Amount Of Coke Research Articles

Kinetic and Thermodynamic Analysis of Guaiacol Hydrodeoxygenation

Kinetics of guaiacol hydrodeoxygenation (HDO) was studied using supported MoxC–SBA-15 and as a comparison 5 wt% Pt/C under 30 bar hydrogen at 200 °C and 300 °C. Catalyst characterization was done by a range of physical methods including also determination of the amount of coke and the nature of adsorbed species. Pt/C gave 2-methoxycyclohexanol as the main product, whereas Mo2C–SBA-15 promoted direct deoxygenation exhibiting also strong adsorption of guaiacol on the catalyst surface and formation of oligomers. Thermodynamics of guaiacol HDO was elucidated and the reaction network was proposed based on which kinetic modelling was done.Graphic

A study of coke formed by heavy oil volatilization/decomposition on Y-zeolite

Coke related catalyst deactivation is still attractive for many researchers as the complexity of carbon precursor. Y-zeolite is one of the most popular catalyst used in petrochemical industry, which is also progressively degrading by coking. In this piece of work, the effects of volatilization/decomposition temperature and sample-to-catalyst ratio on the coke formed from heavy oil volatilization/decomposition in the presence of Y-zeolite catalyst have been investigated. Temperature plays a significant role in determining the nature of the carbon formed, with higher temperatures favouring a higher graphitic-to-amorphous carbon ratio. Higher sample-to-catalyst ratios lead to higher amounts of coke, but does not affect the graphitic-to-amorphous carbon ratio as the same volatilization/decomposition temperature.

Fabrication of nano-catalyst ceria flower and catalyst characterization**Report presented at 9th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2018), 7-11 November 2018, Ninh Binh City, Vietnam.

Flower-like ceria microspheres were prepared by hydrothermal synthesis method and used as a catalyst support to load transition metal Ni nano particles for dry reforming of methane. The nikel nitrate salt was loaded by impregnation method onto the CeO2 flower-like and calcined at 550 °C to obtain the nanoparticles of nikel oxide (NiO) onto the CeO2 flowers. Before the reforming reaction, NiO could be reduced by hydrogen at 800 °C to obtain the flower-catalyst. Paper structured catalyst (PSC) was fabricated from flower-catalyst, alumina-silica fiber and was used as a catalyst for methane reforming. The methane conversion of the PSC-CeO2–NiO sample showed higher efficiency and stability than the sample of PSC-NiO without the CeO2 flowers with the same amount of Ni after 50 h. In addition, the amount of coke formed on the catalyst was significantly reduced in the presence of CeO2 whereas the methane conversion efficiency was maintained.

Ni/Y2O3–ZrO2 catalyst for hydrogen production through the glycerol steam reforming reaction

In the study presented herein, the catalytic activity and stability of a Ni catalyst supported on Y2O3–ZrO2 was examined for the first time in the glycerol steam reforming reaction and compared with a Ni/ZrO2. The addition of Y2O3 stabilized the ZrO2 tetragonal phase, increased the O2 storage capacity of the support and the medium strength acid sites of the catalyst, and although the Ni/Zr catalyst had a higher concentration of basic sites, the Ni/YZr presented more stable monodentate carbonates. Moreover, the Ni/YZr had substantially higher Ni surface concentration and smaller Ni particles. These properties influence the gaseous products’ distribution by increasing the H2 yield and selectivity and preventing the transformation of CO2 to CO, by inhibiting the reverse water gas shift (RWGS) reaction from taking place. For both catalysts the main liquid products identified were allyl alcohol, acetaldehyde, acetone, acrolein, acetic acid and acetol; these were subsequently quantified. The time-on-stream experiments showed that the Ni/YZr was more stable during reaction and had a higher H2 yield after 20 h (2.17 in comparison to 1.50 mol H2/mol C3H8O3, for the Ni/Zr). Extensive investigation of the carbon deposits showed that although lower amounts of coke were deposited on the Ni/Zr catalyst, these structures were more graphitic in nature and had fewer defects, which means they were harder to oxidize. Moreover, transmission electron microscopy (TEM) analysis showed that sintering of Ni nanoparticles during the reaction was significant for the Ni/Zr catalyst, as the mean particle diameter increased from an initial value of 48.2 to 67.9 nm, while it was almost absent on the Ni/YZr catalyst (the mean particle diameter increased from 42.1 to 47.4 nm).

Methods for reducing flue gas emissions from fluid catalytic cracking unit regenerators

The dimethyl ether (DME) carbonylation reaction over mordenite is greatly affected by the mass transfer process. In this research, hierarchical mordenite catalysts were synthesized and characterized to investigate the influence of mesopores on the structure, mass transfer and catalytic performance. The results show that the medium-strong acid sites decrease while strong acid sites increase over the hierarchical samples. The introduced mesopores can significantly improve the mass transfer efficiency and the carbonylation performances are markedly improved on the hierarchical samples. In addition, the polymerization degree of coke deposition on the deactivated samples decreases although the coke amount increases. Excessive usage of mesopore templates can damage the structure of the MOR catalysts, thus leading to the loss of acid sites and the decrease in catalytic performance.

Efficient conversion of extra-heavy oil into distillates using tetralin/activated carbon in a continuous reactor at elevated temperatures

Tetralin/activated carbon was applied to the upgrading of vacuum residue (VR) in a continuous reactor. The experimental performance was evaluated at a fixed pressure of 5.0 MPa in the range of 385–470 °C, and 1.5 and 3.0 h−1 of liquid hourly space velocity. A lower space velocity, which is closely related to the reaction time, led to significantly higher conversion at the cost of forming a carbonaceous product (coke). Increasing the reaction temperature greatly affected the conversion of residue into lighter products. The application of a tetralin/activated carbon to the VR upgrading resulted in high residue conversion (74.5 wt%) and asphaltene reduction (80.8%) at 470 °C, with a small amount of coke (1.2 wt%). Additionally, the tetralin/activated carbon system led to reduction of the sulfur, nitrogen and metal concentrations in the liquid products. The hydrogen-donor solvent/carbon system acts as an attractive hydrogen-donor medium in the extra-heavy oil upgrading.

Regeneration of deactivated H-ZSM-5 for aromatization by dielectric barrier discharge plasma

A dielectric barrier discharge (DBD) plasma regeneration reaction was conducted at atmospheric pressure and temperature. This method was found to be very effective in removing carbon deposits after a non-oxidative aromatization from acetylene. When a fresh H-ZSM-5 catalyst was used for the aromatization, coke was by-produced and it could be ascribed to the primary reason for deactivation. By applying the DBD plasma to the deactivated catalyst bed at ambient temperature and pressure, the removal of carbon deposition with microdischarge and aeration was very effective; therefore, it is believed that additional thermal activation might not be necessary. More amount of coke was removed by supplying higher power to the catalyst bed. According to the results of XRD, physisorption, 27Al MAS NMR, and NH3-TPD analyses, it was confirmed that the structure and the acid site distribution of H-ZSM-5 were successfully retained even after the plasma treatment. Aromatization over the plasma-regenerated catalyst led to mild deactivation at the early stage and afforded comparable BTX selectivity to fresh H-ZSM-5 catalyst. Compared with the results obtained using the thermally regenerated catalyst, the structural stability was found to be higher and the BTX selectivity was kept higher during most of the reaction time for the plasma-regenerated catalyst.

Product distribution of the thermal and catalytic fast pyrolysis of karanja (Pongamia pinnata) fruit hulls over a reusable silica-alumina catalyst

The conversion of karanja fruit hulls by fast pyrolysis was investigated using a drop-type two-stage reactor. The ex-situ catalytic fast pyrolysis of karanja fruit hulls over a silica-alumina catalyst was performed at 500 °C and at a catalyst loading of 0.1 g. The obtained bio-oil yield was 41.09 wt%. The bio-oil contained 84.38% carbonyls. The silica-alumina catalyst reduced the liquid yield to 39.73 wt%. The production of aromatics and hydrocarbons in bio-oil was enhanced, whereas the yield of carbonyls was reduced from 84.38% (non-catalytic) to 7.83% (catalytic). After catalyst regeneration, the aromatic yield was increased from 30.08% (1st run) to 52.18% (5th run), and the deoxygenation degree was increased from 35.15% (1st run) to 57.13% (5th run), thereby demonstrating that the silica-alumina catalyst had satisfactory reusability. The amount of catalytic coke was reduced after catalyst regeneration, because less hard coke was formed.

Partial oxidation of methane over lanthana-supported catalysts derived from perovskites

Abstract Partial oxidation of methane is the most attractive route to produce syngas, since it produces H2/CO (molar) = 2, suitable for Fischer-Tropsch and methanol synthesis, besides the low energy consumption and low tendency to coke formation. A promising catalyst for the reaction is based on cobalt which has low cost and low tendency to coke formation. However, it tends to oxidize and then deactivates during reaction. With the goal of preparing alternative and more efficient catalysts, lanthana-supported catalysts derived from perovskites containing lanthanum, iron and cobalt were studied in this work, using titania as support. Perovskites were prepared by the amorphous citrate method and then reduced to produce the catalysts. The samples were characterized by X-ray diffraction, Mossbauer spectroscopy, temperature programmed reduction, acidity measurements using ammonia temperature programmed desorption, transmission electron microscopy, specific surface area measurements and isotopic exchange reaction. The catalysts were evaluated at 1 atm and 800 °C in methane partial oxidation and analyzed by temperature programmed oxidation after reaction. Iron-based perovskite (LaFeO3) was not reduced regardless the support while cobalt-based perovskite (LaCoO3) produced cobalt oxides (Co3O4 and CoO), metallic cobalt and lanthanum oxide (La2O3). It was found that both titania and iron are beneficial to make cobalt reduction easier, producing more active and stable catalysts. At the end of reaction, the catalyst derived from cobalt-based perovskite (LaCoO3/TiO2) was the most active and selective, the activity and selectivity increasing during reaction. However, the supported catalyst based on iron and cobalt (LaFe0.5Co0.5O3/TiO2) is the most promising for industrial applications since it is highly active and selective since the beginning of reaction. The catalysts produced a negligible amount of coke during reaction.

MATHEMATICAL MODELS OF CRITERIA TECHNOLOGICAL PROCESSES OPTIMIZATION CRITERIA OF THE BLAST FURNACE SMELTING

The mathematical models of optimality criteria of blast, fuel additives and steam consumption for blasting moisture have been developed. The criterion for optimal blast consumption is the furnace performance, which should be maintained at the highest possible level. The maximum possible level of performance varies over time, even at a constant value of blasting. Therefore, optimal amount of blasting search is carried out continuously every 5 to 10 minutes. The mathematical model of furnace efficiency has been developed. It is determined by information on the amount of combined blast and its content of reducing gas, the oxidation of the charge, the amount of gasified oxygen of the charge from one filing, the amount of cast iron, which is smelted from the charge of one feed, the output of the dry blast furnace gas. The mathematical model of the optimization criterion of fuel additives consumption includes mathematical models: the coke coefficient of substitution by a fuel additive; the amount of coke replaced by a fuel additive; the amount of profit from the additive use. The coefficient of coke substitution is defined as the ratio of the heating power in the blast furnace to of coke combustion heat, based on information on the composition of the blast furnace gas, the composition of the fuel additive and coke. The amount of coke substituted by a fuel additive is determined by the value of the substitution coefficient and the fuel additive consumption. The amount of profit from the additive use is determined by the information on the consumption of fuel additive and oxygen, fuel additive price, oxygen and coke, the furnace efficiency. The mathematical model of the optimization criterion of steam consumption for blas-ting moisture includes models; the amount of heat consumed for steam decomposition; the heat input at the expense of improving the degree of hydrogen and carbon monoxide use; the intensity change of carbon combustion in the tuyeres; required mass of coke for heat compensation expended on the decomposition of the blow moisture in the furnace; total savings or over-consumption of coke mass when humidity changes; increase in the furnace's efficiency due to changes in the moisture content of the blast; money saving from steam using for moistening.

COMPLEX ALGORITHM OF THE OPTIMIZATION SYSTEM FUNCTIONING OF PULVERIZED COAL CONSUMPTION

The functioning algorithm of the automated system optimization of the pulverized fuel consumption (PFC) for blast furnace has been developed. It is assumed that the system consists of subsystems: control of information reliability, stabilization of the slag basicity and the theoretical burning temperatures; heat losses compensation and the oxidation process fluctuations of cast iron on the tuyeres; thermal state stabilization of the melting process; PF consumption optimization and blasting. The algorithm includes a set of algorithms for the functioning of these subsystems.According to the information about the technological parameters, the composition of the flue gas is calculated and compared with gas analyzers reading. If the differences between them exceed the given values, we conclude that metrological characteristics of the measuring and computing channels are unsatisfactory and begin checking these channels.The value of the theoretical combustion temperature, which is compared with the given limits has been calculated. The recommendations for changing technological oxygen consumption and blast humidity are determined by the difference between them. For every 10 min, the temperature of tuyere fire flow, theoretical burning temperature and the difference between them is determined, which defines the change in the iron oxidation and adjust the prediction of cast iron quality.The combined principle of controlling the thermal state of blast-furnace smelting is provided. The change in the incoming heat into the zone of indirect restoration, which calculates the recommendations for changing the mass of coke in the feed is determined. The qua-lity of pig iron is determined according to the incoming heat in the lower part of the furnace and recommendations for its stabilization are predicted. Taking into account fluctuations in heat losses with blast furnace gas and cooling water, the complex parameters of the thermal state and the quality prediction of pig iron are adjusted.The coke coefficient of substitution, the amount of coke replaced, the amount of sa-vings is calculated. The optimum amount of PFC is determined by the extreme value of the savings.

Study of the catalytic reactions of ethylene oligomerization in subcritical and supercritical media over a NiBEA catalyst

We report a study of the catalytic reactions of ethylene oligomerization over nickel impregnated in aluminum silicate using subcritical and supercritical media. We found the BET surface area decreases with increasing nickel loading, indicating the deposition of NiO particles on the catalyst surface, which we confirmed via XRD. We compared the performance of the NiBEA catalyst with the protonated form (HBEA) of the commercial support and obtained strong evidence that the protonated form promotes chain growth reactions. In addition, the introduction of nickel in the catalyst facilitates the desorption of the oligomers compared to the HBEA catalyst. Additionally, we used FTIR and GC–MS/FID to characterize the adsorbed and desorbed oligomers and developed reaction pathways for the ethylene oligomerization over the NiBEA catalyst. We found that both adsorbed and desorbed oligomers are aliphatic, and the non-desorbed products constitute the coke. Additionally, we found that pressure and temperature both increase the chain growth and desorption rates of adsorbed oligomers. Under supercritical conditions, the amount of coke formed on the catalyst and the desorbed products molecular weight both increase relative to subcritical conditions. However, the supercritical conditions promote the dissolution of the coke from both NiBEA and HBEA catalysts, which shows the standalone effect of the supercritical ethylene toward the dissolution of coke from the catalyst surface. We provided visual evidence of (1) the formation of coke on the catalyst surface, and (2) the coke dissolution phenomena under supercritical conditions. Finally, we characterized the coke molecules at supercritical conditions as macromolecules connected via C-C (sp3) bonds with the occurrence of cyclic species.

Enhancement of the utilization of methanol in the alkylation of benzene with methanol over 3-aminopropyltriethoxysilane modified HZSM-5

Normally, higher conversion of benzene represented higher utilization rate of methanol. Given these problems, we have modified HZSM-5 with 3-aminopropyltriethoxysilane (AMEO) and the physical-chemistry properties of the catalysts were characterized by XRD, Zeta potential, Contact Angle Measurement, SEM, NH3-TPD and EDS. Meanwhile, the influence of AMEO addition on the catalytic performance of HZSM-5 for the alkylation of benzene with methanol was researched. Results show that HZSM-5 treated with AMEO, not only the selectivity of target product and the utilization of methanol for the alkylation of benzene with methanol were improved, but also the amount of coke was significant reduced.

Development of heavy oil upgrading technologies in China

Abstract Heavy oils have high viscosity, density, and Conradson carbon residue and high contents of sulfur, nitrogen, oxygen, nickel, and vanadium, as well as asphaltenes, which can cause problems for producers, leading to catalyst deactivation and fouling and plugging of tubing, pipes, valves, and reactor flow lines. Heavy oil upgrading can be classified into carbon rejection and hydrogen addition processes, mainly including four technologies: (1) the fluid catalytic cracking (FCC) process, which catalytically converts heavy oil into light fractions, like liquid petroleum gas, naphtha, and light cycle oil; (2) the hydro-processing process, which catalytically converts heavy oil to high-quality feedstock for FCC and hydrocracking processes under the hydrogen atmosphere without coke formation; (3) the coking process, which thermally converts heavy oil into light liquid fractions and large amounts of coke; and (4) the solvent deasphalting process, which fractionates distillation resid to provide feedstock for residue FCC, such as the residue oil solvent extraction. This paper reviews the progress on basic research of heavy oil chemistry and processing technology developments in China. Heavy oils were comprehensively characterized by the supercritical fluid extraction and fractionation technology and high-resolution mass spectrometry. The FCC process for maximizing iso-paraffin, new residue hydroprocessing technologies, progress in coking process, and a new process – the Supercritical Fluid Selective Extraction Asphaltene Technology – were discussed. As an emerging and promising research area, molecular management techniques were prospected, as well as a new concept of coupling the SELEX-Asp with the conventional heavy oil upgrading processes.

Rod-shaped porous alumina-supported Cr2O3 catalyst with low acidity for propane dehydrogenation

Direct catalytic propane dehydrogenation (PDH) to obtain propylene is a more economical and environmentally friendly route for propylene production. In particular, alumina-supported Cr2O3 catalysts can have better potential applications if the acidic properties could be tuned. Herein, a series of rod-shaped porous alumina were prepared through a hydrothermal route, followed by calcination. It was found that the acidity of the synthesized alumina was generally lower than that of the commercial alumina and could be adjusted well by varying the calcination temperature. Such alumina materials were used as supports for active Cr2O3, and the obtained catalysts could enhance the resistance to coke formation associated with similar activity in PDH reaction compared to the commercial alumina. The amount of coke deposited on a self-made catalyst (Cr-Al-800) was 3.6%, which was much lower than that deposited on the reference catalyst (15.7%). The lower acidity of the catalyst inhibited the side reactions and coke formation during the PDH process, which was beneficial for its high activity and superior anti-coking properties.

Studying the Effect of the Process Temperature on the Degree of Bio-Oil Hydrotreatment at Low Hydrogen Contents over NiCu–SiO2 Catalyst with a High Metal Loading

The hydrotreatment of pyrolysis bio-oil by hydrodeoxygenation at 6.0 MPa initial hydrogen pressure in the temperature range of 150–350°C and the presence of a NiCu–SiO2 catalyst synthesized using the sol-gel method is studied. The stability of the catalyst including the agglomeration of active component particles and the deposition of carbon on its surface is also investigated. It is shown that the content of oxygen in the products of the hydrotreatment of lignocellulose pyrolysis liquid decreases from 37 to 15 wt % upon an increase in the process temperature. Using a CHNS-O-analyzer, it is established that the amount of coke on the catalyst’s surfaces at a temperature of 350°C decreases by 4 times, compared with that formed at 150°C. X-ray diffraction shows that increasing the process temperature results in the gradual agglomeration of particles with a subsequent reduction in their size at high temperatures due to the dissolution of active catalyst components in the reaction medium.

Ni-based catalysts for steam reforming of tar model derived from biomass gasification

Tar formation during biomass gasification is a major barrier to utilise the produced syngas, which clogs processing equipment. In the present study, steam reforming of gasification-derived tar (phenol, toluene, naphthalene, and pyrene) was catalysed by Ni/dolomite, Ni/dolomite/Al2O3, Ni/dolomite/La2O3, Ni/dolomite/CeO2, and Ni/dolomite/ZrO2 for hydrogen production. The steam reforming experiment was conducted in a fixed bed reactor at 700 °C and the steam-to-carbon molar ratio of 1 under atmospheric pressure. After the catalytic test, the spent catalysts were characterised by thermogravimetric analysis and variable-pressure scanning electron microscope. The aim of this study is to investigate the catalytic activity of Ni-based catalysts in terms of tar conversion and their deactivation characteristic. The current results revealed that all the catalysts showed almost full conversion of tar (98.8%-99.9%) and considerably low amount of coke deposited in the form of amorphous and filamentous carbon (15.9-178.5 mg gcat-1). Among the catalysts studied, Ni/dolomite/La2O3 gave the highest catalytic activity for steam reforming of gasified biomass tar and lowest coke formation.

Beneficial use of ultrasound irradiation in synthesis of beta-clinoptilolite composite used in heavy oil upgrading process.

A novel beta–clinoptilolite composite was prepared from beta zeolite and alkaline treated clinoptilolite by employing conventional and sonicated mixing procedures. Parent and prepared catalysts were characterized by XRD, FE-SEM, N2 adsorption–desorption and NH3-TPD analyses. Prepared composite of beta zeolite and treated clinoptilolite exhibited improved structural properties especially upon sonicated mixing procedure. Employing ultrasound irradiation notably improved beta distribution in the composite and increased mesoporous volume and specific surface area from 0.245 cm3 g−1 and 171.3 m2 g−1 in conventionally mixed composite to 0.353 cm3 g−1 and 232.9 m2 g−1 in sonicated sample. Catalytic performance of prepared composite was evaluated in heavy oil upgrading process in a continuous fixed bed apparatus. Liquid product was specified by conducting SIMDIS-GC and GC/MS analyses. Spent catalysts were characterized by TGA, FTIR and XRD. Beta–clinoptilolite composite containing only 30 wt% of beta zeolite, exhibited similar performance to beta zeolite catalyst by resulting 75.3% viscosity reduction while producing lower amount of coke. Amount of light hydrocarbons produced over beta–clinoptilolite composite was 33.51 wt% while beta zeolite catalyst produced 35.58 wt% light hydrocarbons in upgrading process. Ultrasound irradiated composite showed more stable structure in catalytic cracking procedure compared to conventionally mixed composite. After 5 h time on stream, relative crystallinity of clinoptilolite phase in the conventionally mixed composite was reduced by 34.5% while sonicated sample remarkably preserved its structure during the reaction and only 1% reduction occurred for this sample.

Influence of tungsten loading on CO2 /O2 reforming of methane over Co-W-promoted NiO-Al2 O3 nanocatalyst designed by sol-gel-plasma

Co-W–promoted NiAl2O4 nanocatalyst with various amount of tungsten (0, 1, 3, and 7 wt.%) was fabricated via hybrid sol-gel-plasma method. The nanocatalysts were evaluated by XRD, FESEM, EDX, BET, and FTIR analyses. The samples were utilized in CO2/O2 reforming of methane to syngas. EDX results proved the existence of all the applied elements in synthesis. FESEM and BET results illustrated that tungsten addition led to lower surface area, larger particle size, and roughly worse particles scattering. Therefore, Co-NiAl2O4 (NCW0A) presented higher yield; however, yields were reduced for the other samples due to the covering impact of tungsten. As a result of time on streams performance (2880 minutes and at 750°C), the 7 wt.% tungsten promoted sample exhibited stable but lower yield (YH2 = 64%). Moreover, NCW1A exhibited more stable and higher yield than NCW0A. Optimum operating parameters were obtained as GHSV = 24 l/gcat.h, CH4/CO2 = 1, and CH4/CO2/O2 = 1/1/0.08. TG-DTG, EDX, and FESEM analyses were applied for the used samples. TG-DTG graphs demonstrated that by rising of tungsten loading, lighter and lower amount of coke was formed. Some agglomerations were observed in the EDX images of NCW0A and NCW1A while lower agglomeration was found for the tungsten-rich sample. Carbon fiber formation was detected in the FESEM images of the used NCW0A while for the others, amount of the deposited coke and carbon fibers decreased.

Steam reforming of ethanol over Ni/MgAl2O4 catalysts

Hydrogen is considered one of the most promising energy vectors in order to match the current energy and environmental issues. Bioethanol steam reforming is a sound opportunity and close to the industrialization considering an integrated biorefinery concept. MgAl2O4 was selected as a stable support, with improved activity, selectivity and stability due to negligible acidity. Increasing the Ni loading from 1.5 to 10 wt% over MgAl2O4 improved the conversion of ethanol as well as the yield of hydrogen, while the carbon deposition and yield of byproducts decreased.Small acidity characterised the samples, attributed exclusively to the Ni active phase. This prevented extensive catalyst coking due to ethylene formation and subsequent polymerisation. Consequently, small coke amount was found on the spent catalysts, mainly amorphous, allowing rather easy regeneration.DRIFT analysis of adsorbed ethanol at variable temperature evidenced the intermediates of reaction and their evolution with temperature, allowing to suggest the main reaction paths. Acetaldehyde was found as intermediate, rapidly evolving to reformate. Among the possible evolution paths of acetaldehyde, the oxidation to acetate and carbonate species (likely stabilised by the support) was preferred with respect to decomposition to methane and CO. This is reflected in the products distribution evidenced through activity testing.