Jing-Pei Cao

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.

Preparation and characterization of bio-oils from internally circulating fluidized-bed pyrolyses of municipal, livestock, and wood waste

Fast pyrolyses of sewage sludge (SS), pig compost (PC), and wood chip (WC) were investigated in an internally circulating fluidized-bed to evaluate bio-oil production. The pyrolyses were performed at 500 °C and the bio-oil yields from SS, PC, and WC were 45.2%, 44.4%, and 39.7% (dried and ash-free basis), respectively. The bio-oils were analyzed with an elemental analyzer, Karl-Fischer moisture titrator, bomb calorimeter, Fourier transformation infrared spectrometer, gel permeation chromatograph, and gas chromatography/mass spectrometry. The results show that the bio-oil from SS is rich in aliphatic and organonitrogen species, while the bio-oil from PC exhibits higher caloric value due to its higher carbon content and lower oxygen content in comparison with that from SS. The bio-oils from SS and PC have similar chemical composition of organonitrogen species. Most of the compounds detected in the bio-oil from WC are organooxygen species. Because of its high oxygen content, low H/C ratio, and caloric value, the bio-oil from WC is unfeasible for use as fuel feedstock, but possible for use as chemical feedstock.

Influence of manure types and pyrolysis conditions on the oxidation behavior of manure char

Livestock manure can be quickly converted into valuable products (H(2), syn-gas and char) by low temperature gasification. Manure char combustion offers energy for the gasification reactions. In the paper, the influence of manure type and pyrolysis conditions on manure char reactivity is addressed. The results show that the oxidation behaviors of manure char are dependent strongly on manure type and pyrolysis conditions employed. The large difference between the oxidation behaviors of pig and hen manure chars can be attributed to the difference in the organic materials and minerals of the samples. High final temperature, flash pyrolysis and water steam atmosphere used for char preparation promote the resultant char reactivity.

Synergic effect of methanol and water on pine liquefaction

Pine liquefaction (PL) and re-liquefaction of its liquefaction residues in sub- and supercritical methanol, water or methanol/water mixed solvents (MWMSs) was investigated. The results show that isometric MWMS has the highest synergic effect on PL. Moreover, the total yield of bio-oil (BO) and conversion from pine and its residue both liquefied in the MWMS were obvious higher than those from PL in methanol (water) and re-liquefaction of its residue in water (methanol), suggesting that the interaction between the two solvents is responsible for synergic effect. This approach facilitates understanding the mechanism for biomass liquefaction in mixed solvents and developing efficient utilization process of biomass.

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.

Low temperature catalytic gasification of pig compost to produce H2 rich gas.

The low temperature catalytic gasification of pig compost before and after acid washing was carried out to produce H2 rich gas using a two-stage fixed-bed reactor. Little effect of the minerals on the manure pyrolysis is determined. Under the presence of Ni/Al2O3 catalyst nearly all the tarry matters were cracked into H2, CO, CO2 and residual carbon. High H2 and CO yields were obtained by low temperature catalytic steam gasification. Acid washing results in the decrease in the content of the ease-hydrolyzed organic components, which volatilize at low temperature. The change in the gas yields from the manure during catalytic decomposition is in accordance with its pyrolysis behavior.

H2 production from fowl manure by low temperature catalytic gasification.

In the paper, H(2) rich gas produced from fowl manure (hen compost-HC) by low temperature catalytic gasification (LTCG) technology is addressed. The pyrolysis behaviors of the samples before and after weak acid pretreatment were investigated using thermal gravimetric analysis. Furthermore, the catalytic influence of HC char and HC ash on the decomposition of the nascent volatiles was determined. A catalytic role of the minerals contained in HC on its pyrolysis behavior was confirmed due to the high content of Ca. LTCG process promotes the complete decomposition of the manure volatiles and significantly increases H(2) yield and the total gas yield. An obvious catalytic effect of HC char and HC ash on the decomposition of the nascent volatiles is attributed to CaO contained in them.

Catalytic reforming of nitrogen-containing volatiles evolved through pyrolysis of composted pig manure.

The pyrolysis of pig compost was performed in a two-stage fixed-bed reactor to determine the effects of decomposition temperatures and catalysts (i.e., transition-metal and non-transition-metal catalysts) on carbon and nitrogen conversions. The secondary decomposition was investigated at different temperatures from room temperature up to 750°C. Then the effects of various catalysts were investigated at 650°C. Approximately 60% of the carbon and 80% of the nitrogen in the pig compost were converted into volatiles during pyrolysis. Conversion of carbon and nitrogen species in tar into gas, and the evolution undesirable NH3 and HCN without catalyst increased with increasing decomposition temperature. Transition-metal catalysts showed excellent activity for conversion of condensable volatiles into gas and NH3 and HCN into N2. Although non-transition-metal catalysts had moderate activity for the conversion of volatiles into gas and negligible activity for the conversion of NH3 into N2, dolomite can provide liquid fuel with negligible amount of nitrogen species.

Identification of Sulfur- and Nitrogen-containing Organic Species in the Extracts from Pocahontas No. 3 Coal

Abstract Pocahontas No. 3 coal was extracted with CS2, n-hexane, benzene, methanol, acetone, and acetone/CS2 (1:1 vol/vol) mixed solvent sequentially. The resulting six extracts were analyzed with gas chromatography/mass spectrometer (GC/MS). Hexathiane, octathiocane, 23 sulfur-containing organic species, and 21 nitrogen-containing organic species were detected in the extracts. Sulfur-containing organic species detected in the extracts include dialkyl- and disulfides, dimexano, dibenzothiophene, benzonaphthothiophene, and their methyl-derivatives, among which dimexano and dixanthogen were seldom reported in any sediments. Methanol is effective for extracting sulfur-containing organic species without aromatic ring. Most of the nitrogen-containing organic species detected in the extracts are acridinone, carbazole and their methyl-derivatives, benzocarbazoles, amines, phenanthridinone, and piperidinone. The species number of nitrogen-containing organic compounds detected in the extracts increased with the increase in solvent polarity. Different from those reported previously, N and O atoms often coexist in the same compounds in the present study.

Sequential ultrasonic extraction of a Chinese coal and characterization of nitrogen-containing compounds in the extracts using high-performance liquid chromatography with mass spectrometry.

Dongming lignite was sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric carbon disulfide/acetone mixed solvent at room temperature to afford extracts 1-5, respectively. High-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry was used to separate and characterize heteroatomic species in the extracts at molecular level. Molecular mass of compounds in the extracts is mainly distributed from 300 to 800 u, and the relative abundance of compounds with molecular mass over 800 u in the carbon disulfide extract is 135 times of that in the petroleum ether extract. The acetone extract has the highest relative abundance for organonitrogen compounds. Double bond equivalence numbers of detected species indicate that most of the organonitrogen compounds contain N-heterocyclic aromatic rings, including pyridine, quinoline and pyrrole. Some organonitrogen isomers in Dongming lignite were separated and identified by high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry, and the corresponding structural information was proposed.