Oxidative desulfurization of dibenzothiophene over Fe promoted Co–Mo/Al_2O_3 and Ni–Mo/Al_2O_3 catalysts using hydrogen peroxide and formic acid as oxidants

This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al_2O_3 catalysts in the oxidative desulfurization(ODS) of dibenzothiophene(DBT) using H_2O_2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60 °C and 150 min reaction time over Fe–Ni–Mo/Al_2O_3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al_2O_3 catalysts following the activity order: Fe–Ni–Mo/Al_2O_3 NFe–Co–Mo/Al_2O_3 NNi–Mo/Al_2O_3 NCo–Mo/Al_2O_3, while H_2O_2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy(SEM), X-ray diffraction(XRD), energy dispersive X-ray(EDX)analysis, Atomic Absorption Spectroscopy(AAS) and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.     

Low-Temperature Growth of Carbon Nanotubes on Bi- and Tri-metallic Catalyst Templates

Low temperature growth process of carbon nanotubes (CNTs) over bi-metallic (Co–Fe) and tri-metallic (Ni–Co–Fe) catalysts on Si/Al/Al₂O₃ substrates is carried out from acetylene precursor using hydrogen, ammonia or nitrogen as a carrier in a low pressure chemical vapor deposition system. Using the tri-metallic Ni–Co–Fe catalyst template, vertically aligned CNTs of ~700 nm length could be grown already at 450 °C within 10 min using ammonia as a carrier. Within the same period of time, on bi-metallic Co–Fe catalyst templates, ~250 nm long aligned nanotubes emerged already at 400 °C in nitrogen carrier. At low temperatures most of the catalyst materials were elevated from the support by the grown nanotubes indicating tip growth mechanism. The structure of catalyst layers and nanotube films was studied using scanning and transmission electron microscopy and atomic force microscopy.     

Bi-metallic catalysts of mesoporous Al2O3 supported on Fe,Ni and Mn for methane decomposition: Effect of activation temperature

Methane decomposition reaction has been studied at three different activation temperatures (500 °C, 800 °C and 950 °C) over mesoporous alumina supported Ni–Fe and Mn–Fe based bimetallic catalysts. On co-impregnation of Ni on Fe/Al₂O₃ the activity of the catalyst was retained even at the high activation temperature at 950 °C and up to 180 min. The Ni promotion enhanced the reducibility of Fe/Al₂O₃ oxides showing higher catalytic activity with a hydrogen yield of 69%. The reactivity of bimetallic Mn and Fe over Al₂O₃ catalyst decreased at 800 °C and 950 °C activation temperatures. Regeneration studies revealed that the catalyst could be effectively recycled up to 9 times. The addition of O₂ (1 ml, 2 ml, 4 ml) in the feed enhanced substantially CH₄ conversion, the yield of hydrogen and the stability of the catalyst.     

Comparative Study on CO2 Hydrogenation to Higher Hydrocarbons over Fe-Based Bimetallic Catalysts

This paper reports on notable promotion of C₂ ⁺ hydrocarbons formation from CO₂ hydrogenation induced by combining Fe and a small amount of selected transition metals. Al₂O₃-supported bimetallic Fe–M (M = Co, Ni, Cu, Pd) catalysts as well as the corresponding monometallic catalysts were prepared, and examined for CO₂ hydrogenation at 573 K and 1.1 MPa. Among the monometallic catalysts, C₂ ⁺ hydrocarbons were obtained only with Fe catalyst, while Co and Ni catalysts yielded higher CH₄ selectively than other catalysts. The combination of Fe and Cu or Pd led to significant bimetallic promotion of C₂ ⁺ hydrocarbons formation from CO₂ hydrogenation, in addition to Fe–Co formulation discovered in our previous work. CO₂ conversion on Ni catalyst nearly reached equilibrium for CO₂ methanation which makes this catalyst suitable for making synthetic natural gas. Fe–Ni bimetallic catalyst was also capable of catalyzing CO₂ hydrogenation to C₂ ⁺ hydrocarbons, but with much lower Ni/(Ni+Fe) atomic ratio compared to other bimetallic catalysts. The addition of a small amount of K to these bimetallic catalysts further enhanced CO₂ hydrogenation activity to C₂ ⁺ hydrocarbons. K-promoted Fe–Co and Fe–Cu catalysts showed better performance for synthesizing C₂ ⁺ hydrocarbons than Fe/K/Al₂O₃ catalyst which has been known as a promising catalyst so far.     

Bulk and Al2O3-supported Ni2P HDS catalysts prepared by separating the nickel and hypophosphite sources

Bulk Ni₂P and Al₂O₃-supported Ni₂P were prepared at low phosphidation temperature (300 °C) from Ni₉S₈ and NH₄H₂PO₂, which were separated to avoid the formation of phosphate inside the support pores. The unsupported product phases were characterized by XRD and the Ni₂P/Al₂O₃ catalysts by XRD, BET and TEM. A 10 wt.% Ni₂P/Al₂O₃ catalyst, made by the Ni(NO₃)₂–NiO–Ni₉S₈–Ni₂P path at a P/Ni ratio of 3, showed the highest activity in the hydrodesulfurization of dibenzothiophene. By separating the nickel and hypophosphite sources, Ni₂P/Al₂O₃ catalysts could be obtained at low phosphidation temperature and with low degree of blockage of pores by surplus phosphorus.     

Synthesis of narrow-diameter carbon nanotubes from acetylene decomposition over an iron-nickel catalyst supported on alumina

Carbon nanotubes (CNTs) were synthesized by the catalytic decomposition of acetylene over 40Fe:60Al₂O₃, 40Ni:60Al₂O₃ and 20Fe:20Ni:60Al₂O₃ catalysts. High density CNTs of 20 nm diameter were grown over the 20Fe:20Ni:60Al₂O₃ catalyst, whereas low growth density CNTs of 40 and 50 nm diameter were found over 40Fe:60Al₂O₃ and 40Ni:60Al₂O₃ catalysts. Smaller catalyst particles enabled the synthesis of highly dense, long and narrow-diameter CNTs. It was found that a homogeneous dispersion of the catalyst was an essential factor in achieving high growth density. The carbon yield and the quality of CNTs increased with increasing temperature. For the 20Fe:20Ni:60Al₂O₃ catalyst, the carbon yield reached 121% after 90 min at 700 °C. The CNTs were grown according to the tip growth mode. Based on reports regarding hydrocarbon adsorption and decomposition over different faces of Ni and Fe, the growth mechanism of CNTs over the 20Fe:20Ni:60Al₂O₃ catalyst are discussed.     

On the Production of Hydrogen from Bio-Oil: A Representative Study Using Propylene Glycol

In a bio-refinery focused on fast pyrolysis, hydrogen (H₂) producible from reforming of the aqueous fraction of bio-oil with steam can be utilized for upgrading pyrolytic lignin into fuels by hydrotreatment. In this work, propylene glycol (PG) was chosen as a typical compound symbolizing higher polyols in the bio-oil aqueous fraction. Catalytic processing of PG into H₂ at low temperature (T = 500°C) was investigated using several commercial catalysts such as Ni/Al₂O₃, Ru/Al₂O₃, Ru/C, Pt/C, and Pd/C in a laboratory-scale fixed-bed reactor. The efficiencies of the catalysts were presented as selectivity to CO, CO₂, CH₄ and H₂, and PG conversion into gaseous phase. Wide ranges of temperature (300–500°C), W/F_O (18.6–92.9 g h/mol), and S/C ratio (5.6–12.7 mol/mol) were examined using Ni/Al₂O₃. At T = 500°C, H₂ selectivity (73.7%) and PG conversion (66.2%) were maximized using ratios of catalyst mass to molar flow rate of PG (W/F_O) = 18.6 g h/mol and steam to carbon (S/C) = 12.7 (10 wt% PG solution). It was found that Ni/Al₂O₃ demonstrates stable operation for at least 6 h of time-on-stream. Finally, a plausible reaction pathway for PG reforming was proposed.     

The effects of cobalt and cerium promoters on hydrogen production performance of alumina-supported nickel catalysts in propane steam reforming

BACKGROUND: The effects of Co and Ce promoters on the performance of Ni (10 wt%)–Co (0.0, 2.75, 5.5 wt%)/Ce (0.0, 5.0, 10.0 wt%)–Al₂O₃ catalysts have been studied for steam reforming of C₃H₈ (SRP). In this work, Ni (NO₃)₂ and Co (NO₃)₂ are co-impregnated on the co-precipitated Al₂O₃–CeO₂ supports. X-ray diffraction, N₂ adsorption–desorption, H₂-temperature-programmed reduction, high-resolution transmission electron microscopy, scanning electron microscopy and thermogravimetric/differential thermal analysis were accomplished to explain the SRP activity of the catalysts. The performance of the resulting catalysts was evaluated under the gas hourly space velocity (GHSV) = 45 000 mL h^-1 g_cat⁻¹, T = 600 °C, steam/C₃H₈ ratio (S/C) = 3 and P = 1 atm. RESULTS: The experimental findings revealed that Ce and Co promoters markedly improved the catalyst activity, stability and H₂ yield of Ni/Al₂O₃ catalyst. The sample with 2.75 wt% Co and 10.0 wt% Ce showed highest C₃H₈ conversion, while maximum yield of H₂ was obtained for catalyst containing 5.5 wt% Co and 5.0 wt% Ce. CONCLUSION: Higher loadings of Co decreased C₃H₈ conversion and catalyst stability due to more coke formation on the catalyst surface, whereas Ce significantly improved catalyst resistance to coke deposition due to the enhanced Ni metal particles distribution over the support. © 2020 Society of Chemical Industry     

Effects of Na, Cu, Ni and Co Modifications on the Activity and Characteristics of Rh/Al2O3 Catalysts for NO Reduction

This study used different metals to modify Rh/Al₂O₃ catalysts for NO reduction in a simulated waste incineration flue gas containing 6% O₂. The characteristics of the modified catalysts were analyzed using BET, TEM and XRD. The results of the experiment reveal that Na addition can significantly affect the properties of Rh/Al₂O₃ catalysts on the BET surface area and Rh metal dispersion. Furthermore, Na addition was found to significantly enhance the NO conversion of Rh/Al₂O₃ at 250–350 °C. On the contrary, Cu, Ni, and Co addition was found to have slight suppression effects.     

A Novel Process for Renewable Methane Production: Combining Direct Air Capture by K<Subscript>2</Subscript>CO<Subscript>3</Subscript>/Alumina Sorbent with CO<Subscript>2</Subscript> Methanation over Ru/Alumina Catalyst

CO₂ methanation over supported ruthenium catalysts is considered to be a promising process for carbon capture and utilization and power-to-gas technologies. In this work 4% Ru/Al₂O₃ catalyst was synthesized by impregnation of the support with an aqueous solution of Ru(OH)Cl₃, followed by liquid phase reduction using NaBH₄ and gas phase activation using the stoichiometric mixture of CO₂ and H₂ (1:4). Kinetics of CO₂ methanation reaction over the Ru/Al₂O₃ catalyst was studied in a perfectly mixed reactor at temperatures from 200 to 300 °C. The results showed that dependence of the specific activity of the catalyst on temperature followed the Arrhenius law. CO₂ conversion to methane was shown to depend on temperature, water vapor pressure and CO₂:H₂ ratio in the gas mixture. The Ru/Al₂O₃ catalyst was later tested together with the K₂CO₃/Al₂O₃ composite sorbent in the novel direct air capture/methanation process, which combined in one reactor consecutive steps of CO₂ adsorption from the air at room temperature and CO₂ desorption/methanation in H₂ flow at 300 or 350 °C. It was demonstrated that the amount of desorbed CO₂ was practically the same for both temperatures used, while the total conversion of carbon dioxide to methane was 94.2–94.6% at 300 °C and 96.1–96.5% at 350 °C.     

Effect of Ni promoter in the oxide precursors of MoS2/MgO–Al2O3 catalysts tested in dibenzothiophene hydrodesulphurization

NiMoS catalysts supported on MgO–Al₂O₃ oxides, with 95 and 80 mol% of MgO, were synthesized by sol–gel method. In order to study the Ni promoter effect, MgO–Al₂O₃ supports were impregnated with a pH = 9 solution of Mo and Ni–Mo, respectively; the catalysts were dried (D) and calcinated (C). Catalytic tests showed a Ni promoter effect of 4.5 on the NiMoMg95Al5-D catalyst and 8.5 on the calcinated one. The latter catalyst is more active than a commercial NiMo/Al₂O₃ catalyst. On the other side, the catalyst supported on Mg80Al20 solid did not show any Ni promoter effect. Raman and UV–vis diffuse reflectance spectroscopy showed that during the impregnation step, a strong support interaction with the ion MoO₄^2? takes place on the Mo/MgO–Al₂O₃ solids. After calcination, MoO₄^2? ion remained on the catalyst surface, but increased its interaction with the support. The presence of Ni²⁺_Th, Ni²⁺_Oh and MoO₄^2? ions on dried NiMo/Mg95Al5 catalysts was confirmed, as well as the presence of Ni²⁺_Th, Ni²⁺_Oh, MoO₄^2? and Mo₇O₂₄^6? ions on the calcinated catalyst. This suggests that Ni²⁺ ion allows polymerization of MoO₄^2? to Mo₇O₂₄^6?, produced by Ni²⁺_Oh–MoO₄^2? and Ni²⁺_Oh–Mo₇O₂₄^6? close interactions. The NiMo/Mg80Al20 solids also showed MoO₃ species and a high Ni²⁺_Th concentration. Thus, the Ni promoter effect and therefore, catalytic activity decreased, due to the formation of Ni²⁺_Th–MgO and Ni²⁺_Th–Al₂O₃ spinels.     

Highly Selective and Active Niobia-Supported Cobalt Catalysts for Fischer–Tropsch Synthesis

The performance of Co/Nb₂O₅ was compared to that of Co/γ-Al₂O₃ for the Fischer–Tropsch synthesis at 20 bar and over the temperature range of 220–260 °C. The C₅₊ selectivity of Nb₂O₅-supported cobalt catalysts was found to be very high, i.e. up to 90 wt% C₅₊ at 220 °C. The activity per unit weight cobalt was found to be similar for Nb₂O₅ and γ-Al₂O₃-supported catalysts at identical reaction temperature. However, due to the low porosity of crystalline Nb₂O₅, the cobalt loading was limited to 5 wt% and consequently the activity per unit weight of catalyst was lower than of Co/γ-Al₂O₃ catalysts with higher cobalt loadings. This low activity was largely compensated by increasing the reaction temperature, although the C₅₊ selectivity decreased upon increasing reaction temperature. Due to the high intrinsic C₅₊ selectivity, Nb₂O₅-supported catalysts could be operated up to ~250 °C at a target C₅₊ selectivity of 80 wt%, whereas γ-Al₂O₃-supported catalysts called for an operation temperature of ~210 °C. At this target C₅₊ selectivity, the activity per unit weight of catalyst was found to be identical for 5 wt% Co/Nb₂O₅ and 25 wt% Co/Al₂O₃, while the activity per unit weight of cobalt was a factor of four higher for the niobia-supported catalyst.     

Improving the Activity of Rh/Al2O3 Catalyst for NO Reduction by Na Addition in the Presences of H2O and O2

The effect of Na addition on the performance of Rh/Al₂O₃ catalyst for NO reduction with CO in the presence of H₂O and O₂ was investigated. The reacted catalysts were analyzed by the FTIR technique to identify the products for further investigation on the possible catalytic reaction mechanisms and the reasons behind the H₂O poisoning. Experimental results show that the removal efficiency of NO by Rh/Al₂O₃ catalyst was 63% at 250 °C but that decreased as the H₂O content increased. Adding Na to modify the Rh/Al₂O₃ catalyst significantly enhanced the conversion of NO to 99% at 250–300 °C even as the H₂O content was 1.6 vol%. The FTIR analyses results reveal that the abundant H₂O in the flue gas can compete with NO to adsorb on the surfaces of Rh/Al₂O₃ and Rh-Na/Al₂O₃ catalysts and further enhance the formation of NO₃ that reacts with H. The effects of H₂O on Rh/Al₂O₃ and Rh-Na/Al₂O₃ catalysts can be eliminated by increasing the reaction temperature to higher than 300 °C. Rh-Na/Al₂O₃ is a feasible catalyst for NO reduction at such condition with relative high H₂O and O₂ contents.     

Effects of bimetallic catalyst composition and growth parameters on the growth density and diameter of carbon nanotubes

Multi-wall carbon nanotubes (MWNTs) were synthesized by catalytic decomposition of acetylene over Fe, Ni and Fe-Ni bimetallic catalysts supported on alumina under various controlled conditions. The growth density and diameter of CNTs were markedly dependent on the activation time of catalysts in H₂ atmosphere, reaction time, reaction temperature, flow rate of acetylene, and catalyst composition. Bimetallic catalysts were apt to produce narrower diameter of CNTs than single metal catalysts. For the growth of CNTs at 600 ‡C under 10/100 seem flow of C₂H₂/H₂ mixture, the narrowest diameter about 20 nm was observed at the reaction time of 1 h for 20Fe : 20Ni : 60Al₂O₃ catalyst, but at that of 1.5 h for 10Fe : 30Ni : 60Al₂O₃ catalyst. It was considered that the diameter and density of CNTs decreased with the increase of the growth time mainly due to hydrogen etching. The growth of CNTs followed the tip growth mode.     

Nano‐engineered nickel catalysts supported on 4‐channel α‐Al2O3 hollow fibers for dry reforming of methane

A nickel (Ni) nanoparticle catalyst, supported on 4‐channel α‐Al₂O₃ hollow fibers, was synthesized by atomic layer deposition (ALD). Highly dispersed Ni nanoparticles were successfully deposited on the outside surfaces and the inside porous structures of hollow fibers. The catalyst was employed to catalyze the dry reforming of methane (DRM) reaction and showed a methane reforming rate of 2040 Lh^?1gNi^?1 at 800°C. NiAl₂O₄ spinel was formed when Ni nanoparticles were deposited on alpha‐alumina substrates by ALD, which enhanced the Ni‐support interaction. Different cycles (two, five, and ten) of Al₂O₃ ALD films were applied on the Ni/hollow fiber catalysts to further improve the interaction between the Ni nanoparticles and the hollow fiber support. Both the catalyst activity and stability were improved with the deposition of Al₂O₃ ALD films. Among the Al₂O₃ ALD coated catalysts, the catalyst with five cycles of Al₂O₃ ALD showed the best performance. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2625–2631, 2018     

Rare earth-doped Ni/MgAl2O4 catalysts prepared via a one-step sol–gel method for steam reforming of volatile organic solvents at low temperatures

To develop efficient steam reforming catalysts that are widely applicable to various volatile organic solvents under low temperatures, rare earth (La, Ce or Pr)-doped Ni/MgAl₂O₄ were prepared via a novel one-step sol–gel method. Through various characterizations and DFT calculations, it demonstrated that the rare earths not only improved the catalyst structure, but also promoted the dispersion, electron density and d-band center of Ni. Consequently, all the rare earth-doped Ni/MgAl₂O₄ catalysts exhibited higher catalytic activity in steam reforming of different volatile organic solvents than the Ni/MgAl₂O₄ in 500–550 °C. Thereinto, the 10Ni-2La/MgAl₂O₄ performed the best, achieving a conversion efficiency of 97.3% at 550 °C for the mixture of toluene, acetone, tetrahydrofuran, and n-hexane. The outstanding performance of Ni-La/MgAl₂O₄ catalyst arises from the structural compatibility between low-spin La atom and Ni cluster, which enables La to modify Ni dispersion and electronic structure more significantly than Ce or Pr.     

Effect of adding nickel to iron-alumina catalysts on the morphology of as-grown carbon nanotubes

The synthesis of carbon nanotubes (CNTs) from ethylene decomposition by Fe/Al₂O₃ and Fe/Ni/Al₂O₃ catalysts (Fe:Ni=10:1) is studied. A small amount of nickel introduced into the catalyst can significantly increase the yield of CNTs, but the nanotubes change from straight tubes with concentric parallel carbon sheets to helical tubes of the fish-bone type. Raman characterization of CNTs prepared at 823 and 1023 K and CNTs annealed at 2473 K shows that CNTs deposited on the Fe/Ni/Al₂O₃ catalyst have poor crystallinity, as compared with that on the Fe/Al₂O₃ catalyst. These differences are explained by a mechanism of formation of helical tubes of the fish bone type that takes into consideration the differences in the chemical nature of the catalyst with and without nickel.     

Hydrogen Production by Steam Reforming of Commercially Available LPG in UAE

Steam reforming of commercially available LPG using Ru/Al₂O₃ and Ni/Al₂O₃ catalysts has been studied at temperatures between 573 and 773 K. Ru/Al₂O₃ catalyst showed higher rates of reaction and lower activation energies of the three main components of LPG, compared with Ni/Al₂O₃. However, Ni/Al₂O₃ catalyst showed a better H₂:CH₄ selectivity. The activation energy of n-butane was the lowest over Ru/Al₂O₃, whereas over Ni/Al₂O₃, propane had the lowest activation energy. The activation energy of i-butane was always the highest over both catalysts, which suggests that both catalysts performed better with unbranched molecules. A slight increase in activation energy was observed, when each component of the LPG mixture was studied separately as a pure gas, compared with being mixed in LPG. At a constant temperature of 773 K, hydrogen production yield and H₂:CH₄ selectivity were determined using Ru/Al₂O₃ at different steam:carbon (S:C) ratios and LPG flow rates. It was found that the yield and selectivity increased with the increase in S:C ratio and the decrease in the flow rate. The highest yield of 0.64 was achieved using S:C ratio of 6.5 and a LPG flow rate of 50 mL min^?1. The work provides valuable information on steam reforming of pure components of LPG, compared with when they are in the mixture. The comparison is done using conventional steam reforming catalyst, Ni/Al₂O₃, and compared with Ru/Al₂O₃. The observed trends and variations in reaction rates, in pure and mixed gases, indicated that the mechanism of steam reforming of a hydrocarbon mixture depends on its composition.     

The performance and structural study of CuNi alloy catalysts for methanol synthesis

Novel CuxNiy/γ-Al₂O₃ alloy catalysts were prepared and studied for methanol synthesis from CO/CO₂ hydrogenation. The structure of the catalysts was characterized using N₂ adsorption–desorption, X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy, X-ray photoelectron spectroscopy and temperature-programmed reduction. The characterization results demonstrated the formation of CuNi alloy. The strong interaction between Cu and Ni had a promotion effect for methanol synthesis. Cu₃Ni₇/γ-Al₂O₃ catalyst exhibited the highest formation rate of CH₃OH, which is 5.86 mmol/g h, much higher than the commercial Cu/ZnO/Al₂O₃ catalyst at the same reaction conditions.     

Role of Pt in the Activity and Stability of PtNi/CeO2–Al2O3 Catalysts in Ethanol Steam Reforming for H2 Production

Hydrogen production from ethanol reforming was investigated on bimetallic PtNi catalysts supported on CeO₂/Al₂O₃. Pt content was varied from 0.5 to 2.5 %. Physico-chemical characterization of the as-prepared and H₂-reduced catalysts by TPR, XRD and XPS showed that Pt phase interacted with the Ni and Ce species present at the surface of the catalysts. This interaction leads to an enhancement of the reducibility of both Ni and Ce species. Loadings of Pt higher than 1.0 wt% improved the activity and stability of the Ni/CeO₂–Al₂O₃ catalyst in ethanol steam reforming, in terms of lower formation of coke, C₂ secondary products and a constant production of CO₂ and H₂. The amount and type of carbon deposited on the catalyst was analyzed by TG–TPO while the changes in crystalline phases after reaction were studied by XRD. It was found that for Pt contents higher than 1 wt% in the catalysts, a better contact between Pt and Ce species is achieved. This Pt–Ce interaction facilitates the dispersion of small particles of Pt and thereby improves the reducibility of both Ce and Ni components at low temperatures. In this type of catalysts, the cooperative effect between Pt⁰, Ni⁰ and reduced Ce phases leads to an improvement in the stability of the catalysts: Ni provides activity in C–C bond breakage, Pt particles enhance the hydrogenation of coke precursors (C_xH_y) formed in the reaction, and Ce increases the availability of oxygen at the surface and thereby further enhances the gasification of carbon precursors.