Kayoko Morishita

Fractionation and identification of organic nitrogen species from bio-oil produced by fast pyrolysis of sewage sludge

Pyrolysis of sewage sludge was performed at 500 degrees C and a sweeping gas flow rate of 300 cm(3)/min in a drop tube furnace. Liquid fraction (i.e., bio-oil) from the sewage sludge pyrolysis was separated by silica-gel column chromatography (SGCC) with different solvents, including mixed solvents, as eluants. A series of alkanenitriles (C(13)-C(18)), oleamide, alkenenitrile, fatty acid amides and aromatic nitrogen species were fractionated from the bio-oil by SGCC and analyzed with a gas chromatography/mass spectrometry (GC/MS). Most of the GC/MS-detectable organic nitrogen species (ONSs) are lactams, amides and N-heterocyclic compounds, among which acetamide is the most abundant. N-heterocyclics with 1-3 rings, including pyrrole, pyridine, indole, benzoimidazole, carbazole, norharman and harman, were observed. The lactams detected include pyrrolidin-2-one, succinimide, phathalimide, glutarimide, piperidin-2-one and 3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione, all of which should be formed via decarboxylation and cyclization of gamma- and delta-amino acids. Such a procedure provides an effective approach to fractionation and identification of ONSs from bio-oil produced by fast pyrolysis of sewage sludge.

Scanning electron microscope observation of the purification behaviour of carbon nanotubes

Carbon nanotubes, with their unique structure, are expected to have a variety of applications as industrial materials. However, carbon nanotubes synthesized using the laser ablation method or arc discharge evaporation method always include other carbonaceous materials. Purification is a very important step in the use of carbon nanotubes as industrial materials. For the efficient recovery of nanotubes it is very important to clarify the gasification behaviour of the nanotube-containing material during the purification step. In this study, the gasification behaviour of a nanotube-containing material with various gasification agents was investigated in detail using a fixed-point observation technique and scanning electron microscopy. The gasification manner of the carbon nanotube-containing material was clarified using oxygen, carbon dioxide and hydrogen plasma as the gasifying agents. The gasification behaviour of the sample depended on the kind of reactant gas. In hydrogen plasma, carbon nanotubes were partly purified. Under the experimental conditions examined, oxygen gasification at 1023 K was the most effective method for purification of carbon nanotubes, and nanotubes were recovered selectively.

Triacetonamine formation in a bio-oil from fast pyrolysis of sewage sludge using acetone as the absorption solvent.

A sewage sludge sample was pyrolyzed in a drop tube furnace at 500 degrees C and sweeping gas flow rate of 300cm(3)/min. Triacetonamine (TAA) was detected with GC/MS as major component in the resulting bio-oil using acetone as the absorption solvent and proven to be a product from the reaction of NH(3) in the bio-oil with the absorption solvent acetone. TAA yield increased with storage time and reached a level about 28.4% (% sludge fed, daf) after 175h. Since the reaction of pure NH(3) with acetone does not proceed, some species in the bio-oil must catalyze the reaction of NH(3) with acetone. TAA was isolated in a high yield (27.9%, daf) and high purity (80.4%) by column chromatography with different solvents, including mixed solvents, as eluants. The study revealed the possibility of sewage sludge as potential resource of TAA.

Hydropyrolysis of coal in a powder-particle fluidized bed

Abstract Coal was pyrolysed in hydrogen in a powder-particle fluidized bed at atmospheric pressure. The coal powder was continuously fed into the bed, in which CoMo Al 2 O 3 catalyst particles or silica sand particles were fluidized. The effect of silica sand on the secondary reactions of volatile matter was quite small, whereas CoMo Al 2 O 3 showed high activity for the cracking of tarry materials. In the presence of CoMo Al 2 O 3 , a hydrocarbon liquid with a narrow product distribution was obtained; the main components were light aromatic hydrocarbons such as BTX and naphthalene. The product composition was quite sensitive to the pyrolysis temperature. The yields of light aromatic hydrocarbons with CoMo Al 2 O 3 increased with temperature to 590 °C and then sharply decreased above 600 °C. Maximum yields of light aromatic hydrocarbons, 7.2wt% (BTX 5.8 wt%, naphthalene 1.4 wt%), ~30 times those with silica sand, were obtained at 590 °C with a bed height of 10 cm. The yields of hydrocarbon gases increased with temperature; the CH4 yield was 32 wt% at 650 °C.

Gasification behavior of carbon nanotubes

Abstract Carbon nanotube-containing carbonaceous materials were gasified in a thermo-balance. The gasification was carried out in 1 vol% oxygen stream at 1023 and 823 K. The gasification behavior of nanotubes was observed using an unique technique, a fixed-point observation technique with a transmission electron microscope. The gasification behavior of carbon nanotubes strongly depended on the gasification temperature. At the gasification temperature of 1023 K, nanotubes were easily gasified at the cracks, defects and strains in the tubes. The destruction from the tip of the tubes was also observed. The gasification rate of the nanoparticles was higher than that of nanotubes. At 823 K, the outer layers of the nanotubes and nanoparticles were disordered with the progress of the gasification and the thin tubes were swelled. The pit formation on the surface of nanotubes was also observed. There was no obvious difference in the gasification rate between nanotubes and nanoparticles in the case of 823 K.

Hydrogen Production from Manure by Low Temperature Gasification

Livestock manure disposal is becoming a problem due to its increasing production and potential pollution. Low temperature gasification can be applied to convert the manure quickly into valuable products (H 2 , syn-gas and char). The pyrolysis behavior of pig and hen composts is presented in the paper. Because of the difference in the organic materials and minerals, the large difference in the pyrolysis behaviors of the pig and hen manure char is observed. The low temperature gasification of the two manures was also investigated in the study. The results show that Ni/Al 2 O 3 catalyst can promote the tar cracking into little molecules and the volatile matters can be converted into H 2 , CO, CH 4 , CO 2 and carbon completely.

Development of Catalytic Tar Decomposition in an Internally Circulating Fluidized-Bed Gasifier

Biomass gasification in an Internally Circulating Fluidized-bed Gasifier (ICFG) using Ni/Ah03 as tar cracking catalyst is studied at low temperature. Reaction conditions of the catalyst bed are discussed, including catalytic temperature and steam ratio. High energy efficiency and hydrogen-rich, low-tar product gas can be achieved in a properly designed multi-stage gasification process, together with high-performance catalyst. In addition, considering the economical feasibility, a newly-developed Ni-loaded brown coal char is developed and evaluated as catalyst in a lab-scale fluidized bed gasifier with catalyst fixed bed. The new catalyst shows a good ability and a hopeful prospect oftar decomposition, gas quality improvement and catalytic stability.