Alumina supported nano-platinum on copper nanoparticles prepared via galvanic displacement reaction for preferential carbon monoxide oxidation in presence of hydrogen

Improved catalytic centres with a minimum mass-loading of expensive platinum (Pt) have been anticipated for various catalytic applications, for instance preferential oxidation (PROX) of carbon monoxide (CO) in the presence of Hydrogen. Here, we report the synthesis of nano-Pt on the surface of copper (Cu) nanoparticles (NPs) supported on γ-Al₂O₃ (Pt_n(Cu)/γ-Al₂O₃) via galvanic displacement reaction (GDR) for the catalytic CO-PROX reaction. Pt_n(Cu)/γ-Al₂O₃ showed much improved CO-PROX performance compared to that of the as-synthesized Pt_l(Cu)/γ-Al₂O₃ catalyst. Importantly, no significant conversion of hydrogen at a lower temperature range (<200 °C) is observed during the CO-PROX reaction which is one of the essential prerequisites for the CO-PROX reaction. Moreover, Pt_n(Cu)/γ-Al₂O₃ showed the durable, long-term catalytic CO-PROX performance for 120 h. These results infer that realization of nano-Pt on the surface of the Cu NPs holds the promise as the catalytic centres with the minimum mass-loading of Pt for the CO-PROX reaction.     

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.     

Enhancing hydrogen production by dry reforming process with strontium promoter

Hydrogen is an ideal energy carrier and can play a very important role in the energy system. The present study investigated the enhancement of hydrogen production from catalytic dry reforming process. Two catalysts namely Ni/γ-Al₂O₃ and Co/γ-Al₂O₃ promoted with different amounts of strontium were used to explore selectivity and yield of hydrogen production. Spent and fresh catalysts were characterized using techniques such as BET, XRD, H₂-TPR, CO₂-TPD, TGA and O₂-TPO. The catalyst activity and characterization results displayed stability improvement due to addition of Sr promoter. The least coke formations i.e. 3.8 wt% and 5.1 wt% were obtained using 0.75 wt% Sr doped in Ni/γ-Al₂O₃ and 0.5 wt% Sr doped in Co/γ-Al₂O₃ catalysts respectively. Time on stream tests of promoted catalysts for about six hours at 700 °C showed stable hydrogen selectivity. Moreover, the hydrogen selectivity was significantly improved by the addition of Sr in Ni and Co based catalysts. For instance the hydrogen selectivity increased from 45.9% to 47.8% for Ni/γ-Al₂O₃ and from 48% to 50.9% for Co/γ-Al₂O₃ catalyst by the addition of 0.75 wt% Sr in Ni/γ-Al₂O₃ and 0.5 wt% Sr in Co/γ-Al₂O₃ catalyst respectively.     

Conversion of sugarcane bagasse to gaseous and liquid fuels in near-critical water media using K2O promoted Cu/γ-Al2O3–MgO nanocatalysts

Bagasse conversion to H₂, CO and light gaseous hydrocarbons as gaseous fuels, and higher alcohols and ethers as liquid fuels and fuel additives were performed in a basic water medium with near-critical condition in presence of potassium promoted Cu/γ-Al₂O₃–MgO catalysts. The catalysts were extensively characterized using ICP, XRD, TPR, BET, CO chemisorption and TEM techniques. In order to investigate support stability at reaction condition, XRD test also was carried out for used catalysts. Maximum dispersion of 48% and minimum average particles sizes of 8.4 nm were obtained for Cu20–K7.5/γ-Al₂O₃–MgO catalyst. Copper and potassium effects on quality and quantity of gaseous and liquid products were investigated. The maximum amounts of H₂ (10 mmol g⁻¹ of bagasse) and total produced gases (41 mmol g⁻¹ of bagasse) were obtained with unpromoted Cu20/γ-Al₂O₃–MgO catalyst. Addition of K increased the bagasse conversion to liquid fuels. Potassium made the process more selective for alcohols and ethers production. Maximum amount of alcohols and ethers (83.3 mmol g⁻¹ of bagasse) was obtained for Cu20–K7.5/γ-Al₂O₃–MgO catalyst.     

Bioethanol/glycerol mixture steam reforming over Pt and PtNi supported on lanthana or ceria doped alumina catalysts

The catalytic activity of Pt and PtNi catalysts supported on γ-Al₂O₃ modified by La and Ce oxides was investigated in the steam reforming of ethanol/glycerol mixtures. In general, all the catalysts fully converted the glycerol at the temperatures tested. However, the conversion of ethanol depended on the reaction temperature and catalyst type. The conversion into gaseous products operating at 500 °C and 450 °C was 100% using the most active catalysts (PtNiAl6La and PtNiAl10Ce). These two bimetallic catalysts gave H₂ yields close to those predicted by thermodynamic equilibrium at these temperatures. However, when the reaction temperature was lowered to 400 °C, these catalytic systems and the PtNiAl one recorded a significant decrease in ethanol conversion and H₂ yield, which moved away from the thermodynamic equilibrium value. This deviation was due to intermediate liquid products (acetaldehyde, acrolein, etc.) not being further reformed and the formation of other gaseous ones (light alkanes and ethylene). PtNiAl10Ce catalyst presented the highest conversion into gas at 400 °C, resulting in the largest H₂ yield, followed by PtNiAl6La and PtNiAl catalysts. This order is in agreement with the Ni/Al surface atomic ratio measured by XPS technique in reduced samples. However, filamentous carbon nanotubes were detected but this carbon type maintained the active sites accessible for reactants, since TEM and TGA results showed that the density of this carbon was lower for PtNiAl₁₀Ce catalyst. Pt catalysts presented lower activity than PtNi catalysts possibly due to the formation of carbon nanotubes, which covered some metallic active sites.     

Coke-resistance enhancement of mesoporous γ-Al2O3 and MgO-supported Ni-based catalysts for sustainable hydrogen generation via steam reforming of acetic acid

Highly ordered mesoporous γ-Al₂O₃ particles and MgO materials were synthesized by evaporation induced self-assembly (EISA) and template-free hydrothermal co-precipitation routes, respectively. Ni, Ni–MgO, and Ni–La₂O₃-containing catalysts were prepared using a wet-impregnation method. The synthesized catalysts were characterized by N₂ adsorption–desorption, XRD, SEM-EDS, DRIFTS, XPS, TGA-DTA, and Raman spectroscopy analysis. The mesoporous γ-Al₂O₃ catalyst support exhibited a high surface area of 245 m²/g and average pore volume of 0.481 cm³/g. The DRIFTS results indicate the existence of large Lewis's acid regions in the pure γ-Al₂O₃ and metal-containing catalysts. Catalytic activity tests of pure materials and metal-containing catalysts were carried out at the reaction temperature of 750 °C and a feed molar ratio of AA/H₂O/Ar:1/2.5/2 over 3 h. Complete conversion of acetic acid and 81.75% hydrogen selectivity were obtained over the catalyst 5Ni@γ-Al₂O₃. The temperature and feed molar ratio had a noticeable impact on H₂ selectivity and acetic acid conversion. Increasing the water proportion in the feed composition from 2.5 to 10 considerably improved the catalytic activity by increasing hydrogen selectivity from 81.75% to 91%. Although the Ni-based γ-Al₂O₃-supported catalysts exhibited higher activity performance compared to the Ni-based MgO-supported catalysts, they were not as resistant to coke formation as were MgO-supported catalysts. The introduction of MgO and La₂O₃ into the Ni@γ-Al₂O₃ and Ni@MgO catalysts' structures played a significant role in lowering the carbon formation (from 37.15% to 17.6%–12.44% and 12.17%, respectively) and improving the thermal stability of the catalysts by decreasing the agglomeration of acidic sites and reinforcing the adsorption of CO₂ on the catalysts' surfaces. Therefore, coke deposition was reduced, and catalyst lifetime was improved.     

High purity hydrogen production via aqueous phase reforming of xylose over small Pt nanoparticles on a γ-Al2O3 support

In this study, aqueous phase reforming (APR) of xylose was conducted over highly dispersed Pt nanoparticles supported on a γ-Al₂O₃ support (Pt-SNP). Formation of small Pt nanoparticles was confirmed by X-ray diffraction and transmission electron microscopy, which revealed that most of the particles ranged between 0.8 and 1.6 nm in size and the average particle size was 1.3 nm. Temperature-programmed reduction analysis indicated that these small Pt nanoparticles were highly reducible under the reducing environment compared to the commercial Pt/γ-Al₂O₃ catalysts (Pt-commercial). The catalytic activities of both Pt-SNP and Pt-commercial catalysts were examined in a semi-batch autoclave reactor system for the APR of xylose. It was found that Pt-SNP showed higher carbon to gas conversion with high hydrogen selectivity than Pt-commercial. This was likely due to the increased density of edge sites in the Pt-SNP catalyst that facilitated the cleavage of the C–C bonds rather than the C–O bonds, leading to greater hydrogen production. Furthermore, the Pt-SNP catalyst showed better carbon deposit resistance as compared to Pt-commercial. The amount of carbon deposition on the Pt-SNP catalyst surface and the organic carbon species dissolved in the post-reaction xylose solution were significantly lower compared to that of Pt-commercial. Finally, high purity hydrogen production was achieved using a continuous fixed-bed hybrid reactor including an aqueous phase reformer and a home-made Pd/Ta dense metallic composite membrane. A stable hydrogen gas production (99.999%) was obtained over the Pt-SNP catalyst, which demonstrated the success of a potentially commercial APR reactor system that continuously converted the aqueous xylose solution to hydrogen with high purity.     

A highly dispersed Pt/γ-Al2O3 catalyst prepared via deposition–precipitation method for preferential CO oxidation

Highly dispersed Pt/γ-Al₂O₃ catalysts were prepared by deposition–precipitation (DP) method with precursor solutions of various pH. The pH was controlled from 6.5 to 9.5 with 5 wt% NaOH solution. As the pH of precursor solution increases over pH 7.5, the metal dispersion and surface PtO_x species decrease and the Pt particle size increases. PrOx test was carried out with a space velocity of 60,000 mL/h g_cat in temperature ranges from 100 to 200 °C. The [O₂]/[CO] ratio was adjusted between 1 and 2 and the effect of H₂O and CO₂ was examined at [O₂]/[CO] = 2. It is interesting that the CO conversion has good agreement with the Pt metal dispersion. In addition, highly dispersed Pt/γ-Al₂O₃ catalyst prepared by DP with pH 7.5 exhibited good catalytic activity below 150 °C in PrOx due to the improvement of the metal dispersion and reducibility of surface PtO_x species at low temperatures compared with the catalyst prepared by impregnation method.     

On the role of size controlled Pt particles in nanostructured Pt-containing Al2O3 catalysts for partial oxidation of methane

The effect of the Pt loadings and particles sizes on the stability of Pt(x wt%)/Al₂O₃ catalysts were investigated in the partial oxidation of methane (POM) reaction. The Al₂O₃ support was prepared by sol-gel method and different Pt loadings, varying from 0.5 to 2.0 wt% were incorporated to alumina through the incipient wetness impregnation method. The physicochemical features of the catalysts were determined by XRD, ICP-OES, Nitrogen-sorption, UV–Visible, H₂-TPR, CO-DRIFTS, SEM-EDS, XPS and HRTEM techniques. The metal dispersion was evaluated in the cyclohexane dehydrogenation reaction. Lower Pt loadings resulted in well dispersed Pt^o nanoparticles with an enhanced activity in cyclohexane dehydrogenation and POM reactions. With increasing Pt loading to 2.0 wt%, the Pt nanoparticles of the Pt(2.0 wt%)/Al₂O₃ showed a methane conversion of 63% in 24 h of time on stream, and the catalyst was very selective to H₂ and CO. Based on the HRTEM, XPS and Raman spectroscopy techniques, an increment in the Pt loadings evidenced an enrichment of Pt^o clusters on the surface, however, no heavy carbon deposits formation was observed.     

Insights into the effects of Pt and PtOx site for electrocatalytic water gas shift reaction via altering supports and calcinated temperatures

Electrocatalytic water-gas shift reaction (EWGSR) at room temperature and atmospheric pressure is an emerging process for high-pure hydrogen production without an additional H₂ separation procedure. Therefore, developing efficient electrocatalysts of EWGSR is one of the critical factors for its wide applications. Herein, the effects of support and calcinated temperature on the EWGSR performance are highlighted by systematically investigating the Pt/γ-Fe₂O₃, Pt/CeO₂, Pt/TiO₂, and Pt/α-Fe₂O₃ catalysts. The results reveal that the γ-Fe₂O₃ supported Pt catalyst (calcined at 400 °C) exhibits the lowest anodic onset potential and the highest activity compared to these prepared catalysts, and the mass activity is 3.5 times as high as 20% Pt/C. Furthermore, the onset potential for the EWGSR shows a strong correlation with the active O in the amorphous PtOx structures, where the active O atoms can promote the activation of the OH⁻ and reduce the onset potential of the reaction. The significantly enhanced catalytic performance and durability are more responsible for the exposed Pt⁰ and the weak adsorption of CO on the Pt/γ-Fe₂O₃ catalyst. This study provides a new and promising route for designing excellent Pt catalysts for EWGSR in the hope that it can be helpful to the scholars in this orientation.     

The effect of Ni:Pt ratio on oxidative steam reforming performance of Pt–Ni/Al2O3 catalyst

Oxidative steam reforming of propane was tested over four Pt–Ni/δ-Al₂O₃ bimetallic catalysts aiming to investigate the effect of metal loadings and Ni:Pt loading ratio on catalyst performance. A trimetallic Pt–Ni–Au/δ-Al₂O₃ catalyst was additionally studied aiming to understand the effect of Au presence. Reaction temperature, carbon to oxygen ratio, and residence time were taken as the reaction parameters. The effect of C/O₂ ratio on the hydrogen production and H₂/CO selectivity was found dependent on the Pt and Ni loadings. The results underlined the importance of C/O₂ ratio as an optimization parameter for product distribution. The highest hydrogen production and H₂/CO ratio levels were obtained for the highest C/O₂ ratio tested. An optimum Ni:Pt weight ratio was found around 50 due to suppressed methanation and enhanced hydrogen production activities of these catalysts. The presence of gold in the trimetallic catalyst caused poor activity and selectivity in comparison to bimetallic catalysts.     

Study of the use of a Pd–Pt-based catalyst for the catalytic combustion of storage tank VOCs

Catalytic combustion is a very cost-effective way to eliminate volatile organic compounds (VOCs). The components of the VOCs in storage tanks are complex, with alkanes, alkenes and aromatic hydrocarbons being the main components. The aromatic hydrocarbons are the most difficult organic compounds among the storage tank VOCs in terms of catalysing combustion, and they are easy to cause catalyst carbon deposition. In this work, the Pt/γ-Al₂O₃, Pd/γ-Al₂O₃, Pd–Pt/γ-Al₂O₃, Pd–Pt/CeO₂/γ-Al₂O₃ and Pd–Pt/CeO₂/γ-Al₂O₃–N catalysts were prepared using an incipient wetness impregnation method. The performances of the catalysts were investigated using toluene and a simulation of VOCs in gas in a storage tank as model reactants. The study found that Pt has a higher catalytic combustion activity than Pd for the alkanes in the VOC gas in the simulation storage tank, and Pd has a higher catalytic combustion activity than Pt for the alkenes and toluene in the VOC gas in the simulation storage tank. The Pt addition enhances the activity of Pd-based catalysts for VOC catalytic combustion, and the Pd–Pt active component has good active stability. The catalyst prepared by using Pd–Pt alone has a defect in that it exhibits an insufficient oxygen supply performance in the catalytic combustion process. The addition of CeO₂ improves the oxygen supply performance of the Pd–Pt-based catalyst. In addition, the activity of the Pd–Pt/CeO₂/γ-Al₂O₃–N catalyst prepared by reducing the validated amount of Pd–Pt is higher than that of a commercial catalyst.     

Improved charge transfer and morphology on Ti-modified Cu/γ-Al2O3/Al catalyst enhance the activity for methanol steam reforming

The metal-oxide interaction has been considered as an effective factor for catalytic performance in methanol steam reforming. In this work, Ti modified Cu/γ-Al₂O₃/Al catalyst was prepared by anodization technology. It is found that the addition of Ti can largely increase the surface area of the carrier and thus improve the dispersion of copper. The co-existence of Ti⁴⁺ and Ti³⁺ makes the charge transfer between Cu and Ti easier, which improves the redox performance of copper. The DFT calculations reveal that Ti also enhance the adsorption capacity of water and methanol on the surface of the catalysts. Besides, Ti also reduce the acid density on the carrier, inhibit methanol dehydration reaction and thereby reduce the selectivity of the DME. The optimal catalyst CuTi_1.9/γ-Al₂O₃/Al achieves nearly 100% conversion at 275 °C, while the methanol conversion of Cu/γ-Al₂O₃/Al is 82%. And the H₂ output of CuTi_1.9/γ-Al₂O₃/Al reached 69.17 mol/(kg_cat·h) at 300 °C.     

Highly dispersed mesoporous Cu/γ-Al2O3 catalyst for RWGS reaction

The extensive use of fossil energy leads to the wanton emission of CO₂ and serious environmental problems. The resource utilization of CO₂ is an effective way to solve this problem. The key of CO₂ resource utilization is the design and preparation of high active CO₂ hydrogenation catalyst. In this paper, supported Cu/γ-Al₂O₃ catalysts were prepared by wet impregnation and grinding methods, respectively. The physicochemical properties of the prepared Cu/γ-Al₂O₃ catalysts were characterized by XRD, BET, CO₂-TPD and Quasi in-situ XPS, and the reducibility of the precursors was studied by H₂-TPR. The results show that Cu content directly affects the Cu⁰ species crystallinity and even affects the adsorption and activation of CO₂ molecules for the Cu/γ-Al₂O₃ catalyst. The dispersion of Cu⁰ species in the prepared Cu/γ-Al₂O₃ catalysts can be further improved by grinding method. The CO₂ reaction rate on the Cu/γ-Al₂O₃ catalyst prepared by grinding method can be significantly increased to 2.12 × 10^?5 mol/g_cat/s at 400 °C.     

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.     

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.     

Hydrogen evolution by templated cadmium indate nanoparticles under natural sunlight illumination

Carbon-doped cadmium indate (CdIn₂O₄) nanoparticles were synthesized by a sol–gel templating method using the block co-polymer surfactant Pluronic F127 and evaluated for hydrogen generation activity under artificial and natural solar illumination. Each catalyst powder was loaded with platinum as a cocatalyst in order to promote charge carrier separation. BET surface area measurements indicated an increase in surface area with F127 introduction of up to 5 times the area of the non-templated sample. Natural sunlight illumination experiments showed the hydrogen evolution rate of CdIn₂O₄ was 17 μmol h⁻¹ as compared to 2.1 μmol h⁻¹ for the Pt:TiO₂ reference material. The H₂ rate was determined to be similar under both stirring and non-stirring conditions for the CdIn₂O₄ catalyst, which resulted from 10 min irradiation exposure times. Laboratory experiments confirmed this effect and showed that at longer, out to 60 min, irradiation times the evolution rate was 3 times greater for stirred over non-stirred samples. The templated nanoparticle CdIn₂O₄ catalysts are promising for solar hydrogen conversion.     

Hydrogen generation from Al-Water reaction promoted by M-B/γ-Al2O3 (M = Co,Ni) catalyst

Al-water reaction promoted by catalysts is a promising hydrogen generation technology. In this work, a high-activity M-B/γ-Al₂O₃ (M = Co, Ni) catalyst is prepared by wet chemical reduction method. It is found that M-B/γ-Al₂O₃ catalyst significantly promotes the Al-water reaction and decreases the induction time. When the molar ratio of γ-Al₂O₃ to Co-M in Co–B/γ-Al₂O₃ catalyst is 1:1, the induction time is only 0.43 h. The catalytic activity of M-B/γ-Al₂O₃ is proportional to its active area. SEM analyses show that M-B particles are dispersed on γ-Al₂O₃ surface, which reduces the agglomeration of M-B and increases the active surface of M-B/γ-Al₂O₃, leading to a high catalytic activity. A possible mechanism is proposed, which shows that the dissociation of water molecules on γ-Al₂O₃ surface and the microgalvanic interaction between M-B and Al can promote the hydration process of passive oxide film on Al particle surface, speeding up the Al-water reaction.     

Catalysts for hydrogen production in a multifuel processor by methanol,dimethyl ether and bioethanol steam reforming for fuel cell applications

Methanol, dimethyl ether and bioethanol steam reforming to hydrogen-rich gas were studied over CuO/CeO₂ and CuO–CeO₂/γ-Al₂O₃ catalysts. Both catalysts were found to provide complete conversion of methanol to hydrogen-rich gas at 300–350 °C. Complete conversion of dimethyl ether to hydrogen-rich gas occurred over CuO–CeO₂/γ-Al₂O₃ at 350–370 °C. Complete conversion of ethanol to hydrogen-rich gas occurred over CuO/CeO₂ at 350 °C. In both cases, the CO content in the obtained gas mixture was low (<2 vol.%). This hydrogen-rich gas can be used directly for fuelling high-temperature PEM FC. For fuelling low-temperature PEM FC, it is needed only to clean up the hydrogen-rich gas from CO to the level of 10 ppm. CuO/CeO₂ catalyst can be used for this purpose as well. Since no individual WGS stage, that is necessary in most other hydrogen production processes, is involved here, the miniaturization of the multifuel processor for hydrogen production by methanol, ethanol or DME SR is quite feasible.     

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).