Insights into catalytic behavior of TiMgn (n=1–12) nanoclusters in hydrogen storage and dissociation process: A DFT investigation

The present study reports the insight of the catalytic behavior of TiMg_n (n = 1–12) nanoclusters in hydrogenation and dissociation reaction mechanism under density functional theory (DFT) investigation. From the variation of thermodynamic and chemical parameters during growth process of TiMg_n, 18-electron TiMg₇ cluster is found as the most stable with orbital sequence 1S²1P⁶1D¹⁰. However, after hydrogenation TiMg₅ is found as the most efficient catalyst in hydrogenation and dissociation reaction. Following the calculated IRC path of the hydrogenation reaction process (H₂+TiMg₅→TiMg₅–2H), it is found that the low activation barrier and reaction energy helps in hydrogenation-dissociation process; and also in the reduction of dehydrogenation temperature. Calculated ELF confirms that the dissociated hydrogen tends to localize on the outer surface of the TiMg₅ cluster. The present investigation provides strong evidence of efficient catalytic behavior of TiMg₅ in hydrogenation process. The findings are important for designing TiMg_n based catalyst in hydrogen storage and dissociation reaction.     

Temperature controlled three-stage catalytic dehydrogenation and cycle performance of perhydro-9-ethylcarbazole

Organic liquid heteroaromatic compounds, e.g. 9-ethylcarbazole, are potentially promising hydrogen storage materials because they can be catalytically hydrogenated and dehydrogenated at relatively moderate temperatures. In the present work, the cyclic hydrogenation of 9-ethylcarbazole and the temperature controlled stage-wise dehydrogenation of perhydro-9-ethylcarbazole were investigated. Full hydrogenation of 9-ethylcarbazole was realized over a 5 wt% Ru/Al₂O₃ catalyst at 180 °C and 80 bar, yielding a gravimetric density of 5.79 wt%. The catalytic dehydrogenation of perhydro-9-ethylcarbazole over a 5 wt% Pd/Al₂O₃ catalyst was found to undergo a three-stage process, i.e. perhydro-9-ethylcarbazole → octahydro-9-ethylcarbazole, octahydro-9-ethylcarbazole → tetrahydro-9-ethylcarbazole, and tetrahydro-9-ethylcarbazole → 9-ethylcarbazole with the initial reaction temperatures of 128 °C, 145 °C and 178 °C, respectively. Our results indicate that 9-ethylcarbazole displays an excellent cycle performance with very little capacity degradation after 10 cycles of catalytic hydrogenation and dehydrogenation. The hydrogen gas produced from the dehydrogenation possesses a high purity of over 99.99% with no carbon monoxide or other poisonous gases for fuel cells.     

Concept design of a novel reformer producing hydrogen for internal combustion engines using fuel decomposition method: Performance evaluation of coated monolith suitable for on-board applications

Hydrogen addition effectively reduces the fuel consumption of spark ignition engines. We propose a new on-board reformer that produces hydrogen at high concentrations and enables multi-mode operations. For the proposed reformer, we employ a catalytic fuel decomposition reaction via a commercial NiO–CaAl₂O₄ catalyst. We explore the physical and chemical aspects of the reforming process using a fixed bed micro-reactor operating at temperatures of 550–700 °C. During reduction, methane is decomposed to form hydrogen and carbon. Carbon formation is critical to hydrogen production, and free space for carbon growth is essential at low temperatures (≤600 °C). We define a new accumulated conversion ratio that quantitatively measures highly transient catalytic decomposition. The free space of the coated monolith clearly aided low-temperature decomposition with negligible pressure drop. The coated substrate is therefore suitable for on-board applications considering that our reformer concept also utilizes the catalytic fuel decomposition reaction.     

Kinetics of the in−situ hydrogenation of phenol with formic acid as a hydrogen source

Highly active phenolic compounds in biomass pyrolysis oil are an important factor for limiting the utilization of the biofuel. The catalytic hydrogenation of phenolic compounds is considered to be an effective method for reforming bio?oil. Pd/CB (carbon black), which was synthesized by using a facile impregnated method, is found to be an effective catalyst for the in-situ hydrogenation of phenol (a representative model compound of bio?oil) using FA as a hydrogen source to produce cyclohexanone. A 98.99% of the conversion of phenol and 90.20% of the selectivity of cyclohexanone were obtained under the optimized reaction conditions. The catalyst also showed excellent stability after three recycled process. The catalytic kinetics study of the in?situ hydrogenation of phenol was investigated using Power?Rate Law model and Langmuir?Hinshelwood model. The Langmuir?Hinshelwood model fit well to the experimental data and the apparent activation energies (E_a) was 50.96 kJ mol^?1.     

Production of a hydrogen-rich gas from fast pyrolysis bio-oils: Comparison between homogeneous and catalytic steam reforming routes

The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: catalytic and non-catalytic steam reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final steam reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the steam reforming experiments, catalytic and non-catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different catalytic reactors were tested in the catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H₂ yields were as follows: catalytic steam reforming of the aqueous fractions in fixed bed (0.17 g H₂/g organics) > non-catalytic steam reforming of the bio-oils (0.14 g H₂/g organics) > non-catalytic steam reforming of the aqueous fractions (0.13 g H₂/g organics) > catalytic steam reforming of the aqueous fractions in fluidized bed (0.07 g H₂/g organics). These different H₂ yields are a consequence of the different temperatures used in the reforming processes (650 °C and 1400 °C for the catalytic and the non-catalytic, respectively) as well as the high spatial velocity employed in the catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.     

A kinetic model for analyzing partial oxidation reforming of heavy hydrocarbon over a novel self-sustained electrochemical promotion catalyst

A kinetic model for analyzing catalytic partial oxidation reforming (POXR) of n-pentadecane over a novel self-sustained electrochemical promotion (SSEP) catalyst which accelerated the reaction rate at relatively lower temperatures below 650 °C was proposed. The SSEP-POXR model consists of two parts: a conventional Langmuir–Hinshelwood (L–H) model, describing normal partial oxidation reforming and a new model describing the SSEP mechanism. The kinetic parameters of L–H model were estimated by curve-fitting experimental results of POXR of n-pentadecane on a conventional Ni/NiO/Cu/CeO₂ catalyst whereas those for the SSEP process were evaluated using typical geometric configurations of components of the SSEP catalyst and their electrochemical properties. The SSEP-POXR model was used to establish a relationship between input and output parameters and explain the trend of the experimental results in terms of the impact of temperature on the fuel conversion. The computational results agreed well with experimental results of the POXR of n-pentadecane on the SSEP catalyst in a temperature range of 450–650 °C. The maximum error of computational results of fuel conversion was 3.1% in the reaction temperature range. The SSEP-POXR model is capable of quantifying the enhancement of the fuel conversion attributed to the SSEP process.     

Ni–Mo nanoparticles stabilized by ether functionalized ionic polymer: A novel and efficient catalyst for hydrodeoxygenation of 4-methylanisole as a representative of lignin-derived pyrolysis bio-oils

In the present study, nickel-molybdenum nanoparticles stabilized with ether functionalized ionic polymer were synthesized and utilized as a novel and efficient catalyst for hydrodeoxygenation of 4-methylanisole as a representative of lignin-derived bio-oil. The catalytic upgrading process was performed in the presence of hydrogen with a batch reactor at temperature of 80–200 °C, hydrogen pressure of 10–50 bar, reaction time of 0.5–15 h and catalyst loading of 1–5 mol%. The major reaction classes during 4-methylanisole upgrading were hydrodeoxygenation and hydrogenolysis which resulted in production of 4-methylphenol, toluene, phenol and benzene as the main products. The experimental results indicated that the catalytic activity of Ni–Mo (20%–80%) nanoparticles stabilized with ionic polymer is superior to that with low Mo content. Also, it is observed that the selectivity of deoxygenated products including toluene and benzene improves with increasing the Mo content of the catalyst. Finally, regarding to the excellent catalytic activity of synthesized nanocatalyst during upgrading process of bio-oil at mild operating condition, ether functionalized ionic polymer was introduced as an applicable and effective stabilizers for nickel-molybdenum nanoparticles.     

Fe3C/C nanoparticles encapsulated in N-doped graphene aerogel: an advanced oxygen reduction reaction catalyst for fiber-shaped fuel cells

Flexible fuel cells directly convert the chemical energy to electricity, and represent one of the most promising power generators using in bendable electronic equipments such as curved displays and wearable devices. The ambient oxygen is the most acceptable oxidant, and therefore the design of highly actived and low cost oxygen reduction reaction (ORR) catalysts is extremely important for future commercialization. Here we report a facile process to fabricate the catalyst by encapsulating the Fe₃C/C nanoparticles on the nitrogen-doped graphene aerogel scaffolds. Benefitting from the meso-porous structure and presence of Fe–N–C functionalities that serve as the catalytic sites, the conductivity and active-site accessibility in the composites are significantly improved. The resulting hybrid electrocatalysts show a comparable catalytic performance with 20 wt% commercial Pt/C powder, but possess a much lower capital cost and higher tolerance to fuel in the durability test. Consequently, the fiber-shaped fuel cell delivers a high-power density of 4.57 W m⁻² and current density of 22.5 A m⁻², outperforming many flexible fuel cells reported previously. Such a non-noble-metal ORR catalyst opens new avenue to trigger the electricity generation by fiber-shaped fuel cell under the folded and rolled-up conditions.     

Effects of structure on the carbon dioxide methanation performance of Co-based catalysts

Mesoporous Co/KIT-6 and Co/meso-SiO₂ catalysts were prepared via hydrogen reduction and were subsequently used in CO₂ catalytic hydrogenation to produce methane. The properties of these catalysts were investigated via low-angle X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, and transmission electron microscopy (TEM). The results indicate that the synthesized Co/KIT-6 and Co/meso-SiO₂ catalysts have mesoporous structures with well-dispersed Co species, as well as high CO₂ catalytic hydrogenation activities. The Co/KIT-6 catalyst has a large specific surface area (368.9 m² g⁻¹) and a highly ordered bicontinuous mesoporous structure. This catalyst exhibits excellent CO₂ catalytic hydrogenation activity and methane product selectivity, which are both higher than those of the Co/meso-SiO₂ catalyst at high reaction temperatures. The CO₂ conversion and methane selectivity of the Co/KIT-6 catalyst at 280 °C are 48.9% and 100%, respectively. The high dispersion of the Co species and the large specific surface area of the prepared Co-based catalysts contribute to the high catalytic activities. In addition, the highly ordered, bicontinuous, mesoporous structure of the Co/KIT-6 catalyst improves the selectivity for the methane product.     

A highly efficient and stable catalyst for liquid phase catalytic exchange of hydrogen isotopes in a microchannel reactor

The liquid phase catalytic exchange of hydrogen isotopes is a promising process for upgrading recycle water in nuclear power station. To facilitate the isotope catalytic reaction, a series of two-dimensional hydrophobic catalysts of Pt/modified carbon nitride (Pt/s-C₃N₄) with different Pt loadings were fabricated and applied in microchannel reactor. Their excellent catalytic performances were found in our experiments by comparing with purchased Pt/activated carbon (Pt/AC), the Turn-Over-Frequency (TOF) of Pt/s-C₃N₄ is 3 times higher than Pt/AC. Because the Pt clusters of 0.82 ± 0.08 nm were uniformly distributed on the support of two-dimensional carbon nitride (C₃N₄) to improve availability of the Pt catalyst by exposing more active sites and decreasing effect of the internal diffusion. The catalytic activity of Pt/s-C₃N₄ catalysts remained stable after 1800 min reaction, whereas Pt/AC displayed a 20% drop. Hydrophobicity of the catalyst maintained its high activity and stability in the liquid phase catalytic exchange reaction.     

Highly dispersed NiCu nanoparticles on SBA-15 for selective hydrogenation of methyl levulinate to γ-valerolactone

Copper and nickel nanoparticles highly dispersed on an ordered mesoporous silica support (SBA-15) were prepared by a glycol-assisted impregnation method and tested for the catalytic transfer hydrogenation reaction of methyl levulinate to γ-valerolactone (GVL). Characterizations by high resolution transmission electron microscopy, X-ray diffraction, N₂ sorption, H₂ temperature-programmed reduction and X-ray absorption spectroscopy confirm that the highly dispersed nanoparticles were well-anchored to the mesopores of SBA-15 with the strong interaction. Comparing to a catalyst synthesized by a conventional aqueous impregnation method, our catalyst shows a higher conversion and greater selectivity towards GVL of reaction at 140–170 °C using 2-propanol as a solvent and a hydrogen donor. Results showed that NiCu/SBA-15 (EG) had much better activity, providing 91.3% conversion of ML with 89.7% selectivity towards GVL in 3 h at 140 °C. The high compositional homogeneity, uniform distribution of the nanoparticles in the mesoporous channels and the strong interaction between the metal nanoparticles and SBA-15 contribute to the superior catalytic performance. This catalyst also demonstrates superb stability over the course of 5 reaction cycles without significant loss in catalytic activity and selectivity towards GVL formation.     

Slow catalytic pyrolysis of rapeseed cake: Product yield and characterization of the pyrolysis liquid

The performance of three catalysts during slow catalytic pyrolysis of rapeseed cake from 150 to 550 °C over a time period of 20 min followed by an isothermal period of 30 min at 550 °C was investigated. Na₂CO₃ was premixed with the rapeseed cake, while γ-Al₂O₃ and HZSM-5 were tested without direct biomass contact. Catalytic experiments resulted in lower liquid and higher gas yields. The total amount of organic compounds in the pyrolysis liquid was considerably reduced by the use of a catalyst and decreased in the following order: non-catalytic test (34.06 wt%) > Na₂CO₃ (27.10 wt%) > HZSM-5 (26.43 wt%) > γ-Al₂O₃ (21.64 wt%). In contrast, the total amount of water was found to increase for the catalytic experiments, indicating that dehydration reactions became more pronounced in presence of a catalyst. All pyrolysis liquids spontaneously separated into two fractions: an oil fraction and aqueous fraction. Catalysts strongly affected the composition and physical properties of the oil fraction of the pyrolysis liquid, making it promising as renewable fuel or fuel additive. Fatty acids, produced by thermal decomposition of the biomass triglycerides, were converted into compounds of several chemical classes (such as nitriles, aromatics and aliphatic hydrocarbons), depending on the type of catalyst. The oil fraction of the pyrolysis liquid with the highest calorific value (36.8 MJ/kg) was obtained for Na₂CO₃, while the highest degree of deoxygenation (14.0 wt%) was found for HZSM-5. The aqueous fraction of the pyrolysis liquid had opportunities as source of added-value chemicals.     

Elucidating reaction equations of TiFx (x = 4,3,2) catalysts for hydrogen storage applications

In the never ending quest for clean energy, storing chemical energy in the form of hydrogen molecules in solid state materials is a premier choice. The release of H₂ from the H-storage (absorbent) material is hindered by the on-set of reaction mechanism which depends on the energy barrier. In a search for efficient onset (re)hydrogenation temperature, stimuli like catalysts have drawn more attention in the hydrogen fuel economy. It is laborious to down-select the aspirant candidates by screening their material properties and the thermochemical energy which are required for bond breaking. An understanding on perceptible energies involved in breaking/creating bonds has been obtained using the novel “Interface Reaction tool”. To enlighten the underpinning catalytic reaction mechanism to the absorbent, the energetics of interactions between the catalyst and the solid metal hydrides have been derived. For this test study, a leading catalyst TiF_x (x = 4,3, and 2) has been added to the well-studied high gravimetric metal hydrides such as MgH₂, Mg(BH₄)₂, and Mg(AlH₄)₂. The reaction equation at ambient condition has been validated using the total energies from Kohn-Sham density-functional-theory, and the outcome emphasizes the importance of bonding analysis. Hence, we exemplified the bonding states of all the Ti–F derivatives namely TiF₄, TiF₃ and TiF₂ in an effort to elucidate the role of fluorine for the onset of catalytic reaction. Our detailed analysis of reaction pathways indicate the vitality of TiF₄ as an additive before and after the H₂ release. Our work pioneers the study on often overlooked reaction possibilities at ambient condition. The calculated reaction energy of less than 40 kJ/mol and 4.64 wt % of H₂ release for TiF₄ and TiF₃ underscores their catalytic activity and meet the system targets set by DoE for the year 2020. This work presents “significant disclosures” on the hydrogen decomposition mechanism and provides a platform for the feasibility study of a new material. This proposes an innovative methodology for predicting the suitability of a new material for efficient production of H₂ fuel.     

ZIF-L-Co@carbon fiber paper composite derived Co/Co3O4@C electrocatalyst for ORR in alkali/acidic media and overall seawater splitting

Green and clean energy technologies, including fuel cells, metal-air batteries, water splitting et al., are becoming more significant for our lives. Oxygen reduction reaction (ORR), hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are key reaction processes for fuel cells, metal-air batteries and water splitting. Therefore, it is highly desirable to design a multifunctional catalyst, which owns catalytic performance under a widely applied range. Herein, we demonstrate a novel multifunctional catalyst (Co/Co₃O₄@C) by carbonizing a composite material constructed of zeolite imidazolate framework and carbon fiber paper (ZIF-L-Co@CP). It is a carbon-based material containing metallic Co and Co₃O₄ as a low-cost and effective catalyst toward the ORR and overall water splitting. For ORR, the Co/Co₃O₄@C catalyst shows high half-wave potential in both alkaline and acidic media, 0.823 V for 0.1 M KOH and 0.672 V for 0.1 M HClO₄. More importantly, it exhibits good catalytic activities of hydrogen and oxygen evolutions to perform overall splitting in actual seawater.     

Simultaneous dehydrogenation of 1,4- butanediol to γ-butyrolactone and hydrogenation of benzaldehyde to benzyl alcohol mediated over competent CeO2–Al2O3 supported Cu as catalyst

Hydrogen being a dynamically impending energy transporter is widely used in hydrogenation reactions for the synthesis of various value added chemicals. It can be obtained from dehydrogenation reactions and the acquired hydrogen molecule can directly be utilized in hydrogenation reactions. This correspondingly avoids external pumping of hydrogen making it an economical process. We have for the first time tried to carryout 1,4-butanediol dehydrogenation and benzaldehyde hydrogenation simultaneously over ceria-alumina supported copper (Cu/CeO₂–Al₂O₃) catalyst. In this concern, 10 wt% of Cu supported on CeO₂–Al₂O₃ (3:1 ratio) was synthesized using wet impregnation method. The synthesized catalyst was then characterized by various analytical methods such as BET, powder XRD, FE-SEM, H₂-TPR, NH₃ and CO₂-TPD, FT-IR and TGA. The catalytic activity towards simultaneous 1,4-butanediol dehydrogenation and benzaldehyde hydrogenation along with their individual reactions was tested for temperature range of 240 °C–300 °C. The physicochemical properties enhanced the catalytic activity as clearly interpreted from the results obtained from the respective characterization data. The best results were obtained with 10 wt% of Cu supported on CeO₂–Al₂O₃ (3:1 ratio) catalyst with benzaldehyde conversion of 34% and 84% selectivity of benzyl alcohol. The conversion of 1,4-butanediol was seen to be 90% with around 95% selectivity of γ-butyrolactone. The catalyst also featured physicochemical properties namely increased surface area, higher dispersion and its highly basic nature, for the simultaneous reaction towards a positive direction. In terms of permanence, the Cu/CeO₂–Al₂O₃ (10CCA) catalyst was quite steady and showed stable activity up to 24 h in time on stream profile.     

Enhanced Electro-catalytic Activity of Nitrogen-doped Reduced Graphene Oxide Supported PdCu Nanoparticles for Formic Acid Electro-oxidation

Successful commercialization of direct formic acid fuel cells (DFAFCs) is restricted because of its apparent instability in acidic medium and high cost of typically noble metal based anode catalyst. To adequately address these key issues, in this work, a series of palladium-copper alloy catalyst supported on nitrogen-doped reduced graphene oxide (N-rGO) were synthesized via wet chemical reduction process. Several microscopic and spectroscopic techniques were employed to determine the crystal pattern, particle size, composition and morphology of the synthesized material. Electro-catalytic performance of the synthesized catalysts was carefully verified with respect to formic acid oxidation. All N-doped reduced graphene oxide (N-rGO) supported catalyst show enhanced catalytic activity in comparison to commercial Pd/C catalyst. Electrochemical study reveals precisely that Pd₇₅Cu₂₅/N-rGO catalysts have highest electro catalytic activity 1738 mA mg⁻¹_pd among all synthesized catalyst which is 3.67 times higher than commercial Pd/C catalyst. Pd₇₅Cu₂₅/N-rGO catalyst show lowest Tafel slope (119 mV dec⁻¹) and excellent stability after 250 potential cycles. These extensive studies signify that N-rGO support material can remarkably improve the catalytic activity and stability of the catalysts which may be due to outstanding electron transfer capability and synergy between PdCu metallic and N-rGO support. This work helps further design of alloy nanoparticles on N-rGO support as a highly active and stable catalyst for application in the fuel cell.     

Catalytic upgrading of 4-methylaniosle as a representative of lignin-derived pyrolysis bio-oil: Process evaluation and optimization via coupled application of design of experiment and artificial neural networks

Catalytic upgrading of 4-methylanisole as a representative of lignin-derived pyrolysis bio-oil was investigated over Pt/γ-Al₂O₃ catalyst. The catalytic upgrading process was conducted at different operating condition to determine the detailed reactions network. Additionally, artificial neural network and design of experiment were applied by feeding the reaction temperature, operating pressure and space velocity to predict 4-methylanisole conversion, main products selectivity, reactions rate and reactions network. The main products of 4-methylanisole upgrading were toluene, phenol derivatives, cyclohexanone, 4-methylcyclohexanone, and 2-tert-butyl-4-methylphenol. The major classes of reactions during the upgrading process were hydrogenolysis, hydrodeoxygenation, alkylation, and hydrogenation. For optimization of experimental data obtained at suggested conditions by design of experiment, the response surface methodology was applied. Artificial neural network model was used to investigate the kinetics behavior of the system due to the complex nature of system. A combination of the response surface methodology, artificial neural network, and design of experiment has revealed its ability to solve a quadratic polynomial model. The coefficients of determination were close to 1, and the mean square error of the artificial neural network model was close to 0 which showed the high accuracy of model predictions. It was inferred that during the upgrading process of 4-methylanisole, increasing temperature and pressure and setting space velocity at the minimum value are the reasons to come close to the optimum reaction rate. The comparison of experimental results with simulated data from the artificial neural network and the response surface methodology models illustrated that the developed model can create an applicable situation for practical design of large-scale production of valuable fuels from renewable resources.     

A lithium-air battery with a potential to continuously reduce O2 from air for delivering energy

A lithium-air battery, in which the catalytic reduction of O₂ in an alkaline aqueous electrolyte and the metallic lithium in a non-aqueous electrolyte were subtly united together by a super-ionic conductor glass film (LISICON), was established in the present work. For this system, Mn₃O₄ based air diffusion electrode and metallic lithium were used as positive electrode and negative electrode, respectively. 500 h continuous discharge performance indicates that this kind of lithium-air battery has a potential to realize continuous reduction of O₂ from air to deliver energy like a fuel cell. During the long-time discharge process, the air electrode has delivered a special capacity of 50,000 mAh g⁻¹ based on total mass of catalytic electrode (carbon + binder + catalyst). This result is much higher than that of previous studies about Lithium-air batteries.     

Preparation, characterization and application of heterogeneous solid base catalyst for biodiesel production from soybean oil

A solid base catalyst was prepared by neodymium oxide loaded with potassium hydroxide and investigated for transesterification of soybean oil with methanol to biodiesel. After loading KOH of 30 wt.% on neodymium oxide followed by calcination at 600 °C, the catalyst gave the highest basicity and the best catalytic activity for this reaction. The obtained catalyst was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), N₂ adsorption-desorption measurements and the Hammett indicator method. The catalyst has longer lifetime and maintained sustained activity after being used for five times, and were noncorrosive and environmentally benign. The separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and reaction time were investigated. The experimental results showed that a 14:1 M ratio of methanol to oil, addition of 6.0% catalyst, 60 °C reaction temperature and 1.5 h reaction time gave the best results and the biodiesel yield of 92.41% was achieved. The properties of obtained biodiesel are close to commercial diesel fuel and is rated as a realistic fuel as an alternative to diesel.     

Photo-generation of ultra-small Pt nanoparticles on carbon-titanium dioxide nanotube composites: A novel strategy for efficient ORR activity with low Pt content

Despite extensive work on Pt/C based catalyst materials for fuel cells towards oxygen reduction reaction, the high cost of catalyst is still a major problem for efficient use of fuel cells in daily life. This demands at designing a new electrocatalyst with high catalytic activity for oxygen reduction reaction. In this regard, we present a novel composite material consisting of functionalized acetylene black and TiO₂ nanotube (FAB/TNT) as the substrate for Pt as catalyst. Using this novel composite, Pt was decorated using photo-reduction process. Due to the presence of photo-electrons all over the conducting part of the material, H₂PtCl₆ was photo-reduced to Pt nanoparticles with extremely small size ∼1.6 nm. The material demonstrated that even with as less as 3.5 wt% of Pt, mass activity was found to be 37.5 A/g and specific actitvity was found to be 0.75 A/m² which is higher than commercial catalyst, Pt-Vulcan XC-72 (mass activity and specific activity was found to be 10.7 A/g and 0.81 A/m², respectively) at 0.85 V vs RHE.