Catalytic CO2 Reforming Research Articles

Thermo-photo catalytic anode process for carbonate-superstructured solid fuel cells.

Converting hydrocarbons and greenhouse gases (i.e., carbon dioxide, CO2) directly into electricity through fuel cells at intermediate temperatures (450 to 550 °C) remains a significant challenge, primarily due to the sluggish activation of C-H and C=O bonds. Here, we demonstrated a unique strategy to address this issue, in which light illumination was introduced into the thermal catalytic CO2 reforming of ethane in the anode as a unique thermo-photo anode process for carbonate-superstructured solid fuel cells. The light-enhanced fuel activation led to excellent cell performance with a record-high peak power density of 168 mW cm-2 at an intermediate temperature of 550 °C. Furthermore, no degradation was observed during ~50 h operation. Such a successful integration of photo energy into the fuel cell system provides a new direction for the development of efficient fuel cells.

Ternary Fe- or Mo-Au-Ni/GDC as Candidate Fuel Electrodes for the Internal Dry Reforming of CH4: Physicochemical and Kinetic Investigation

The present study deals with the physicochemical and catalytic/kinetic investigation of Fe, Au, Fe-Au, and Mo-Au modified Ni/GDC electrocatalysts towards their performance for the DRM, RWGS, and CH4 decomposition reactions. For this purpose, Au-NiO/GDC (where Au = 1 or 3 wt.%), Fe-NiO/GDC (where Fe = 0.5 or 2 wt.%), 0.5Fe-3Au-NiO/GDC, and 0.4Mo-3Au-NiO/GDC were synthesized via deposition (co-) precipitation. There is discussion on the structural properties of the electrocatalysts on the oxidized and reduced state, as well as their use as electrolyte-supported (half) cells. A key remark after H2-reduction is the formation of binary or ternary solid solutions. Ni/GDC was the most active for the catalytic CO2 reforming of CH4 and the CH4 decomposition reactions and as a result the most prone to carbon deposition. On the other hand, the modified 3Au-Ni/GDC, 0.5Fe-3Au-Ni/GDC, and 0.4Mo-3Au-Ni/GDC exhibited the following properties: (i) the highest Ea,app for the non-desired RWGS reaction, (ii) high tolerance to carbon formation due to lower activity for the CH4 decomposition, and (iii) were also less active for H2 and CO production. Finally, 0.4Mo-3Au-Ni/GDC seems to perform the DRM reaction through a different mechanism when compared to Ni/GDC. Overall, the above three samples are proposed as potential fuel electrodes for further electrocatalytic measurements for the SOFC internal DRM process.

Dual site contiguity study for CO2 catalytic activation and CO2 reforming of CH4 over Ni and NiM2 catalysts with MgO-spinel support

In catalytic CO2 reforming of CH4 reaction, CO2 is activated by the basic sites and CH4 by the metallic sites on the catalysts. The contiguity of the dual sites, i.e., how the two kinds of sites neighbor to each other and how the adsorption species form and interact with each other, determines the activity, selectivity, and stability of the reaction. Following our earlier studies, catalysts with different ratios of Mg/Al and the different second metal (Co, Cu, Fe, or Mn) to the primary metal Ni were prepared using the coprecipitation method. Extensive characterizations showed the catalysts had basic sites of various basicity strength and metallic particles of different sizes. The pulse adsorption experiments showed that the ability of CO2 activation on the basic sites was varying with not only the site basicity itself (pushing effect) but also the pulling effect from the neighbor metallic sites. On the other hand, the ability of CH4 dissociation on the metallic site was determined by the metallic sites themselves and the basic sites that burned the carbon and made the metallic sites recovered. The correlation between the turnover frequency of CO2 and CH4 based on the number of metallic sites indicated that the size of metallic particles was the main factor that determined the catalyst performance once the two kinds of sites were made neighbor to each other with proper Mg/Al ratio. Studies with the catalysts reduced at a higher temperature confirmed these observations. Further analysis of the catalyst deactivation revealed that the decrease in H2/CO ratio (selectivity) in the CO2 reforming of CH4 may be caused by the C–Hx species from the incomplete dissociation of CH4 on the weakened metallic sites and their interaction with the activated CO2 on the basic sites.

Recent development in catalyst and reactor design for CO2 reforming of alcohols to syngas: A review

Global energy demand has had a significant impact on the Green House Gases (GHGs) emission, which have harmful effects on the environment and human health. Catalytic CO2 reforming of biomass-derived alcohols converted into syngas is regarded as a viable option for reducing GHGs. Even though this is sustainable and ecologically beneficial for utilizing value-added biomass, little research has been done on the topic. Due to the high reaction temperature, metal sintering and coke formation have been widely reported as the major challenges in the CO2 reforming process. These conditions could reduce the catalyst efficiency and cause the reactor system to shut down. To address these issues, this article provides a review of the current catalyst and reactor design development for CO2 reforming of methanol, ethanol, glycerol, and butanol to generate synthetic gas. Thermodynamic analysis, catalyst performance, optimizing reaction parameters, and future potential catalyst design are also covered.

Quasi-Monolayer Rh Nanoclusters Stabilized on Spinel MgAl2O4 Nanosheets for Catalytic CO2 Reforming of Methane

Quasi-Monolayer Rh Nanoclusters Stabilized on Spinel MgAl₂O₄ Nanosheets for Catalytic CO₂ Reforming of Methane

Understanding Catalytic CO2 Reforming of CH4: Effect of Basic Support (Dolomite, Talc and Alkaline Sludge) on NiO-Based Catalyst

Supports material contain Mg and/or Ca influence the reactivity of NiO-based catalysts. Thus, the development of NiO/Dolomite, NiO/Talc and NiO/AS successfully synthesized by the simple wet-impregnation method. The characterization of prepared catalysts by XRD and N2 adsorption-desorption analysis reveals that the contained species in each catalyst greatly affected the textural properties of catalysts such as BET surface area, porosity, crystallite, and particle size. Thus, TPR-H2 displayed reducability of active metal influence by physical properties. Meanwhile, basic sides of prepared catalysts contributed by O2- ion attributed by Mg and/or Ca in the support material. Thus, the apparent Ea of NiO/Dolomite, NiO/Talc and NiO/AS are +115.47, +114.90 and +135.21 kJ mol-1 respectively. In addition, the formation of carbon is strongly affected by crystallite and particle sizes together with the dispersion of NiO species. In conclusion, the catalytic performance of NiO-based catalyst much influence by the physicochemical properties of catalyst which contributed by Mg and/or Ca contain in the support’s material.

Catalytic CO2 reforming of CH4 over MgAl2O4 supported Ni-Co catalysts for the syngas production

Ni, Co and Ni–Co bimetallic catalysts of different ratios were synthesized by the Incipient Wetness Impregnation Method (IWI) over Magnesium Aluminate support, keeping the total metal loading 15 wt.%, characterized and tested for the reforming of methane with carbon dioxide at 873 K and 1 atm pressure. Magnesium Aluminate supported catalysts were also compared with Al2O3 supported Ni catalysts with similar metal loading. The results obtained revealed that MgAl2O4 exhibited excellent thermal stability as compared to Al2O3 as support at higher temperatures. Ni–Co catalyst, with an explicit Ni:Co (3:1) ratio for the 75Ni25Co/MgAl2O4 provided the highest CH4 conversion and was about 1.82 times that of the 100Ni/MgAl2O4; CO2 conversion also followed similar trends. Co-existence of Ni and Co with synergic effect in an explicit Ni:Co (3:1) ratio reduced the reduction temperature and increased the amount of metal in 75Ni25Co/MgAl2O4. CH4 and CO2 conversions, TOFDRM, H2: CO ratios and catalyst deactivations were related to the concentrations of the Ni–Co and particularly an explicit ratio of 3:1 for the Ni:Co in 75Ni25Co/MgAl2O4 catalyst provided the best initial & final conversions, TOFDRM and H2:CO ratio. Detail carbon analysis suggested that the type of coke deposited on 75Ni25Co/MgAl2O4 after the DRM reaction is of the same nature and are originating from the CH4 cracking reaction and are of reactive type.

Enhancement of plasma-assisted catalytic CO2 reforming of CH4 to syngas by avoiding outside air discharges from ground electrode

This work presents the effects of the insulation of ground electrode and operating parameters on CO2 reforming of CH4 to syngas in a coaxial-cylindrical dielectric barrier discharge (DBD) plasma reactor coupled with Ni/α-Al2O3 catalyst. For the conventional plasma reactor, abnormal outside discharge inevitably ignites and develops from the ground electrode, giving rise to the formation of harmful substances (e.g., NOx) and the waste of energy. The power dissipation for the conventional reactor therefore includes both that used for the dry reforming reactions and the loss of energy due to the air discharge. The new finding of this work is that by covering the ground electrode with an insulating oil jacket, not only the NOx formation is prevented but also the conversion rates, product selectivity and energy efficiency are largely enhanced by roughly 30, 10 and 100% at a specific energy input of about 47 kJ, respectively. The results are associated with the extinguishment of the discharge occurring outside the reactor, which is usually neglected when designing DBD reactors.

Syngas Production from Catalytic CO2 Reforming of CH4 over CaFe2O4 Supported Ni and Co Catalysts: Full Factorial Design Screening

In this study, the potential of dry reforming reaction over CaFe2O4 supported Ni and Co catalysts were investigated. The Co/CaFe2O4 and Ni/CaFe2O4 catalysts were synthesized using wet impregnation method by varying the metal loading from 5-15 %. The synthesized catalysts were tested in methane dry reforming reaction at atmospheric pressure and reaction temperature ranged 700-800 oC. The catalytic performance of the catalysts based on the initial screening is ranked as 5%Co/CaFe2O4 < 10%Co/CaFe2O4 < 5%Ni/CaFe2O4 < 10%Ni/CaFe2O4 according to their performance. The Ni/CaFe2O4 catalyst was selected for further investigation using full factorial design of experiment. The interaction effects of three factors namely metal loading (5-15 %), feed ratio (0.4-1.0), and reaction temperature (700-800 oC) were evaluated on the catalytic activity in terms of CH4 and CO2 conversion as well as H2 and CO yield. The interaction between the factors showed significant effects on the catalyst performance at metal loading, feed ratio and reaction temperature of 15 %, 1.0, and 800 oC. respectively. The 15 wt% Ni/CaFe2O4 was subsequently characterized by Thermogravimetric (TGA), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS), N2-physisorption, Temperature Programmed Desorption (TPD)-NH3, TPD-CO2, and Fourier Transform Infra Red (FTIR) to ascertain its physiochemical properties. This study demonstrated that the CaFe2O4 supported Ni catalyst has a good potential to be used for syngas production via methane dry reforming.

Analysis of CO2 utilization into synthesis gas based on solar thermochemical CH4-reforming

In this study, the solar thermochemical reactor performance for CO2 utilization into synthesis gas (H2 + CO) based on CH4 reforming process was investigated in the context of carbon capture and utilization (CCU) technologies. The P1 radiation heat transfer model is adopted to establish the heat and mass transfer model coupled with thermochemical reaction kinetics. The reactor thermal behavior with direct heat transfer between gaseous reactant and products evolution and the effects of different structural parameters were evaluated. It was found that the reactor has the potential to utilize by ∼60% of CO2 captured with 40% of CH4 co-fed into syngas (72.9% of H2 and 27.1% of CO) at 741.31 kW/m2 of incident radiation heat flux. However, the solar irradiance heat flux and temperature distribution were found to significantly affect the reactant species conversion efficiency and syngas production. The chemical reaction is mainly driven by the thermal energy and higher species conversion into syngas was observed when the temperature distribution at the inner cavity of the reactor was more uniform. Designed a solar thermochemical reactor able to volumetric store concentrated irradiance could highly improve CCU technologies for producing energy-rich chemicals. Besides, the mixture gas inlet velocity, operating pressure and CO2/CH4 feeding ratio were crucial to determining the efficiency of CO2 utilization to solar fuels. Catalytic CO2-reforming of CH4 to chemical energy is a promising strategy for an efficient utilization of CO2 as a renewable carbon source.

Effects of preparation technique and lanthana doping on Ni/La2O3-ZrO2 catalysts for hydrogen production by CO2 reforming of coke oven gas

A series of Ni/La2O3-ZrO2 catalysts were prepared by homogeneous precipitation, template or sol-gel technique and used for hydrogen production from coke oven gas by CO2 reforming. The catalysts were characterized by BET, XRD, TPR, TPH, TEM and TG–DSC. A study is also carried out to observe the effect of lanthana loading on the reforming reaction. TPH results indicated the presence of more than two types of carbonaceous species on the used catalysts, which are categorized based on temperature difference. The low-temperature carbon species could be considered as the active sites for the reforming reaction. Experiments and TG-DSC results revealed that all of the catalysts present good catalytic performance and excellent anti-carbon property. The test results showed that the catalysts prepared by sol-gel method exhibited the highest catalytic activity due to their suitable pore size distribution. The Ni/La2O3-ZrO2 catalyst with 8wt% lanthanum oxide loading provides the best catalytic activity, which will be promising application on catalytic CO2 reforming of COG in the future.

Comparative modeling study of catalytic membrane reactor configurations for syngas production by CO2 reforming of methane

Modeling based analysis of catalytic CO2 reforming of methane in fixed bed (FBR) and membrane reactors (MR) has been carried out for the production of syngas. Four Ni-based catalysts have been studied separately in FBR to identify suitable catalyst on the basis of carbon formation tendency at the reactor operating conditions of temperature (973–1073K), and CO2/CH4 molar feed ratio (CMR=1, 2, and 3). The simulation has resulted in Ni/La2O3 as most suitable catalyst at 1073K and CMR=1. Addition of 10% H2 to the feed further reduces the carbon formation tendencies. Two fixed bed reactor configurations [FBR1 (Ni/La2O3), and FBR2 (Rh/γ-Al2O3)], and two membrane reactor configurations [MR1 (FBR1+dense membrane), and MR2 (FBR2+porous membrane)] have been evaluated by simulation to identify the favorable configuration at operating conditions for syngas production. The yields of H2 and CO are found maximum as 94.5% and 98% respectively at CMR=1 in reactor MR1. Also the H2/CO ratio has been found close to unity at 1073K and CMR=1 in reactor MR1 with no significant effect of sweep gas. Hence, the membrane reactor MR1 is the best reformer configuration to produce syngas by dry reforming of methane.

Preparation of a high performance cobalt catalyst for CO2 reforming of methane

The novel silica supported cobalt catalysts powders promoted by ruthenium and zirconium (CRZS) were prepared via a coprecipitation method for the catalytic CO2 reforming. The optimum metals loadings and pH of solution were systematically investigated in order to obtain a high performance and coke resistant catalyst. The most active, stable, and coke resistance catalyst was found in the catalyst prepared at pH 1 with the combination of 14.68wt.%, 0.14wt.%, 5.00wt.%, and 80.00wt.%, respectively for cobalt, ruthenium, zirconium and silica. BET, XRD, TPR, and H2 chemisorption analyzer found that the phenomena of Co3O4 cluster enlargement as the increase of cobalt loadings, the higher reduction degree and pore diameter as the increase of ruthenium loadings, and the inhibition of strong Co–SiO2 interaction in the proper zirconium loading were confirmed as the variation of metals loadings. The variable of pH solution during catalysts preparation gave significant effects on the catalysts stability and coke formation. The deactivation of catalyst prepared in low pH was related with the presence of surface ZrO of catalyst without any relation with coke formation. The obtained parameters of methane consumption rate based on Eley–Rideal mechanism showed that the surface chemical reaction between methane and surface oxygen became the rate-determining step of the reaction.

Catalytic CO2 reforming of CH4 over Cr-promoted Ni/char for H2 production

The objective of the study is to investigate the catalytic performance of Cr-promoted Ni/char in CO2 reforming of CH4 at 850 °C. The char obtained from the pyrolysis of a long-flame coal at 1000 °C was used as the support. The catalysts were prepared by incipient wetness impregnation methods with different metal precursor doping sequence. The characterization of the composite catalysts was evaluated by XRD, XPS, SEM-EDS, TEM, H2-TPR, CO2-TPD, CH4-TPSR, and CO2-TPO. The results indicate that the catalyst prepared by co-impregnation of Ni and Cr possess higher activity than those by sequential impregnation. The optimal loading of Cr on 5 wt% Ni/char is 7.8 wt‰. Moreover, the molar feed ratio of CH4/CO2 has a considerable effect on both the stability and the activity of Cr–Ni/char. The main effect of Cr is the great enhance of the adsorption to CO2. It is interesting that the conversions of CH4 and CO2 over Cr-promoted Ni/char and Ni/char decrease initially, following by a steady rise as the reaction proceeds with time-on-stream (TOS). In addition, cyclic tests were conducted and no distinct deterioration in the catalytic performance of the catalysts was observed. On the basis of the obtained results, nickel carbide was speculated to be the active species which was formed during the CO2 reforming of CH4 reaction.

Syngas production by CO2 reforming of coke oven gas over Ni/La2O3–ZrO2 catalysts

Syngas production by CO2 reforming of coke oven gas (COG) was studied in a fixed-bed reactor over Ni/La2O3–ZrO2 catalysts. The catalysts were prepared by sol–gel technique and tested by XRF, BET, XRD, H2-TPR, TEM and TG–DSC. The influence of nickel loadings and calcination temperature of the catalysts on reforming reaction was measured. The characterization results revealed that all of the catalysts present excellent resistance to coking. The catalyst with appropriate nickel content and calcination temperature has better dispersion of active metal and higher conversion. It is found that the Ni/La2O3–ZrO2 catalyst with 10 wt% nickel loading provides the best catalytic activity with the conversions of CH4 and CO2 both more than 95% at 800 °C under the atmospheric pressure. The Ni/La2O3–ZrO2 catalysts show excellent catalytic performance and anti-carbon property, which will be of great prospects for catalytic CO2 reforming of COG in the future.

CO2 reforming of toluene as model compound of biomass tar on Ni/Palygorskite

Catalytic CO2 reforming of biomass tar on palygorskite-supported nickel catalysts using toluene as a model compound of biomass tar was investigated. The experiments were performed in a bench scale installation a fixed bed reactor. All experiments were carried out at 650, 750, 800°C and atmospheric pressure. The effect of Ni loading, reaction temperature and concentration of CO2 on H2 yield and carbon deposit was investigated. Ni/Palygorskite (Ni/PG) catalysts with Ni/PG ratios of 0%, 2%, 5% and 8% were tested, the last two show the best performance. H2 yield and carbon deposit diminished with the increase of reaction temperature, Ni loading, and CO2 concentration.

Carbon dioxide reforming of methane to synthesis gas over a TiO2–Ni inverse catalyst

TiO2–Ni inverse catalysts were prepared using an atomic layer deposition (ALD) process, and catalytic CO2 reforming of methane (CRM) reactions over the catalysts (either bare Ni or TiO2 coated-Ni particles) were performed using a continuous flow reactor at 800°C. The TiO2–Ni inverse catalyst had a higher catalytic reactivity at the initial stage of the CRM reaction at 800°C compared to that of bare Ni catalysts. Moreover, the high activity of the TiO2–Ni catalyst was maintained over 65h of the CRM reaction at 800°C, whereas deactivation of the bare Ni surface began within 1h under the same conditions. Surface analysis using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy showed that deposition of graphitic carbon was effectively suppressed in the presence of TiO2 nanoparticles on the Ni surface, thereby improving the catalytic activity and stability of the TiO2–Ni catalytic system. We suggest that utilizing the decorative effect of oxide nanoparticles on the surface of metal catalyst has great potential for the development of metal-based catalysts with high stability and reactivity.

Carbon dioxide reforming of methane in a SrCe0.7Zr0.2Eu0.1O3−δ proton conducting membrane reactor

Utilizing CO2 for fuel production holds the promise for reduced carbon energy cycles. In this paper we demonstrate a membrane reactor, integrating catalytic CO2 reforming of methane with in-situ H2 separation, that results in increased CO2 and CH4 conversion and H2 production compared to a Ni catalyst alone. The tubular proton-conducting SrCe0.7Zr0.2Eu0.1O3−δ membrane reactor demonstrates that the addition of the membrane improves CO2 conversion, due to in-situ H2 removal, by 10% and 30% at 900 °C for CH4/CO2 = 1/1 and CH4/CO2/H2O = 2/1/1 feed ratios, respectively. It also improves total H2 production at 900 °C by 15% and 18% for CH4/CO2 = 1/1 and CH4/CO2/H2O = 2/1/1, respectively. Further, the H2/CO in the reactor side effluent can be adjusted for subsequent desired Fischer-Tropsch products by combining CO2 reforming and steam reforming of methane.

Investigation of mechanistic aspects of the catalytic CO2 reforming of methane in a dielectric-barrier discharge using optical emission spectroscopy and kinetic modeling

The CO2 reforming of methane by the combination of catalysts with a dielectric-barrier discharge is investigated as an alternative approach to the conventional pure catalytic process. It is shown that the use of nickel or calcium-promoted nickel catalysts in combination with the discharge leads to an increase in the CO yield of 20 to 40%. The identified products are CO, H2, water, ethane and ethylene, propane, n-butane and methanol. In addition to the experimental investigation, extensive kinetic modeling was performed. Besides a good description of the plasma reactions by a set of 308 reactions and 57 species, the programs used offered the possibility of identifying the main reaction routes towards the different products. To get an insight into the mechanistic aspects of the catalyst–plasma interaction, the gas phase was investigated with optical emission spectroscopy (OES) during the experiment. Special emphasis was placed on the interpretation of differences in the emission spectra from experiments with and without a catalyst in the discharge. A significant difference was observed for the CH A 2Δ–X 2Π band. Therein, the intensity of the signal was proportional to the activity of the catalysts used, in the sense that the CH signal was higher for a more active catalyst. Based on these results, a tentative reaction scheme is proposed that explains the enhancing effects of the catalysts in the CO2 reforming reaction. It starts with the adsorption of methane and methane fragments from the gas phase, followed by their gasification by oxygen and oxygen-containing species supplied by the discharge plasma.