hydrochar. The extraction of biocrude from human-excreta-derived hydrochar not only provided a higher-quality fuel with enhanced combustion properties but also improved hydrochar characteristics, suggesting its potential as a soil additive for enhanced plant growth.

Catalytic condensation of α-pinene with formaldehyde

While synthesis of hydroxymethyl derivatives of common terpenes by a reaction with formaldehyde (FA) has been commercialized, no open data are available on the preparation of such α-pinene derivatives. Here, an approach for the renewable (–)-α-pinene catalytic utilization by its condensation with FA into a novel terpenoid 8-acetoxy-6-hydroxymethyllimonene is proposed. Both common homogeneous acids and aluminosilicates (halloysite nanotubes pretreated with H3PO4 and HCl, montmorillonite K-10, zeolite H-Beta-25) have been investigated. The solids were characterized by SEM, EDX, 27Al and 29Si MAS NMR, as well as FTIR with pyridine and N2 adsorption–desorption methods. Traditional Lewis and Brønsted acids (ZnCl2, FeCl3, H3PO4 etc.) catalyzed the desired condensation although selectivity did not exceed 24 % in the case of phosphoric acid due to the side reactions, including opening of the α-pinene cyclobutane ring, as well as skeletal rearrangements of its bicyclic structure. On aluminosilicates with a weak to moderate Lewis and Brønsted acidity (45–104 µmol/g), the products of a direct substrate protonation (up to 52.8 %) were predominantly formed. In the presence of strongly acidic H-Beta-25 (301 µmol/g) and phosphoric acid, selectivity to α-pinene addition products with formaldehyde (32.3–35.3 %) and substrate direct protonation (30.0–36.8 %) were comparable. However, with H3PO4 the content of borneol derivatives formed via the Wagner-Meerwein rearrangement was the smallest (13.5 %) giving subsequently the largest selectivity to the desired 8-acetoxy-6-hydroxymethyllimonene. Higher selectivity to the target product was observed at lower reaction temperature and a larger formaldehyde amount. The reaction mechanism has been proposed and elucidated using kinetic and quantum chemical approaches. The developed kinetic model adequately describes the experimental results. The DFT calculations showed that in the presence of H3PO4 there are no significant differences between the energy of the intermediates formed due to formaldehyde addition to α-pinene or its direct protonation. Synthesis of 8-acetoxy-6-hydroxymethyllimonene was performed on 22 g scale. This compound can be considered as a chiral platform for further utilization, including synthesis of heterocyclic compounds.

Surface Modification of Fe-ZSM-5 Using Mg for a Reduced Catalytic Pyrolysis Temperature of Low-Density Polyethylene to Produce Light Olefin

Although the catalytic pyrolysis of low-density polyethylene (LDPE) to produce light olefin has shown potential industrial application advantages, it has generally suffered when using higher pyrolysis temperatures. In this work, Mg-modified Fe-ZSM-5 was used for catalytic conversion of LDPE to obtain light olefin in a fixed bed reactor. The effects of catalyst types, pyrolysis temperatures, and Mg loading on the yield of light olefin were investigated. The 1 wt% Mg loading slightly improved the yield of light olefin to 38.87 wt% at 395 °C, lowering the temperature of the pyrolysis reaction. We considered that the higher light olefin yield of Fe-Mg-ZSM-5 was attributed to the introduction of Mg, where Mg regulated the surface acidity of the catalyst, inhibited the secondary cracking reaction, and reduced coking during the pyrolysis process. Furthermore, the addition of Mg also dramatically reduced the average particle size of Fe oxides from 40 nm to 10 nm, which is conducive to a lower catalytic reaction temperature. Finally, the spent catalyst could be easily regenerated at the conditions of 600 °C in airflow with a heating rate of 10 °C/min for 1 h, and the light olefin yield remained higher than 36.71 wt% after five cycles, indicating its excellent regeneration performance.

Oxygen vacancy of Pt/CeO2 enabled low-temperature hydrogen generation from methanol and water

Aqueous-phase reforming of methanol (APRM) represents an alternative approach to achieve a sustainable hydrogen generation and safe storage. Nonetheless, the limitations imposed by the high operating temperatures of heterogeneous catalysts serve as a bottleneck for the widespread adoption of this system. Herein, we demonstrated that the Pt nanoparticles supported on porous nanorods of CeO2 with abundant oxygen vacancies (Pt/PN-CeO2) enabled the efficient H2 generation through low-temperature (<60 °C) APRM reaction. The presence of oxygen vacancies on PN-CeO2 could enhance the electronic density of supported Pt nanoparticles through strong metal-support interaction, thereby promoting the activation of methanol. Meanwhile, the oxygen vacancies could further promote the H2O activation. Consequently, the interface between Pt and PN-CeO2 enabled efficient H2 generation at 60 °C with a TOF values of 173.5 h−1 and suppress CO generation. This finding provides a promising pathway towards the low-temperature APRM reaction.

Low‐Temperature N‐Alkylation of Amines with Alcohols in Protic Solvents Catalyzed by Iridium Complexes Bearing N‐Heterocyclic Carbenes

AbstractAmines are important compounds found in natural products, pharmaceuticals, and fine chemicals. Therefore, the development of elegant, environmentally friendly, and simple synthetic methods is desirable. Recently, the borrowing‐hydrogen (BH) strategy has received considerable attention for C−N bond formations because of its high atomic efficiency and the absence of toxic waste generation. Researchers have recently reported that the use of N‐heterocyclic carbene (NHC) ligands with strong electron‐donating properties and protic solvents can increase the catalytic activity in the BH strategy. Therefore, herein, we focused on the versatility of the synthetic methods, such as a synthetic system that allows simple synthesis, operates at low reaction temperatures, and involves the use of effective solvent simultaneously. The catalyzed N‐alkylation of alcohols and amines in protic solvents under mild conditions was investigated using simple NHC complexes developed by our group. We achieved the synthesis of various alkylamines under mild conditions, such as 40–60 °C, using iridium complexes comprising NHC ligands with simple structures and protic solvents such as 2,2,2‐trifluoroethanol and 1,1,1,3,3,3‐hexafluoroisopropanol.

The study of Correlated Barrier Hopping (CBH) conduction mechanism and modulus spectroscopy of YFe0.5Co0.5O3 compound

This research paper studied the electrical properties of Yttrium orthoferrite by substituting 50-mol percent of Co into the Fe-site. The crystalline morphology of the obtained compound, YFe0.5Co0.5O3, was studied using XRD and Rietveld refinement with FullProf software. A low-temperature solid-state reaction technique was used to make this compound. X-ray diffraction results indicate that the obtained compound has an orthorhombic structure with space group Pbnm. X-ray peak broadening analysis was used to evaluate crystallite size and strain using Williamson-Hall plots (W–H plot). FESEM with EDX data revealed the phase purity of the obtained compound. XPS studies showed the presence of multiple oxidation states of Fe and Co in the compound. The Nyquist plots show non-Debye-type behavior in all samples. The CBH (Correlated Barrier Hopping) Model was adopted to explain the conduction mechanism.

Si4Al2O2N6 regulating chemical states of Co catalyst for improved hydrogen production from ethanol steam reforming

Tuning the metal-support interaction is a general strategy of regulating the chemical state of catalytic active site for high-efficiency hydrogen production from ethanol steam reforming (ESR) reaction. In this work, a Co catalyst supported on the Si4Al2O2N6 solid solution of Si3N4 and Al2O3 (Co/Si4Al2O2N6) has been developed to effectively catalyze ESR reaction. Our results demonstrate that the Co/Si4Al2O2N6 catalyst exhibits remarkably improved performances as compared with the Co/Si3N4 and Co/Al2O3 catalysts. In the Co/Si4Al2O2N6-catalyzed ESR reaction, ethanol conversion of 97 % has been achieved with hydrogen yield reaching 73 %. Long-time catalytic experiment manifests the Co/Si4Al2O2N6 catalyst possesses excellent durability. X-ray photoelectron spectroscopy (XPS) studies reveal that the enhanced metal-support interaction (MSI) and charge transfer from Si4Al2O2N6 support to Co species in the Co/Si4Al2O2N6 catalyst confer lower valence state on the Co catalyst supported on Si4Al2O2N6, thus promoting the C–C bond cleavage capability, leading to high C1 product yield and boosting the hydrogen-production efficiency. The catalytic mechanism studies explored by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveal that the Co/Si4Al2O2N6 exhibits a remarkable preference for C1 products over the Co/Si3N4 and Co/Al2O3 catalysts at low reaction temperature, thus resulting in high hydrogen-production efficiency with excellent catalytic durability.

Low-temperature oxidation of n-butanol in a jet-stirred reactor: Detailed species measurements and modeling studies

n-Butanol is a new generation of liquid biofuel. A detailed understanding of the low-temperature combustion chemistry of n-butanol is instructive for its practical application in advanced low-temperature engines. The high-temperature combustion chemistry of n-butanol has been extensively studied, but its low-temperature combustion chemistry remains underexplored, especially the detailed species distribution. In this work, ozone addition was used to enhance the low-temperature oxidation reaction activity to achieve the oxidation of n-butanol in a jet-stirred reactor (JSR) at atmospheric pressure and in the temperature range of 400–800 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was used for detailed measurements of species distribution. The identification of some intermediate species contributed to elucidating and verifying the low-temperature oxidation reaction pathways of n-butanol, such as butanal, C4 hydroxyalkyl hydroperoxides, C4 hydroxyl cyclic ether, and C4 keto-hydroperoxide. Furthermore, the formation of several elusive intermediates was also identified (e.g., C2H4O2, C3H6O2, C4H6On (n = 1∼3), and C4H8O2), highlighting the necessity of further kinetic studies on the low-temperature oxidation of n-butanol. Based on detailed experimental measurements, the n-butanol model was further developed to improve the model predictions by updating the rate constants for the H-atom abstraction reactions of n-butanol by the ȮH radical, adding the detailed butanal sub-mechanism, etc. Especially, the premature formation of CO2 in the present experiment was satisfactorily explained and predicted by the addition of a generally accepted reaction class (i.e., RȮ2 + RȮ2 = RȮ + RȮ + O2 of butanal). Overall, this updated model satisfactorily predicts both the ignition delay time reported in the literature and the species distribution obtained in this work.

Thermolysis of Biphenylene toward Cyclo‐ortho‐phenylenes

AbstractThe solvent and catalyst free thermolysis of biphenylenes at 350 °C furnishes [n]cyclo‐ortho‐phenylenes ([n]COPs, n=4–10) in one step and in high yields. At 400 °C biphenylene dimerizes into tetraphenylene, but lower reaction temperatures produce cyclooligomers. If suitably substituted, the oligomers are soluble and can be isolated and characterized. The products are exclusively cyclic. In the crystalline state, [6]COP displays an alternating crown‐shaped conformation.

Thermolysis of Biphenylene toward Cyclo-ortho-phenylenes.

The solvent and catalyst free thermolysis of biphenylenes at 350 °C furnishes [n]cyclo-ortho-phenylenes ([n]COPs, n=4-10) in one step and in high yields. At 400 °C biphenylene dimerizes into tetraphenylene, but lower reaction temperatures produce cyclooligomers. If suitably substituted, the oligomers are soluble and can be isolated and characterized. The products are exclusively cyclic. In the crystalline state, [6]COP displays an alternating crown-shaped conformation.

CO2 to Cyclic Carbonate: A Mechanistic Insight of a Benign Route Using Zinc(II) Salophen Complexes

AbstractZinc(II) Schiff base complexes with different substituents at 5, 5’ positions have been synthesized to study the effect of the electronic environment of the metal towards the cycloaddition reaction between CO2 and epoxide. The complexes have been characterized by FT‐IR, XPS, NMR, electronic spectroscopy, LC–MS, and TGA. We have used density functional theory to study the electronic structure of the Zn(II) complexes and modelled the electronic spectra and the mechanism of catalysis. Results obtained from DFT and LC–MS indicate the dimeric structures for all the complexes except ZnL4. The monomeric ZnL4 has the strongest electron withdrawing group, i. e., −NO2 at 5, 5’ positions along with two labile water molecules attached to the Zn center. The dimeric complexes exhibit good to moderate yield for cycloaddition reaction to styrene carbonate under solvent‐free conditions and a relatively low reaction temperature of 80 °C, with CO2 pressure of ~1 atm. The best yield has been achieved by ZnL4. Different rate‐determining steps are captured by the DFT studies for dimeric and monomeric complexes. Without taking any preventing measure of dimerization by attaching the bulky tBu groups, relatively lesser catalytic amounts of all the complexes have shown yields of cyclic carbonate between 53–74 %, depending on the nature of the substituent present.

Synergistic effect of oxygen-containing and nitrogen-containing groups on promoting low-temperature denitration over non-metallic carbon-based catalyst

Oxygen-containing and nitrogen-containing groups on the surface of non-metallic carbon-based catalysts have been regarded as active sites for NH3 selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx) at low temperature. In this study, series of AC-xO-yN catalysts were prepared via grafting oxygen-containing and/or nitrogen-containing groups on active carbon (AC). The activity test results showed that the denitration efficiency of AC-5O-0 N and AC-0O-4 N catalyst were only 20 and 44 % at a temperature of 120 °C and a GHSV of 4500 h−1, respectively, while the activity of the AC-5O-4 N catalysts reached 97 % at the same condition, indicating that the oxygen-containing and nitrogen-containing groups exhibited a superior synergistic effect in facilitating the low-temperature NH3-SCR denitration reaction. Characterization results revealed that the oxygen-containing groups (mainly carboxyl and lactone groups) contribute to NH3 adsorption and activation, while the nitrogen-containing groups (especially pyridine nitrogen groups) could promote NO adsorption and oxidation. The co-existence of oxygen-containing and nitrogen-containing groups can synergistically advance the low-temperature NH3-SCR denitration reaction on the surface of the AC catalyst via a fast SCR route. This work might provide insight into designing and preparing non-metallic carbon-based catalysts with high denitration performance.