Biodiesel, which is a new, renewable and biological origin alternative diesel fuel, has been receiving more attention all over the world due to the energy needs and environmental consciousness Biodiesel is usually produced from food-grade vegetable oils using transesterification process Using food-grade vegetable oils is not economically feasible since they are more expensive than diesel fuel Therefore, it is said that the main obstacle for commercialization of biodiesel is its high cost Waste cooking oils, restaurant greases, soapstocks and animal fats are potential feedstocks for biodiesel production to lower the cost of biodiesel However, to produce fuel-grade biodiesel, the characteristics of feedstock are very important during the initial research and production stage since the fuel properties mainly depend on the feedstock properties This review paper presents both biodiesel productions from various feedstocks and their effects on the fuel properties

Biodiesel production from various feedstocks and their effects on the fuel properties.

Enzymatic biodiesel: Challenges and opportunities

Increasing energy demand and environment concerns have prompted an evolution of alternative fuel sources. As an alternative fuel source, biodiesel is attractive because it reduces engine emissions. However, biodiesel produces higher NOx emissions compared to ordinary diesel fuel. Previous researches have established many factors that cause biodiesel to produce elevated NOx emissions. This study reviews the impacts of biodiesel combustion on NOx emissions and their reduction approaches in diesel engines. The first part of this study recaps the NOx formation mechanisms for understanding the kinetics behind the NOx forming reactions. The second part describes the factors affecting on NOx emissions. This paper established that higher NOx emissions are produced for biodiesel combustion which influenced by several factors such as physicochemical properties and molecular structure of biodiesel, adiabatic flame temperature, ignition delay time, injection timing and engine load conditions etc. The final section discusses on the reduction of NOx emissions from biodiesel fuelled engines for both pre and post combustion techniques. The results of reduction approaches of the NOx emissions implies, exhaust gas recirculation (EGR) and retarded injection timing are effective as well as low cost techniques than others. Between these two techniques, EGR reduces the NOx emissions at 5–25% EGR rate adequately in biofuelled engine by controlling oxygen content and combustion peak temperature with slightly decreasing HC and CO emissions. However this technique shows few penalties on smoke and PM emissions as well as brake specific fuel consumption if not perfectly optimized.

Impacts of biodiesel combustion on NOx emissions and their reduction approaches

Production of hydrogen by aqueous-phase reforming of glycerol

Next-generation biofuels, such as cellulosic bioethanol, biomethane from waste, synthetic biofuels obtained via gasification of biomass, biohydrogen, and others, are currently at the center of the attention of technologists and policy makers in search of the more sustainable biofuel of tomorrow. To set realistic targets for future biofuel options, it is important to assess their sustainability according to technical, economical, and environmental measures. With this aim, the review presents a comprehensive overview of the chemistry basis and of the technology related aspects of next generation biofuel production, as well as it addresses related economic issues and environmental implications. Opportunities and limits are discussed in terms of technical applicability of existing and emerging technology options to bio-waste feedstock, and further development forecasts are made based on the existing social-economic and market situation, feedstock potentials, and other global aspects. As the latter ones are concerned, the emphasis is placed on the opportunities and challenges of developing countries in adoption of this new industry.

Next‐Generation Biofuels: Survey of Emerging Technologies and Sustainability Issues

A thermodynamic analysis of hydrogen production by steam reforming of glycerol

A glut of inexpensive glycerol has resulted from expanding biodiesel production around the world. This glycerol could be used as a good renewable source to produce hydrogen fuel. Hydrogen production from glycerol via a steam reforming process over Ni/CeO2, Ni/MgO, and Ni/TiO2 catalysts was studied. The catalysts were characterized by using X-ray diffraction, thermogravimetric analysis, BET surface area analysis, metal dispersion, active surface area analysis, and hydrogen temperature programmed reduction. Ni/CeO2 had the highest surface area (67.0 m2/g) followed by Ni/TiO2 (64.9 m2/g) and Ni/MgO (50.2 m2/g). Also, Ni/CeO2 showed the highest metal dispersion (6.14%) compared to Ni/MgO (0.38%) and Ni/TiO2 (0.29%). Effects of reaction temperatures, feed flow rates (FFRs), and water/glycerol molar ratios (WGMRs) on hydrogen selectivity and glycerol conversion were analyzed. Ni/CeO2 was found to be the best performing catalyst compared to Ni/MgO and Ni/TiO2 under the experimental conditions investigated. Ni/Ce...

Conversion of Glycerol to Hydrogen via a Steam Reforming Process over Nickel Catalysts

Flame temperature analysis of biodiesel blends and components

This paper discusses the experimental results of the water−gas shift reaction over supported nickel catalysts in comparison to thermodynamic equilibrium composition at the same reaction conditions. The effects of different supports on the performance of H2 production over nickel-supported catalysts are also evaluated at both low and high temperatures. Ceria-promoted nickel catalyst supported on powder alumina (Ni/CeO2−Al2O3) demonstrated excellent performance. The catalyst was not stable at low temperature (250 °C) but showed good stability at high temperature (450 °C). At 450 °C, with a catalyst loading of 0.05 g, CO/S (S = steam) ratio of 1:3, and gas hourly space velocity (GHSV) ≈ 200 L h−1 gcat−1, the activity of Ni/CeO2−Al2O3 was 95% with a H2 yield of 52% and a H2 selectivity of 73%.

S. D. Filip To

Papers

A thermodynamic analysis of hydrogen production by steam reforming of glycerol

Conversion of Glycerol to Hydrogen via a Steam Reforming Process over Nickel Catalysts

Flame temperature analysis of biodiesel blends and components

Hydrogen production through the water-gas shift reaction: thermodynamic equilibrium versus experimental results over supported Ni catalysts

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