Autothermal reforming of iso-octane and gasoline over Rh-based catalysts: Influence of CeO2/γ-Al2O3-based mixed oxides on hydrogen production

Autothermal reforming (ATR) of iso-octane in the presence of Rh-based catalysts (0.5 wt% of Rh) supported onto γ-Al₂O₃, CeO₂, and ZrO₂ were initially carried out at 700 °C with a S/C ratio of 2.0, an O/C ratio of 0.84, and a gas hourly space velocity (GHSV) of 20,000 h⁻¹. The activity of Rh/γ-Al₂O₃ was found to be higher than Rh/CeO₂ and Rh/ZrO₂, with H₂ and (H₂ + CO) yields of 1.98 and 2.48 mol/mol C, respectively, after 10 h. This Rh/γ-Al₂O₃ material, however, was potentially susceptible to carbon coking and produced 3.5 wt% of carbon deposits following the reforming reaction, as evidenced by C, H, N, and S elemental analysis. In contrast, Rh/CeO₂ catalyst exhibited lower activity but higher stability than Rh/γ-Al₂O₃, with nearly no carbon being formed within 10 h. To combine the superior activity originated from Rh/γ-Al₂O₃ with high stability from Rh/CeO₂, Rh/CeO₂/γ-Al₂O₃ catalysts with different CeO₂ contents were synthesized and examined for the ATR reactions of iso-octane. Compared to Rh/γ-Al₂O₃, the newly prepared Rh/CeO₂/γ-Al₂O₃ catalysts (0.5 wt% of Rh and 20 wt% of CeO₂) showed even enhanced activity during 10 h, and H₂ and (H₂ + CO) yields were calculated to be 2.08 and 2.62 mol/mol C, respectively. In addition, as observed with Rh/CeO₂, the catalyst was further found to be stable with less than 0.3 wt% of carbon deposition after 10 h. The Rh/γ-Al₂O₃ and Rh/CeO₂/γ-Al₂O₃ catalysts were eventually tested for ATR reactions using commercial gasoline that contained sulfur, aromatics, and other impurities. The Rh/γ-Al₂O₃ catalyst was significantly deactivated, showing decreased activity after 4 h, while the Rh/CeO₂/γ-Al₂O₃ catalyst proved to be excellent in terms of stability against coke formation as well as activity towards the desired reforming reaction, maintaining its ability for H₂ production for 100 h.     

Synergistic tuning of the phase structure of alumina and ceria-zirconia in supported palladium catalysts for enhanced methane combustion

CeO₂–ZrO₂–Al₂O₃ composite oxides supported palladium catalysts (Pd/CZA) are promising candidates for catalytic oxidation reactions. However, the efficient and stable oxidation of methane over Pd-based catalysts remains a longstanding challenge. Herein, we present a facile strategy to boost the catalytic performance of Pd/CZA through elaborately tuning the phase structure of supports. Calcining supports at relatively high temperatures (1200, 1300 °C) induced the phase transition of alumina (from γ-to α-) and the development of CeO₂–ZrO₂ solid solution (CZ). The weak interaction between α-Al₂O₃ and PdO resulted in an improved reducibility of catalysts. Meanwhile, the higher oxygen mobility originated from well-crystallized CZ phase contributed to the reoxidation of Pd to PdO, giving rise to abundant surface active Pd²⁺ species. Coupled with the hydrophobicity of α-Al₂O₃, the catalyst prepared with CZA supports calcined at 1300 °C demonstrated an excellent low-temperature activity, astounding stability and greatly enhanced water resistance towards methane combustion.     

Thermochemical hydrogen production using Rh/CeO2/γ-Al2O3 catalyst by steam reforming of ethanol and water splitting in a packed bed reactor

This study is focused on investigating the dual performance of Rh/CeO₂/γ-Al₂O₃ catalyst for steam reforming of ethanol (SRE) and thermochemical water splitting (TCWS) using a packed bed reactor. The catalyst is designed to be thermally stable containing an active phase of Rh and the redox component of CeO₂ for oxygen exchange, supported on γ-Al₂O₃. The catalyst has been characterised by SEM, XRD, BET, TPR, TPD, XPS and TGA before testing in the reactor. The optimal temperature for SRE reaction over this catalyst is between 700 °C and 800 °C to produce high concentrations of hydrogen (~60%), and low CO and CH₄. The selectivity towards CO and CH₄ is higher at low temperatures and drops with rise in reaction temperature. Further, Rh/CeO₂/γ-Al₂O₃ is found to be active for TCWS at relatively low temperatures (≤1200 °C). At temperatures as low as 800 °C, this catalyst is especially found suitable for multiple redox cycles, producing a total of 48.9 mmol/g_cat in four redox cycles. The catalyst can be employed for large number of redox cycles when the reactor is operated at lower temperatures. Finally, the reaction pathways have been proposed for both SRE and TCWS on Rh/CeO₂/γ-Al₂O₃ catalyst.     

Rh- and Rh–Ni–MgO-based structured catalysts for on-board syngas production via gasoline processing

Rh/Ce_0.75Zr_0.25O_2-δ-ƞ-Al₂O₃/FeCrAl and Rh/Ni–MgO/Ce_0.75Zr_0.25O_2-δ-ƞ-Al₂O₃/FeCrAl FeCrAlloy wire mesh supported catalysts were prepared via multistep procedure. They were characterized by XRD, SEM and TEM techniques. A comparative study of autothermal reforming (ATR) of isooctane and simulated gasoline (blends of isooctane, ortho-xylene and naphthalene) over Rh/Ce_0.75Zr_0.25O_2-δ-ƞ-Al₂O₃/FeCrAl and Rh/Ni–MgO/Ce_0.75Zr_0.25O_2-δ-ƞ-Al₂O₃/FeCrAl was performed. Both catalysts showed excellent performance in ATR of isooctane at molar ratios of O₂:C = 0.51 and H₂O:C = 2.59, T = 750°С and GHSV = 10000 h⁻¹. In the ATR of isooctane – o-xylene blend in presence of Rh–Ni-containing catalyst carbon formation was observed. Rh-containing catalyst demonstrated rather good activity and stability even in the case of isooctane – o-xylene – naphthalene blend.     

Screening of supported transition metal catalysts for hydrogen production from glucose via catalytic supercritical water gasification

In total 17 heterogeneous catalysts, with combinations of 4 transition metals (Ni, Ru, Cu and Co) and various promoters (e.g., Na, K, Mg, or Ru) supported on different materials (γ-Al₂O₃, ZrO₂, and activated carbon (AC)), were investigated with respect to their catalytic activity and stability for H₂ production from glucose via supercritical water gasification (SCWG). The experiments were carried out at 600 °C and 24 MPa in a bench-scale continuous-flow tubular reactor. Ni (in metallic form) and Ru (in both metallic and oxidized forms) supported on γ-Al₂O₃ exhibited very high activity and H₂ selectivity among all of the catalysts investigated for a time-on-stream of 5-10 h. With Ni20/γ-Al₂O₃ (i.e., γ-Al₂O₃ with 20 wt% Ni), a H₂ yield of 38.4 mol/kg glucose was achieved, approximately 20 times higher than that obtained during the blank test without catalyst (1.8 mol/kg glucose). In contrast, Cu and Co catalysts were much less effective for glucose SCWG reactions. As for the effects of catalyst support materials on activity, the following order of sequence was observed: γ-Al₂O₃ > ZrO₂ > AC. In addition, Mg and Ru were found to be effective promoters for the Ni/γ-Al₂O₃ catalyst, suppressing coke and tar formation.     

Steam reforming of liquefied petroleum gas using catalysts supported on ceria-silica

Hydrogen production from steam reforming of liquefied petroleum gas (SR-LPG) process was studied over nickel, platinum, rhodium, and ruthenium-based catalysts supported on CeO₂–SiO₂ (CS). BET surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR) and X-ray absorption near edge spectroscopy (XANES) techniques were used to characterize the samples. The catalytic activity and stability of the samples during SR-LPG were measured at 400 °C and 600 °C, respectively. XRD data were used to estimate the average crystallite size of ceria, which was small in all samples. For Pt and Rh containing samples, no diffraction peaks related to the metals were identified, which suggests high dispersion of these metals on the support. TPR and XANES experimental results showed that the addition of metals promoted the reduction of ceria. The order of catalyst activity for during SR-LPG at 400 °C was: Rh/CS » Pt/CS > Ru/CS » Ni/CS. Pt/CS and Rh/CS samples exhibited lower deactivation than nickel and ruthenium catalysts for SR-LPG at 600 °C during 24 h. Catalysts deactivation was mainly due to carbon deposition. In situ XRD data collected during SR-LPG at 600 °C revealed small increases in the mean particle sizes of Ni(0) and Ru (0), which could be pointed out as an additional cause for faster deactivation of the Ru/CS and Ni/CS catalysts.     

Oxidative catalytic steam gasification of sugarcane bagasse for hydrogen rich syngas production

Reactive Flash Volatilization (RFV) is an emerging thermochemical method to produce tar free hydrogen rich syngas from waste biomass at relatively lower temperature (<900 °C) in a single stage catalytic reactor within a millisecond residence time. Here, we show catalytic RFV of bagasse using Ru, Rh, Pd, or Re promoted Ni/Al₂O₃ catalysts under steam rich and oxygen deficient environment. The optimum reaction conditions were found to be 800 °C, steam to carbon ratio = 1.7 and carbon to oxygen ratio = 0.6. Rh–Ni/Al₂O₃ performed the best, resulting in highest hydrogen concentration in the synthesis gas at 54.8%, with a corresponding yield of 106.4 g-H₂/kg bagasse. A carbon conversion efficiency of 99.96% was achieved using Rh–Ni, followed by Ru–Ni, Pd–Ni, Re–Ni and mono metallic Ni catalyst in that order. Alkali and Alkaline Earth Metal species present in the bagasse ash and char, that deposited on the catalyst, was found to enhance its activity and stability. The hydrogen yield from bagasse was higher than previously reported woody biomass and comparable to the microalgae.     

From wood wastes to hydrogen – Preparation and catalytic steam reforming of crude bio-ethanol obtained from fir wood

Fir wood wastes were used to produce crude bio-ethanol by two methods: simultaneous saccharification and fermentation (SSF) and acid hydrolysis followed by the fermentation of the acid hydrolyzate. The main components of crude bio-ethanol are ethanol and acetic acid. In addition, low concentrations of a wide range of alcohols, acids, esters, ethers and aldehydes are also present. Ethanol concentration is higher in the SSF process than in the acid hydrolysis: 43.69 g/L compared to 37.53 g/L, respectively. Opposite to ethanol concentration, the acetic acid concentration is higher in the acid hydrolysis process: 16.36 g/L compared to 10.24 g/L, respectively. The crude bio-ethanol was used to produce hydrogen by catalytic steam reforming. The tested catalysts were the common Ni/Al₂O₃ and two rare earth oxides promoted Ni catalysts: Ni/La₂O₃–Al₂O₃ and Ni/CeO₂–Al₂O₃ prepared by successive wet impregnation. The characterization techniques revealed that the addition of rare earth oxides improves the Ni dispersion and the reducibility of the promoted catalysts. The best feed rate which assures the optimal ratio between conversion and catalyst deactivation is 0.8 mL/min bio-ethanol. The addition of extra oxide (La₂O₃ and CeO₂) to the support improves the ethanol conversion especially at 250 °C, but no significant effect on the acetic acid conversion was observed. At 250 °C the ethanol conversion is almost 90% for Ni/La₂O₃–Al₂O₃ and Ni/CeO₂–Al₂O₃, but the acetic acid conversion is below 30% for all catalysts. At 350 °C both ethanol and acetic acid present maximum conversion. At this temperature the best hydrogen production is obtained for Ni/La₂O₃–Al₂O₃ due to better ethanol conversion and better selectivity for hydrogen formation. At 350 °C the promoted catalysts are stable for 4 h time on stream, different degrees of deactivation being obtained at lower temperatures.     

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.     

Evaluation of regenerative function and activity of reforming toluene by composite catalyst containing spinel oxide

Catalysts that can maintain the activity for a long time are indispensable for the distributed power generation consisting of biomass gasifier and Solid Oxide Fuel Cell (SOFC). This study aims to reveal and develop the regenerative function of composite catalysts containing NiAl₂O₄ that can be regenerated by reduction and oxidation (Red-Ox) for converting tar from biomass. Regenerative function of composite oxide catalyst containing NiAl₂O₄ spinel (NAO) and Ru added to NAO (RNAO) by Red-Ox cycles and their activity of autothermal reforming of toluene were examined. Regenerating function of NAO and RNAO were investigated by temperature programmed reduction (TPR) and oxidation at 850 °C repeatedly. After 7th times Red-Ox cycles at 850 °C, though the regenerated amount of Ni in NAO decreased by 70%, that in RNAO was maintained. By Red-Ox of NAO and RNAO, Ni was oxidized to NiO at 350–650 °C and dissolved into γ-Al₂O₃ to form the NiAl₂O₄ spinel at above 750 °C. In RNAO, RuO₂ particles were more dispersed, decreasing its particle size than the initial, with the Red-Ox cycles, since Ru was dissolved into the Ni particles exsoluted from NiAl₂O₄. By evaluating the activity of autothermal reforming of toluene, NAO and RNAO showed 1.5–3.0 times higher activity than Pt/γ-Al₂O₃, due to the highly dispersive active sites unoccupied by CO. Since the active metals can be redispersed by oxidation and reduction at the range from 750 °C to 850 °C, NAO and RNAO would contribute the maintenance free system for reforming tar from biomass gasification.     

Electrocatalysts supported on multiwalled carbon nanotubes for direct borohydride–hydrogen peroxide fuel cell

Electrocatalysts of Rh, Ru, Pt, Au, Ag, Pd, Ni, and Cu supported on multiwalled carbon nanotubes for direct borohydride–hydrogen peroxide fuel cells are investigated. Metal/γ-Al₂O₃ catalysts for NaBH₄ and H₂O₂ decomposition tests are manufactured and their catalytic activities upon decomposition are compared. Also, the effects of XC-72 and multiwalled carbon nanotube (MWCNT) carbon supports on fuel cell performance are determined. The performance of the catalyst with MWCNTs is better than that of the catalyst with XC-72 owing to a large amount of reduced Pd and the good electrical conductivity of MWCNTs. Finally, the effect of electrodes with various catalysts on fuel cell performance is investigated. Based on test results, Pd (anode) and Au (cathode) are selected as catalysts for the electrodes. When Pd and Au are used together for electrodes, the maximum power density obtained is 170.9 mW/cm² (25 °C).     

The influence of Ni loading on coke formation in steam reforming of acetic acid

Steam reforming of acetic acid on Ni/γ-Al₂O₃ with different nickel loading for hydrogen production was investigated in a tubular reactor at 600 °C, 1 atm, H2O/HAc = 4, and WHSV = 5.01 g-acetic acid/g-cata.h^?1. The catalysts were characterized by temperature programmed oxidation (TPO) and differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that the amount of deposited carbidic-like carbon decreased and graphitic-like carbon increased with Ni loading increasing from 9 to 15 wt%. The Ni/γ-Al₂O₃ catalyst with 12 wt% Ni loading had higher catalytic activity and lower coke deposited rate.     

Zr promotion effect in CO2 methanation over ceria supported nickel catalysts

Carbon dioxide methanation is an interesting way to reduce greenhouse effect gases emission and, simultaneously, provide a renewable energy source of methane. Ceria and 15 at.% Zr-doped ceria supported nickel catalysts were characterized by means of various techniques (BET, XRD, Raman, H₂-TPR, CO₂-TPD, O₂-TPO, OSC and H₂-chemisorption) and evaluated in carbon dioxide methanation. Zr incorporation into catalyst formulation reduced catalyst's basicity but favored its reducibility, nickel availability and oxygen storage capacity. These characteristics gave rise to an improved catalytic performance both in terms of activity and stability: temperature required to achieve 50% conversion was reduced in 20 °C and low temperature (250 °C) stability was improved in around 8%. Initial rates approach was employed to determine reaction rates and apparent activation energies for CO₂ methanation, which resulted in 113 and 121 kJ mol⁻¹for Ni/CeO₂ and Ni/Ce_0.85Zr_0.15O₂, respectively.     

Room temperature hydrogen generation from aqueous ammonia-borane using noble metal nano-clusters as highly active catalysts

Nano-clusters of noble metals Ru, Rh, Pd, Pt and Au have been supported on γ-Al₂O₃, C and SiO₂, of which the catalytic activities have been investigated for hydrolysis of NH₃BH₃. Among these catalysts, the Ru, Rh and Pt catalysts exhibit high activities to generate stoichiometric amount of hydrogen with fast kinetics, whereas the Pd and Au catalysts are less active. Support effect has been studied by testing the hydrogen generation reaction in the presence of Pt supported on γ-Al₂O₃, VULCAN^® carbon and SiO₂, and it is found that Pt on γ-Al₂O₃, which has the smallest particle size, is the most active. Concentration dependence of the hydrogen generation from aqueous NH₃BH₃ solutions has been investigated in the presence of Pt/γ-Al₂O₃ by keeping the amount of Pt/γ-Al₂O₃ catalyst unchanged, which exhibits that the hydrogen release versus time (ml H₂ min⁻¹) does not significantly change with increasing the NH₃BH₃ concentration, indicating that the hydrogen release rate is not dependent on the NH₃BH₃ concentration and the high activity of the Pt catalyst can be kept at high NH₃BH₃ concentrations. Activation energies have been measured to be 23, 21 and 21 kJ mol⁻¹ for Ru/γ-Al₂O₃, Rh/γ-Al₂O₃ and Pt/γ-Al₂O₃ catalysts, respectively, which may correspond to the step of B–N bond breaking on the metal surfaces. The particle sizes, surface morphology and surface areas of the catalysts have been obtained by TEM and BET experiments.     

Powder and structured Pt/Ce0.75Zr0.25O2-based catalysts: Water gas shift performance and quasi in situ XPS studies

The data on the performance in water gas shift reaction of a powder 5 wt% Pt/Ce_0.75Zr_0.25O₂ and a structured 0.33 wt% Pt/Ce_0.75Zr_0.25O₂/θ-Al₂O₃/FeCrAl catalysts are reported in this work. For the powder one the lowest outlet CO concentrations were shown to be 0.5, 0.9 and 1.5 vol% corresponding to the initial ones of 5, 10 and 15 vol%, respectively; the temperature required to reach these values did not exceed 310 °C. The quasi in situ XPS data have shown that doping CeO₂ with Zr enhances the reducibility of the oxide allowing Ce³⁺ formation without any treatment. Additionally, it was found that there are 20–30% of nonmetallic Pt atoms on the surface even after a treatment in CO at 300 °C. For the structured catalyst the downward temperature gradient along the monolith was observed with a dispersion of 50–60 °C. The lowest CO concentrations were observed at the temperatures at the catalyst's back point of 280 °C–3.9 and 4.3 vol% CO in the dry gas for 15,700 and 31,400 cm³·g_cat⁻¹·h⁻¹, respectively, for 10 vol% CO in the feed gas.     

Catalytic steam reforming of complex gasified biomass tar model toward hydrogen over dolomite promoted nickel catalysts

The complex mixture of gasified tar model (phenol, toluene, naphthalene, and pyrene) was steam reformed for hydrogen production over 10 wt% nickel based catalysts. The catalysts were prepared by co-impregnation method with dolomite promoter and various oxide supports (Al₂O₃, La₂O₃, CeO₂, and ZrO₂). Steam reforming was carried out at 700 °C at atmospheric pressure with steam to carbon molar ratio of 1 and gas hourly space velocity of 20 L/h·g_cat. The catalysts were characterised for reducibility, basicity, crystalline, and total surface area properties. Dolomite promoter strengthened the metal-support interaction and basicity of catalyst. The Ni/dolomite/La₂O₃ (NiDLa) catalyst with mesoporous structure (26.42mn), high reducibility (104.42%), and strong basicity (5.56 mmol/g) showed superior catalytic performance in terms of carbon conversion to gas (77.7%), H₂ yield (66.2%) and H₂/CO molar ratio (1.6). In addition, the lowest amount of filamentous coke was deposited on the spent NiDLa after 5 h.     

Double oxalates of Rh(III) with Ni(II) and Co(II) – Effective precursors of nanoalloys for hydrocarbons steam reforming

Heteronuclear coordination compounds of d-metals are suitable single-source precursors for bimetallic nanoalloys, which often show extraordinary catalytic properties due to synergetic effect. In particular, Ni- and Rh-based catalysts are highly effective in low temperature steam reforming processes. Double oxalates of Rh with Ni and Co of the formula {[Rh(H₂O)₂(C₂O₄)μ-(C₂O₄)]₂M(H₂O)₂}·6H₂O (M = Ni, Co) were synthesized and structurally characterized. According to thermogravimetric analysis, the complexes decompose completely in He and H₂ atmospheres to form corresponding nanoalloys at ∼300 °C. The calcination in O₂ atmosphere leads to formation of spinel type mixed oxide. The supported Co–Rh/Al₂O₃ and Ni–Rh/Al₂O₃ catalysts were prepared by impregnation of double oxalate complexes in porous support with subsequent calcination and tested in propane low temperature steam reforming in CH₄ excess. The Co-containing catalyst showed comparable activity regarding to pure Rh/Al₂O₃ sample, while bimetallic Ni–Rh/Al₂O₃ catalyst revealed to be appreciably more active, than monometallic catalysts with higher active component loadings. Rh–Ni catalyst allowed for complete propane conversion at T ≈ 350 °C, whereas for Rh catalyst the temperature was T ≈ 410 °C, and Rh–Co did not reach complete C₃H₈ conversion at all.     

Experimental optimization analysis on operating conditions of CO removal process from hydrogen-rich reformate

The catalytic effects of CO preferential oxidation and methanation catalysts for deep CO removal under different operating conditions (temperature, space velocity, water content, etc.) are systematically studied from the aspects of CO content, CO selectivity, and hydrogen loss index. Results indicate that the 3 wt% Ru/Al₂O₃ preferential oxidation catalysts reduce CO content to below 10 ppm with a high hydrogen consumption of 11.6–15.7%. And methanation catalysts with 0.7 wt% Ru/Al₂O₃ also exhibit excellent CO removal performance at 220–240 °C without hydrogen loss. Besides, NiCl_x/CeO₂ methanation catalysts possess the characteristics of high space velocity, high activity, and high water-gas resistance, and can maintain the CO content at close to 20 ppm. Based on these experimental results, the coupling scheme of combining NiCl_x/CeO₂ methanation catalysts (low cost and high reaction space velocity) with 0.7 wt% Ru/Al₂O₃ methanation catalysts (high activity) to reduce CO content to below10 ppm is proposed.     

Bio-oil production from hydrogenation liquefaction of rice straw over metal (Ni,Co, Cu)-modified CeO2 catalysts

This paper describes catalytic hydrogenation liquefaction of rice straw over metal (Ni, Co, and Cu)-modified CeO₂ catalysts for bio-oil production. The results show that the highest rice straw conversion (89.08%) and bio-oil yield (66.7%) were obtained over Ni/CeO₂ catalyst. The bio-oil contains mainly phenols, high-value-added, and widely used chemicals. Furthermore, metal-modified CeO₂ catalysts can significantly influence the components of bio-oil with the highest percentage of C7-C10 compounds. This work thus demonstrates that metal/CeO₂ catalysts can be effective in improving the bio-oil yield and selectivity in hydro-liquefaction of rice straw into bio-oil.     

Catalysts of Ni/α-Al2O3 and Ni/La2O3-αAl2O3 for hydrogen production by steam reforming of bio-oil aqueous fraction with pyrolytic lignin retention

This paper reports on the steam reforming, in continuous regime, of the aqueous fraction of bio-oil obtained by flash pyrolysis of lignocellulosic biomass (sawdust). The reaction system is provided with two steps in series: i) thermal step at 200 °C, for the pyrolytic lignin retention, and ii) reforming in-line of the treated bio-oil in a fluidized bed reactor, in the range 600–800 °C, with space-time between 0.10 and 0.45 g_catalyst h (g_bio-oil)⁻¹. The benefits of incorporating La₂O₃ to the Ni/α-Al₂O₃ catalyst on the kinetic behavior (bio-oil conversion, yield and selectivity of hydrogen) and deactivation were determined. The significant role of temperature in gasifying coke precursors was also analyzed. Complete conversion of bio-oil is achieved with the Ni/La₂O₃-αAl₂O₃ catalyst, at 700 °C and space-time of 0.22 g_catalyst h (g_bio-oil)⁻¹. The catalyst deactivation is low and the hydrogen yield and selectivity achieved are 96% and 70%, respectively.