Effect of ionic liquid in Ni/ZrO2 catalysts applied to syngas production by methane tri-reforming

This study investigates the influence of ionic liquid in morphology, acid-base properties, metal dispersion and performance of 5%Ni/ZrO₂ catalysts in the methane tri-reforming reaction. Zirconia was prepared by precipitation and the catalysts by wet impregnation. The ionic liquid modified the acid and basic character of the catalysts and positively influenced the methane tri-reforming reaction efficiency. The reaction was evaluated with synthetic biogas and with stoichiometric feed molar ratio (CH₄: CO₂: H₂O: O₂ = 1:0.5:0.5:0.1 and CH₄: CO₂: H₂O: O₂ = 1:0.33:0.33:0.16). The Ni/ZrO₂ prepared with ionic liquid exhibits promising catalytic activity and stability in methane tri-reforming at 800 °C in 4 h run, without coke formation. An increase in the reaction temperature results in an increase of hydrogen yield and the methane conversion, reaching ∼85% at 850 °C. The presented results demonstrate that the tri-reforming reaction could be used for production of syngas with H₂/CO ratio appropriate for methanol synthesis.     

Adsorption and catalytic decomposition of dimethyl sulfide on H-BEA zeolite

Catalytic direct decomposition of dimethyl sulfide (DMS) was performed using solid acid catalysts to develop an on-site hydrogen-free desulfurization system for utilization in small systems, such as fuel cells. DMS was decomposed to CH₃SH and H₂S at 500 °C on SiO₂–Al₂O₃ and various zeolite catalysts. Among the catalysts, H-BEA zeolite with Si/Al = 18.5 (H-BEA-18.5) showed the highest performance for DMS decomposition at 500 °C. While the catalytic activity at 500 °C maintained a DMS conversion of greater than 30% for up to 114 h, a large amount of carbon deposition caused gradual deterioration. At a low temperature of 400 °C, DMS decomposition to CH₃SH on H-BEA-18.5 continued for 100 h with a stable conversion of approximately 30%, although the adsorption of DMS on the catalyst surface was also confirmed. To achieve a high performance for the DMS decomposition, high temperatures were required to avoid the adsorption of sulfur species.     

Catalytic performance of CH4–CO2 reforming over metal free nitrogen-doped biomass carbon catalysts: Effect of different preparation methods

A series of nitrogen doped biomass carbon catalysts were prepared through two different nitrogen doped methods by using soybean meal as the raw material, melamine as nitrogen source and KOH as the activators. The catalysts were characterized by BET, SEM, CO₂-TPD, EA, FTIR, XPS and Raman. The catalytic performances of CH₄–CO₂ reforming over different samples were also studied. The results show that the preparation method of the catalyst significantly affects the structural characteristics, N content and N species type of the catalyst. The characterization results also show the proportion of pyrrolic-N in the catalyst prepared by in-situ nitrogen doped method (Y-NC) is higher than that in prepared by the post-treatment method (H-NC). Pyrrole-N is more conducive to the adsorption and activation of CO₂. So, the catalyst prepared by in-situ nitrogen doped method has good catalytic activity and stability. The conversion of CH₄ and CO₂ were respectively 40% and 65% at 900 °C after 50 h of CH₄–CO₂ reforming reaction.     

Biogas dry reforming for hydrogen production over Ni-M-Al catalysts (M = Mg,Li, Ca,La, Cu,Co, Zn)

Biogas can be highlighted as a renewable raw material for the production of hydrogen. In this study, Ni-M-Al catalysts were evaluated to obtain hydrogen from the biogas reforming. The catalysts were synthesized by coprecipitation with Ni and Al with a molar percentage of 55 and 33%, respectively, varying the third component M = Mg, Li, Ca, La, Cu, Co, Zn, with a molar percentage of 11%. The reactions were carried out in a fixed bed tubular reactor using a synthetic biogas (70% of CH₄ and 30% of CO₂). The results showed that the CH₄ conversion increased with the temperature up to 700 °C for La11, Cu11, and Zn11 catalysts. CO₂ conversion increased for all catalysts in the range of 500–700 °C. The H₂/CO molar ratios observed in the reactions were higher than 1 due to the contribution of the CH₄ decomposition reaction. The catalyst containing La presented better stability in the reactions due to the stronger acid sites and high resistance to sintering. Carbon filaments were produced by all catalysts at 600 and 700 °C. Sintering was the main cause of deactivation of the catalysts, except for La11.     

Hydrogen production enhancement using hot gas cleaning system combined with prepared Ni-based catalyst in biomass gasification

This paper investigates the hot gas temperature effect on enhancing hydrogen generation and minimizing tar yield using zeolite and prepared Ni-based catalysts in rice straw gasification. Results obtained from this work have shown that increasing hot gas temperature and applying catalysts can enhance energy yield efficiency. When zeolite catalyst and hot gas temperature were adjusted from 250 °C to 400 °C, H₂ and CO increased slightly from 7.31% to 14.57%–8.03% and 17.34%, respectively. The tar removal efficiency varies in the 70%–90% range. When the zeolite was replaced with prepared Ni-based catalysts and hot gas cleaning (HGC) operated at 250 °C, H₂ contents were significantly increased from 6.63% to 12.24% resulting in decreasing the hydrocarbon (tar), and methane content. This implied that NiO could promote the water-gas shift reaction and CH₄ reforming reaction. Under other conditions in which the hot gas temperature was 400 °C, deactivated effects on prepared Ni-based catalyst were observed for inhibiting syngas and tar reduction in the HGC system. The prepared Ni-based catalyst worked at 250 °C demonstrate higher stability, catalyst activity, and less coke decomposition in dry reforming. In summary, the optimum catalytic performance in syngas production and tar elimination was achieved when the catalytic temperature was 250 °C in the presence of prepared Ni-based catalysts, producing 5.92 MJ/kg of lower heating value (LHV) and 73.9% tar removal efficiency.     

H2 production from methane decomposition by fullerene at low temperature

Carbon materials have previously been reported to work as catalysts for hydrogen (H₂) production from hydrocarbons. Mechanisms of the catalytic behavior of graphite and carbon black (CB) have often been discussed in literature. Graphite and CB is constructed from mainly 6-membered rings with sp² bonds. To understand the catalytic behavior of carbon materials for H₂ production by methane (CH₄) decomposition, the catalytic behavior of fullerenes with 6-membered rings and also those comprising 5- and 7-membered rings with sp² bonds and their associated mechanisms should be investigated. In this study, the fullerene catalyst activity has been investigated using gas chromatography and the electronic states and nanoscale structures have been analyzed.H₂ production started at 400 °C and the H₂ production rate gradually increased with time, and the activation energy of the fullerene for H₂ production by CH₄ decomposition was found to be 166 kJ/mol. Moreover, in situ heating X-ray photon spectroscopy (XPS) measurements showed that the π-π1 transition signal becomes stronger with increasing temperature above the threshold of 300 °C. The transition of the π electrons to π1 orbitals upon heating is expected to decompose CH₄ absorbed on fullerene. Moreover, transmission electron microscopy (TEM) analysis revealed that the generated carbon atoms from the CH₄ decomposition were deposited onto the surfaces of the fullerenes, forming amorphous and layered concentric sphere carbon. Amorphous carbon is reported to not work as a catalyst for CH₄ decomposition at around 400 °C. From XPS analysis and TEM observations of these two structures, it is anticipated that the ring structures without 6-membered rings in carbon materials with sp² bonding contribute to this catalytic behavior for CH₄ decomposition at a low temperature of 400 °C.     

Biogas dry reforming over Ni-Al catalyst: Suppression of carbon deposition by catalyst preparation and activation

Biogas dry reforming is as an alternative renewable route for the hydrogen production. However, the major drawback of this process is the catalyst deactivation by carbon deposition and sintering. In this work, Ni-Al catalysts were studied aiming to suppress the carbon deposition in the dry reforming of biogas. The catalysts were prepared by coprecipitation and evaluated the washing step. The reactions were carried out with unreduced and reduced catalysts in a fixed bed tubular reactor using a synthetic biogas (60% CH₄ and 40% CO₂). The washing and activation steps influenced the characteristics of the catalysts and the catalytic properties in the biogas reforming. The unwashed sample resulted in an oxide containing potassium nickelate with high basicity and low surface area. Both washed samples, reduced and unreduced, showed a high amount of carbon formation, whereas no carbon formation was observed in the unwashed samples for the reactions in the temperature range of 500–750 °C. The unwashed and unreduced sample was the only one that maintained the activity during all the reaction time at 700 °C (40% CH₄ conversion and 75% CO₂ conversion), low coke amount and no evidence of sintering, which was confirmed by XRD, TPO, and SEM analyses. The carbon suppression was related to the nickelate phase and to the Ni carbide formation in the unwashed and unreduced catalyst. In summary, the carbon deposition in biogas dry reforming was completely controlled between 600 and 750 °C using the unwashed and unreduced Ni-Al catalyst.     

Effect of Ni content on CO2 methanation performance with tubular-structured Ni-YSZ catalysts and optimization of catalytic activity for temperature management in the reactor

This paper presents high-performance Ni-YSZ tubular catalysts for CO₂ methanation prepared by the extrusion molding. We fabricated tubular-shaped Ni-YSZ catalysts with various Ni contents (25–100 wt% NiO) and investigated the effect of Ni content on CO₂ methanation performance under various temperatures and gas flow rates. Catalysts with Ni contents >75 wt% showed CH₄ yields >91% above 270 °C with high CH₄ selectivities (>99%). High CH₄ yields were also observed under high GHSVs at 300 °C: 93% and 92% at 8700 and 17,500 h⁻¹, respectively. Investigation of methanation with the catalysts revealed that CO₂ methanation was accelerated by a localized hotspot at the reactor inlet arising from the interaction between reaction kinetics and heat generation. Using a numerical simulation, we considered the optimum arrangement of catalytic activity in the reactor to avoid hotspot generation and realize a stable high CO₂ methanation performance. We can simultaneously achieve high CH₄ production and prevent hotspot formation by properly arranging catalysts with different activities.     

Novel LaNi intercalated Egyptian bentonite clay for direct conversion of methane using CO2 as soft oxidant

Natural Egyptian bentonite clay intercalated with both La and Ni having different molar ratio (La: Ni = 2:1, 1:1 & 1:2) were prepared, saving 5mmole pillar/gm clay, using ultrasonic assistance method. The prepared catalysts were calcined at 450 and then reduced at 400 °C & 600 °C.Characterization of the prepared LaNi-PILC was achieved by X-ray diffraction (XRD), Furrier transform infrared spectroscopy (FTIR), N₂ adsorption desorption isotherm (BET) and H₂-temperature programmed reduction (H₂-TPR). The data confirm the success of intercalation process for both La & Ni in the lamellar structure of bentonite clay. The La: Ni molar ratio affected the specific surface area, Ni crystal size, dispersion and reducibility of the prepared catalyst. The reduction temperature had a great effect on the reactivity and product selectivity during CO₂/CH₄ reforming at different reaction temperatures (600–800 °C). Where, reduction at 400 °C gives rise to CH₄ oxidation reaction (MOR) with formaldehyde as a main product. While reduction at 600 °C enhances the activity and stability for CO₂ reforming of methane (CRM) and syngas production (H₂/CO ~ 1.19). The most active and stable LaNi_1:2-PILC₅ catalyst (CO₂ and CH₄ conversions reached 85% and 90% respectively) is superior with respect to the performance of PILC based catalysts reported in the literatures.     

Low-temperature catalytic conversion of greenhouse gases (CO2 and CH4) to syngas over ceria-magnesia mixed oxide supported nickel catalysts

Running dry reforming of methane (DRM) reaction at low-temperature is highly regarded to increase thermal efficiency. However, the process requires a robust catalyst that has a strong ability to activate both CH₄ and CO₂ as well as strong resistance against deactivation at the reaction conditions. Thus, this paper examines the prospect of DRM reaction at low temperature (400–600 °C) over CeO₂–MgO supported Nickel (Ni/CeO₂–MgO) catalysts. The catalysts were synthesized and characterized by XRD, N₂ adsorption/desorption, FE-SEM, H₂-TPR, and TPD-CO₂ methods. The results revealed that Ni/CeO₂–MgO catalysts possess suitable BET specific surface, pore volume, reducibility and basic sites, typical of heterogeneous catalysts required for DRM reaction. Remarkably, the activity of the catalysts at lower temperature reaction indicates the workability of the catalysts to activate both CH₄ and CO₂ at 400 °C. Increasing Ni loading and reaction temperature has gradually increased CH₄ conversion. 20 wt% Ni/CeO₂–MgO catalyst, CH₄ conversion reached 17% at 400 °C while at 900 °C it was 97.6% with considerable stability during the time on stream. Whereas, CO₂ conversions were 18.4% and 98.9% at 400 °C and 900 °C, respectively. Additionally, a higher CO₂ conversion was obtained over the catalysts with 15 wt% Ni content when the temperature was higher than 600 °C. This is because of the balance between a high number of Ni active sites and high basicity. The characterization of the used catalyst by TGA, FE-SEM and Raman Spectroscopy confirmed the presence of amorphous carbon at lower temperature reaction and carbon nanotubes at higher temperature.     

Microstructure and activity of Pd catalysts prepared on commercial carbon support for the liquid phase decomposition of formic acid

In this work, a series of Pd catalysts supported on commercially available activated carbon (Norit ®) were prepared by employing different metal precursors (Pd(NO₃)₂ and Na₂PdCl₄) by the impregnation-reduction method at different pH. Catalysts were tested for the liquid phase decomposition of formic acid to generate hydrogen. The best results, in terms of small particle size and high catalytic activity were achieved for the Pd/C sample prepared by using Pd(NO₃)₂ salt impregnated at pH = 2.5, and reduced with sodium borohydride. The particle size of the best Pd/C catalyst is (4.1 ± 1.4) nm with initial TOFs of 2929 and 683 h^?1 at 60 and 30 °C respectively and an apparent activation energy of 40 kJ mol^?1. Samples prepared by using Na₂PdCl₄ precursor, consisted of particles with higher size and thus lower activity than the ones prepared with Pd(NO₃)₂. Regardless the Pd precursor employed, the best results in terms of particle size and activity were achieved at the point of zero charge of the support when the Pd species and the carbon surface were both neutral. The impregnation pH not only determines the particle size, but also the nature of the reducing agent does. The catalytic activity was shown to be size-dependent and it was shown that a mixture of surface Pd⁰ and Pd^II oxidation states is beneficial for the activity. When comparing with literature catalysts with similar composition, we found that our best catalyst is competitive enough and that Norit ® support could be promising for future studies on this reaction.     

Reaction gas treatment promoting activity and stability of PdO for lean methane oxidation over phosphorus modified Pd/Al2O3 catalysts

Pretreatment under specific atmosphere is a general strategy to activate catalysts. How physicochemical properties of supports are modulated during activation process and their influence on active sites are still the ongoing topic. Herein, the effect of reaction gas treatment on performance of phosphorus modified Pd/Al₂O₃ catalysts in lean methane oxidation was studied. The pretreated Pd/P-doped Al₂O₃ catalyst exhibited a full conversion of CH₄ at ∼400 °C, excellent stability under both dry and wet conditions. Characterization results reveal that the uniform and stable P species in Al₂O₃ enhanced the metal-support interaction and availability of oxygen in support. Under reaction gas condition, PdO-support connection was further promoted to favor generation of oxygen vacancies on support with the help of CH₄, leading to weakened Pd–O bond, facile reformation and increased fraction of PdO. These facilitated formation of intermediates and surface dehydroxylation and mitigated the deactivation caused by thermodynamic decomposition of PdO.     

Conversion of hydrogen/carbon dioxide into formic acid and methanol over Cu/CuCr2O4 catalyst

Cu/CuCr₂O₄ catalysts were prepared by impregnation method at various calcination temperatures (300, 400, and 500 °C) and then reduced in H₂ stream. The aggregated particles and decreasing surface area/pore volumes of the deactivated catalysts during HCOOH and CH₃OH formations were also observed. Particularly, the EXAFS data showed that first shells of Cu atoms transforms from Cu–O to Cu–Cu after catalytic reactions, their bond distances and coordination numbers are quite different, respectively. It revealed that metallic Cu atoms are one of the important active species over catalyst surface at different reaction temperatures having many unoccupied binding sites for HCOOH and CH₃OH formations. Additionally, the optimal calcination temperature for Cu/CuCr₂O₄ catalysts was demonstrated at 400 °C that attributed to its strongest acidity and basicity. The catalytic reactions in the duration of HCOOH and CH₃OH preparation were proposed that were composed of HCOOH formation, CH₃OH formation, and CH₃OH decomposition happening at CuCr₂O₄, Cu, and CuO active sites, respectively. The highest CO₂ conversion (14.6%), HCOOH selectivity/yield (87.8/12.8%), and TON/TOF values (4.19/0.84) were obtained at 140 °C and 30 bar in 5 h, respectively. Optimal rate constant (2.57 × 10^?2 min^?1) and activation energy (16.24 kJ mol^?1) of HCOOH formation were evaluated by pseudo first-order model and Arrhenius equation, respectively.     

Preparation and characterization of 5%Ni/γ-Al2o3 catalysts by complexation with NH3 derivatives active in methane steam reforming

5 wt%NiO/γ-Al₂O₃ supported nickel catalysts were prepared by incipient wetness impregnation (IWI) method. Ammonia (NH₃) derivatives aliphatic amines based on: ethylamine (EA), diethylamine (DEA) and triethylamine (TEA) were used as ligands to complex Ni(NO₃)_2,6H₂O nickel nitrates salts. Various techniques including: Thermogravimetric (TGA)- Differential thermal analysis DTA, XRF, SEM, XRD, RTP and BET were used to characterize the physic-chemical properties of the mentioned catalysts. The catalytic performances were evaluated in steam methane reforming reaction at different temperatures ranging from 500 to 800 °C. According to the results, Ni²⁺ ions form strongly different complexes with NH₃, EA, DEA and TEA amines. Based on DRX and TPR measurements, the relative stronger encumbrance due to the bigger aliphatic amines volume of the corresponding intermediate complexes avoids the growing of NiAl₂O₄ spinel phase and leads to a sensitive decrease of the average NiO crystallites size from 15 to 9 nm appearing in high dispersion state and strongly interacting with the support with Strong Metal Support Interaction (SMSI). High catalytic performances are achieved with Ni-Diethylamine and Ni-Triethylamine catalysts at 700 °C in steam reforming reaction (CH₄ conversion = 99%, H₂ yield = 82%) under GHSV 24 × 10³ mL g_cat⁻¹.h⁻¹and H₂O/CH₄ = 3.     

Preparation of methanation catalysts for high temperature SOEC by β-cyclodextrin-assisted impregnation of nano-CeO2 with transition metal oxides

The aim of this work was to prepare and examine the catalytic activity of nanometric CeO₂ decorated with transition metal oxides – Ni, Co, Cu, Fe and Mn – towards a high-temperature methanation process under SOEC CO₂/H₂O simulated co-electrolysis conditions. Samples were prepared using the wet impregnation method via the conventional process and with the addition of native cyclodextrin. The influence of β-cyclodextrin (βCD) onto the size, dispersion and integration of the obtained metal nanoparticles was investigated. The differences between the catalysts’ reducibility revealed that samples prepared from βCD-containing solutions, in most cases, resulted in the creation of smaller Me_xO_y NPs on the surface of the substrate material compared to those prepared using traditional nitrate solutions. The samples containing Ni and Co were the only ones that observably catalysed methane synthesis. The high dispersion and integration of NPs prepared via the proposed synthesis route resulted in increased catalytic activity and enhanced stability, which was most pronounced for the Co-impregnated sample. The methane production peak for Ni-βCD/CeO₂ at 375 °C was characterised by nearly 99% CO conversion and 80% selectivity towards CH₄ production. Co-βCD/CeO₂ reached 84% CO conversion and almost 60% methane selectivity at 450 °C. The usage of CeO₂ coupled with βCD for the preparation of catalysts for high-temperature methane synthesis for use in SOECs gave promising results for further application.     

Effect of Co,Fe and Rh addition on coke deposition over Ni/Ce0.5Zr0.5O2 catalysts for steam reforming of ethanol

Ni-based monometallic and bimetallic catalysts (Ni, NiRh, NiCo and NiFe) supported on Ce_0.5Zr_0.5O₂ support were evaluated on the steam reforming of ethanol (SRE) performance. The supports of Ce_0.5Zr_0.5O₂ composite oxide was prepared by co-precipitation method with Na₂CO₃ precipitant and assigned as CeZr(N). The monometallic catalyst was prepared by incipient wetness impregnation method and assigned as Ni/CeZr(N). The bimetallic catalysts were prepared by co-impregnation method to disperse the metals on the CeZr(N) support and assigned as NiM/CeZr(N). All samples were characterized by using XRD, TPR, BET, EA and TEM techniques at various stages of the catalyst. The results indicated that the facile reduction and smaller particle size of Ni/CeZr(N) (T₉₉ = 300 °C) and NiRh/CeZr(N) (T₉₉ = 250 °C) catalysts were preferential than the NiFe/CeZr(N) (T₉₉ = 325 °C) and NiCo/CeZr(N) (T₉₉ = 375 °C) catalysts. Also, both the Ni/CeZr(N) and NiRh/CeZr(N) catalysts displayed better durability among these catalysts over 100 h and 400 h, respectively. Since the serious coke formation for the NiCo/CeZr(N) catalyst, the activity only maintained around 6 h, the durability on the NiFe/CeZr(N) catalyst approached 50 h.     

Water enhanced methanol decomposition for simultaneous heat recovery and ready-to-use synthesis gas production over CO2 capture enhanced Ni/zeolite 4A catalyst

Methanol decomposition is considered as a “one stone two birds” approach for simultaneously recovering waste heat and affording synthesis gas. However, this approach requires efficient catalysts with high CO selectivity and low selectivity to byproducts. Herein, a rational design of CO₂ capture enhanced Ni/zeolite 4 A catalyst for synthesis gas production by water enhanced methanol decomposition is reported. 5%-Ni/NaA-500 catalyst achieves the Y_H2 of 80.6%, Y_CO of 76.2%, H₂/CO molar ratio of 2.11, high stability, low selectivity to CO₂ and CH₄, and no coke at 325 °C. Ni atoms highly disperse on the surface and microporous of zeolite 4 A, and the strong interaction between Ni atoms and zeolite 4 A inhibits the reduction of Ni atoms. Consequently, Ni³⁺, Ni²⁺ and Ni⁰ coexist in 5%-Ni/NaA-500, and the redox couples of Ni³⁺↔Ni²⁺, Ni²⁺↔Ni⁰, and Ni³⁺↔Ni⁰ will enhance the redox processes during methanol decomposition. CO₂ capture capacity of x%-Ni/NaA-Y below 350 °C promotes the reverse water gas shift reaction by concentrating CO₂ molecules, which hence increases CO selectivity and declines the selectivity to byproducts. The reaction path follows CH₃OH→CH₃O→CH₂O→CHO→CO. This work will pave the way to industrial applications that combine ready-to-use synthesis gas production and heat recovery.     

Thermogravimetric analysis of coking during dry reforming of methane

Nickel-based catalysts used for dry reforming of methane (DRM) suffer from coking and sintering, which hinders the broad application of the process in the industry. Thermogravimetric analysis was employed to investigate coking on a commercial nickel catalyst with an anti-coking additive (CaO). It was found that the catalyst sintered at temperatures between 850 and 900 °C, which resulted in permanent catalyst deactivation. For the tested Ni/CaO–Al₂O₃ catalyst, the coking and carbon gasification rates are equal at the temperatures of 796–860 °C, depending on the heating rate (5–20 K/min). Significant differences in the temperatures related to the maxima on TG curves for various heating rates follow from DRM kinetics. This work reveals that the coking rate is lower at higher temperatures. After 50 min, the weight gains amount to about 20% and 40% at 800 °C and 600 °C, respectively. Lower sample weight gains were observed at higher temperatures for a methane decomposition reaction over the Ni/CaO catalyst, unlike for the second tested catalyst – activated carbon. For the nickel catalyst, the reaction order for methane decomposition is 0.6 in the temperature range 640–800 °C, while the sign of the activation energy changes at 700 °C. The elaborated kinetic equation predicts the initial CH₄ decomposition rate with 15% accuracy.     

Solid-state synthesis method for the preparation of cobalt doped Ni–Al2O3 mesoporous catalysts for CO2 methanation

In this study, a simple solid-state synthesis method was employed for the preparation of the Ni–Co–Al₂O₃ catalysts with various Co loadings, and the prepared catalysts were used in CO₂ methanation reaction. The results demonstrated that the incorporation of cobalt in nickel-based catalysts enhanced the activity of the catalyst. The results showed that the 15 wt%Ni-12.5 wt%Co–Al₂O₃ sample with a specific surface area of 129.96 m²/g possessed the highest catalytic performance in CO₂ methanation (76.2% CO₂ conversion and 96.39% CH₄ selectivity at 400 °C) and this catalyst presented high stability over 10 h time-on-stream. Also, CO methanation was investigated and the results showed a complete CO conversion at 300 °C.     

Coke-resistance over Rh–Ni bimetallic catalyst for low temperature dry reforming of methane

Methane and carbon dioxide can be converted into syngas using the prospective dry reforming of methane technology. Carbon deposition is a major cause of catalyst deactivation in this reaction, especially at low temperature. The superior stability of bimetallic catalysts has made their development more and more appealing. Herein, a series of bimetallic RhNi supported on MgAl₂O₄ catalysts were synthesized and used for low temperature biogas dry reforming. The results demonstrate that the bimetallic RhNi catalyst can convert CH₄ and CO₂ by up to 43% and 52% over at low reaction temperature (600 °C). Moreover, the reaction rate of CH₄ and CO₂ of RhNi–MgAl₂O₄ remains stable during the 20 h long time stability test, most importantly, there was no obviously carbon deposition observed over the spent catalyst. The enhanced coking resistance should be attributed to the addition of a little amount of noble metal Rh can efficiently suppress dissociation of CH_X1 species into carbon, and the high surface areas of MgAl₂O₄ support can also promote the adsorption and activation of carbon dioxide to generate more O1 species. Balancing the rate of methane dissociation and carbon dioxide activation to inhibit the development of carbon deposition is a good strategy, which provides a guidance for design other high performance dry reforming of methane catalysts.