Formation Of Carbon Oxides Research Articles

Self-cleaning photoactive cotton fabric modified with nanocrystalline TiO2 for efficient degradation of volatile organic compounds and DNA contaminants

In this paper, we describe the chemical engineering aspects of the preparation of highly active and stable photocatalytic textiles and show several examples of the application of these materials for the efficient degradation of harmful volatile organic compounds (VOCs) and adverse macromolecules, namely, deoxyribonucleic acid (DNA) contaminants. The photoactive textiles were obtained by the impregnation method. Titanium(IV) oxysulfate and titanium(IV) isopropoxide were used as the precursors of TiO2 and were hydrolyzed under different conditions. The effect of the preparation conditions on the photocatalytic activity of the materials was investigated. The addition of nanocrystalline TiO2 to the impregnating compound during the synthesis substantially increased the photocatalytic activity of the materials. As a result, we proposed a technique for the modification of cotton fabric using titanium(IV) isopropoxide and nanocrystalline TiO2, which allowed the production of textiles with high stability toward washing and with photocatalytic activity similar to the activity of powdered TiO2 photocatalysts. The complete oxidation of VOCs with the formation of carbon oxides and water as the final oxidation products was detected on the surface of synthesized textiles under UV light. In the case of an S-containing pollutant, deactivation of the material was observed during long-term oxidation, but as an advantage over powdered photocatalysts, the textile material could be easily reactivated by simple washing. Additionally, in this paper, we show using the polymerase chain reaction (PCR) technique the ability of photoactive textiles to decompose human genomic DNA contaminants under UV light.

Development of Method for Direct Deoxidation of Titanium using Mixtures of Magnesium Chloride and Rare-Earth Chlorides

To decrease the cost of Ti sponge, Ti scrap is added during the remelting process to produce an ingot. However, the use of Ti scrap as an additive during this process is limited because Ti scrap is contaminated by oxygen (O) and iron (Fe), which are not removable during the remelting process. Here we introduce a new electrochemical deoxidation process for Ti scrap using a mixture of magnesium chloride (MgCl2) and rare-earth chlorides (RECl3, RE: Y and Ho) as a flux. Ti and carbon were used as the cathode and anode, respectively. Mg is deposited on the Ti cathode and reduces the oxygen in the Ti to oxide ions (O2). The activity of the generated O2” in the system,aQi-, is maintained at a low level through the formation of rare-earth oxy chloride (REOCl), and is further decreased by the formation of carbon oxides on the anode. During this process, the concentration of oxygen in the Ti is effectively decreased to 100 mass ppm in the MgCl2-YCl3flux at 1,200 K. This new deoxidation method is considered applicable to the recycling process of Ti scrap containing large amounts of oxygen.

Production of fuels via thermal decomposition of copper oleates from CuO

In this work, the thermal decomposition of copper carboxylates formed from CuO and different proportions of oleic acid and CuO was used to produce liquid and gaseous fuels. These reactions gave rise to solid, liquid and gaseous fractions that were studied by different techniques, such as XRD, TG, Raman spectroscopy, FTIR, SEM, TEM, NMR and GC–MS. The liquid fraction obtained was the largest, made up mainly of oleic acid, i.e., the starting reagent was regenerated in the reaction. The gas fraction was the second largest, consisting mainly of hydrogen gas, with selectivity above 80%. The solid fraction was the smallest but showed the formation of metallic copper, carbon and copper(I) oxide. This work showed that it was possible to produce materials from acid oils and metal oxides that, after being thermally decomposed, generated gas fuels of great industrial interest, as well as metal phases, and the regeneration of the acid used as the starting reagent.

Evaluation of a Ti-Base Alloy as Steam Cracking Reactor Material.

Low-coking reactor material technologies are key for improving the performance and sustainability of steam crackers. In an attempt to appraise the coking performance of an alternative Ti–base alloy during ethane steam cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe–Ni–Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti–base alloy, however, its coking performance was significantly worse compared to the typically used Fe–Ni–Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti–base alloy cannot be considered an industrially noteworthy steam cracking reactor alloy.

Photoelectrochemical Homocoupling of Methane under Blue Light Irradiation

Direct conversion of methane (CH4) into valuable chemicals with low-energy input is an important goal in the sustainable chemical industry. Herein, we report a photoelectrochemical activation of CH4 in the gas phase under visible light irradiation at room temperature. The proof-of-concept study revealed that homocoupling of CH4 to form ethane (C2H6) with high selectivity of 54% was induced by photogenerated holes over a tungsten trioxide (WO3) gas-diffusion photoanode coated with a proton-conducting ionomer in the presence of water vapor. The gas–electrolyte–solid triple-phase boundary enables the oxidation of the inert carbon–hydrogen bond of CH4, and the formation of carbon oxides and ethane with a carbon–carbon bond. The gas-phase photoelectrochemical system shows incident photon-to-current conversion efficiency of 11% under blue light at an applied voltage of 1.2 V. This work is also the first demonstration of a visible-light-driven hydrogen evolution from CH4. The hydrogen is separated from CH4 and o...

Selected metal oxides for C[sbnd]H bond activation of n-octane and propensity for COx formation: An empirical study

The propensity of a range of monometallic oxide catalysts, namely, TiO2; V2O5; Cr2O3; MnO2; Fe2O3; Co3O4; CuO; ZnO; and CeO2, to form carbon oxides during the oxidative activation of n-octane was investigated. The catalysts showed varied selectivity at iso-conversion. PXRD, BET surface area analysis, H2-TPR, NH3-TPD and O2-TPD were employed to probe the physical and chemical properties of the catalysts in order to understand their catalytic behaviour. The activity of a metal oxide in the activation of n-octane was found to be dependent on its extent of reduction, the extent to which molecular oxygen chemisorbs to its surface and surface acidity. It was also observed that metal oxides with a low band gap energy showed a higher propensity toward total oxidation than those with high energy. All these factors played a key role in carbon oxide formation, some more than others depending on the oxide in question, with TiO2 showing the lowest selectivity and CuO the highest.

Sulfide Catalysts for Production of Motor Fuels from Fatty Acid Triglycerides

Patents dealing with the production of motor fuel components by hydrodeoxygenation of renewable raw materials based on fatty acid triglycerides are analyzed. Various methods of using sulfide catalysts in hydrodeoxygenation of fatty acid triglycerides and of their mixtures with petroleum fractions are described. The ways to overcome problems that arise in hydrodeoxygenation, based on using sulfide catalysts differing in the active component and support composition, are considered. For example, the use of supported MoS2 catalysts free of Co and Ni ensures the conversion of fatty acid triglycerides along the “direct hydrodeoxygenation” pathway to avoid the formation of carbon oxides and related process problems. The use of sulfide catalysts on zeolite-containing supports allows synthesis of products with improved low-temperature properties due to isomerization (or mild hydrocracking) of С15–С18 alkanes formed by hydrodeoxygenation of fatty acid triglycerides.

A proposed reaction mechanism for the selective oxidation of methane with nitrous oxide over Co-ZSM-5 catalyst forming synthesis gas (CO + H2)

Probable reaction intermediates and mechanistic steps involved for the selective oxidation of methane (CH4) with nitrous oxide (N2O) forming synthesis gas (CO + H2) over Co-ZSM-5 was examined. To assess the reaction kinetics reactions were conducted within a temperature range of 300 °C–550 °C and at atmospheric pressure, and the composition of reactant feed (N2O/CH4) was varied between three fixed ratios (5, 3, and 1). TPD, XRD, TEM and FT-IR techniques were used for catalyst characterization and mechanistic studies. It was found, that H2 selectivity is higher for feeds with lower N2O concentration. Furthermore, CO formation commences at lower temperatures in comparison to H2 gas which is a result of the formation of methanol (CH3OH) and carbon oxides (CO and CO2) at low CH4 conversions.Based on the reaction conditions, the literature proposes direct and an indirect mechanistic route for synthesis gas formation. Our catalytic study suggests a direct route for the synthesis gas formation; i.e. H2 gas is formed by the decomposition of intermediate species (methoxy and CH2O). This is supported by spectroscopic investigation. Under favourable reaction conditions and over the Co-ZSM-5 catalyst, N2O first oxidizes CH4 to CH3OH, an active reaction intermediate, which then subsequently is converted into (formaldehyde) CH2O and H2. CH2O is highly reactive and decomposes into CO and H2.

Lanthanum vanadate catalysts for selective and stable methane oxybromination

A series of lanthanum vanadium oxides, LaVxO2.5x+1.5, with molar V:La ratios in the range of x = 0–1.2 have been synthesized using the citrate method and evaluated in the oxybromination of methane. This reaction aims at valorizing natural gas by its selective conversion into bromomethanes (CH3Br and CH2Br2) that can be used as a platform for the production of fuels and chemicals. In order to establish relationships between the composition, structure, and catalytic performance, the materials in fresh and equilibrated forms have been characterized by X-ray diffraction, N2 sorption, scanning transmission electron microscopy, elemental mapping, and Raman, 51V nuclear magnetic resonance, and X-ray photoelectron spectroscopies. At x = 1, the catalyst comprises nanocrystals of monoclinic-LaVO4, which are accompanied by crystalline hexagonal-La2O3 or amorphous vanadium oxide at sub-stoichiometric (x < 1) or over-stoichiometric (x > 1) ratios, respectively. Pure LaVO4 displays a pretty high selectivity to bromomethanes (86–78% at methane conversions of 15–25%) and stable structural and catalytic behavior. The selectivity is increased to 92–95% when a certain excess of lanthanum is used (e.g., LaV0.5O2.75) due to synergistic effects of the mixture of LaVO4 and tetragonal-LaOBr nanocrystals, formed by partial bromination of La2O3. In this catalyst, LaOBr moderates the oxidation potential of LaVO4 and minimizes the formation of carbon oxides, while LaVO4 avoids agglomeration of the LaOBr phase and secures stable operation. Catalysts outside the compositional window of x = 0.2–1 deactivate due to sticking of LaOBr particles (x < 0.2) or the volatilization of free vanadium oxide (x > 1). These results emphasize that the tuning the composition of LaVxO2.5x+1.5 enables to attain catalysts competing with the best reported oxybromination systems.

Influence of Phase Composition of Bulk Tungsten Vanadium Oxides on the Aerobic Transformation of Methanol and Glycerol

A series of W–V–O catalysts with different m‐WO3 and h‐WO3 phase contents were hydrothermally synthesized by employing different tungsten, vanadium, and ammonium precursors and characterized by powder XRD, N2 adsorption, SEM, X‐ray energy‐dispersive spectroscopy, thermogravimetric analysis, Raman and FTIR spectroscopy, NH3 temperature programmed desorption, H2 temperature‐programmed reduction, and XPS. Finally, the acid/redox properties were analyzed by using aerobic transformation of methanol as a characterization reaction. A correlation between phase composition as well as acid and redox properties was observed, which were correlated to the catalytic performance of the title materials in a one‐pot oxydehydration reaction of glycerol. The hexagonal tungsten bronze (h‐WO3) phase shows a significantly higher concentration of acid sites than monoclinic m‐WO3, so that the acid properties of W–V–O oxides are directly related to the presence of h‐WO3 crystals. The presence of a higher concentration of acid sites in V‐containing h‐WO3 crystals is a key factor to achieve high selectivity to both acrolein and acrylic acid during one‐pot glycerol oxydehydration. Also, V sites in h‐WO3 show higher selectivity in the consecutive reaction (partial oxidation of acrolein to acrylic acid), while V sites in the m‐WO3 phase fundamentally lead to the formation of carbon oxides.

Coking Tendency of 25Cr-35Ni Alloys: Influence of Temperature, Sulfur Addition, and Cyclic Aging

25Cr-35Ni base alloys are the most frequently used materials for steam cracking reactors. The influence of cyclic aging, reactor temperature, and adding sulfur containing compounds before or during cracking on the rate of coke deposition on a classical 25Cr-35Ni alloy is evaluated using a jet stirred reactor equipped with an electrobalance. As expected, the initial and asymptotic coking rate increased with increasing reactor temperature. Scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) analysis indicated that more Ni and Fe is present on the surface at higher cracking temperatures. Presulfidation led to increased coke deposition and decreased CO yields compared to the reference. When a sulfur containing compound was added continuously, coke deposition increased significantly but carbon oxide formation was suppressed. A pronounced amount of coke was measured in the reactor, followed by suppressed generated amounts of carbon oxides downstream. When combined with the continuous add...

Selective Methane Oxybromination over Nanostructured Ceria Catalysts

This article studies the impact of the carrier type (MgO, SiO2, SiC, Al2O3, and ZrO2) and synthesis method (dry impregnation, coprecipitation, hydrothermal synthesis, and mechanochemical synthesis) on the structure, redox properties, and performance of supported CeO2 catalysts for methane oxybromination. Major distinctions are evidenced in the product distribution with respect to bulk CeO2, and the selectivity to methyl bromide (CH3Br) varies in the following order: CeO2/MgO (61–81%) > CeO2/SiC (56–73%) ≈ CeO2/SiO2 (52–71%) > bulk CeO2 (40%) ≈ CeO2/ZrO2 > CeO2/Al2O3 (28–35%) at 6–40% methane conversion. The selectivity is primarily governed by the catalyst propensity to combust CH3Br and byproduct dibromomethane (CH2Br2), which is strongly affected by the choice of the carrier. Specifically, the formation of carbon oxides is substantially suppressed over CeO2 nanoparticles stabilized on basic MgO (COx selectivity <10%) with respect to bulk CeO2 (COx selectivity ≥50%), whereas it is promoted by near atomic...

Use of a Dual-Bed System for Producing Diesel Fuel from a Mixture of Straight-Run Diesel and Rapeseed Oil over Sulfide Catalysts

A dual-bed catalytic system including MoS2/Al2O3 and Co–MoS2/Al2O3 catalysts is proposed for the process of production of diesel fuel with the sulfur content of less than 10 ppm from a straight-run diesel fraction containing 10–45 wt % rapeseed oil. The conversion of rapeseed oil to alkanes proceeds in the MoS2/Al2O3 catalyst bed via the route of “direct” hydrodeoxygenation without the formation of carbon oxides, and the hydrodesulfurization of the diesel fraction occurs in the bed of the Co–MoS2/Al2O3 hydrotreating catalyst. Using this system provides an increase in the yield of diesel fuel and a decrease in the formation of greenhouse gases in comparison with conventional Co(Ni)–MoS2/Al2O3 catalysts.

DEVELOPMENT OF RATIONAL METHOD OF SYNTHESIS OF NANOCRYSTALLINE LEAD MOLYBDATE IN MELTS OF Na2MO2O7 - PbCO3 SYSTEM

The work presents material on interaction of dimolybdate of sodium and carbonate of lead, and also data on the development of a rational method for the synthesis of PbMoO4 in the melts, characterized by high productivity and yield of the target product of "h.с." brand in the nanocrystalline state. To achieve the work aims the thermodynamic assessment of the ability of the synthesis of molybdate of lead in melts of the system Na2Mo2O7 – PbCO3 was given. It is shown that the thermodynamic probability of formation of molybdate of lead in a number of Na2Mo2O7 – PbO(PbO2, PbCO3), is maximal for the process in the system of dimolybdate sodium – lead carbonate. The starting material for the synthesis of lead molybdate – dimolybdate sodium – was synthesized from recrystallized and dehydrated sodium molybdate and molybdenum oxide (VI). The melting temperature of synthesized dimolybdate sodium is 612 °C (614 °C – literature data). Synthesis of lead molybdate was done after careful grinding of the initial reagents and sifting through a sieve. The temperature of the synthesis process of 650 °C was maintained for 1.5 h until reaching the constant weight of mixture. Then mixture was sintered, cooled to room temperature and leached with hot (70-80 °C) distilled water. The precipitate of lead molybdate was filtered, washed on the filter to a negative reaction on molybdate ion. Synthesized molybdate of lead was dried, washed and calcined to constant weight. The yield of lead (II) molybdate was of 99.88% of the theoretical. Analysis of the obtained product was based on reaction between PbMoO4 with sodium carbonate with the formation of sodium molybdate, lead oxide (II) and carbon oxide (IV). Thus obtained sample was sintered, leached with hot distilled water and filtered. The residue was treated with acetic acid obtained from acetate of lead, the latter is determined in a form of lead molybdate (sodium molybdate deposition). To determine molybdenum from the filtrate from PbO, the inverse sedimentation method was used, in the form of BaMoO4, which is its weight form. The work also contains a material on the identification of the synthesized product by modern research methods.For citation:Shurdumov G.K., Cherkesov Z.A., Kandurova E.F. Development of rational method of synthesis of nanocrystalline lead molybdate in melts of Na2Mo2O7 – PbCO3 system. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 78-84.

V- and Nb-containing tungsten bronzes catalysts for the aerobic transformation of ethanol and glycerol. Bulk and supported materials

This work report the applicability of reflux to the synthesis of supported tungsten bronzes (i.e. W-V-O and W-Nb-O), using mesoporous KIT-6 as inert support. For comparison, the corresponding bulk materials prepared by reflux or by hydrothermal synthesis have been also prepared. The catalysts were characterized by several techniques (X-ray diffraction, N2 adsorption, temperature programmed desorption (NH3), and Raman and FTIR spectroscopies) and tested in the selective aerobic transformation of ethanol and glycerol. These results demonstrate the formation of V- and Nb-containing tungsten oxide bronzes in all of the heat-treated samples (bulk and supported materials), as well as the effective incorporation of metals (V or Nb) in the framework of tungsten bronzes. During the aerobic transformation of ethanol, diethyl ether and ethylene (in Nb-containing catalysts) and acetaldehyde, diethyl ether and ethylene (in V-containing catalysts) were the main reaction products, with very small formation of carbon oxides. During the aerobic transformation of glycerol, acrolein was mainly formed over Nb-containing catalysts, whereas acrylic acid, acrolein and COx were mainly observed over V-containing catalysts. The differences between bulk and supported catalysts have been explained according to changes in their physico-chemical properties: V-containing catalysts presenting both acid and redox sites; and Nb-containing catalysts presenting acid sites. In this way, supported materials seems to be effective in both redox and acid reactions due to the small modifications of the acid characteristics of catalysts.

(Invited) Direct Conversion of Methane to Methanol and Other Value Products in SOFC

The direct conversion of methane to liquid fuels and chemicals is highly sought, especially at low-scale to more effectively utilize remote natural gas resources. Direct conversion has proven to be a very difficult problem, because methane is highly unreactive, though tends to over-oxidize once activated. Methanol is primarily produced today by the steam reformation of methane at high temperatures and pressures to synthesis gas (carbon monoxide plus hydrogen), followed by catalytic conversion at intermediate temperatures and high pressures. Though highly selective, this technology is not well suited for low production wellheads. The direct conversion of methane to methanol and other liquids would be a game changer, potentially leading to much lower production costs. In our presentation we will be reporting the development of the metal oxide-based electrocatalysts, which provide an oxygen activity needed for the partial oxidation of methane to liquid fuels suitable for applications in intermediate temperature fuel cells. The tests were performed at atmospheric pressure at different CH4 flow rates and different temperatures in the 200-700oC range.The product analysis was performed by online quadrupole mass spectrometer as well as by GC-MS. Methanol is the primary product of methane conversion at temperatures below 400oC. At 600-700oC, ethane, ethylene, propane, propene, n-butane, iso-butane, 2-butyne, and benzene formation was observed. In all tests the formation of carbon oxides was observed as well. Separately, the catalysts were evaluated using diffuse reflectance infrared Fourier Transform Infrared Spectroscopy (DRIFTS), TGA and in operando XRD. The kinetics of oxygen gain appeared to be slower that the oxygen loss. Somewhat longer time was needed to re-oxidize the catalyst. Kinetics are faster and conversion of CH4 was greater at higher temperatures. The post-test analysis was done using SEM and XRD. Figure 1. Methane conversion (right y-axis) and the rates of methanol, CO, and CO2 formation (left y-axis) at 300oC. Figure 2. Relative hydrocarbon distribution at 700oC. Figure 1

Analysis of the flamelet model for calculation of emissions of pollutants by combustors

Features of the simulation of the formation of pollutants—nitrogen oxides (NOx) and carbon oxide (CO)—in combustion are considered. The causes of a possible decrease in accuracy in the estimation of NOx and CO emission in the context of the stationary flamelet model, which is caused by the nonequilibrium character of combustion, are analyzed. It is shown that, in the case of diffusion combustion of fuel in traditional chambers, the formation of NOx and CO has a nonstationary character amplified by an additional factor, i.e., high gradients of the scalar dissipation of the recovered fuel concentration. A promising method for enhancing the flamelet model, which is connected with transfer to the model in the nonstationary formulation, is considered. By the example of combustion of methane as a model fuel for natural gas, it shown that the flamelet model in the nonstationary formulation favors enhanced accuracy when evaluating NOx and CO emission.

The Effect of Introducing B and N on Pyrolysis Process of High Ortho Novolac Resin.

In this contribution, high ortho novolac resins modified with phenylboronic acid were synthesized. The thermal stability of novolac resins cured with hexamethylenetetramine (HMTA) and chemical states of B and N via a pyrolysis process were studied. For the cured o-novolac modified with phenylboronic acid, the temperature with maximum decomposition rate increased by 43.5 °C, and the char yield increased by 5.3% at 800 °C compared with cured o-novolac. Density functional theory (DFT) calculations show the existence of hydrogen bonding between N of HMTA and H of phenol in modified resin. Thus, N could still be found at high temperature and C=N structure could be formed via a pyrolysis process. B2O3 was obtained at 400 °C by the cleavage of B–O–C and B–C bonds and it reduces the oxygen loss which may take part in the formation of carbon oxides in the system. The melting B2O3 on the surface of the resin will prevent small molecules and carbon oxides from releasing. Moreover, introducing B into the system helps to decrease the interlayer distance and improve graphite structures via a pyrolysis process.

Complete oxidation of 1,4-dioxane over zeolite-13X-supported Fe catalysts in the presence of air

Zeolite-13X-supported Fe (Fe/zeolite-13X) catalysts with various Fe contents were prepared by the wet impregnation method. The catalysts were characterized by N2 adsorption-desorption isotherms to estimate the Brunauer–Emmett–Teller surface areas and Barrett–Joyner–Hanlenda pore size distributions. X-ray diffraction, scanning electron microscopy, temperature-programmed reduction, and temperature-programmed desorption of NH3 were used to investigate the textural properties of the Fe/zeolite-13X catalysts. Their catalytic activities were determined for the complete oxidation of 1,4-dioxane using air as the oxidant in a fixed‐bed flow reactor in the temperature range 100–400 °C. The influences of various process parameters, such as reaction temperature, metal loading, and gas hourly space velocity (GHSV), on the dioxane removal efficiency by catalytic oxidation were investigated. The stability of the catalyst was tested at 400 °C by performing time-on-stream analysis for 50 h. The Fe/zeolite-13X catalyst with 6 wt% Fe exhibited the best catalytic activity among the Fe/zeolite-13X catalysts at 400 °C and a GHSV of 24000 h−1, with 97% dioxane conversion and 95% selectivity for the formation of carbon oxides (CO and CO2). Trace amounts (< 3%) of acetaldehyde, ethylene glycol monoformate, ethylene glycol diformate, 1,4-dioxane-2-ol, 1,4-dioxane-2- one, and 2-methoxy-1,3-dioxalane were also formed as degradation products. A plausible degradation mechanism is proposed based on the products identified by GC-MS analysis.

Enhanced methane decomposition over nickel–carbon–B2O3 core–shell catalysts derived from carbon dioxide

Nickel–carbon–B2O3 nanocomposites (Ni@C-B2O3s) were synthesized from a single-step reaction of CO2 with NaBH4 at 1bar and investigated as catalysts for methane decomposition. These catalysts exhibited an unprecedented activity for producing hydrogen and graphitic carbon nanoonions (CNOs) without any generation of carbon oxides (COx), despite of the absence of a catalyst reduction step by hydrogen. Around 90% of methane conversion with 61mmolmin−1gNi−1 was achieved using 13wt% nickel-containing Ni@C-B2O3 (13Ni@C-B2O3) at 850°C under 46.15 LCH4h−1gNi−1. The uncompromising activity of the catalyst comes from the two major contributions: the absence of nickel oxide eliminates the formation of carbon oxides and the amorphous core–shell structure of Ni@C-B2O3s facilitates nano-sized nickel cores to escape the CNOs and directly decompose methane. This was verified by various microscopic and spectroscopic investigations. The generated CNOs on 13Ni@C-B2O3 were partially oxidized by CO2 as a mild oxidant with the production of CO. The catalytic activity of 13Ni@C-B2O3 was maintained for 15 cycles, providing a potential of enabling the cyclic process of CH4 decomposition/CO2 regeneration. By synthesizing Ni@C-B2O3s from CO2 and using them to the cyclic operation, not only was CO2 converted to the valuable catalyst, but hydrogen, CNOs, and CO were also produced from the greenhouse gases of methane and CO2.