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The functionalities of the fluorine and carbon present in fly ashes formed in pulverized coal combustion have been studied with X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques. The ash samples include 20–130μg/g-dry and 0.4–4.1mass%-dry of fluorine and carbon elements, respectively, and these components are enriched at the outermost layer of the ash surface...
Biomass gasification produces a low to medium-BTU product gas (or syngas) containing primarily CO 2 , H 2 , CO, CH 4 and (C 2 +C 3 ), as well as some contaminants such as tars, NH 3 , H 2 S and SO 2 . In order to achieve better efficiencies of the syngas applications, these contaminants must be removed before the syngas is used for internal...
The fate of the chlorine and fluorine present in a sub-bituminous coal from Indonesia during pyrolysis and gasification has been studied with fixed and entrained bed reactors. The rate profile for HCl evolved in the temperature programmed pyrolysis exhibits the main and shoulder peaks at 480 and 600°C, respectively. Model experiments and subsequent Cl 2p XPS measurements show that HCl reacts with...
A novel hot gas cleanup method to decompose a low concentration of NH 3 to N 2 with metal cations present inherently in low rank coals has been studied with a quartz reactor under the conditions of 750–850°C, 0.1MPa and high space velocity of 45,000h −1 . Each coal is pyrolyzed at 900°C to prepare the char, which is subjected to the decomposition of 2000ppm NH 3 after...
Decomposition of NH 3 to N 2 with Fe and Ca catalysts supported on brown coal chars has been studied with a cylindrical quartz reactor from a viewpoint of hot gas cleanup. The catalyst is prepared by pyrolyzing a brown coal with Fe or Ca ions added. In the decomposition of 2000 ppm NH 3 diluted with He at 750 o C and at a space velocity of 45,000 l/h, 2-6wt% Fe catalysts...
Cracking of a mixture of petroleum asphaltene and 10wt% Fe catalyst supported on mesoporous molecular sieve (SBA-15) possessing a hexagonal array of uniform mesopores has been studied with a fixed bed reactor at 573 K under atmospheric He. When average pore diameter of Fe/SBA-15 is varied between 4.5 and 15 nm, asphaltene conversion increases almost linearly with increasing pore diameter up to 12...
Pyrolysis of 10 coals with carbon contents of less than 80wt%(daf) has been studied with a fixed bed quartz reactor to examine mainly nitrogen release from char-N without volatile matters. When temperature is raised from 1000 to 1350 o C, N 2 yield increases but char-N decreases for all the coals used. There is a strong reverse correlation between N 2 and char-N, which points...
Formation of N 2 during temperature programmed pyrolysis at 10 o C/min of low rank coals up to 1350 o C has been studied with a fixed bed quartz reactor. When Ca 2+ ions are exchanged with the raw or demineralized coals by using a saturated aqueous solution of Ca(OH) 2 , the Ca enhances the formation rate mainly at around 820 or 850-1100 o C, respectively...
Nitrogen release from several coals with different ranks during CO 2 gasification at 0.1MPa and 1000°C has been studied with a fixed-bed quartz reactor. Among HCN, NH 3 , N 2 , and tar-N analyzed, N 2 is the main product for all the samples in the whole range of coal conversion. As the gasification of every char after devolatilization proceeds, N 2 increases...
Formation of HCN, NH 3 , and N 2 during fixed-bed pyrolysis at 10K min -1 has been studied using coal samples after partial demineralization followed by addition of metal hydroxides from aqueous systems. Without additives, NH 3 is the predominant product at ≤ 700°C, showing the two peaks in the formation rate profile, whereas N 2 is the only product at...
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