A study on the stability of a NiO–CaO/Al2O3 complex catalyst by La2O3 modification for hydrogen production

This paper details the study of La₂O₃ modifications and their effect on the stability of a NiO–CaO/Al₂O₃ sorption complex catalyst used in the ReSER (reactive sorption enhanced reforming) process of hydrogen production. The La₂O₃-modified NiO–CaO/Al₂O₃ sorption complex catalyst was prepared by isometric impregnation. The microstructure, morphology and reducibility of the La₂O₃-modified sorption complex catalyst were characterized by means of BET, TEM, XRD and TPR. The stability of the catalyst used in the ReSER process was evaluated on a laboratory-scale fixed-bed reactor. Our results showed that modifying the sorption complex catalyst with La₂O₃ improved its stability up to 30 cycles of the ReSER process for hydrogen production, while only seven cycles were obtained without La₂O₃ modification. We showed that the source of the stability improvement that the La₂O₃ in the catalyst not only functioned to restrain the decrease of the support surface area and reduce the sintering of nano-CaCO₃, which could limit the decay of the sorption capacity and stability of the catalyst, but also increased the interaction between nickel oxide and the support, which improved the stability of the catalyst by increasing the dispersion of nickel grains and inhibited the growth of nickel grain size.     

Nanocrystallites-forming hierarchical porous Ni/Al2O3–TiO2 catalyst for dehydrogenation of organic chemical hydrides

Dehydrogenation of organic chemical hydrides has been improved by reconstructing the catalyst in the form of hierarchical porous structure nanocatalyst, in which the economical Ni was adopted as catalytic component and nano Al₂O₃–TiO₂ hybrid composite as support. The Al₂O₃–TiO₂ composite was prepared by spontaneous self-assembly of nano Al₂O₃ and TiO₂ aggregates by hydrolysis of tetra-n-butyl-titanate under continuous agitation. The multi-scaled distribution of Al₂O₃–TiO₂ aggregates with hierarchy could be observed in dynamic light scattering spectrometer. The aggregates are comprised of nano-sized γ-Al₂O₃ and anatase TiO₂ crystallites with sizes of about 5 and 7 nm, respectively. The surface modulation by TiO₂ could be verified in FTIR Spectra. The migration of Ti species and crystallite growth were hindered by the Al₂O₃ skeleton and the hierarchical porous structure was sustained during the thermal related process. The multi-scaled distributed pores were confirmed by both TEM analysis and N₂ adsorption results. The results of dehydrogenation experiments showed that the hierarchical porous structure nano Ni/Al₂O₃–TiO₂ exhibited superior catalytic performance to Ni/Al₂O₃ with the optimum conversion of 99.9% at 400 °C, while the catalyst of Ni/Al₂O₃ exhibited only 16.5% under the same condition.     

Magnetic field effects on selective catalytic reduction of NO by NH3 over Fe2O3 catalyst in a magnetically fluidized bed

Selective catalytic reduction (SCR) of NO from simulated flue gas by ammonia with Fe₂O₃ particles as the catalyst was performed using a magnetically fluidized bed (MFB). X-ray diffraction (XRD) spectroscopy and Brunauer–Emmett–Teller (BET) method were used to analyze Fe₂O₃ catalyst. Important effects of magnetic fields were observed in the SCR of NO by ammonia over Fe₂O₃ catalyst. The apparent activation energies of SCR were reduced by external magnetic fields, and the SCR activity of Fe₂O₃ catalyst was improved with the magnetic fields at low temperatures. Thus the scope of temperature with high efficiency of NO removal was extended from 493–523 K to 453–523 K by magnetic fields. Magnetic fields of 0.01–0.015 T were suggested for NO removal on Fe₂O₃ catalyst with MFB. The results suggested that the magnetoadsorption of NO onto Fe₂O₃ surface together with NH₂ and NO free radicals effects induced by the external magnetic fields both acted to improve the rate of SCR of NO on Fe₂O₃ catalyst. On the other hand, magnetic field effects were also attributed to improved gas–solid contact in MFB.     

ZnO–Bi2O3/graphene oxide photocatalyst with high photocatalytic performance under visible light

Abstract

Photocatalytic nanomaterials are attracting more and more attention because of their potential for solving environmental problems. ZnO, as one of the most promising photocatalysts, can only be excited by ultraviolet (UV) or near UV radiation. The objective of the study is to describe an efficient visible light driven ZnO based photocatalyst. In this regard, we communicate the preliminary research on the synthesis, characterisation and photocatalytic properties of ZnO–Bi₂O₃/graphene oxide (GO) composite materials. It was found that the photodegradation of methylene blue in the presence of ZnO–Bi₂O₃/GO reached 99·62% after irradiation with visible light for 2 h. The presence of GO enhances the stability of ZnO–Bi₂O₃ and reduces the recombination of charge carriers. ZnO–Bi₂O₃/GO also shows high photocatalytic activity for the degradation of acid blue, acid yellow, reactive red, acid red, reactive yellow and reactive blue under visible light irradiation. The novel aspect is the combination of GO and Bi₂O₃ doped ZnO. The use of GO enhances the efficiency of photocatalysis, and Bi₂O₃ doping ZnO excites the absorption of visible light. The impact of the research concerns the study of ZnO–Bi₂O₃/GO, which can be used as a promising photocatalyst for the treatment of textile wastewater.     

Reforming of bioethanol over Ni/Al2O3 and Ni/CeZrO2/Al2O3 catalysts in supercritical water for hydrogen production

Bioethanol was reformed in supercritical water (SCW) at 500 °C and 25 MPa on Ni/Al₂O₃ and Ni/CeZrO₂/Al₂O₃ catalysts to produce high-pressure hydrogen. The results were compared with non-catalytic reactions. Under supercritical water and in a non-catalytic environment, ethanol was reformed to H₂, CO₂ and CH₄ with small amounts of CO and C2 gas and liquid products. The presence of either Ni/Al₂O₃ or Ni/CeZrO₂/Al₂O₃ promoted reactions of ethanol reforming, dehydrogenation and decomposition. Acetaldehyde produced from the decomposition of ethanol was completely decomposed into CH₄ and CO, which underwent a further water-gas shift reaction in SCW. This led to great increases in ethanol conversion and H₂ yield on the catalysts of more than 3-4 times than that of the non-catalytic condition. For the catalytic operation, adding small amounts of oxygen at oxygen to ethanol molar ratio of 0.06 into the feed improved ethanol conversion, at the expense of some H₂ oxidized to water, resulting in a slightly lower H₂ yield. The ceria-zirconia promoted catalyst was more active than the unpromoted catalyst. On the promoted catalyst, complete ethanol conversion was achieved and no coke formation was found. The ceria-zirconia promoter has important roles in improving the decomposition of acetaldehyde, the enhancement of the water-gas shift as well as the methanation reactions to give an extremely low CO yield and a tremendously high H₂/CO ratio. The SCW environment for ethanol reforming caused the transformation of gamma-alumina towards the corundum phase of the alumina support in the Ni/Al₂O₃ catalyst, but this transformation was slowed down by the presence of the ceria-zirconia promoter.     

Hydrogen production from dimethyl ether over Cu/γ-Al2O3 catalyst with zeolites and its effects in the lean NOx trap performance

The purpose of this study is to investigate the effects of mixing three kinds of zeolites (MFI, MOR, and BEA) with the dimethyl ether steam reforming(DME-SR) Cu/γ-Al₂O₃ catalyst to improve H₂ yield at low temperatures, and to identify the de-NOx performance of a combined system of SR catalyst and Lean NOx Trap(LNT). The SR catalyst was prepared by the impregnation method, and a commercialized LNT catalyst was used. The SR reaction experiment was conducted to investigate the effect of the coexistence of CO₂, O₂, NO, and NO₂ among the exhaust gases of the DME engine on the H₂ yield. The study found that the proper mixing of Cu/γ-Al₂O₃ and zeolite increased the H₂ yield at low temperature improving DME hydrolysis. The variation in the H₂ yield according to the kinds of zeolite in the SR catalyst was due to the characteristics of zeolite. The Cu10/γ-Al₂O₃ catalyst mixed with 10% MOR showed the highest H₂ yield. A combined system of SR and LNT uses the H₂ generated mainly from the Cu-based catalyst using the DME-SR reaction for the LNT. When H₂ generated from the SR (Cu10/γ-Al₂O₃ + MOR10) catalyst was used as the reductant of LNT, the NOx conversion at 350 °C or below was improved up to 15% compared to when DME was used. This demonstrates that H₂ as the reductant of LNT is more beneficial than DME. The H₂ generated from the SR catalyst can be used as the reductant of LNT in an after-treatment system. Meanwhile, the SR catalyst that was mixed with zeolite caused the carbon deposition, but the combined system of SR + LNT caused no carbon deposition because the carbon deposited on the SR catalyst reacted with O₂ during the lean-operating period.     

Study on photocurrent of bilayers photoanodes using different combination of WO3 and Fe2O3

Bilayer photoanodes were prepared onto glass substrates (FTO) in order to improve generated photocurrents using UV-vis light by water splitting process. A comparative study of photocatalytic was performed over the films surface using Fe₂O_3, WO₃ and mixture of bicomponents (Fe₂O₃:WO₃). Different types of films were prepared using Fe₂O_3, WO₃ and bicomponents (mixture) on FTO substrates. The films were grown by sol gel method with the PEG-300 as the structure-directing agent. The photo-generated of the samples were determined by measuring the currents and voltages under illumination of UV-vis light. The morphology, structure and related composition distribution of the films have been characterized by SEM, XRD and EDX respectively. Photocurrent measurements indicated surface roughness as the effective parameter in this study. The deposited surfaces by bicomponents or mixture are flat without any feature on the surface while the deposited surfaces by WO₃ appears rough surface as small round (egg-shaped particles) and cauliflower-like. The surface deposited by Fe₂O₃ show rough no as well as WO₃ surface. The deposited surfaces by WO₃ reveal the higher value of photocurrent measurement due to surface roughness. Indeed, the roughness can be effective in increasing contact surface area between film and electrolyte and diffuse reflection (light scattering effect). The solution (Fe₂O₃:WO₃) shows the low photocurrent value in compare to WO₃ and Fe₂O₃ hat it may be due to decomposition the compound at 450 ± 1 °C to iron-tungstate Fe₂(WO₄)₃.     

Stabilized zirconia-based sensor utilizing SnO2-based sensing electrode with an integrated Cr2O3 catalyst layer for sensitive and selective detection of hydrogen

A highly selective hydrogen (H₂) sensor has been successfully developed by using an yttria-stabilized zirconia (YSZ)-based mixed-potential-type sensor utilizing SnO₂ (+30 wt.% YSZ) sensing electrode (SE) with an intermediate Al₂O₃ barrier layer which was coated with a catalyst layer of Cr₂O₃. The sensor utilizing SnO₂ (+30 wt.% YSZ)-SE was found to be capable of detecting H₂ and propene (C₃H₆) sensitively at 550 °C. In order to enhance the selectivity towards H₂, a selective C₃H₆ oxidation catalyst was employed to minimize unwanted responses caused by interfering gases. Among the examined metal oxides, Cr₂O₃ facilitated the selective oxidation of C₃H₆. However, the addition or lamination of Cr₂O₃ to SnO₂ (+30 wt.% YSZ)-SE was found to diminish the sensing responses to all examined gases. Therefore, an intermediate layer of Al₂O₃ was sandwiched between the SE layer and the catalyst layer to prevent the penetration of Cr₂O₃ particles into the SE layer. The sensor using SnO₂ (+30 wt.% YSZ)-SE coated with a catalyst layer of Cr₂O₃ as well as an intermediate layer of Al₂O₃ exhibited a sensitive response toward H₂, with only minor responses toward other examined gases at 550 °C under humid conditions (21 vol.% O₂ and 1.35 vol.% H₂O in N₂ balance). A linear relationship was observed between sensitivity and H₂ concentration in the range of 20–800 ppm on a logarithmic scale. The results of sensing performance evaluation and polarization curve measurements indicate that the sensing mechanism is based on the mixed-potential model.     

A novel membrane for DMFC - Na2Ti3O7 nanotubes/Nafion composite membrane

In this study, novel sodium titanate (Na₂Ti₃O₇) nanotube/Nafion^® composite membranes were prepared by a solution casting method. The properties of these composite membranes were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Additionally, the water uptake, methanol permeability, proton conductivity, and selectivity of the composite membranes were measured to evaluate the applicability of these membranes in DMFCs. It was found that the addition of Na₂Ti₃O₇ nanotubes enhanced the water uptake and reduced the methanol permeability of the composite membranes. The proton conductivity and methanol permeability depend on the Na₂Ti₃O₇ nanotube content. Using the selectivity, the optimal nanotube contents was found to be 5 wt%. The new composite membrane was found to have significantly higher selectivity than a pure Nafion^® membrane and thus has good potential to outperform Nafion^® in DMFCs.     

Steam reforming of dimethyl ether over Cu–Ni/γ-Al2O3 bi-functional catalyst prepared by deposition–precipitation method

Cu–Ni/γ-Al₂O₃ catalysts with different metal contents for dimethyl ether steam reforming (DME SR) were prepared by the method of deposition–precipitation. Characterization of specific surface area measurement (BET), X-ray diffraction (XRD) and hydrogen temperature-programmed reduction (H₂-TPR) revealed that nickel improved the dispersion of copper, increased the interaction between copper and γ-Al₂O₃, and therefore, inhibited the sintering of copper. Ammonia temperature-programmed desorption (NH₃-TPD) showed that metal particles could occupy the acid sites, leading to the decrease in acid amount and acid strength of Cu–Ni/γ-Al₂O₃ catalyst. Kinetic measurements indicated that γ-Al₂O₃ is vital for DME SR and a higher content of γ-Al₂O₃ in catalyst was needed. The addition of nickel suppressed the water gas shift (WGS) reaction. Initial durability testing showed that the conversion of DME over Cu–Ni/γ-Al₂O₃ catalyst was always almost complete during the 30 h experimental reaction time. Therefore, Cu–Ni/γ-Al₂O₃ could be a potential DME SR catalyst for the production of hydrogen.     

Effects of modifying Ni/Al2O3 catalyst with cobalt on the reforming of CH4 with CO2 and cracking of CH4 reactions

Alumina supported nickel (Ni/Al₂O₃), nickel–cobalt (Ni–Co/Al₂O₃) and cobalt (Co/Al₂O₃) catalysts containing 15% metal were synthesized, characterized and tested for the reforming of CH₄ with CO₂ and CH₄ cracking reactions. In the Ni–Co/Al₂O₃ catalysts Ni–Co alloys were detected and the surface metal sites decreased with decrease in Ni:Co ratio. Turnover frequencies of CH₄ were determined for both reactions. The initial turnover frequencies of reforming (TOF_DRM) for Ni–Co/Al₂O₃ were greater than that for Ni/Al₂O₃, which suggested a higher activity of alloy sites. The initial turnover frequencies for cracking (TOF_CRK) did not follow this trend. The highest average TOF_DRM, H₂:CO ratio and TOF_CRK were observed for a catalyst containing a Ni:Co ratio of 3:1. This catalyst also had the maximum carbon deposited during reforming and produced the maximum reactive carbon during cracking. It appeared that carbon was an intermediate product of reforming and the best catalyst was able to most effectively crack CH₄ and oxidize carbon to CO by CO₂.     

Properties of Ni/Y2O3 and its catalytic performance in methane conversion to syngas

Ni/Y₂O₃, with Y₂O₃ support prepared by the conventional precipitation method, was prepared by an impregnation method. The physicochemical properties of Y₂O₃ and Ni/Y₂O₃ were characterized by BET, CO₂-TPD, NH₃-TPD, TPR, XRF and TGA, and compared with those of γ-Al₂O₃ and Ni/γ-Al₂O_3, respectively. The catalytic performance of Ni/Y₂O₃ in the reaction of partial oxidation of methane (POM) to syngas was evaluated and compared with that of Ni/γ-Al₂O₃ catalyst, too. The results showed that, Y₂O₃ was a basic support with few acidic sites while γ-Al₂O₃ was an acidic support. NiO particles supported on Y₂O₃ were more easily to be reduced than those supported on γ-Al₂O₃. In the partial oxidation of methane, Ni/Y₂O₃ catalyst showed high catalytic activity and exhibited better catalytic stability than Ni/γ-Al₂O₃. After POM reaction at 700 °C for 550 h, methane conversion decreased little and only 2.2 wt% carbon was deposited on Ni/Y₂O₃ catalyst. Ni/Y₂O₃ was stable in POM even after a series of reaction temperature variations within the temperature range of 400 ∼ 800 °C.     

Evaluation of Ni/Y2O3/Al2O3 catalysts for hydrogen production by autothermal reforming of methane

Ni/xY₂O₃–Al₂O₃ (x = 5, 10, 15, 20 wt%) catalysts were prepared by sequential impregnation synthesis. The catalytic performance for the autothermal reforming of methane was evaluated and compared with Ni/γ-Al₂O₃ catalyst. The physicochemical properties of catalysts were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-Ray Photoelectron Spectrometer (XPS), Thermo Gravimetric Analyzer (TGA) and H₂-temperature programmed reduction techniques (TPR). The decrease of nickel particle size and the change of reducibility were found with Y modification. The CH₄ conversion increased with elevating levels of Y₂O₃ from 5% to 10%, then decreased with Y content from 10% to 20%. Ni/xY₂O₃–Al₂O₃ catalysts maintained high activity after 24 h on stream, while Ni/Al₂O₃ had a significant deactivation. The characterization of spent catalysts indicated that the addition of Y retarded Ni sintering and decreased the amount of coke.     

Electrocatalysis of carbon black- or chitosan-functionalized activated carbon nanotubes-supported Pd with a small amount of La2O3 towards methanol oxidation in alkaline media

The Pd/C catalysts with and without a small amount of La₂O₃ were synthesized by a simple reduction reaction with sodium borohydride in aqueous solution. The structure and morphology of these catalysts were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy and transmission electron microscopy. The electrocatalytic performance of these catalysts for methanol oxidation in alkaline media was investigated using cyclic voltammetry, chronoamperometry and CO stripping experiments. The results show that the Pd–La₂O₃/C catalyst has a higher catalytic activity than the Pd/C catalyst, but the effect of La₂O₃ cannot be explained by a bi-functional mechanism. X-Ray photoelectron spectroscopy analyses suggest that the higher content of metallic Pd caused by the addition of La₂O₃ contributes to the better catalytic activity of Pd–La₂O₃/C. Based on the good electrocatalytic performance of Pd–La₂O₃/C, the Pd–La₂O₃ catalyst supported on chitosan (CS)-functionalized activated carbon nanotubes was prepared, and it exhibited a better catalytic activity. The improvement is attributed to the good dispersion status of metal particles and the further increase of metallic Pd due to the presence of CS.     

Effect of N2O-mediated calcination on nickel species and the catalytic activity of nickel catalysts supported on γ-Al2O3 in the steam reforming of glycerol

The steam reforming of glycerol over supported nickel catalysts is a promising and cost-effective method for producing hydrogen. The activity of nickel catalysts supported on γ-Al₂O₃ is low, primarily due to the formation of inactive nickel species during high temperature calcination in air. In order to address this problem, a Ni/γ-Al₂O₃ catalyst was prepared by calcination at 700 °C in a nitrous oxide (N₂O) environment. The N₂O calcined catalyst showed an enhanced activity for the steam reforming of glycerol. A variety of characterization techniques (XRD, TPR, XPS and H₂ Chemisorption) confirmed that the high temperature N₂O calcination resulted in a significant decrease in the levels of nickel aluminate. The N₂O calcination also led to an enhancement in the amount of NiO as well as nickel ions present on the surface of the catalyst. Interestingly, compared to an air calcined catalyst, the N₂O calcined catalyst contained larger nickel particles after reduction but the N₂O calcined catalyst had a much larger nickel surface area and dispersion, which resulted in higher glycerol conversion and hydrogen yield.     

Catalytic effect of Gd2O3 and Nd2O3 on hydrogen desorption behavior of NaAlH4

This study investigated the effect of Nd₂O₃ and Gd₂O₃ as catalyst on hydrogen desorption behavior of NaAlH₄. Pressure-content-temperature (PCT) equipment measurement proved that both two oxides enhanced the dehydrogenation kinetics distinctly and increasing Nd₂O₃ and Gd₂O₃ from 0.5 mol% to 5 mol% caused a similar effect trend that the dehydrogenation amount and average dehydrogenation rate increased firstly and then decreased under the same conditions. 1 mol% Gd₂O₃–NaAlH₄ presented the largest hydrogen desorption amount of 5.94 wt% while 1 mol% Nd₂O₃–NaAlH₄ exerted the fastest dehydrogenation rate. Scanning Electron microscopy (SEM) analysis revealed that Gd₂O₃–NaAlH₄ samples displayed uniform surface morphology that was bulky, uneven and flocculent. The difference of Nd₂O₃–NaAlH₄ was that with the increasing of Nd₂O₃ content, the particles turned more and more big. Compared to dehydrogenation behavior, this phenomenon demonstrated that small particles structure were beneficial to hydrogen desorption. Besides, the further study found that different catalysts and addition amounts had different effects on the microstructure of NaAlH_4.     

CO2 reforming of methane on Ni/γ-Al2O3 catalyst prepared by dielectric barrier discharge hydrogen plasma

Ni/γ-Al₂O₃ catalyst was prepared by direct treatment of Ni(NO₃)₂/γ-Al₂O₃ precursor with dielectric barrier discharge (DBD) hydrogen plasma at different input powers, characterized by XRD, H₂-TPR, CO₂-TPD, N₂ adsorption and TEM, respectively, and used as the catalyst for CO₂ reforming of methane (CRM). The results showed that the input power obviously affected the reduction degree and catalytic performances of catalysts. Low input power under 40 W mainly resulted in the decomposition of nickel nitrate into Ni oxides. The reduction degree, catalytic activity and stability increase with the input power. Similar catalytic performances in CRM reaction can be obtained when the power exceeds 80 W. Compared with the Ni/Al₂O₃ catalyst prepared by traditional method, Ni/γ-Al₂O₃ samples prepared by H₂ DBD plasma exhibit better activities, stability and anti-carbon deposit performances. It is mainly ascribed to smaller Ni particle size, more basic sites and weaker basicity. The increase of Ni particle sizes due to the sintering at high temperature results in the decrease of catalytic activities and coke formation.     

Facile fabrication of Bi2O3/TiO2-xNx nanocomposites for excellent visible light driven photocatalytic hydrogen evolution

Mesoporous Bi₂O₃/TiO_2−xN_x nanocomposites (BiNT) were synthesized by soft chemical template free homogeneous co-precipitation technique. XRD, XPS, TEM, UV-Vis DRS and photoluminescence studies were adapted to determine the structural, electronic and optical properties. The photocatalytic activities of the catalysts were evaluated for water splitting to generate clean hydrogen fuel under visible light irradiation (λ ≥ 400 nm). BiNT-400 catalyst showed highest results towards hydrogen production (198.4 μmol/h) with an apparent quantum efficiency of 4.3%. The pronounced activity of BiNT-400 sample towards hydrogen production was well consistent with high crystallinity, large surface area, proper excitation by N doping and Bi₂O₃ sensitization.     

Morphological, optical and photocatalytic properties of TiO2–Fe2O3 multilayers

Morphological, optical and photocatalytic properties of TiO₂, Fe₂O₃ and TiO₂–Fe₂O₃ samples (formed by 1, 3 and 5 coatings) were studied. The layers were deposited on glass substrate by the sol–gel method. The catalytic activity of the samples was studied by the photodecomposition of methylene blue (MB) under visible light illumination. The FTIR results indicate that all samples present surface OH radicals that are bound either to the Ti or Fe atoms. This effect is better visualized at larger number of coatings in the TiO₂–Fe₂O₃/glass systems. Also, two mechanisms are observed during the photodecomposition of the MB.     

CO2 reforming of methane combined with steam reforming or partial oxidation of methane to syngas over NdCoO3 perovskite-type mixed metal-oxide catalyst

CO₂ reforming with simultaneous steam reforming or partial oxidation of methane to syngas over NdCoO₃ perovskite-type mixed metal oxide catalyst (prereduced by H₂) at different process conditions has been investigated. In the simultaneous CO₂ and steam reforming, the conversion of methane and H₂O and also the H₂/CO product ratio are strongly influenced by the CO₂/H₂O feed-ratio. In the simultaneous CO₂ reforming and partial oxidation of methane, the conversion of methane and CO₂, H₂ selectivity and the net heat of reaction are strongly influenced by the process parameters (viz. temperature, space velocity and relative concentration of O₂ in the feed). In both cases, no carbon deposition on the catalyst was observed. The reduced NdCoO₃ perovskite-type mixed-oxide catalyst (Co dispersed on Nd₂O₃) is a highly promising catalyst for carbon-free CO₂ reforming combined with steam reforming or partial oxidation of methane to syngas.