Emine Yagmur

The effect of swelling pretreatment on the coal liquefaction in tetralin with microwave energy

Three Turkish coals, a Zonguldak coal and Tunçbilek and Beypazari lignites were used to examine the effect of solvent swelling pretreatment on the solubilization and dissolution behavior. Methanol, THF (tetrahydrofuran) and TBAH (tetrabutylammonium hydroxide) were used as swelling agents. For the investigation of dissolution behavior of coals, the microwave heating period was changed from 10 to 30 min at 5 min intervals. While solvent pretreatment enhanced the THF solubles yields for the Zonguldak coal, solvent treatment decreased the THF solubles yields for the Tunçbilek and Beypazari lignites. The data obtained in this study indicated that the formation mechanism of AS (asphaltenes), PAS (preasphaltenes) and oils depend on the coal and swelling agent type.

Effect of O-methylation on solubility and swelling of coals

Abstract Zonguldak bituminous coal and Mugla–Yatagan, Seyitomer and Bolu–Goynuk lignites were O -methylated with potassium hydroxide–dimethyl sulphate (KOH–DMS) and acetone–potassium carbonate–dimethyl sulphate (acetone–K 2 CO 3 –DMS) methods. Effects of O -methylation on the swelling ratio and on the tetrahydrofuran (THF) solubility were studied. Methoxyl contents of coals were found to be larger after O -methylation with acetone–K 2 CO 3 –DMS (a) while O -methylation with acetone–K 2 CO 3 –DMS (b) resulted in significantly lower methoxyl formation. Coals O -methylated with acetone–K 2 CO 3 –DMS (b), although showed lower methoxyl contents, have comparably larger solubility than those treated according to the other two methods. Yet, no strong correlation with the methoxyl contents of coals and their swelling and solubility can be claimed. It can be reported here that the swelling and solubility, although dependent on the methoxyl content, are greatly influenced by the structure of the coal.

Reactions of Coal Model Compounds in Tetralin Using Microwave Energy: Effects of Catalysts

Reaction mechanisms of model compounds of coal in tetralin by microwave energy were investigated. Diphenylmethan (DFM), phenyl-methyl ether (anisole), and phenyl-methyl ketone (acetophenon) were chosen as model compounds. Experiments were carried out for 10 minutes of microwave energy and different catalysts were used (pyratol, zeolite, BaCl2, AlNiMo) to find out the distribution of reaction products of the model compounds. GC and GC/MS are used to analyze the reaction products. The main reaction products from DFM and tetralin under microwave radiation with catalysts were ethyl benzene, naphthalene, 2-methyl naphthalene, 3,4-dihydronaphthaleneone, 1-1′-ethyldene 1-benzene, and 1-methyl 4-phenyl methyl benzene. The main reaction products from anisole and tetralin under microwave radiation were ethyl benzene, phenol, methyl phenol, decahydronaphthalene, and tetrahydronaphthalenol. The main reaction products from acetophenon and tetralin under microwave radiation with catalysts were ethyl benzene, methoxy benzene, decahydronaphthalene, naphthalene, tetrahydronaphthalenol, 3,4-dihydronaphthalenone and 2-butene-1-one-1,3 diphenyl. The estimated mechanism of the model compounds with tetralin is compared with the results taken from GC/MS analysis. It is obtained that the results suggested theoretically were similar with the GC/MS results.

Examination of gas and solid products during the preparation of activated carbon using phosphoric acid

Activating agents play significant roles in the preparation of activated carbon (AC) from biomasses and their wastes, which are widely used in AC production. Application methods are also important for the production process. Products give remarkable ideas regarding the method and heat treatment process. The activated carbon was produced from waste tea in accordance with either the conventional method or microwave energy pretreated method using phosphoric acid (H3PO4) as activating agent. The yields of the activated carbons were 51.8% for conventional method and 46.0% for microwave pretreated method. The acid suppressed the formation of tar and promoted the amount of solid and aromatic structure accordance to sp2 hybridisation. Additionally, the waste tea was directly carbonised (without H3PO4) and the yield was 36.3%. Major gas (H2, CH4, C2H6, C2H4, CO2 and CO) products obtained during heat treatment process in a conventional furnace were examined in terms of quantity and quality. The solid products were characterised in terms of surface area, pore size and surface properties. The result of gas analysis showed that phosphoric acid affected formation of activated carbon mechanism and significant reactions occurred during microwave pretreatment process.