Hary Devianto

Fluid dynamics and kinetic simulation for steam reforming of ethanol using a microchannel reactor

Proton Exchange Membrane Fuel Cell (PEMFC) has been recognized to be the potential source for future vehicles due to environmentally friendly. Supplying hydrogen for mobile vehicles is becoming of interest since storing compressed hydrogen in the bottle is not only dangerous but also energy consuming. One way to overcome the drawback is by performing the ethanol steam reforming in situ. In this way, microreactor offers the potential benefit to convert ethanol to hydrogen due to very fast mass and heat transfer. Fluid dynamics inside the microreactors and the kinetic aspects for ethanol steam reforming using Pt/Al2O3 catalyst were investigated with aim to determine the proper microreactor design having uniform fluid distribution and to study the influence of reaction temperature, fluid velocity, and reactor length. It was found that placing an obstacle inside the microreactors in certain position gave more uniform distribution of fluid flow. The reaction temperature and fluid velocity showed their influence on hydrogen productivity.

Digesters, Gasifiers and Biorefineries: Plants and Field Demonstration

In the present chapter an indication is given of the degree of industrialization reached so far by the biomass and waste conversion technologies described in Chaps. 3 and 4. Anaerobic digestion is a consolidated technology, which is reflected by the vast diffusion of waste water treatment plants. However, there is great potential for increased exploitation of this technology, especially by utilization of the diverse byproducts from the process. The future of anaerobic digestion is therefore closely related to the development of the biorefinery concept. As regards gasification, the flexibility of possible feedstock and the many varieties of syngas production routes lead to a large number of demonstration sites, with only few plants commercially in operation. These are summarized according to technology and geographical location.

Catalytic oxidation of benzene using nano-CuO/γ-Al2O3 and commercial catalysts

Volatile organic compounds (VOC) such as benzene are among the most dangerous air pollutants emitted by chemical industry stacks, as they may contribute to environment and health issues. Lean catalytic oxidation of benzene has been considered as most proper method to abate it from the flue gas. This work developed nano-based copper oxide catalysts for lean oxidation of benzene. The aim of this study was to evaluate the activity performance of the nano-based copper oxide catalyst and compare to commercial catalyst. On the basis of the commercial catalyst, this study was also aimed to determine the reaction rate and its kinetic parameter. The oxidation of benzene was conducted in a fixed bed reactor at 300°C, 1 atm, and GHSV of 15,000 h−1. The concentration of benzene in the feed and product were measured using online gas detector (Cosmos Gas Detector). The catalyst activity of nano-based copper oxide catalysts showed 20-30% conversion of benzene, while for commercial catalyst showed 86%. The reaction rate determination for first order reaction of benzene indicated that the activation energy was 48 kJ/mol with Arrhenius constant of 3×104 s−1.

Influence of incubation temperature on biofilm formation and corrosion of carbon steel by Serratia marcescens

Microbial induced corrosion (MIC) or biocorrosion is one type of corrosion, directly or indirectly influenced by microbial activities, by forming biofilm and adhering on the metal surface. When forming biofilm, the microorganisms can produce extracellular products which influence the cathodic and anodic reactions on metal surfaces. This will result in electrochemical changes in the interface between the biofilm and the metal surface, leading to corrosion and deterioration of the metal. MIC might be caused by various types of microorganism which leads to different corrosion mechanism and reaction kinetics. Furthermore, this process will also be influenced by various environmental conditions, such as pH and temperature. This research is aimed to determine the effect of incubation temperature on corrosion of carbon steel caused by Serratia marcescens in a mixture solution of synthetic seawater with Luria Bertani medium with a ratio of 4:1. The incubation was performed for 19 days with incubation temperature ...

Structural and preliminary electrochemical characteristics of palm oil based carbon nanospheres as anode materials in lithium ion batteries

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Effect of hydrogen temperature and current load on the performance of proton exchange membrane fuel cell under start-stop operation

Proton Exchange Membrane Fuel Cell (PEMFC) is one of fuel cell type that suitable for vehicular application because it has low operation pressure and temperature, stable, relatively small, and highly mobile. The major concern of PEMFC as vehicular power is its resistance toward start-stop cycle and constant load. PEMFC on vehicular application require fuel processor to produce hydrogen as fuel source. Output temperature of hydrogen from fuel processor is about 80°C, which is high enough for PEMFC. The temperature is allegedly affecting the performance of PEMFC. This research is focused on studying the effect of hydrogen feed temperature on the performance of PEMFC. Fuel cell is operated in the start-stop cycle and constant load to simulate the conditions in vehicular application. PEMFC stack has been operated with 10 start-stop cycles under constant load of 0.05 and 0.1 A/cm2 at temperatures 25, 40, 60, and 80°C. The electrochemical characterizations were carried out using chronopotentiometry and potentiodynamic polarization, while post experimental physical observations were carried out by using XRD and SEM. The experimental results show that under low constant load (0.05 A/cm2), the increase of hydrogen temperature has raised stack performance when operated with start-stop cycles, but lowered the stack performance when operated without start-stop cycle. Under high constant load (0.1 A/cm2), higher hydrogen temperature increased the stack performance, either operated with or without start-stop cycle. Post experimental XRD and SEM analysis show that the decrease of PEMFC performance is caused by platinum catalyst particles growth and MEA thickness alteration.

Process intensification of hydrogen production from Ethanol using microreactor

Hydrogen as potential energy source for Proton Exchange Membrane Fuel Cells (PEMFCs) possesses great challenge to replace gasoline due to their high calorific value. Hydrogen can be generated directly through Ethanol Steam Reforming (ESR) on portable reaction — microreactor. In this study, ESR was conducted by nine different variations of Pt/α- Al2O3 catalyst prepared by electroless plating method and four variations of reaction temperature between 270–315°C, atmospheric pressure, liquid feed flow of 0.5 mL/hour and molar feed composition of steam to ethanol 3:1. The result showed that the highest catalyst activity was reached at 300°C and 315°C. Time needed to reach stable hydrogen productivity at 285°C was longer than others. Average hydrogen productivity in stable condition varied between 6.31% (at 270°C) — 14.51% (at 300°C) of the highest hydrogen productivity achieved during six hours of ESR.

Effect of start-stop cycle on Direct Ethanol Fuel Cell for transportation purpose

Energy has become fundamental human needs throughout the world. One form of renewable energy as an alternative fuel is hydrogen fuel cell. Fuel cell is an electrochemical device that can convert chemical energy directly into electrical energy and heat with high efficiency and a low negative impact on the environment. Direct Ethanol Fuel Cell (DEFC) is one type of fuel cell that can utilize ethanol derived from biomass. Studies have shown that addition of sodium hydroxide is able to improve the performance of DEFC. However, the effect of pH in the fuel cell has not been studied. In addition, application of DEFC always works with start and stop cycle, which may affect its durability. This study focused on the endurance test of DEFC fueled with synthetic bioethanol influenced by start-stop cycles in various pH (6-8). Constant load of 1 and 2 mA/cm2 were given. The performance of DEFC was analyzed using electrochemical characterization methods, such as the Open Circuit Potential and Potentiodynamic. Physical characterization using Scanning Electron Microscopy (SEM). The Results shown ethanol variation pH 8 produce best power density than the others after repeated cycles on a certain constant load. The addition of sodium hydroxide push electro-oxidation reaction perfectly takes place. Degradation phenomenon occurred particularly detachment catalyst that affected performance of DEFC.

Effect of start-stop cycles and hydrogen temperature on the performance of Proton Exchange Membrane Fuel Cell (PEMFC)

Vehicular application of Proton Exchange Membrane Fuel Cells (PEMFC) poses durability and stability issues toward the multiple start-stops operation. Start-stop cycle leads to performance decay for PEMFC over time. Considering its reliability, PEMFCs performance recovery becomes a major concern. In electrical vehicle which does not used hydrogen tank due to safety, PEMFC require fuel processor to produce hydrogen as fuel source from ethanol. Output temperature of hydrogen from fuel processor is about 80°C, which is quite high for PEMFC. Temperature is alleged having an impact on the performance of PEMFC. This research is focused on studying the effect of start-stop cycle and hydrogen temperature on the performance of PEMFC under constant loads using electrochemical characterisation. The number of start-stop cycle was varied by 10, 20 and 30 cycles under constant loads of 1 and 0.5 ampere. The temperature that used for hydrogen was 40°C. The result shows that heating hydrogen to 40°C does not have significant effect to PEMFCs performance. However, enhancing start-stop cycle number has increased degradation of PEMFC stack.

SO X and NO X impurities effect on the performance of proton exchange membrane fuel cell (PEMFC) for electric vehicle application

Exposure to polluted ambient air is inevitable in vehicular application of proton exchange membrane fuel cell (PEMFC). SO₂ and NO₂ are common pollutants which in individual are known to alter PEMFC performance for their presence in the oxidant, as indicated by preceding researchers. However, interacting effects of SO₂ and NO₂ in the oxidant on PEMFC have not been extensively studied. Concerning the vehicular application of PEMFC, durability issue related with SO₂ and NO₂ - poisoned PEMFC are also necessary to be studied in order to maintain the vehicles performance. Hence this research encompasses the poisoning effects of SO₂ and NO₂ on PEMFC performance. Polluted air resulted a significant decrease in performance of PEMFC.