Molten Hydroxide Coal Desulfurization Using Model Systems

Utz, Bruce R.; Friedman, S.; Soboczenski, Steven K.

doi:10.1021/bk-1986-0319.ch005

Cited by 8 publications

(4 citation statements)

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“…It is also possible that the oxide ion reacts with the small molecules generated from the thermal degradation of PTFE to promote the formation of F − and CO 2 . It has also been found that molten MOH is a particularly effective agent for the decomposition of small organic compounds containing halogen or sulfur, such as CCl 4 , 27 chlorobenzene, 28 coal, 29 and even hazardous mixed organic waste. 30 Thus, as shown in eqn (6), if our system progresses ideally, PTFE can be processed without the generation of exhaust gases and can be efficiently mineralized.…”

Section: Resultsmentioning

confidence: 99%

Mineralization of poly(tetrafluoroethylene) and other fluoropolymers using molten sodium hydroxide

Yanagihara

Katoh

2022

Green Chem.

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Section: Resultsmentioning

confidence: 99%

Mineralization of poly(tetrafluoroethylene) and other fluoropolymers using molten sodium hydroxide

Yanagihara

Katoh

2022

Green Chem.

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“…The diameters of OH À , K + , and Na + ions are 0.220, [39] 0.203, and 0.166 nm, respectively, and, thus, these species could migrate throughout the particles and catalyze the breaking of the C S bonds in petcoke. According to the products of the reaction, Utz et al [40] inferred that the C S bond undergoes homolysis in the presence of the hydroxides at 375 C to generate a free radical, which can be capped by hydrogen or through polymerization, releasing the sulphur as a sulphide or sulphate species. [12][13][14] The sulphur released from petcoke during activation reacts with the alkali ions to form Na 2 S, K 2 S, Na 2 SO 4 , and K 2 SO 4 , which have (pure F I G U R E 5 Scanning electron microscopy (SEM) analysis of polished samples of petcoke activated with KOH but not washed; (A-C) different magnifications of the sample, (D) potassium mapping, and (E) sulphur mapping.…”

Section: Pore Development and Chemical Phase Behaviourmentioning

confidence: 99%

Distribution of potassium during chemical activation of petroleum coke: Electron microscopy evidence and links to phase behaviour

Montes

Xiao

et al. 2022

Can J Chem Eng

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In this study, direct evidence for chemical penetration into petroleum coke particles during activation is presented. In addition, the porosity development was directly related to the sulphur loss and phase behaviour of the species present.Petroleum coke (petcoke, 6 wt.% sulphur) was activated with KOH and NaOH at temperatures between 400 and 800 C. The C S bonds were broken before 400 C in the presence of KOH and before 500 C in the presence of NaOH. Electron microscopy analysis of cross-sectioned and ultramicrotomed samples revealed that sulphur was still present within the particles and that the hydroxide activation agents had penetrated to the centre of the particles (90-150 μm). After heating to 800 C and washing with a weak acid aqueous solution, essentially all the sulphur was removed, as was any remaining chemical agent. The characterization results, phase diagrams, and complementary experiments with carbonate chemical agents or steam suggest that, during heating, a molten phase formed around the petcoke particles. The composition of this molten phase changed as activation proceeded and both sulphur and ash components were liberated from the petcoke. This better understanding of the activation process will improve the efficiency of preparing activated carbon.

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“…Although the alkali leaching either alone or with dissolved oxygen is very effective for pyritic sulfur removal, yet it can also remove the organic sulfur, in this work about 78% organic sulfur could be removed (at alkali concentration of 0.25 molarity, partial pressure of oxygen of 200 psi, reaction time of 4 hours, at temperature 120 o C, and with particle size of 40µm).. Ca Michael (Nowak et al 1989) worked on the mechanism of organic sulfur removal from coal by sodium hydroxide NaOH, he observed that alkali hydroxide containing large alkali metal cation are more effective in decomposition of thiophenes and furan of organic sulfur present in the coal. B.R Utz (Utz, Friedman, and Soboczenski 1986) found the chemistry of molten alkali hydroxide for organic species in the coal. He used the mixture of NaOH and KOH to study the organic sulfur species in the coal, he selected benzothiophene and dibenzothiophene as model compounds that simulated the organosulfur compounds in the coal.…”

Section: Organic Sulfurmentioning

confidence: 99%

Desulfurization of thar lignite by oxidative alkali leaching under pressure

Usto

Abbasi

Maitlo

et al. 2021

International Journal of Coal Preparation and Utilization

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Pakistan is the world largest lignite bearing country in the world due to the Thar coal reserves. Sulfur contained in this coal need to be removed prior to combustion. Oxidative alkali leaching in dissolved oxygen technique was used to remove the sulfur from Thar coal. This method removed enough all three types of sulfur; about 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur and more than 82S% of total sulfur removal was achieved. Effect of various reaction parameters were observed, it was investigated that reaction time and partial pressure of oxygen has positive effect on the desulfurization, higher the reaction time and oxygen partial pressure higher the degree of desulfurization, also the desulfurization increased with increase in reaction temperature and alkali concentration till some optimum value and then decreases with further increase in value of temperature and concentration of alkali, although desulfurization was observed maximum with minimum particle size. Coal was also characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that combustion properties of processed coal were improved and black smoke in processed coal was reduced.

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Molten Hydroxide Coal Desulfurization Using Model Systems

Cited by 8 publications

References 0 publications

Mineralization of poly(tetrafluoroethylene) and other fluoropolymers using molten sodium hydroxide

Mineralization of poly(tetrafluoroethylene) and other fluoropolymers using molten sodium hydroxide

Distribution of potassium during chemical activation of petroleum coke: Electron microscopy evidence and links to phase behaviour

Desulfurization of thar lignite by oxidative alkali leaching under pressure

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