This study was carried out with a object of determining structural characteristics of reductive alkylation product. Benzene soluble portion (BS-1) prepared from Taiheiyo coal was used as the starting materials. BS-1 was repeatedly methylated three times without using naphthalene, since BS itself plays a role of an electron transfer agent. The n-hexane soluble portion (HS) and the BS from the 1∼4 reductive methylation steps were separated by gel permeation chromatography, and the molecular weight distributions of them were determined using a vapor-pressure osmometry. HS at each step was also separated into six relatively distinct compound types-saturates, monoaromatics, diaromatics, etc-through dual-packed column to examine the contents of these type-compounds. Furthermore some of HS-GPC. fractions, molecular weight range 602∼283, were analysed by gas chromatography/mass spectrometry. From these results, it was clearly observed that the change of high molecular weight fractions into lower ones, the transfer of benzene eluate into polar mixture and methanol eluates, and the convesion of type-compound with Z No.-22 into that with Z No.-18 had occurred by step-wise methylation. Thus unit structure of coal had a tendency to be gradually uniformized.
Physical change in coal particle and effect of limestone flux on char reactivity were studied with a laboratory-scale entrained flow gasifier at atmospheric pressure, using a Blair Athor coal at a design flow rate of 2kg/h. Results were obtained from a series of tests at an oxygen-coal ratio of 0.8, a limestone flux-coal ash ratio of 35wt%. The temperature in the gasification zone was in a range of 1400 to 1650°C. A special sample probe was used to collect char samples at three different axial positions in the 670mm long reactor for the observation and measurement of residual char properties. Devolatilization was initiated very quickly in the forward region of the reactor with particle blowhole formation and fragmentation. During gasification, macropore surface and crack in char particle markedly developed, and, thus, the amount of fragment increased.Several types of fragment such as plate, block, skelton and ball type, were observed after the gasification zone of the reactor. The observed coal conversion obtained from the flux addition experiments was about 5% higher than that conversion obtained from the flux addition experiments was about 5% higher than that from the non-flux experiments. This suggested that melting ash in char particle was attributed to increases in macropore and fragmentation of char, and, thus, enhanced overall char reactivity.
The conversion of naphtha fractions of a coal liquid on pentasil-type H-Ga-silicate was examined. Although model compounds (octane and cyclohexane) exhibited quite high reactivities on H-Ga-silicate, the naqhtha fractions showed negligible reactivities on the catalyst. By examining the model reaction in the presence of quinoline or cresol, the authors attributed the low reactivity of the coal liquid to the following three reasons: a) adsorption of the basic components on the acid sites of the catalyst, b) inhibitory effect phenols, c) rapid deactivation of the catalyst due to the deposition of coke precursors formed during storage of the coal liquid. Washing the naphtha fractions with 3%HCI and then 10%NaOH aqueous solutions to remove these inhibitors significantly increased the reactivities of these naphtha fractions, and the reactions of the washed naphtha fractions on H-Ga-silicate afforded BTX in ca. 50% yields. Inhibitory effect of phenols on the conversion of hydorcabons was unexpected because facile alkylations of phenols with methanol on microporous catalysts are well known; therefore the reaction of phenols on H-Ga-silicate was examined. At low temperatures, phenol molecules were strongly adsorbed in the pores of the H-Ga-silicate and inhibited the conversion of the hydrocabons. At high temperatures, phenols were apparently deoxygenated on H-Ga-silicate yielding aromatic hydrocabons; however, the catalyst was rapidly deactivated.