Masaru Watanabe | Tohoku University (original) (raw)

Papers by Masaru Watanabe

Energy & Fuels, 2003

ABSTRACT

Carbohydrate Research, 2005

Industrial & Engineering Chemistry Research, 1998

The catalytic hydrodesulfurization (HDS) reactions of both specific organosulfur compounds and a ... more The catalytic hydrodesulfurization (HDS) reactions of both specific organosulfur compounds and a coalderived liquid were studied in a continuous, back-mixed, internally circulated (gradlentless) laboratory reactor using a commercial cobalt-molybdenum on alumina ...

Green Chemistry, 2006

Hydrothermal synthesis of metal oxide (AlOOH/Al 2 O 3 , CuO, Fe 2 O 3 , NiO, ZrO 2 ) nanoparticle... more Hydrothermal synthesis of metal oxide (AlOOH/Al 2 O 3 , CuO, Fe 2 O 3 , NiO, ZrO 2 ) nanoparticles from metal nitrate aqueous solution was carried out at 673 K and pressures ranging from 25 MPa to 37.5 MPa with a flow-through supercritical water method. Size, phase and crystallinity of the obtained particles were characterized by TEM, XRD and TG, respectively. Effect of the difference of the metals in starting materials, pressures and concentrations on particle size and crystallinity was analyzed on the basis of supersaturation, which was evaluated by estimated metal oxide solubility. The result suggests that supersaturation should be set to higher than around 10 4 in this method to obtain particles under 10 nm in diameter. Further, crystallinity of the obtained particles was evaluated as weight loss through TG analysis. It was found that higher supersaturation decreased the crystallinity. This result can be explained that high supersaturation led to the inclusion of water molecules during the formation of particles.

Applied Catalysis A-general, 2005

The effects of TiO 2 (anatase TiO 2 or rutile TiO 2 ) and ZrO 2 (monoclinic/tetragonal mixture Zr... more The effects of TiO 2 (anatase TiO 2 or rutile TiO 2 ) and ZrO 2 (monoclinic/tetragonal mixture ZrO 2 ) on glucose and fructose reactions were examined in hot-compressed water at 473 K with a batch type reactor. Rutile TiO 2 (r-TiO 2 ) is inactive during glucose reactions. A monoclinic/ tetragonal mixture of ZrO 2 (m/c-ZrO 2 ) was the basic catalyst for the reaction at this temperature. Anatase TiO 2 (a-TiO 2 ) showed both acidity and basicity during the reactions. In order to understand the catalytic activity of a-TiO 2 , r-TiO 2 , and m/c-ZrO 2 , we measured the acidity and basicity by means of NH 3 -and CO 2 -TPD, respectively. The TPD analysis showed us that the amount of acid (670 mmol/g) and base (550 mmol/g) sites on m/c-ZrO 2 were the highest among these three catalysts, while the density of acid site (17 mmol/m 2 ) and that of basic site (9 mmol/m 2 ) of the a-TiO 2 were the highest. Such the acidity and basicity analyses suggested that the amount of basicity was the key factor for the isomerization while the density of acidity and basicity was important for the HMF formation from glucose. #

Biomass & Bioenergy, 2002

We conducted the batch experiments for hydrogen production from biomass (glucose and cellulose) w... more We conducted the batch experiments for hydrogen production from biomass (glucose and cellulose) with ZrO2 catalyst in supercritical water (673-713 K and 30 -35 MPa). For comparison, we also conducted the experiments with alkali and without catalyst at the same conditions. The yield of hydrogen with zirconia was almost twice as much as that without catalyst for all the starting materials (glucose and cellulose). ?

Energy Conversion and Management, 2005

The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was me... more The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was measured with a high pressure optical cell. The results showed that CH 4 in the hydrate gradually moved to the liquid CO 2 phase while CO 2 in the liquid phase penetrated into the hydrate from the quantitative analysis. The decomposing process of the CH 4 hydrate during the replacement was analyzed with in situ Raman spectroscopy, which allowed us to distinguish the cage structure of the CH 4 hydrate and discuss the microscopic view of the replacement in the hydrate. It was found that the decomposition of the medium cage (Mcage) in the CH 4 hydrate proceeded faster than that of the small cage (S-cage). The observed rate difference could be related to the stability of the S-cage in the CH 4 hydrate or the re-formation tendency of CH 4 and water molecules in the S-cage after decomposing the hydrate structure, whereas the guest molecule exchange of CH 4 with CO 2 could occur in the M-cage. Based on the experimental data, we developed a kinetic model for calculation of the CH 4 remaining in the hydrate considering the decomposition rate difference between the M-cage and S-cage in the CH 4 hydrate. The results indicate that the driving force could be the fugacity difference between the fluid phase and the hydrate phase for the replacement process.

Green Chemistry, 2008

Catalytic dehydration of fructose into 5-hydroxymethylfurfural by microwave heating was studied i... more Catalytic dehydration of fructose into 5-hydroxymethylfurfural by microwave heating was studied in acetone-water mixtures in the presence of a cation exchange resin catalyst. The use of acetone-water reaction media resulted in yields of 5-HMF as high as 73.4% for 94% conversion at 150 • C. It was confirmed that there was no decrease of catalytic activity and selectivity for five reuses of the resin, which was in accordance with the elemental analysis results that showed that sulfonic acid groups attached on the resin were stable at the experimental conditions. A comparison between conventional sand bath heating and microwave heating revealed that the latter had a remarkable accelerating effect not only on fructose conversion, but also on 5-HMF yield. Under the conditions (5 ml of 2 wt% fructose solution, 0.1 g of resin, 150 • C and 10 min), fructose conversion and HMF yields by microwave heating (91.7% and 70.3%, respectively) were higher than those by sand bath heating (22.1% and 13.9% respectively). Therefore, the process that we developed in this study showed that high 5-HMF yields from fructose could be achieved under mild conditions.

Energy & Fuels, 2004

... Mudge, LK, Eds.; Elsevier Applied Science Publishers: London, 1985; pp 95−119. (9) Schmieder,... more ... Mudge, LK, Eds.; Elsevier Applied Science Publishers: London, 1985; pp 95−119. (9) Schmieder, H.; Abeln, J.; Boukis, N.; Dinjus, E.; Kruse, A.; Kluth, M.; Petrich, G.; Sadri, E.; Schacht, M. J. Supercrit. Fluids 2000, 17, 145−153. ...

Fluid Phase Equilibria, 2005

The dynamics of CH 4 replacement in CH 4 hydrate with high-pressure CO 2 was observed with in sit... more The dynamics of CH 4 replacement in CH 4 hydrate with high-pressure CO 2 was observed with in situ laser Raman spectroscopy at temperatures ranging from 271.2 to 275.2 K and at an initial pressure of 3.25 MPa. The amount of CH 4 hydrate decomposition was found to be almost proportional to that of CO 2 hydrate formation for a series of 150 h experiments at fixed temperatures. This confirmed that the CH 4 -CO 2 replacement mainly occurred in the hydrate phase. Based on the rate data, a kinetic model was developed for CH 4 hydrate decomposition and CO 2 hydrate formation. Under CH 4 -CO 2 replacement in the hydrate, the activation energies were determined to be 14.5 kJ/mol for CH 4 hydrate decomposition and 73.3 kJ/mol for CO 2 hydrate formation after a given initial period (ca. 10 h). It was found that CH 4 hydrate decomposition was probably dominated by re-arrangement of water molecules in the hydrate whereas CO 2 hydrate formation seemed to be dominated by diffusion in the hydrate phase.

Journal of Supercritical Fluids, 2001

ABSTRACT

Industrial & Engineering Chemistry Research, 2000

We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The d... more 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 H 2 -SCW atmosphere. Even in the case of a H 2 -CO 2 -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 CO 2 was the main product of the gas-phase reaction. Partial oxidation of dibenzothiophene (with a sulfur-treated NiMO/Al 2 O 3 catalyst) and n-hexadecane (without catalysts) were also examined. Hydrodesulfurization of dibenzothiophene proceeds effectively in water. For n-hexadecane oxidation, the alkane/alkene ratio increased with increasing water density. The observed product distribution is probably due to the production of carbon monoxide, which is followed by the formation of active hydrogenating species via the water-gas shift reaction. This work demonstrates that hydrogenation reactions can be greatly accelerated in supercritical water through the use of either direct introduction of carbon monoxide or in situ formation of carbon monoxide through the partial oxidation of hydrocarbons. . Hydrogenation of DBT through partial oxidation in O2-SCW and CO-SCW (T ) 400°C, water density ) 0.42 g/cm 3 ). 11

Chemical Reviews, 2004

SATO, T.; INOMATA, H.; SMITH, R. L. J.; ARAI, K.; KRUSE, A.; DINJUS, E.; Chem. Rev. (Washington, ... more SATO, T.; INOMATA, H.; SMITH, R. L. J.; ARAI, K.; KRUSE, A.; DINJUS, E.; Chem. Rev. (Washington, D. C.) 104 (2004) 12, 5803-5821; Res. Cent. Supercrit. Fluid Technol., Tohoku Univ., Aoba, Sendai 980, Japan; Eng.) -Lindner 11-294

Combustion Science and Technology, 2006

Research in biomass gasification with subcritical and supercritical water is reviewed. Catalytic ... more Research in biomass gasification with subcritical and supercritical water is reviewed. Catalytic conversion of biomass in sub- and supercritical water is a low-temperature gasification technique that can be carried out from 473 to 973 K. Research is categorized according to temperature and water density, since reaction mechanisms greatly depend on these variables.

Bioresource Technology, 2007

Glycerol conversion was conducted in hot-compressed water (HCW: 573-673 K, 25-34.5 MPa) using a b... more Glycerol conversion was conducted in hot-compressed water (HCW: 573-673 K, 25-34.5 MPa) using a batch and a flow apparatus and the influences of temperature, H 2 SO 4 , glycerol concentration, and pressure, were examined. The yield of acrolein was enhanced by higher glycerol and H 2 SO 4 concentration, and higher pressure. Approximately 80% selectivity of acrolein was obtained at 90% of glycerol conversion with an acid catalyst in supercritical condition (673 K and 34.5 MPa). The rate constant of acrolein decomposition was always higher than that of acrolein formation in the absence of acid catalyst but the rate constant of acrolein formation could be overcome that of acrolein decomposition by addition acid in supercritical condition.

Fuel, 2003

Partial oxidative gasification of n-hexadecane (n-C 16 ) and organosolv-lignin (lignin) was studi... more Partial oxidative gasification of n-hexadecane (n-C 16 ) and organosolv-lignin (lignin) was studied by use of a batch type reactor in supercritical water: 673 K, 0.52 cm 23 of water density (40 MPa of water pressure at 673 K), and 0.3 of O/C ratio for the n-C 16 experiments; 673 K, 0.35 cm 23 of water density (30 MPa of water pressure at 673 K), and 1.0 of O/C ratio for the lignin experiments. The experiments without O 2 were also conducted for lignin (lignin decomposition). For all the cases (n-C 16 partial oxidation, lignin decomposition, lignin partial oxidation), NaOH or zirconia (ZrO 2 ) was added in the system as catalysts. Through n-C 16 studies, the catalytic effect of NaOH and ZrO 2 on partial oxidation in supercritical water were examined. In the case of lignin partial oxidation, we studied the possibility of partial oxidation in supercritical water for gasification technique of wastes. The yield of H 2 from n-C 16 and lignin with zirconia was twice as same as that without catalyst at the same condition. The H 2 yield with NaOH was 4 times higher than that without catalyst. Thus, a base catalyst has a positive effect on partial oxidation of n-C 16 and lignin to produce H 2 . The catalytic effect of NaOH and ZrO 2 was found to be enhancement of decomposition of intermediate (aldehyde and ketone) into CO, through n-C 16 studies. In the case of lignin studies, the enhancement of decomposition of the carbonyl compounds by catalytic effect of NaOH and ZrO 2 inhibit char formation and promotes CO and thus H 2 formation. q

Journal of Supercritical Fluids, 1998

Energy & Fuels, 2003

ABSTRACT

Carbohydrate Research, 2005

Industrial & Engineering Chemistry Research, 1998

The catalytic hydrodesulfurization (HDS) reactions of both specific organosulfur compounds and a ... more The catalytic hydrodesulfurization (HDS) reactions of both specific organosulfur compounds and a coalderived liquid were studied in a continuous, back-mixed, internally circulated (gradlentless) laboratory reactor using a commercial cobalt-molybdenum on alumina ...

Green Chemistry, 2006

Hydrothermal synthesis of metal oxide (AlOOH/Al 2 O 3 , CuO, Fe 2 O 3 , NiO, ZrO 2 ) nanoparticle... more Hydrothermal synthesis of metal oxide (AlOOH/Al 2 O 3 , CuO, Fe 2 O 3 , NiO, ZrO 2 ) nanoparticles from metal nitrate aqueous solution was carried out at 673 K and pressures ranging from 25 MPa to 37.5 MPa with a flow-through supercritical water method. Size, phase and crystallinity of the obtained particles were characterized by TEM, XRD and TG, respectively. Effect of the difference of the metals in starting materials, pressures and concentrations on particle size and crystallinity was analyzed on the basis of supersaturation, which was evaluated by estimated metal oxide solubility. The result suggests that supersaturation should be set to higher than around 10 4 in this method to obtain particles under 10 nm in diameter. Further, crystallinity of the obtained particles was evaluated as weight loss through TG analysis. It was found that higher supersaturation decreased the crystallinity. This result can be explained that high supersaturation led to the inclusion of water molecules during the formation of particles.

Applied Catalysis A-general, 2005

The effects of TiO 2 (anatase TiO 2 or rutile TiO 2 ) and ZrO 2 (monoclinic/tetragonal mixture Zr... more The effects of TiO 2 (anatase TiO 2 or rutile TiO 2 ) and ZrO 2 (monoclinic/tetragonal mixture ZrO 2 ) on glucose and fructose reactions were examined in hot-compressed water at 473 K with a batch type reactor. Rutile TiO 2 (r-TiO 2 ) is inactive during glucose reactions. A monoclinic/ tetragonal mixture of ZrO 2 (m/c-ZrO 2 ) was the basic catalyst for the reaction at this temperature. Anatase TiO 2 (a-TiO 2 ) showed both acidity and basicity during the reactions. In order to understand the catalytic activity of a-TiO 2 , r-TiO 2 , and m/c-ZrO 2 , we measured the acidity and basicity by means of NH 3 -and CO 2 -TPD, respectively. The TPD analysis showed us that the amount of acid (670 mmol/g) and base (550 mmol/g) sites on m/c-ZrO 2 were the highest among these three catalysts, while the density of acid site (17 mmol/m 2 ) and that of basic site (9 mmol/m 2 ) of the a-TiO 2 were the highest. Such the acidity and basicity analyses suggested that the amount of basicity was the key factor for the isomerization while the density of acidity and basicity was important for the HMF formation from glucose. #

Biomass & Bioenergy, 2002

We conducted the batch experiments for hydrogen production from biomass (glucose and cellulose) w... more We conducted the batch experiments for hydrogen production from biomass (glucose and cellulose) with ZrO2 catalyst in supercritical water (673-713 K and 30 -35 MPa). For comparison, we also conducted the experiments with alkali and without catalyst at the same conditions. The yield of hydrogen with zirconia was almost twice as much as that without catalyst for all the starting materials (glucose and cellulose). ?

Energy Conversion and Management, 2005

The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was me... more The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was measured with a high pressure optical cell. The results showed that CH 4 in the hydrate gradually moved to the liquid CO 2 phase while CO 2 in the liquid phase penetrated into the hydrate from the quantitative analysis. The decomposing process of the CH 4 hydrate during the replacement was analyzed with in situ Raman spectroscopy, which allowed us to distinguish the cage structure of the CH 4 hydrate and discuss the microscopic view of the replacement in the hydrate. It was found that the decomposition of the medium cage (Mcage) in the CH 4 hydrate proceeded faster than that of the small cage (S-cage). The observed rate difference could be related to the stability of the S-cage in the CH 4 hydrate or the re-formation tendency of CH 4 and water molecules in the S-cage after decomposing the hydrate structure, whereas the guest molecule exchange of CH 4 with CO 2 could occur in the M-cage. Based on the experimental data, we developed a kinetic model for calculation of the CH 4 remaining in the hydrate considering the decomposition rate difference between the M-cage and S-cage in the CH 4 hydrate. The results indicate that the driving force could be the fugacity difference between the fluid phase and the hydrate phase for the replacement process.

Green Chemistry, 2008

Catalytic dehydration of fructose into 5-hydroxymethylfurfural by microwave heating was studied i... more Catalytic dehydration of fructose into 5-hydroxymethylfurfural by microwave heating was studied in acetone-water mixtures in the presence of a cation exchange resin catalyst. The use of acetone-water reaction media resulted in yields of 5-HMF as high as 73.4% for 94% conversion at 150 • C. It was confirmed that there was no decrease of catalytic activity and selectivity for five reuses of the resin, which was in accordance with the elemental analysis results that showed that sulfonic acid groups attached on the resin were stable at the experimental conditions. A comparison between conventional sand bath heating and microwave heating revealed that the latter had a remarkable accelerating effect not only on fructose conversion, but also on 5-HMF yield. Under the conditions (5 ml of 2 wt% fructose solution, 0.1 g of resin, 150 • C and 10 min), fructose conversion and HMF yields by microwave heating (91.7% and 70.3%, respectively) were higher than those by sand bath heating (22.1% and 13.9% respectively). Therefore, the process that we developed in this study showed that high 5-HMF yields from fructose could be achieved under mild conditions.

Energy & Fuels, 2004

... Mudge, LK, Eds.; Elsevier Applied Science Publishers: London, 1985; pp 95−119. (9) Schmieder,... more ... Mudge, LK, Eds.; Elsevier Applied Science Publishers: London, 1985; pp 95−119. (9) Schmieder, H.; Abeln, J.; Boukis, N.; Dinjus, E.; Kruse, A.; Kluth, M.; Petrich, G.; Sadri, E.; Schacht, M. J. Supercrit. Fluids 2000, 17, 145−153. ...

Fluid Phase Equilibria, 2005

The dynamics of CH 4 replacement in CH 4 hydrate with high-pressure CO 2 was observed with in sit... more The dynamics of CH 4 replacement in CH 4 hydrate with high-pressure CO 2 was observed with in situ laser Raman spectroscopy at temperatures ranging from 271.2 to 275.2 K and at an initial pressure of 3.25 MPa. The amount of CH 4 hydrate decomposition was found to be almost proportional to that of CO 2 hydrate formation for a series of 150 h experiments at fixed temperatures. This confirmed that the CH 4 -CO 2 replacement mainly occurred in the hydrate phase. Based on the rate data, a kinetic model was developed for CH 4 hydrate decomposition and CO 2 hydrate formation. Under CH 4 -CO 2 replacement in the hydrate, the activation energies were determined to be 14.5 kJ/mol for CH 4 hydrate decomposition and 73.3 kJ/mol for CO 2 hydrate formation after a given initial period (ca. 10 h). It was found that CH 4 hydrate decomposition was probably dominated by re-arrangement of water molecules in the hydrate whereas CO 2 hydrate formation seemed to be dominated by diffusion in the hydrate phase.

Journal of Supercritical Fluids, 2001

ABSTRACT

Industrial & Engineering Chemistry Research, 2000

We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The d... more 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 H 2 -SCW atmosphere. Even in the case of a H 2 -CO 2 -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 CO 2 was the main product of the gas-phase reaction. Partial oxidation of dibenzothiophene (with a sulfur-treated NiMO/Al 2 O 3 catalyst) and n-hexadecane (without catalysts) were also examined. Hydrodesulfurization of dibenzothiophene proceeds effectively in water. For n-hexadecane oxidation, the alkane/alkene ratio increased with increasing water density. The observed product distribution is probably due to the production of carbon monoxide, which is followed by the formation of active hydrogenating species via the water-gas shift reaction. This work demonstrates that hydrogenation reactions can be greatly accelerated in supercritical water through the use of either direct introduction of carbon monoxide or in situ formation of carbon monoxide through the partial oxidation of hydrocarbons. . Hydrogenation of DBT through partial oxidation in O2-SCW and CO-SCW (T ) 400°C, water density ) 0.42 g/cm 3 ). 11

Chemical Reviews, 2004

SATO, T.; INOMATA, H.; SMITH, R. L. J.; ARAI, K.; KRUSE, A.; DINJUS, E.; Chem. Rev. (Washington, ... more SATO, T.; INOMATA, H.; SMITH, R. L. J.; ARAI, K.; KRUSE, A.; DINJUS, E.; Chem. Rev. (Washington, D. C.) 104 (2004) 12, 5803-5821; Res. Cent. Supercrit. Fluid Technol., Tohoku Univ., Aoba, Sendai 980, Japan; Eng.) -Lindner 11-294

Combustion Science and Technology, 2006

Research in biomass gasification with subcritical and supercritical water is reviewed. Catalytic ... more Research in biomass gasification with subcritical and supercritical water is reviewed. Catalytic conversion of biomass in sub- and supercritical water is a low-temperature gasification technique that can be carried out from 473 to 973 K. Research is categorized according to temperature and water density, since reaction mechanisms greatly depend on these variables.

Bioresource Technology, 2007

Glycerol conversion was conducted in hot-compressed water (HCW: 573-673 K, 25-34.5 MPa) using a b... more Glycerol conversion was conducted in hot-compressed water (HCW: 573-673 K, 25-34.5 MPa) using a batch and a flow apparatus and the influences of temperature, H 2 SO 4 , glycerol concentration, and pressure, were examined. The yield of acrolein was enhanced by higher glycerol and H 2 SO 4 concentration, and higher pressure. Approximately 80% selectivity of acrolein was obtained at 90% of glycerol conversion with an acid catalyst in supercritical condition (673 K and 34.5 MPa). The rate constant of acrolein decomposition was always higher than that of acrolein formation in the absence of acid catalyst but the rate constant of acrolein formation could be overcome that of acrolein decomposition by addition acid in supercritical condition.

Fuel, 2003

Partial oxidative gasification of n-hexadecane (n-C 16 ) and organosolv-lignin (lignin) was studi... more Partial oxidative gasification of n-hexadecane (n-C 16 ) and organosolv-lignin (lignin) was studied by use of a batch type reactor in supercritical water: 673 K, 0.52 cm 23 of water density (40 MPa of water pressure at 673 K), and 0.3 of O/C ratio for the n-C 16 experiments; 673 K, 0.35 cm 23 of water density (30 MPa of water pressure at 673 K), and 1.0 of O/C ratio for the lignin experiments. The experiments without O 2 were also conducted for lignin (lignin decomposition). For all the cases (n-C 16 partial oxidation, lignin decomposition, lignin partial oxidation), NaOH or zirconia (ZrO 2 ) was added in the system as catalysts. Through n-C 16 studies, the catalytic effect of NaOH and ZrO 2 on partial oxidation in supercritical water were examined. In the case of lignin partial oxidation, we studied the possibility of partial oxidation in supercritical water for gasification technique of wastes. The yield of H 2 from n-C 16 and lignin with zirconia was twice as same as that without catalyst at the same condition. The H 2 yield with NaOH was 4 times higher than that without catalyst. Thus, a base catalyst has a positive effect on partial oxidation of n-C 16 and lignin to produce H 2 . The catalytic effect of NaOH and ZrO 2 was found to be enhancement of decomposition of intermediate (aldehyde and ketone) into CO, through n-C 16 studies. In the case of lignin studies, the enhancement of decomposition of the carbonyl compounds by catalytic effect of NaOH and ZrO 2 inhibit char formation and promotes CO and thus H 2 formation. q

Journal of Supercritical Fluids, 1998