La2O3 Catalyst Research Articles

Construction of mesoporous lanthanum oxide and supported Co-N catalysts for high-efficient synthesis of furfuryl alcohol

The mesoporous lanthanum oxide materials were designed via the solvent evaporation-induced self-assembly method, and Co-N/La2O3 catalysts were prepared to evaluate performance in the reaction of furfural hydrogenation. The characterization analyses proved that Co/La2O3 and Co-2N/La2O3 catalysts had high specific surface area and open mesoporous channels (> 20nm), moreover doped nitrogen not only promoted the distribution of Co species and regulated size of metallic Co nanoparticles (~17.37nm), but also increased electron-rich Co0 (57.8%) and CoNx sites. The highest conversion (>99.9%) and selectivity (98.6%) were achieved on Co-2N/La2O3 catalyst under 140oC, 1.5MPa H2 and 3h, which was attributed to the combination of Co0 and CoNx sites enhancing the dissociation of H2 and adsorption of furfural by DFT calculation, meanwhile the doped nitrogen brought more acidic sites (~ 2.81mmol NH3/g) of Co-2N/La2O3 catalyst. Additionally, the Co-2N/La2O3 catalyst showed the stable catalytic activity for 5 recycles and excellent universality for hydrogenation reactions of biomass platform molecules.

Hydrogen production from ammonia decomposition in electric field over La-based materials

Hydrogen is rapidly emerging as a pivotal clean energy carrier for both stationary and transport applications. However, the storage of hydrogen as compressed gas at high pressures poses significant challenges in terms of cost, transportation, and safety. Chemical storage, particularly using compounds like ammonia, has emerged as a viable alternative due to its high hydrogen content and narrow flammable range. This study investigates the catalytic decomposition of ammonia under an electric field using Ni based La2O3 catalysts. The catalytic performance is evaluated in terms of ammonia conversion and energy efficiency. High catalytic activity is obtained in the presence of 15 wt%NiO/La2O3, the energy efficiency is 0.29 mmol/kJ. This is attributed to the semiconducting properties of NiO. Catalyst characterization techniques, including X-ray diffraction, transmission electron microscopy, and photoelectron spectroscopy, provide insights into catalyst morphology, chemical composition before and after reaction. It is shown that hydroxylation of La2O3 proceeds during ammonia decomposition and a reaction mechanism is provided.

Harvesting high-performance electro-water oxidation and selective MB degradation through dual functional Gd2O3–La2O3 photo-electrocatalysts

Interestingly, catalytic oxygen evolution reaction (OER) in an alkaline medium with minimizing the overpotential is the most trustworthy electrocatalyst for the output of hydrogen energy from copious water electrochemical activity. Currently, amalgamated trivalent cations metal oxides have gained desirability as a low-cost anode electrocatalyst to replace noble metal-supported electrocatalysts for water oxidation and are also used for photo-degradation applications. In the present work, we have successfully synthesized Gd2O3 supported La2O3 composites via hydrothermal pathways for efficient OER and selective methylene blue (MB) degradation applications. XRD, UV–Vis DRS, FT-IR, XPS, SEM-EDX, HR-TEM, DLS, and BET analyzers confirmed the successful synthesis of photo-electrocatalysts. Gd2O3–La2O3 composites achieved 5.66 and 3.37-fold larger surface areas than La2O3 and Gd2O3, respectively. The results of the Gd2O3 supported La2O3 composite electrode demonstrated better OER performance under 1 M KOH, and it exhibited a lower Tafel slope and overpotential of 72 mV dec−1 and 310 mV at 10 mA cm−2. A chronoamperometry examination confirms that the fabricated Gd2O3–La2O3 electrode has good stability at a fixed potential of 1.540 V vs. RHE for water oxidation. Although the, Gd+3 inspired La2O3 electrode actively takes part in OER activity owing to its high Cdl value of 40.222 μF cm−2. The selective degradation of MB dye using the Gd2O3–La2O3 composite achieved an acceptable degradation efficiency of 84.80 % compared to other pollutants under UV-light irradiation for 120 min, and the specified pH condition is 9 for the degradation of MB dye, and it follows the first-order kinetics model. Notably, post-OER and photocatalytic results exhibited good stability and reusability characteristics. Therefore, the Gd2O3–La2O3 catalyst can be used for real-time water oxidation and MB dye removal from polluted water.

Investigating the Impact of Na2WO4 Doping in La2O3-Catalyzed OCM Reaction: A Structure–Activity Study via In Situ XRD-MS

The La2O3 catalyst exhibits good performance in OCM reactions for its promising C2 selectivity and yield. Previous studies have affirmed that the formation of carbonates in La2O3 impedes the catalyst’s activity as a result of poisoning from CO2 exposure. In this study, a series of Na2WO4-impregnated La2O3 catalysts were synthesized to investigate the poisoning-resistant effect. The bulk phase and kinetics of the catalysts were analyzed in reactors employed with in situ XRD-MS and online MS, focusing on the CO2 adsorption on La2O3 and the phase transition process to La2O2CO3 in temperature zone correlated to OCM light-off. In situ XRD analysis revealed that, with Na2WO4 doped, CO2 exposure at elevated temperatures formed La2O2CO3 in tetragonal crystal phases, exhibiting distinctive differences from the hexagonal phase carbonates in undoped commercial La2O3. The ability to develop tetragonal or monoclinic La2O2CO3 was suggested as a descriptor to assess the sensitivity of La2O3 catalysts to CO2 adsorption, a tunable characteristic found in this study through varying Na2WO4 doping levels. Coupled XRD-MS analysis of CO2 adsorption uptake and phase change further confirmed a positive dependence between the resistivity of La2O3 catalyst to CO2 adsorption and its low-temperature C2 selectivity. The results extended the previous CO2 poisoning effect from multiple perspectives, offering a novel modification approach for enhancing the low-temperature performance of La2O3 catalysts in OCM.

Evaluation of Life Cycle Assessment of Jatropha Biodiesel Processed by Esterification of Thai Domestic Rare Earth Oxide Catalysts

The Thai domestic rare earth oxides, including cerium, lanthanum, and neodymium oxides, with the effects of calcination temperatures (500–1000 °C), were utilized as catalysts for twelve Jatropha biodiesel alternatives via an esterification reaction. This study applied life cycle assessment (LCA) methodology from well-to-wheel analysis to assess energy efficiency and the global warming impact with and without land use change. The results of the life cycle analysis showed that the Jatropha biodiesel alternatives using the La2O3 catalyst in all conditions (0.89–1.06) were found to be potential fuel substitutes for conventional diesel (0.86) in terms of net energy ratios; however, the results showed that they generated a higher global warming impact. Considering the improvement process of Jatropha biodiesel in the utilization of waste heat recovery, the Jatropha biodiesel reduced the impacts of the net energy ratios and the global warming impact by 22–24% and 34–36%, respectively. The alternative Jatropha biodiesel using the La2O3 catalyst with a calcination temperature of 600 °C was shown to be the most environmentally friendly of all the studied fuels; relatively, it had the highest energy ratios of 1.06–1.37 (with and without waste heat recovery) and the lowest total global warming impact of 47.9–70.7 kg CO2 equivalent (with land use change). The integration of the material and process development by domestic catalysts and the recovery of waste heat would improve the sustainability choices of biofuel production from renewable resources for transportation fuels in Thailand.

Optimization of MxOy (La2O3 or Gd2O3) content in Rh/MxOy-Al2O3 catalyst formulation for the propane steam reforming reaction

Heading full speed towards the extensive use of H2 for humanity's energy needs, blue hydrogen production from light hydrocarbons is one of the most promising alternatives. In this study the production of hydrogen through propane steam reforming (PSR) reaction is investigated over Rh nanoparticles dispersed on MxOy-Al2O3 supports of variable MxOy (M: La, Gd) content towards optimizing catalytic performance. The intrinsic activity and the formation of intermediate CH4 are markedly affected by varying MxOy content passing through a maximum for 10 wt% La2O3 or Gd2O3. Up to 8- and 3.5-fold increases in turnover frequency (TOF) at 400 °C are achieved on these optimally loaded with La2O3 and Gd2O3 catalysts, respectively, accompanied by more than two-fold higher H2 yields. The reducibility of both rhodium species and the MxOy-Al2O3 support strongly depends on the MxOy content, which then determines the catalytic activity. In situ diffuse reflectance infrared furrier transform spectroscopy (DRIFTS) experiments revealed that CHx species generated by the dissociative adsorption of propane interact either with H2 yielding CH4 and/or with hydroxyl groups producing formate species and eventually COx and H2 in a manner which depends on MxOy content. However, the latter path is over-favored for samples with 20 wt% MxOy possessing excessive reducibility, and in combination to an over-strengthening of formates adsorption, the conversion rate to COx and H2 is strongly inhibited. Scaling-up the fabrication of the most active Rh/10%La2O3-Al2O3 catalyst at higher application readiness (structured as pellets) and testing under realistic conditions revealed its suitability for propane reformers.

Performance and reaction mechanism of Mg-doped and Li-doped La2O3 catalysts in oxidative coupling of methane: DFT and experiment study

Lanthanum oxide (La2O3) catalyst is a promising catalytic system for oxidative coupling of methane (OCM) reaction, while low activity for methane dissociation restricts its widespread application. Low-value dopants can enhance methane conversion activity on La2O3 catalysts. This work systematically studied the mechanism and catalytic performance of OCM reaction on Mg-doped and Li-doped La2O3 catalysts using a combination of DFT and experimental methods. The results show that Mg-doped and Li-doped can significantly improve CH4 dissociation activity and C2H4 selectivity on La2O3(001) surface. The microscopic property analysis shows that the p-band center of lattice oxygen on Mg-doped and Li-doped La2O3(001) is closer to the Fermi level, compared with undoped La2O3(001), which is more conducive to the activation of methane. Furthermore, Mg-doped and Li-doped La2O3 catalysts are prepared and their OCM catalytic performance are investigated. The catalytic performance of Mg-doped La2O3 catalyst reaches its best at 750 °C, with a high CH4 conversion (above 30.9 %) and the highest C2+ hydrocarbons selectivity (about 47.5 %) and C2+ yield (about 14.7 %). However, Li-doped La2O3 shows poorer catalytic performance than undoped La2O3, primarily due to the loss of the doped Li during the OCM process. In addition, the OCM reaction cycle and the mechanism of action of oxygen species on Mg doped La2O3(001) have been studied. The results show that lattice oxygen and peroxide species are the major active oxygen species for activating methane.

Effect of different valence metals doping on methane activation over La2O3(001) surface

La2O3 as a catalyst is used for oxidative coupling of methane (OCM) reactions due to its excellent stability and high C2 selectivity, but poor activity on methane dissociation limits its wide application. Different valence metals are doped on the La2O3(001) surface to improve the methane conversion activity, and the activation of methane on metal-doped La2O3(001) surfaces has been investigated via the density functional theory (DFT) calculations. The relationship between the valence states of doped metals and the methane conversion activities shows that doping low valence metals (Li, Na, K, Mg, Ca, Sr and Ba) and equivalent metals (Al, Ga, In) can significantly improve the conversion activity of methane. Among them, the activation energy of methane on the Li-La2O3(001) surface is the lowest, which is only 13.0 kJ/mol. However, doping of high valence metals (Zr, Nb, Re and W) cannot improve the CH4 dissociation activity. Furthermore, the relationships between surface oxygen vacancy formation energies, acid-base properties and the activation energies of CH4 have also been investigated. The results show that with the increase of metal valence state, the oxygen vacancy formation energy increases, while the dissociation activity of CH4 decreases. The introduction of alkali and alkaline earth metals increases the alkalinity of La2O3(001) surface, and the alkalinity of La2O3(001) doped with the alkali metal is stronger than that with the alkaline earth metal, exhibiting higher dissociation activity of CH4. Our research may provide a guide for improving methane conversion activity on La2O3 catalysts.

Effect of ionic radius and valence state of alkali and alkaline earth metals on promoting the catalytic performance of La2O3 catalysts for glycerol carbonate production

Alkali metals and alkaline earth metals have been used to promote the catalytic performance of metal oxides in transesterification of glycerol and dimethyl carbonate, however, the promotional roles of the dopants in influencing the catalytic performance of the metal oxides have not been fully investigated which hinder the development of low-cost and high-efficiency catalysts in transesterification of glycerol and dimethyl carbonate. This paper, for the first time, systematically studied the influence of ionic radius and valence state of dopants, surface concentration of dopants and the basicity of the catalysts on the catalytic performance of La2O3 in transesterification of glycerol and dimethyl carbonate. Our results suggest that the ionic radius and valence state of the dopants are the determining factors, while the basic site density is not a crucial factor, although the basicity of catalyst surface is important in activating glycerol and dimethyl carbonate. Among alkali and alkaline earth metals, 25 mol% Na/La2O3 catalyst achieved the highest glycerol conversion (85 %) and glycerol carbonate yield (60 %) in the 70 °C and 2-hour reaction. After the detailed investigation, a plausible mechanism of glycerol and dimethyl carbonate transesterification on Na/La2O3 catalyst has been proposed. This research could help understand the promotional role of alkali metals and alkaline earth metals and the results may guide future design of metal oxide catalysts.

The role of lanthanum hydride species in La2O3 supported Ru cluster catalyst for ammonia synthesis

To exploit the ammonia as a carrier for sustainable energy, development of efficient catalysts is highly desired. Oxide supported Ru catalysts have been widely studied in ammonia synthesis for their superior catalytic performances under mild conditions. Here, sub-nanometer Ru clusters on La2O3 (Ru clusters/La2O3) catalyst has been synthesized and exhibits superior catalytic performance in ammonia synthesis under mild conditions. Multiple characterizations results reveal that surface La-H species, in situ generated on the surface of catalyst, can significantly boost the activity of Ru clusters/La2O3 catalyst in ammonia synthesis. Detailed mechanistic studies demonstrate that the active La-H species on the La2O3 can not only promote activation and dissociation of nitrogen molecules but also directly involve in ammonia synthesis reaction process via a La-H species-mediated reaction pathway. This work promotes molecular level understanding the active sites and reaction mechanism under real reaction conditions, and will also offer opportunity for guiding the design of efficient Ru-based catalysts for ammonia synthesis.

Optimizing Ni dispersion and stability over SiO2 supported Ni–La2O3 catalysts by preparation method for enhancing H2 selectivity and durability on steam reforming of methylcyclohexane

In the application of catalytic liquid hydrocarbons steam reforming to hydrogen production, Ni-based catalysts are easy to sintering and carbon deposition owing to poor stability and Ni nanoparticles aggregation at high temperature. Hence, the preparation of well-dispersed and stable Ni nanocatalyst has become research focus. In this work, different preparation methods are adopted to optimize Ni dispersion and stability in SiO2 supported Ni–La2O3 catalysts. Moreover, methylcyclohexane steam reforming is used to evaluate their catalytic behaviors. Structure-activity correlation suggests that the catalyst prepared by sol-gel shows larger pore structure, higher dispersion of Ni nanoparticles, smaller particle size (∼3 nm) and strong interaction of metal-support because of its unique network structure. Meanwhile, it exhibits 100% gas yield and 68% H2 selectivity at 750 °C during activity testing. The gas yield of stability testing remains above 60% after running 50 h at 750 °C and carbon formation rate is only 8.86 mg/gCat·h. Besides, ReaxFF molecular dynamics simulation results substantiate that smaller Ni size can afford more active sites to improve methylcyclohexane conversion, consistent with experimental results. This study can provide guidance on preparation of highly dispersed and stable Ni-based catalysts and analysis of methylcyclohexane steam reforming reaction pathway.

Construction of bimetallic Pt–Pd/CeO2–ZrO2–La2O3 catalysts with different Pt/Pd ratios and its structure–activity correlations for three-way catalytic performance

A series of Pt–Pd bimetallic catalysts supported on CeO2–ZrO2–La2O3 mixed oxides were synthesized through the conventional impregnation method. Three-way catalytic performance evaluations along with detailed physio-chemical characterizations were carried out to establish possible structure–activity correlations. Results show that on the one hand, different Pt/Pd ratios can strongly affect the TWC behaviors of Pt–Pd/CZL catalysts by modulating the synergistic effect between Pt and Pd. On the other hand, higher Pt/Pd ratio also favors better dispersion of precious metals. Such improved precious metals (PM) dispersion can promote the metal-support interaction and increase the surface oxygen vacancies concentration, thereby raising the dynamic oxygen storage/release capacity, improving the redox ability as well as enhancing the thermal stability of the Pt–Pd/CZL catalyst. Moreover, the strong metal-support interaction can augment surface oxygen vacancy concentration, thereby benefiting low temperature CO and NO reaction via augmented NOx adsorption and nitrate conversion.

Combustion synthesis of lanthanum oxide supported Cu, Ni, and CuNi nanoparticles for CO2 conversion reaction

The reverse water gas shift (RWGS) process is considered a feasible method for lowering greenhouse gas emissions by utilizing CO2 and converting it to CO. Herein, we evaluated the catalytic conversion of CO2 through the RWGS reaction over transition metal nanoparticles supported on lanthanum. Catalysts of selected active metals (Cu, Ni, and CuNi) on lanthanum oxide support were investigated in a packed bed tubular reactor within a temperature range of 100–600 °C to assess their catalytic activity and selectivity towards CO. The results of the catalyst's activity and stability experiments showed maximum CO2 conversions of 57%, 68% and 74% for Cu–La2O3, Ni–La2O3, and CuNi–La2O3, respectively, at 600 °C and excellent stability over a 1440-min time on stream (TOS) with a carbon deposition rate of less than 3 wt%. However, among all investigated catalysts, only the 1 wt% Cu–La2O3 catalyst displayed a CO selectivity of 100% at all the studied temperatures, whereas the nickel-containing catalysts showed selectivity for methane along with carbon monoxide. Furthermore, the morphological properties of the support and catalysts, as well as the effect of the reaction conditions on the catalysts surface, were studied using a variety of techniques, including XRD, TEM, SEM-EDX and TPR. The results showed promising potential for the application of transition metal catalysts on lanthanum oxide support for RWGS that could be extended to other hydrogenation reactions.

High activity and stability of nano‐nickel catalyst based on LaNiO3 perovskite for methane bireforming

AbstractIn this study, a nano‐nickel Ni0 catalyst for bireforming of methane was in‐situ synthesized from the sol‐gel fabricating LaNiO3 perovskite. The various physico‐chemical methods such as powder X‐ray diffraction (XRD), energy‐dispersive X‐ray spectroscopy (EDS), H2 temperature‐programmed reduction (H2‐TPR), scanning electron microscopy (SEM), and CO2 temperature‐programmed desorption (CO2‐TPD) were used for characterization of the obtained samples. The coke accumulation was investigated via the temperature‐programmed oxidation (TPO) method. The results confirmed the formation of both LaNiO3 perovskite structure and a small amount of NiO with high crystallinity. H2‐TPR profiles and XRD patterns showed that the highly dispersed nanocrystals Ni0 on La2O3 catalysts were formed by in‐situ reduction of LaNiO3 at 800°C for as short as 1 hour or more. The crystal sizes of Ni0 and La2O3 crystals are in the range of 17‐18 nm and 18‐19 nm, respectively. The activity of the catalysts was studied in bireforming of methane by the micro‐flow method in a temperature range of 550‐800°C. LaNiO3‐based catalyst showed excellent performance for methane bireforming reaction. Of which, LaNiO3 sample calcined at 800°C for 1.5 hours and reduced at 800°C for 1.5 hours showed the highest activity when it reached the CH4 conversion of 87% and abnormally high CO2 conversion, reaching 97 % at 700°C and approximately 100 % at 800°C with an ideal H2/CO ratio of approximately 2. At 800°C, the activity of the most outstanding catalyst remained stable for 100 hrs thanks to the high sintering resistance of excellent dispersion of Ni in LaNiO3 lattice and high coke tolerance of the catalyst. The catalytic activity remained stable even when the amount of inert γ‐carbon reached 8.58 mgC/gcat.

Promising La2O3 Nanocatalysts for Low-Temperature Oxidative Coupling of Methane Reaction: A Short Review

This paper reviews the recent literature on La2O3 catalysts for the oxidative coupling of methane (OCM), which aims at ethylene production. The following subjects are discussed: (a) the main properties affecting the reaction mechanism such as oxygen vacancy, acid-base property, temperature, and morphology (b) prospects of nano-scale catalysts to improve the performance of the OCM process (c) the contribution of La2O3 nanocatalysts to the formation of ethane and ethylene (C2 hydrocarbon) during the oxidative coupling of methane.

Effects of Mg, Ca, Sr, and Ba Dopants on the Performance of La2O3 Catalysts for the Oxidative Coupling of Methane.

Oxidative coupling of methane (OCM) is a reaction to directly convert methane into high value-added hydrocarbons (C2+) such as ethylene and ethane using molecular oxygen and a catalyst. This work investigated lanthanum oxide catalysts for OCM, which were promoted with alkaline-earth metal oxides (Mg, Ca, Sr, and Ba) and prepared by the solution-mixing method. The synthesized catalysts were characterized using X-ray powder diffraction, CO2-programmed desorption, and X-ray photoelectron spectroscopy. The comparative performance of each promoter showed that promising lanthanum-loaded alkaline-earth metal oxide catalysts were La-Sr and La-Ba. In contrast, the combination of La with Ca or Mg did not lead to a clear improvement of C2+ yield. The most promising LaSr50 catalyst exhibited the highest C2+ yield of 17.2%, with a 56.0% C2+ selectivity and a 30.9% CH4 conversion. Catalyst characterization indicated that their activity was strongly associated with moderate basic sites and surface-adsorbed oxygen species of O2–. Moreover, the catalyst was stable over 25 h at a reactor temperature of 700 °C.

Performance of Zn-Al co-doped La2O3 catalysts in the oxidative coupling of methane

Zn-doped and Zn-Al co-doped La2O3 catalysts were prepared by citric acid sol-gel method and characterized by a series of in situ technologies, to investigate the structure-activity relationship of La2O3-based catalysts in the oxidative coupling of methane (OCM). The in situ XRD results reveal a thermal expansion of the La2O3 crystal along the c-axis at high temperature. The H2-TPR results show two types of oxygen species on the La2O3-based catalysts, viz., the strong-binding oxygen species and weak-binding oxygen species; in addition, the XPS results indicate that the strong-binding oxygen species is probably attributed to anion radical O−. The doping with Zn can significantly increase the number of oxygen vacancies in the Zn-doped La2O3 catalysts, which can promote the activation of oxygen and generate more strong-binding oxygen species; as a result, the Zn-doped La2O3 catalyst shows better performance in OCM in comparison with the unmodified La2O3 catalyst. Moreover, the co-doping with Al can promote the dispersion of Zn in La2O3 and further raise the number of strong-binding oxygen species in the Zn-Al co-doped La2O3 catalysts, which is beneficial to enhance the selectivity to C2+ hydrocarbons in the OCM reaction.

Kinetic Assessment of the Dry Reforming of Methane over a Ni–La2O3Catalyst

The dry reforming of methane is a promising technology for the abatement of CH4 and CO2. Ni–La2O3 catalysts are characterized by their long-term stability (100 h) when tested at full conversion. The kinetics of dry reforming over these types of catalysts has been studied using both power-law and Langmuir–Hinshelwood-based approaches. However, these studies typically deal with fitting the net CH4 rate, hence disregarding competing and parallel surface processes and the different possible configurations of the active surface. In this work, we synthesized a Ni–La2O3 catalyst and tested six Langmuir–Hinshelwood mechanisms considering both single and dual active sites for assessing the kinetics of dry reforming and the competing reverse water–gas shift reaction and investigated the performance of the derived kinetic models. In doing this, it was found that: (1) all of the net rates were better fitted by a single-site model that considered that the first C–H bond cleavage in methane occurred over a metal–oxygen pair site; (2) this model predicted the existence of a nearly saturated nickel surface with chemisorbed oxygen adatoms derived from the CO2 dissociation; (3) the CO2dissociation can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH4 activation. These findings contribute to a better understanding of the dry reforming reaction’s kinetics and provide a robust kinetic model for the design and scale-up of the process.

Synthesis of Dimethyl Carbonate by Transesterification of Propylene Carbonate with Methanol on CeO2-La2O3 Oxides Prepared by the Soft Template Method.

In this study, CeO2, La2O3, and CeO2-La2O3 mixed oxide catalysts with different Ce/La molar ratios were prepared by the soft template method and characterized by different techniques, including inductively coupled plasma atomic emission spectrometry, X-ray diffraction, N2 physisorption, thermogravimetric analysis, and Raman and Fourier transform infrared spectroscopies. NH3 and CO2 adsorption microcalorimetry was also used for assessing the acid and base surface properties, respectively. The behavior of the oxides as catalysts for the dimethyl carbonate synthesis by the transesterification of propylene carbonate with methanol, at 160 °C under autogenic pressure, was studied in a stainless-steel batch reactor. The activity of the catalysts was found to increase with an increase in the basic sites density. The formation of dimethyl carbonate was favored on medium-strength and weak basic sites, while it underwent decomposition on the strong ones. Several parasitic reactions occurred during the transformation of propylene carbonate, depending on the basic and acidic features of the catalysts. A reaction pathway has been proposed on the basis of the components identified in the reaction mixture.

Study of Ni<sup>(0)</sup>/La<sub>2</sub>O<sub>3</sub> perovskite coated on monolith substrates as a promising catalyst for CO<sub>2</sub> dry reforming with steam reforming of methane in syn-gas production

Coated monolith/foam catalysts are promising materials for chemistry applications due to structured reactor configuratiions providing low expansion coefficient, good thermal stability and low pressure loss. In this study, powedered Ni(0)/La2O3 catalysts in perovskite structures, were deposited on cordierite monolith substrates (2MgO-2Al2O3-5SiO2) by dip-coating method. The catalysts were characterized by N2 adsorption, XRD, TPR-H2 analysis. The activity of structured catalysts with various powder loadings (4, 8, 12, 20 and 30 wt %) were evaluated in combined Steam-CO2 reforming reaction (CH4/CO2/H2O = 2/1/2 vol%) at GHSV = 60.000 h-1. XRD and TPR results showed that the active phase LaNiO3 were mainly Ni and La2O3 distributed on the surface of cordierite channels after air calcination of 850oC, 3 hours and hydrogen reduction of 600oC, 2 hours . The conversion of methane and CO2 on monolith catalysts, with proper active sites loadings of 12 – 20 wt%, were close to 80 vol% at 800oC. At the same reaction amount of active sites, the feedstock conversion on LaNiO3/monolith (12 %wt LaNiO3/monolith) was significantly higher than on corresponding powdered type, respectively 1.6 times of CH4, 1.8 times of CO2 conversion.