HR: 0830h
AN: V51H-0385    [PDF]
TI: The Influence of ZnBr$_{2}$ and ZnCl$_{2}$ Liquid in Rock-Eval Pyrolysis of Separated Macerals
AU: * Su, P
EM: catcat@geo.ncu.edu.tw
AF: Central Geological Survey, 2 Ln109 HuaHsing St, Chung-Ho, 325 Taiwan
AU: Tsai, L
AF: Ins Applied Geology, National Central University, 300 JungDa Rd, JungLi, 320 Taiwan
AB: This study examined the influence of density liquid in Rock-Eval pyrolysis results of separated macerals. Zinc bromide and zinc chloride were chosen as density liquids for separating macerals. The samples are mid-Miocene high volatile bituminous coals which are from lower member of Shitih Formation in Taiwan. Samples were all crushed to pass \#20 sieve and soaked in five different densities (from 1.0 to 1.5 g/cm3) of both zinc bromide and zinc chloride density liquids. After soaking for 2 hrs, the samples were divided into two parts. One was dried directly, and another part was dried after thorough washing by distilled water, until the specific gravity of filtrate water is come to 1.000. It revealed that pyrolytic parameters could be resumed back to their original values after washing. Rock-Eval pyrolysis was performed for all samples afterwards, with heating rate 25$\deg$C/min from 250 to 550$\deg$C. We found that T$_{max}$ decrease with specific gravity of soaking density liquid in soaked samples. As the trend of T$_{max}$, S$_{2}$ has similar effect in soaked samples. It might has two reasons: 1) the density liquids made the pyrolytic reaction speed up faster. Hydrocarbons can be cracked early, and the peak of S$_{2}$ advanced earlier in time. Thus when the peak showed early, the temperature of the peak was lower. 2) Zinc bromide and zinc chloride both melted at temperature over 400$\deg$C. The liquid wrapped up the coal particles like walls and the hydrocarbon can not been completely cracked out. When S$_{2}$ decrease, the peak of S$_{2}$ appears early, and T$_{max}$ becomes lower, too. In Rock-Eval pyrolysis, zinc bromide and zinc chloride will melt before peak S$_{2}$ sine their melt points were lower than 400$\deg$C. The melting materials will wrap up samples and hinder hydrocarbon to crack. It has to be noticed that T$_{max}$ and S$_{2}$ may reduce with liquid gravity in using both two materials as density liquid. The effect of these density liquids can be removed by wash, although washing may still result in the decrease of S$_{1}$. Chemical compounds with low melting point were expected to wrap the coal particles and causing T$_{max}$ to be advanced, and S$_{2}$ to be decreased. This influence is more conspicuous when higher density liquid is prepared for maceral separation.
DE: 1055 Organic geochemistry
DE: 1094 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting