수소 반응분위기에서 Chloroethylene 열분해 반응경로 특성

Abstract

염화탄화수소의 고온열분해 반응에서 생성물 반응경로 특성을 파악하기 위해 <TEX>$H_2$</TEX> 반응분위기에서 1,1-dichloroethylene(<TEX>$CH_2CCl_2$</TEX>) 열분해반응 실험을 수행하였다. 열분해반응 실험은 등온관형반응기를 이용하여 반응온도 <TEX>$650{\sim}900^{\circ}C$</TEX>, 반응시간 0.3~2.0초에서 진행하였으며, 반응물 mole 분율은 전체 실험에서 <TEX>$CH_2CCl_2:H_2$</TEX> = 4:96 일정하게 유지하였다. 반응물 <TEX>$CH_2CCl_2$</TEX>가 완전분해온도는(분해율 99% 이상) <TEX>$825^{\circ}C$</TEX>(반응시간 1초 기준)였으며, <TEX>$H_2$</TEX> 반응분위기에서 <TEX>$CH_2CCl_2$</TEX> 주요 분해반응경로는 H원자 추출 및 첨가교체치환 연쇄반응으로 파악되었다. <TEX>$CH_2CCl_2$</TEX>가 46% 분해되는 <TEX>$700^{\circ}C$</TEX>에서 1차 생성물로 <TEX>$CH_2CHCl$</TEX>가 28%로 가장 높은 농도로 검출되었다. <TEX>$775^{\circ}C$</TEX> 이상에서는 탈염소화된 <TEX>$C_2H_4$</TEX>가 2차 생성물로 가장 많이 생성되었으며, 반응온도가 증가할수록 염소 원자수가 작은 화합물이 생성되었으며 이들 화합물은 열화학적으로 안정된 물질이다. <TEX>$825^{\circ}C$</TEX> 이상의 고온반응영역에서 탈염소반응의 부산물인 HCl과 <TEX>$C_2H_4$</TEX>, <TEX>$C_2H_6$</TEX>, <TEX>$CH_4$</TEX> <TEX>$C_2H_2$</TEX> 등과 같은 열화학적으로 안정된 탄화수소가 주요생성물로 검출되었다. 본 연구에서 고찰된 반응계에서 분해와 생성물분포 특성을 고려하고 열화학이론 및 반응속도론을 기초로 주요 반응경로를 제시하였다. The pyrolytic reaction of 1,1-dichloroethylene(<TEX>$CH_2CCl_2$</TEX>) has been conducted to investigate thermal decomposition of chlorocarbon and product formation pathways under hydrogen reaction environment. The reactions were studied in a isothermal tubular flow reactor at 1 atm total pressure in the temperature range <TEX>$650{\sim}900^{\circ}C$</TEX> with reaction times of 0.3~2.0 sec. A constant feed molar ratio <TEX>$CH_2CCl_2:H_2$</TEX> of 4:96 was maintained through the whole experiments. Complete decay(99%) of the parent reagent, <TEX>$CH_2CCl_2$</TEX> was observed at temperature near <TEX>$825^{\circ}C$</TEX> with 1 sec. reaction time. The important decay of <TEX>$CH_2CCl_2$</TEX> under hydrogen reaction environment resulted from H atom cyclic chain reaction by abstraction and addition displacement. The highest concentration (28%) of <TEX>$CH_2CHCl$</TEX> as the primary product was observed at temperature <TEX>$700^{\circ}C$</TEX>, where up to 46% decay of <TEX>$CH_2CCl_2$</TEX> was occurred. The secondary product, <TEX>$C_2H_4$</TEX> as main product was detected at temperature above <TEX>$775^{\circ}C$</TEX>. The one less chlorinated ethylene than parent increase with temperature rise subsequently. The HCl and dechlorinated hydrocarbons such as <TEX>$C_2H_4$</TEX>, <TEX>$C_2H_6$</TEX>, <TEX>$CH_4$</TEX> and <TEX>$C_2H_2$</TEX> were the main products observed at above <TEX>$825^{\circ}C$</TEX>. The important decay of <TEX>$CH_2CCl_2$</TEX> resulted from H atom cyclic chain reaction by abstraction and addition displacement. The important pyrolytic reaction pathways to describe the features of reagent decay and intermediate product distributions, based upon thermochemical and kinetic principles, were suggested.