Space Velocity Research Articles

Investigation of physics-informed deep learning for the prediction of parametric, three-dimensional flow based on boundary data

The placement of temperature sensitive and safety-critical components is crucial in the automotive industry. It is therefore inevitable, even at the design stage of new vehicles, that these components are assessed for potential safety issues. However, with increasing number of design proposals, risk assessment using Computational Fluid Dynamics (CFD) quickly becomes expensive. We therefore present a parameterized surrogate model for the prediction of three-dimensional flow fields in aerothermal vehicle simulations. The proposed physics-informed neural network (PINN) design is aimed at learning families of flow solutions according to a geometric variation. The novelty of our method compared to existing works in the field of PINN lies in the extension of parametric flow prediction to three-dimensional space by applying a mini-batch based Quasi-Newton optimization. We contribute a parametric minibatch training algorithm which enables the utilization of the large datasets necessary for the three-dimensional flow modeling. Further, we introduce a continuous resampling algorithm that allows to represent domain variations, while operating on one static dataset of reduced size. In scope of this work, we could show that our nondimensional, multivariate scheme can be efficiently extended to predict the velocity and pressure distribution in three-dimensional space for different design scenarios and geometric scales. Every feature of our methodology is tested individually and verified against conventional CFD simulations. Finally, we apply our proposed method in context of an exemplary real-world automotive application.

Surface engineered sustainable nanocatalyst with improved coke resistance for dry methane reforming to produce hydrogen

The ever-growing carbon-based economy has led to alarming increases in greenhouse gas (GHG) emissions, particularly methane (CH4) and carbon dioxide (CO2). These emissions accelerate global warming, pollution and environmental challenges. Methane Dry Reforming (DRM) offers a promising technology to address this issue by converting CH4 and CO2 into a valuable syngas (CO + H2) mixture, which is a valuable fuel and a building block for many important chemical reactions (Fischer-Tropsch process). However, finding affordable and environmentally friendly catalysts for large-scale applications remains a critical hurdle. This study delves into the development of stable nickel-zirconia catalysts prepared via impregnation method. The weight percentage of nickel and zirconia was varied to optimize the catalyst's activity by controlling deactivation phenomenon that is a major challenge at higher temperatures during DRM. Various characterization techniques (XRD, FT-IR, SEM-EDX, TGA, TEM and BET) were employed to evaluate synthesized catalysts physio-chemical properties. Additionally, catalytic performance was assessed at temperatures ranging from 550 to 750 °C and a gas hourly space velocity (GHSV) of 72,000 mL/h.gcat. Among tested catalysts, 15% Ni/ZrO2 displayed remarkable conversion values for both CH4 (62.9%) and CO2 (64.9%). Importantly, it exhibited significantly lower weight loss (ca. 15.42%) compared to other variants, indicating better resilience against coke deposition. This enhanced stability can be attributed to synergistic interplay between nickel and zirconia support, effectively suppressing carbon formation. These findings demonstrate potential of 15% Ni/ZrO2 as a promising catalyst for experimental DRM application. With the obvious high activity and stability, 15% Ni/ZrO2 candidate serves as an eco-friendly candidate for greenhouse gas conversion into green fuel energy, contributing to a sustainable economy and clean environment.

Interface reconfiguration of MnCO3/Mn3O4 heterostructure enhances the ozone decomposition in the entire humidity range

The catalytic efficiency of manganese-based catalysts in practical ozone decomposition applications is limited by challenging desorption of intermediate oxygen species and competitive adsorption of H2O molecules in humid environments. In this work, MnCO3/Mn3O4 composites with heterogeneous structures were synthesized through a facile one-step strategy. The obtained MnCO3/Mn3O4-1/2 catalyst exhibited high content of oxygen vacancies, fast electron mobility rate and obvious advantages in catalytic ozone decomposition performance at a space velocity of 600 L g−1 h−1 and 95% RH. In-situ DRIFT spectra indicated that the rate-determining steps for ozone decomposition of MnCO3 and Mn3O4 are the reaction of atomic oxygen with ozone to form O22- and desorption of O22-, respectively. MnCO3/Mn3O4 heterogeneous catalyst undergoes reconfiguration under ozone atmosphere, inducing discontinuous MnOx coatings on the MnCO3 surface, which form a potential difference with Mn3O4. MnCO3/Mn3O4 heterogeneous structure modulates the electronic state of active site, and the synergistic effect of MnCO3 and Mn3O4 improves catalytic performance.

Preparation of palladium-based catalyst by plasma-assisted atomic layer deposition and its applications in CO2 hydrogenation reduction

Supported Pd catalyst is an important noble metal material in recent years due to its high catalytic performance in CO2 hydrogenation. A fluidized-bed plasma assisted atomic layer deposition (FP-ALD) process is reported to fabricate Pd nanoparticle catalyst over γ-Al2O3 or Fe2O3/γ-Al2O3 support, using palladium hexafluoroacetylacetonate as the Pd precursor and H2 plasma as counter-reactant. Scanning transmission electron microscopy exhibits that high-density Pd nanoparticles are uniformly dispersed over Fe2O3/γ-Al2O3 support with an average diameter of 4.4 nm. The deposited Pd-Fe2O3/γ-Al2O3 shows excellent catalytic performance for CO2 hydrogenation in a dielectric barrier discharge reactor. Under a typical condition of H2 to CO2 ratio of 4 in the feed gas, the discharge power of 19.6 W, and gas hourly space velocity of 10000 h−1, the conversion of CO2 is as high as 16.3% with CH3OH and CH4 selectivities of 26.5% and 3.9%, respectively.

Influence of nickel contents on synthesis gas production over nickel-based catalysts supported by treated activated carbon in dry reforming of methane

This study focuses on the utilization of activated carbon (AC) as a catalyst support after undergoing treatment with HNO3. The treated AC exhibited a microporous structure and a high specific surface area (SBET) of 1483.8 m2 g−1. In this study, supported nickel-based catalysts were synthesized using the wet impregnation method with varying amounts of NiO (2.5, 5, 7.5, 10, 12.5, and 15 wt%). The calcined catalyst samples were then evaluated for their performance in the dry reforming of methane (DRM). Characterization of the catalysts was conducted through FESEM, TPO, H2-TPR, XRD, and N2 adsorption-desorption (BET) analyses. The results revealed that catalytic efficiency increased with an increase in the nickel loading percentage, up to 12.5 wt%. The NiO (12.5)/AC catalyst demonstrated the highest CH4 (60%) and CO2 (68%) conversions and exhibited good stability at 700 °C during 10 h of reaction. Additionally, the catalyst's efficiency decreased with an increase in the calcination temperature from 400 to 600 °C. However, alterations in the CH4/CO2 molar ratio from 0.5 to 1.5 indicated that CH4 and CO2 conversions decreased from 85% to 40% and increased from 63% to 74% at 700 °C, respectively. Moreover, the findings demonstrated that elevating the gas hourly space velocity (GHSV) from 12,000 to 18,000 ml h−1.g−1cat resulted in a decline in catalytic efficiency at a temperature of 700 °C. Moreover, the catalytic efficiency declined with an increase in the reduction temperature from 500 to 600 °C.

Catalytic combustion of toluene over highly dispersed Pt NPs embedded in porous TiO2 via in situ pyrolysis of MOFs

In this work, a series of x wt% Pt@TiO2 (x = 0.18, 0.42, and 0.84) catalysts with highly dispersed Pt nanoparticles (NPs) are synthesized via pyrolysis method using Ti-based metal-organic frameworks (MOFs) as precursors. Physicochemical properties of the catalysts are characterized by a number of analytical techniques. It is shown that all samples possess mesoporous structure with surface area of 59–75.6 m2/g, thus can suppress the aggregation of Pt NPs, and enhance toluene adsorption and diffusion. The 0.84 wt% Pt@TiO2 catalyst exhibits the best catalytic performance for toluene oxidation (T90% =150 °C at space velocity = 20,000 mL/ (g h)), which is attributed to the higher surface area, abundant adsorbed oxygen and Pt0 species, and strong interaction between Pt NPs and TiO2. In addition, the possible reaction mechanism of toluene oxidation is proposed based on in situ DRIFTS technique.

Supported highly dispersed molybdenum nitride derived from molybdate-intercalated Mg‒Al hydrotalcite-like compounds as a catalyst for ammonia decomposition

Molybdate-intercalated magnesium–aluminum hydrotalcite-like compounds (HTlc) were synthesized by anion-exchange and used as precursor to prepare supported molybdenum nitride catalyst for ammonia decomposition. The as-synthesized precursors and the derived mixed metal oxides and nitride catalysts were characterized by ICP, XRD, Raman spectroscopy, XPS, H2-TPR, and HAADF-STEM-EDX. The characterizations indicated that molybdate was well intercalated into the HTlc interlayer as MoO42– and the Mo content was tunable by altering the intercalation degree of molybdate. Upon calcination, molybdena was dominantly presented as isolated tetrahedrally coordinated MoOx species. Upon nitridation with ammonia at 700 ºC, highly dispersed and composition-uniform molybdenum nitride (Mo2±xN) was formed. The Mo0.5Mg3Al nitride catalyst showed good activity for ammonia decomposition, providing nearly full conversion of ammonia at 625 ºC under a space velocity of 5,000 mL gcat–1 h–1. The optimal catalyst also exhibited high catalytic stability during 100 h operation at 625 ºC, and no obvious aggregation took place, attributable to the strong metal–support interaction between molybdenum nitride and Mg–Al mixed oxide. It is suggested that the hydrotalcite-derived Mg–Al mixed oxide supported highly dispersed Mo2±xN species was active and stable for ammonia decomposition.

Promoting effect of potassium over Pd/SiO2 catalyst for ambient formaldehyde oxidation

Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process. Interestingly, in this work, an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst (Pd/SiO2) by adding alkali metal potassium (K). A formidable promotion effect was observed when the K doping to Pd/SiO2 catalysts. It achieves a conversion rate of 93% for 270 ppmV of HCHO to harmless CO2 and H2O at a weight hourly space velocity (WHSV) of 300,000 mL/(g·hr) at 25°C. Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition, which not only stabilized Pd species on the carrier surface but also markedly enhanced its dispersal on the SiO2 carrier. The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO2 catalysts. The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover, which also contributed to elevating the electron density on the Pd sites. Meanwhile, the oxygen vacancies favored the O2 activation to form more reactive oxygen species participating in the HCHO oxidation reaction, thus improving the performance of Pd/SiO2 catalysts displayed for HCHO oxidation. This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.

Efficient CO Oxidative Coupling to Dimethyl Oxalate over the Pd/Al2O3 Nanocatalyst with the Assistance of Co Doping

AbstractCO oxidative coupling to dimethyl oxalate (DMO) is an important approach for the product of ethylene glycol and CO elimination. In this work, the Co doped Pd/Al2O3 nanocatalyst was highly effective for CO oxidative coupling and enhanced remarkably CO conversion and the formation of DMO. The maximum DMO STY reached 1082 g L−1 h−1 over the Pd/Al2O3@1/20Co catalyst at 130 °C for 2 h under the space velocity of 3000 h−1, which is two times higher than that over the Pd/Al2O3 catalyst. The Co modification and its influence on the structure of the Pd/Al2O3 catalyst were also studied systematically by XRD, TEM, CO‐TPD, N2 physical adsorption and XPS techniques. An appropriate Co doing was confirmed to promote distinctly the generation of smaller Pd particles and the adjustment of the adsorption or activation of CO over the catalyst. A positive interaction between Pd nanoparticles and the modulated support with Co doping was demonstrated and favored the enhanced activity of the catalyst for the reaction.

Efficient catalysis of acetylene semi-hydrogenation through synergistic action of supported ionic liquid-nickel catalyst

In the semi-hydrogenation of acetylene, nickel-based catalysts offer a promising alternative to precious metal palladium catalysts. Despite the positive hydrogenation activity of nickel-based catalysts, there is still room for improvement in terms of their selectivity and stability. In this study, a simple incipient wetness impregnation method was employed to prepare Ni(OAC)2-IL/Al2O3 catalyst and its performance in the selective hydrogenation of acetylene was investigated. It was found that under the conditions of 170 °C and a space velocity of 600 h−1, the 3 % Ni(OAC)2-IL/Al2O3 catalyst achieved a 95.3 % acetylene conversion with an 85.6 % ethylene selectivity. Furthermore, the catalyst exhibited outstanding stability over a 100 hour test. TEM, XPS and C2H4-TPD experiments showed that the Ni species were encapsulated in the ionic liquids (ILs), and the interaction between the metal ions, nickel, and the ILs ensured a high dispersion and stability of the actives on the carriers, and the electronic effect between the ionic nickel and the ionic liquids increased the electron cloud density of the Ni, which improved the catalyst selectivity, which is the main reason for its excellent catalytic performance.

Geometrically parametrised reduced order models for studying the hysteresis of the Coanda effect in finite element-based incompressible fluid dynamics

This article presents a general reduced order model (ROM) framework for addressing fluid dynamics problems involving time-dependent geometric parametrisations. The framework integrates Proper Orthogonal Decomposition (POD) and Empirical Cubature Method (ECM) hyper-reduction techniques to effectively approximate incompressible computational fluid dynamics simulations. To demonstrate the applicability of this framework, we investigate the behaviour of a planar contraction-expansion channel geometry exhibiting bifurcating solutions known as the Coanda effect. By introducing time-dependent deformations to the channel geometry, we observe hysteresis phenomena in the solution.The paper provides a detailed formulation of the framework, including the stabilised finite elements full order model (FOM) and ROM, with a particular focus on the considerations related to geometric parametrisation. Subsequently, we present the results obtained from the simulations, analysing the solution behaviour in a phase space for the fluid velocity at a probe point, considered as the Quantity of Interest (QoI). Through qualitative and quantitative evaluations of the ROMs and hyper-reduced order models (HROMs), we demonstrate their ability to accurately reproduce the complete solution field and the QoI.While HROMs offer significant computational speedup, enabling efficient simulations, they do exhibit some errors, particularly for testing trajectories. However, their value lies in applications where the detection of the Coanda effect holds paramount importance, even if the selected bifurcation branch is incorrect. Alternatively, for more precise results, HROMs with lower speedups can be employed.

An active, stable cubic molybdenum carbide catalyst for the high-temperature reverse water-gas shift reaction.

Although technologically promising, the reduction of carbon dioxide (CO2) to produce carbon monoxide (CO) remains economically challenging owing to the lack of an inexpensive, active, highly selective, and stable catalyst. We show that nanocrystalline cubic molybdenum carbide (α-Mo2C), prepared through a facile and scalable route, offers 100% selectivity for CO2 reduction to CO while maintaining its initial equilibrium conversion at high space velocity after more than 500 hours of exposure to harsh reaction conditions at 600°C. The combination of operando and postreaction characterization of the catalyst revealed that its high activity, selectivity, and stability are attributable to crystallographic phase purity, weak CO-Mo2C interactions, and interstitial oxygen atoms, respectively. Mechanistic studies and density functional theory (DFT) calculations provided evidence that the reaction proceeds through an H2-aided redox mechanism.

TiO2 modified limonite for selective catalytic reduction of NO from cement kiln flue gas with NH3

Limonite was used as a precursor and TiO2 as a modifier to synthesize TiO2/Limonite composites through the wet impregnation method. The influences of the TiO2 doping amount, the calcination temperature on the denitration efficiency and the structure and properties of composites were systematically studied. The results showed that the modified catalyst over the Ti/Fe mass ratio was 0.07 and the calcination temperature was 300°C exhibited excellent catalytic activity, good stability, and remarkable resistance to water and sulfur dioxide within reaction temperature of 100 ∼ 240°C. When NO initial concentration was 0.05 % and gas hourly space velocity (GHSV) was 36,000 h−1 and the reaction temperature was 130°C, the NO conversion efficiency reached 100 %, and the N2 selectivity was 99.6 %. When the catalyst was exposed to 10 %H2O at 150°C, it maintained a 100 % NO conversion efficiency. In the presence of 10 %H2O and 50 ppm SO2 at 200°C, the NO conversion efficiency remained at 100 %. The TiO2/Limonite catalyst possessed improved performance due to the introduction of the anatase TiO2, which led to more lattice defects, weak Lewis acid sites, and higher adsorbed oxygen mobility.

Deep understanding the formation of MnCoOx in-situ grown on foam nickel towards efficient lean methane catalytic oxidation

Methane is the second largest greenhouse gas in the world, with a stronger greenhouse effect than carbon dioxide. The efficient elimination of methane in the atmosphere has important engineering significance in slowing down global temperature rise, energy resource utilization, collaborative control of pollutants, and promoting technological innovation. In this work, a general hydrothermal synthesis method was introduced to in-situ construct four different morphologies of MnCoOx (including rod-, spherical-, filamentous- and bulk-shape) on foam nickel (NF). The synthesis of MnCoOx/NF with different morphologies was due to changes in NF pretreatment conditions and precipitants, which affected the nucleation and growth rates of MnCoOx, ultimately resulting in different morphologies. When the four different morphologies of MnCoOx/NF were used as catalysts for lean methane catalytic oxidation, MnCoOx/NF-r exhibited the best excellent catalytic activity, and the T90 occurred at 428 °C in space velocity of 48,000 mL g−1 h−1. Such an outstanding performance was attributed to the unique properties of the MnCoOx/NF-r including the larger surface area and more oxygen vacancies for providing more active sites and a higher oxygen migration rate, which was very beneficial for improving the catalytic oxidation performance of methane.

Alkali-modified copper manganite spinel for room temperature catalytic oxidation of formaldehyde in air

Formaldehyde (FA) is present ubiquitously in indoor environment as a hazardous pollutant with carcinogenic risks. For the efficient mitigation of FA, catalytic oxidation is a recommendable option to simultaneously satisfy both material cost (e.g., avoiding noble metals) and low-energy requirement (under dark and at room temperature (RT)). From this perspective, a cost-effective alkali modified copper manganite spinel (CuMn2O4) catalyst has firstly been prepared and employed for FA oxidation. Specifically, alkali (1 mol L−1 potassium hydroxide)-modified CuMn2O4 (1-CuMn2O4) achieves 100% FA (50 ppm (gas hourly space velocity of 4777 h−1)) conversion (XFA) at RT. The steady-state reaction rate of 1-CuMn2O4 at 10% XFA is 8.18 × 10−2 mmol g−1 h−1. According to in situ diffuse reflectance infrared Fourier transform spectroscopy, FA molecules are oxidized into water and carbon dioxide through dioxymethylene and formate intermediates. Based on density functional theory simulation, the higher catalytic performance of 1-CuMn2O4 for FA oxidation is attributed to the combined effects of firmer attachment of FA molecules to 1-CuMn2O4 surface, lower energy cost of FA adsorption, and lower desorption energy for the final products from the substrate surface. The present work is expected to provide insights into high-performing non-noble metal catalysts for RT oxidative removal of FA from indoor air.

High-resolution Pan-STARRS and SMA Observations of IRAS 23077+6707: A Giant Edge-on Protoplanetary Disk

We present resolved images of IRAS 23077+6707 (“Dracula’s Chivito”) in 1.3 mm/225 GHz thermal dust and CO gas emission with the Submillimeter Array (SMA) and optical (0.5–0.8 μm) scattered light with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The Pan-STARRS data show a bipolar distribution of optically scattering dust that is characteristic for disks observed at high inclinations. Its scattered light emission spans ∼14″, with two highly asymmetric filaments extending along the upper bounds of each nebula by ∼9″. The SMA data measure 1.3 mm continuum dust as well as 12CO, 13CO, and C18O J = 2 − 1 line emission over 12″–14″ extents, with the gas presenting the typical morphology of a disk in Keplerian rotation, in both position–velocity space and in each CO line spectrum. IRAS 23077+6707 has no reported distance estimate, but if it is located in the Cepheus star-forming region (180–800 pc), it would have a radius spanning thousands of astronomical units. Taken together, we infer IRAS 23077+6707 to be a giant and gas-rich edge-on protoplanetary disk, which to our knowledge is the largest in extent so far discovered.

Robust and conservative dynamical low-rank methods for the Vlasov equation via a novel macro-micro decomposition

Dynamical low-rank (DLR) approximation has gained interest in recent years as a viable solution to the curse of dimensionality in the numerical solution of kinetic equations including the Boltzmann and Vlasov equations. These methods include the projector-splitting and Basis-update & Galerkin (BUG) DLR integrators, and have shown promise at greatly improving the computational efficiency of kinetic solutions. However, this often comes at the cost of conservation of charge, current and energy. In this work we show how a novel macro-micro decomposition may be used to separate the distribution function into two components, one of which carries the conserved quantities, and the other of which is orthogonal to them. We apply DLR approximation to the latter, and thereby achieve a clean and extensible approach to a conservative DLR scheme which retains the computational advantages of the base scheme. Moreover, our approach requires no change to the mechanics of the DLR approximation, so it is compatible with both the BUG family of integrators and the projector-splitting integrator which we use here. We describe a first-order integrator which can exactly conserve charge and either current or energy, as well as an integrator which exactly conserves charge and energy and exhibits second-order accuracy on our test problems. To highlight the flexibility of the proposed macro-micro decomposition, we implement a pair of velocity space discretizations, and verify the claimed accuracy and conservation properties on a suite of plasma benchmark problems.

N‐Butane Isomerization over 0.5 Pt/HPA/MCM‐41 Catalyst: Optimization Study Using Central Composite Design

AbstractIn this research, 0.5 % platinum (Pt)/HPAs/MCM‐41 (Mobil Composition of Matter No. 41) bifunctional catalysts (with different weight percentages of phosphotungstic acid (HPW) and silicotungstic acid (HSiW)) were synthesized for use in the n‐butane isomerization. The synthesized catalysts were characterized by X‐ray diffraction, X‐ray fluorescence spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller, and ammonia temperature‐programmed desorption analyses. The best catalytic activity and highest initial isobutane yield at 250 °C, weight hourly space velocity of 0.15 h−1, and H2/nC4 molar ratio of 3:1 belonged to 0.5 %Pt/20 % HPW/MCM‐41 (41 %) and 0.5 % Pt/40 % HSiW/MCM‐41 (45 %) samples. Subsequently, the yield of isobutane over these catalysts was evaluated and optimized by a central composite experimental design. According to the quadratic model, the maximum isobutane yield under optimal operating conditions was 34.5 % and 41.36 %, respectively, for 0.5 % Pt/20 % HPW/MCM‐41 and 0.5 % Pt/40 % HSiW/MCM‐41 catalysts.

Compositing of Co3O4 with boron nitride to promote the catalytic performance for methane oxidation

Engineering a suitable catalyst support holds great importance to ensure a high catalytic performance in heterogeneous catalysis. Herein, an advanced boron nitride nanosheet (BNNS) supported Co3O4 composite (Co3O4/BNNS) was tailor-orchestrated to serve as an active and stable catalyst for methane oxidation. BNNS helps dispersion and binding small nano Co3O4 catalyst with augmented defective structures e.g., oxygen vacancies, lattice distortion etc. This facilitates the creation of more active oxygen species on Co3O4. Meanwhile, an interfacial electronic interaction was built to maintain Co3O4 in an electron-rich state. An excellent methane oxidation performance was guaranteed for Co3O4/BNNS with methane conversion rate of 58.3 mol·gCo3O4-1·h−1, 1.9 times that of Co3O4 catalyst at reaction temperature of 366 °C and weight hourly space velocity of 40,000 mL·g−1·h−1. Moreover, a strong metal and support interaction (SMSI) was in-situ formed, resulting a BOx over-layer confined Co3O4, which promises a robust hydrothermal stability for Co3O4/BNNS catalyst. This work exemplifies the pivotal role of BNNS as an excellent support to enhance the methane oxidation performance of Co3O4 catalyst.

Extraordinary synergy on 3D hierarchical porous Co-Cu nanocomposite for catalytic elimination of VOCs at low temperature and high space velocity

It is still a challenge to develop hierarchically nanostructured catalysts with simple approaches to enhance the low-temperature catalytic activity. Herein, a set of mesoporous Co-Cu binary metal oxides with different morphologies were successfully prepared via a facile ammonium bicarbonate precipitation method without any templates or surfactants, which were further applied for catalytic removal of carcinogenic toluene. Among the catalysts with different ratios, the CoCu0.2 composite oxide presented the best performance, where the temperature required for 90% conversion of toluene was only 237°C at the high weight hour space velocity (WHSV) of 240,000 mL/(gcat·hr). Meanwhile, compared to the related Co-Cu composite oxides prepared by using different precipitants (NaOH and H2C2O4), the NH4HCO3-derived CoCu0.2 sample exhibited better catalytic efficiency in toluene oxidation, while the T90 were 22 and 28°C lower than those samples prepared by NaOH and H2C2O4 routes, respectively. Based on various characterizations, it could be deduced that the excellent performance was related to the small crystal size (6.7 nm), large specific surface area (77.0 m2/g), hollow hierarchical nanostructure with abundant high valence Co ions and adsorbed oxygen species. In situ DRIFTS further revealed that the possible reaction pathway for the toluene oxidation over CoCu0.2 catalyst followed the route of absorbed toluene → benzyl alcohol → benzaldehyde → benzoic acid → carbonate → CO2 and H2O. In addition, CoCu0.2 sample could keep stable with long-time operation and occur little inactivation under humid condition (5 vol.% water), which revealed that the NH4HCO3-derived CoCu0.2 nanocatalyst possessed great potential in industrial applications for VOCs abatement.