剑桥滤片捕集装置-热重-气相色谱-质谱法研究低温下纤维素热解形成苯并[a]芘的过程

设计和建立了剑桥滤片捕集装置-热重(Thermogravimetry,TG)-气相色谱-质谱(GC-MS)联用系统,按照划分温度段收集的方法,将其应用于低温下纤维素热解形成苯并[a]芘过程的研究,以验证该联用系统的可靠性。在10℃/min升温速率、200 mL/min氮气流速下,用剑桥滤片装置分别对纤维素主失重区间内270℃-450℃和450℃-600℃两个温度段的逸出气体进行捕集、萃取,并采用GC/MS进行定性定量分析。结果表明,1)在升温速率和载气流速不变的情况下,用直径为8 mm的小型剑桥滤片,并保持剑桥滤片入口与出口处流量一致的情况下捕集效果均达到最佳;2)低温下纤维素热解形成苯并[a]芘的过程随着温度段的变化而变化,450℃-600℃温度段内的生成量远大于270℃-450℃温度段;3)低温下苯并[a]芘生成量与文献报道值接近,同时各温度段下苯并[a]芘生成量的相对标准偏差(n=3)均小于10%,验证了该联用系统的可靠性。

The formation of benzo[a] pyrene in low temperature cellulose pyrolysis with cambridge filter trapping device-thermogravimetry-gas chromatography mass spectrometry

A new system of cambridge filter trapping device-thermogravimetry-gas chromatography-mass spectrometry wasestablished and applied to study the formation of benzo(a) pyrene in low temperature cellulose pyrolysis by collectingsamples in different temperature ranges.Cambridge filter trapping device was used to collect evolved gas in 270℃-450℃ and 450℃-600℃ under flowing nitrogen of 200 mL/min and heating rate of 10 ℃ /min.Benzo [a] pyrene was qualita-tively and quantitatively analyzed by gas chromatography/mass spectrometry(GC/MS) after extracting from the trappedcambridge filter.Results showed that 1) applying small cambridge filter(8 mm in diameter) and keeping same flow rate of carrier gas at both entrance and exit of cambridge filter was the optimal condition based on trapping effect of benzo [a] pyrene;2) benzo[a]pyrene yield in 450℃-600℃ temperature range was higher than that of 270℃-450℃;and 3) reli-ability of this system was verified since yields of benzo [a] pyrene was very close to quoted value and RSDs(n=3) wereall below 10%.