The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Kunio Arai - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of the density effect on Partial Oxidation of methane in supercritical water
The Journal of Supercritical Fluids, 2004Co-Authors: Takafumi Sato, Masaru Watanabe, Tadafumi Adschiri, Richard L. Smith, Kunio AraiAbstract:Abstract Partial Oxidation of methane was conducted in supercritical water at O 2 /CH 4 ratios of 0.03 at 673 K with a flow-type reactor. The main products were CO, methanol, formaldehyde and a small amount of CO 2 and H 2 . With increasing water density, methane conversion increased due to the formation of formaldehyde. A free radical reaction model was applied to this reaction and it was confirmed that the dependence of selectivities for CO and CO 2 on pressure could be well described. The experimental results and model prediction shows that an increase of water density shifted product distribution to Partial Oxidation products and formaldehyde was found to play an important role in the product selectivity and the Partial Oxidation chemistry.
-
Partial Oxidation of n-hexadecane and polyethylene in supercritical water
The Journal of Supercritical Fluids, 2001Co-Authors: Masaru Watanabe, Makoto Mochiduki, Shuhei Sawamoto, Tadafumi Adschiri, Kunio AraiAbstract:In this study, we show the results of Partial Oxidation experiments of n-hexadecane (n-C16) and polyethylene (PE) in supercritical water (SCW). The experiments were carried out at 673 or 693 K of reaction temperature and 5 or 30 min of reaction time using a 6 cm3 of a batch type reactor. Water density ranged from 0.1 to 0.52 g/cm3 (water pressure: 20–40 MPa). The loaded amount of oxygen was set to 0.3 of the ratio of oxygen atom to carbon atom. Some experiments were made using CO instead of oxygen for the Partial Oxidation of n-C16 and PE to explore the effect of water gas shift reaction. In the results of Partial Oxidation of n-C16, the yield of CO and some compounds containing oxygen atoms, such as aldehydes and ketones increased with increasing water density. Moreover, 1-alkene/ n-alkane ratio in the products decreased with increasing water density. The 1-alkene/n-alkane ratio was lower than that of pyrolysis in SCW. Also for the case of PE experiments, in dense SCW (0.42 g/cm3), the 1-alkene/n-alkane ratio in Partial Oxidation was lower than that in SCW pyrolysis. In the case of CO experiments for n-C16 and PE, 1-alkene/n-alkane ratio was a little lower than that of pyrolysis in SCW. These results show that the yield of n-alkane, which is a hydrogenated compound, was higher through water gas shift reaction in SCW and also through Partial Oxidation in SCW. Therefore, these results suggest the possibility of hydrogenation of hydrocarbon through Partial Oxidation followed by the water gas shift reaction.
-
Hydrogenation of Hydrocarbons through Partial Oxidation in Supercritical Water
Industrial & Engineering Chemistry Research, 2000Co-Authors: Kunio Arai, Tadafumi Adschiri, Masaru WatanabeAbstract:We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The discussion in this paper is composed of three parts: (1) hydrogenation through water-gas shift reaction in supercritical water, (2) selective formation of carbon monoxide by Partial Oxidation in supercritical water and through combinations of these two, and (3) hydrogenation of hydrocarbons through their Partial Oxidation in supercritical water. In the experiments involving hydrogenation of dibenzothiophene, carbazole, and naphthalene, faster hydrogenation rates could be obtained in a CO−SCW atmosphere than in a H2−SCW atmosphere. Even in the case of a H2−CO2−SCW atmosphere, similarly faster reaction rates were obtained, which suggests that an intermediate species of the water-gas shift reaction is the actual reason for the high hydrogenation rates. Partial Oxidation experiments were conducted for hexylbenzene and n-hexadecane. The selectivity of CO increased with increasing density of water, while CO2 was the...
Masaru Watanabe - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of the density effect on Partial Oxidation of methane in supercritical water
The Journal of Supercritical Fluids, 2004Co-Authors: Takafumi Sato, Masaru Watanabe, Tadafumi Adschiri, Richard L. Smith, Kunio AraiAbstract:Abstract Partial Oxidation of methane was conducted in supercritical water at O 2 /CH 4 ratios of 0.03 at 673 K with a flow-type reactor. The main products were CO, methanol, formaldehyde and a small amount of CO 2 and H 2 . With increasing water density, methane conversion increased due to the formation of formaldehyde. A free radical reaction model was applied to this reaction and it was confirmed that the dependence of selectivities for CO and CO 2 on pressure could be well described. The experimental results and model prediction shows that an increase of water density shifted product distribution to Partial Oxidation products and formaldehyde was found to play an important role in the product selectivity and the Partial Oxidation chemistry.
-
Partial Oxidation of n-hexadecane and polyethylene in supercritical water
The Journal of Supercritical Fluids, 2001Co-Authors: Masaru Watanabe, Makoto Mochiduki, Shuhei Sawamoto, Tadafumi Adschiri, Kunio AraiAbstract:In this study, we show the results of Partial Oxidation experiments of n-hexadecane (n-C16) and polyethylene (PE) in supercritical water (SCW). The experiments were carried out at 673 or 693 K of reaction temperature and 5 or 30 min of reaction time using a 6 cm3 of a batch type reactor. Water density ranged from 0.1 to 0.52 g/cm3 (water pressure: 20–40 MPa). The loaded amount of oxygen was set to 0.3 of the ratio of oxygen atom to carbon atom. Some experiments were made using CO instead of oxygen for the Partial Oxidation of n-C16 and PE to explore the effect of water gas shift reaction. In the results of Partial Oxidation of n-C16, the yield of CO and some compounds containing oxygen atoms, such as aldehydes and ketones increased with increasing water density. Moreover, 1-alkene/ n-alkane ratio in the products decreased with increasing water density. The 1-alkene/n-alkane ratio was lower than that of pyrolysis in SCW. Also for the case of PE experiments, in dense SCW (0.42 g/cm3), the 1-alkene/n-alkane ratio in Partial Oxidation was lower than that in SCW pyrolysis. In the case of CO experiments for n-C16 and PE, 1-alkene/n-alkane ratio was a little lower than that of pyrolysis in SCW. These results show that the yield of n-alkane, which is a hydrogenated compound, was higher through water gas shift reaction in SCW and also through Partial Oxidation in SCW. Therefore, these results suggest the possibility of hydrogenation of hydrocarbon through Partial Oxidation followed by the water gas shift reaction.
-
Hydrogenation of Hydrocarbons through Partial Oxidation in Supercritical Water
Industrial & Engineering Chemistry Research, 2000Co-Authors: Kunio Arai, Tadafumi Adschiri, Masaru WatanabeAbstract:We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The discussion in this paper is composed of three parts: (1) hydrogenation through water-gas shift reaction in supercritical water, (2) selective formation of carbon monoxide by Partial Oxidation in supercritical water and through combinations of these two, and (3) hydrogenation of hydrocarbons through their Partial Oxidation in supercritical water. In the experiments involving hydrogenation of dibenzothiophene, carbazole, and naphthalene, faster hydrogenation rates could be obtained in a CO−SCW atmosphere than in a H2−SCW atmosphere. Even in the case of a H2−CO2−SCW atmosphere, similarly faster reaction rates were obtained, which suggests that an intermediate species of the water-gas shift reaction is the actual reason for the high hydrogenation rates. Partial Oxidation experiments were conducted for hexylbenzene and n-hexadecane. The selectivity of CO increased with increasing density of water, while CO2 was the...
Bo Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Exergy analysis of biomass utilization via steam gasification and Partial Oxidation
Thermochimica Acta, 2012Co-Authors: Yaning Zhang, Bo ZhangAbstract:Abstract Steam gasification and Partial Oxidation (with oxygen) of biomass produce higher heating value gases than air gasification, thereby being two important technologies to make use of biomass energy. However, the dominance may be leveled off if the heat exergy for generating steam or heating oxygen is taken into consideration. Based on experimental data from literature, the exergy values and efficiencies of product gas, tar and unreacted carbon (including char and coke) from biomass steam gasification and Partial Oxidation (with oxygen) are studied in this paper. The exergy for generating steam are much higher than that for heating oxygen, but both of these are much lower than the exergy input by biomass, the exergy efficiencies of product gas, tar and unreacted carbon are therefore mainly determined by the exergy values of product gas, tar and unreacted carbon, respectively. When gasification temperature increases from 800 °C to 1200 °C, the exergy efficiencies of product gas, tar and unreacted carbon from steam gasification are in ranges of 49.31–58.48%, 0–16.15% and 5.17–9.53%, respectively, being higher than the corresponding ones from Partial Oxidation, which range in 35.45–43.49%, 0–8.03% and 4.77–8.76%, respectively. Higher gasification temperature leads to higher exergy efficiencies of product gas and lower exergy efficiencies of tar, proper high gasification temperature therefore can be considered to improve the processes of biomass steam gasification and Partial Oxidation.
Ke Zhang - One of the best experts on this subject based on the ideXlab platform.
-
The search of proper oxygen carriers for chemical looping Partial Oxidation of carbon
Applied Energy, 2017Co-Authors: Jinzhi Zhang, Bin Li, Tao He, Ke Zhang, Zhiqi Wang, Jinhu WuAbstract:Chemical looping Partial Oxidation process has more advantages over conventional chemical looping process, which can not only completely avoid the problem of greenhouse gas emissions, but also supply syngas products for chemical industry. The aim of the present work is to perform fundamental investigation on chemical looping Partial Oxidation of solid fuels. Production of CO through chemical looping Partial Oxidation of carbon was investigated in order to find proper oxygen carrier with good reactivity and high selectivity. A simple and easy to use method based on the zone division of Ellingham diagram was offered to distinguish the Oxidation ability of various metal oxides, and three zones including complete Oxidation, Partial Oxidation and inert zones were divided. CaFe2O4, Ca2Fe2O5 and FeAl2O4 in Partial Oxidation zone together with Fe2O3 in complete Oxidation zone were chosen as target oxygen carriers (OCs) for chemical looping Partial Oxidation of carbon in this work. Of the target metal oxides, CaFe2O4 and Ca2Fe2O5 were found to have fast reaction rate, large oxygen-carrying capacity, high CO selectivity, and good regeneration performance, which made them very attractive for the purpose of chemical looping Partial Oxidation of solid fuels in real applications.
-
The search of proper oxygen carriers for chemical looping Partial Oxidation of carbon
Applied Energy, 2017Co-Authors: Jinzhi Zhang, Zhiqi Wang, Min Zhu, Ke ZhangAbstract:Chemical looping Partial Oxidation process has more advantages over conventional chemical looping process, which can not only completely avoid the problem of greenhouse gas emissions, but also supply syngas products for chemical industry. The aim of the present work is to perform fundamental investigation on chemical looping Partial Oxidation of solid fuels. Production of CO through chemical looping Partial Oxidation of carbon was investigated in order to find proper oxygen carrier with good reactivity and high selectivity. A simple and easy to use method based on the zone division of Ellingham diagram was offered to distinguish the Oxidation ability of various metal oxides, and three zones including complete Oxidation, Partial Oxidation and inert zones were divided. CaFe2O4, Ca2Fe2O5 and FeAl2O4 in Partial Oxidation zone together with Fe2O3 in complete Oxidation zone were chosen as target oxygen carriers (OCs) for chemical looping Partial Oxidation of carbon in this work. Of the target metal oxides, CaFe2O4 and Ca2Fe2O5 were found to have fast reaction rate, large oxygen-carrying capacity, high CO selectivity, and good regeneration performance, which made them very attractive for the purpose of chemical looping Partial Oxidation of solid fuels in real applications. (C) 2017 Elsevier Ltd. All rights reserved.
Tadafumi Adschiri - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of the density effect on Partial Oxidation of methane in supercritical water
The Journal of Supercritical Fluids, 2004Co-Authors: Takafumi Sato, Masaru Watanabe, Tadafumi Adschiri, Richard L. Smith, Kunio AraiAbstract:Abstract Partial Oxidation of methane was conducted in supercritical water at O 2 /CH 4 ratios of 0.03 at 673 K with a flow-type reactor. The main products were CO, methanol, formaldehyde and a small amount of CO 2 and H 2 . With increasing water density, methane conversion increased due to the formation of formaldehyde. A free radical reaction model was applied to this reaction and it was confirmed that the dependence of selectivities for CO and CO 2 on pressure could be well described. The experimental results and model prediction shows that an increase of water density shifted product distribution to Partial Oxidation products and formaldehyde was found to play an important role in the product selectivity and the Partial Oxidation chemistry.
-
Partial Oxidation of n-hexadecane and polyethylene in supercritical water
The Journal of Supercritical Fluids, 2001Co-Authors: Masaru Watanabe, Makoto Mochiduki, Shuhei Sawamoto, Tadafumi Adschiri, Kunio AraiAbstract:In this study, we show the results of Partial Oxidation experiments of n-hexadecane (n-C16) and polyethylene (PE) in supercritical water (SCW). The experiments were carried out at 673 or 693 K of reaction temperature and 5 or 30 min of reaction time using a 6 cm3 of a batch type reactor. Water density ranged from 0.1 to 0.52 g/cm3 (water pressure: 20–40 MPa). The loaded amount of oxygen was set to 0.3 of the ratio of oxygen atom to carbon atom. Some experiments were made using CO instead of oxygen for the Partial Oxidation of n-C16 and PE to explore the effect of water gas shift reaction. In the results of Partial Oxidation of n-C16, the yield of CO and some compounds containing oxygen atoms, such as aldehydes and ketones increased with increasing water density. Moreover, 1-alkene/ n-alkane ratio in the products decreased with increasing water density. The 1-alkene/n-alkane ratio was lower than that of pyrolysis in SCW. Also for the case of PE experiments, in dense SCW (0.42 g/cm3), the 1-alkene/n-alkane ratio in Partial Oxidation was lower than that in SCW pyrolysis. In the case of CO experiments for n-C16 and PE, 1-alkene/n-alkane ratio was a little lower than that of pyrolysis in SCW. These results show that the yield of n-alkane, which is a hydrogenated compound, was higher through water gas shift reaction in SCW and also through Partial Oxidation in SCW. Therefore, these results suggest the possibility of hydrogenation of hydrocarbon through Partial Oxidation followed by the water gas shift reaction.
-
Hydrogenation of Hydrocarbons through Partial Oxidation in Supercritical Water
Industrial & Engineering Chemistry Research, 2000Co-Authors: Kunio Arai, Tadafumi Adschiri, Masaru WatanabeAbstract:We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The discussion in this paper is composed of three parts: (1) hydrogenation through water-gas shift reaction in supercritical water, (2) selective formation of carbon monoxide by Partial Oxidation in supercritical water and through combinations of these two, and (3) hydrogenation of hydrocarbons through their Partial Oxidation in supercritical water. In the experiments involving hydrogenation of dibenzothiophene, carbazole, and naphthalene, faster hydrogenation rates could be obtained in a CO−SCW atmosphere than in a H2−SCW atmosphere. Even in the case of a H2−CO2−SCW atmosphere, similarly faster reaction rates were obtained, which suggests that an intermediate species of the water-gas shift reaction is the actual reason for the high hydrogenation rates. Partial Oxidation experiments were conducted for hexylbenzene and n-hexadecane. The selectivity of CO increased with increasing density of water, while CO2 was the...
