Abstract:
The Box-Behnken experimental design was used to optimize the microwave pyrolysis process of the coconut clothes by response surface method (RSM). The effects of microwave pyrolysis temperature, nitrogen flow rate, heating rate and pyrolysis time on liquid yield were investigated. The results showed that the regression equation model fitted well and was significant. The influence order of various factors on liquid product yield was microwave pyrolysis temperature > nitrogen flow rate > pyrolysis time > heating rate. The optimum conditions were temperature 550℃, nitrogen flow rate 80 mL/min, heating rate 20℃/min and pyrolysis time 20 min. According to this process, the obtained yield of liquid product value was 38.28%. The analyses of properties and composition of liquid product showed that the water content in the liquid product was 14.32%, the pH value was 3.78, and the maximum heating value under the best pyrolysis conditions was 24.61 MJ/kg.By GC-MS analysis of bio-oil, under the optimal conditions, the liquid product was composed of phenols, aldehydes, acids, ketones and so on, and their contents were 84.35%, 6.01%, 3.37%, 2.05%. The phenols included phenol(33.51%),
p-cresol(9.71%), 2-methoxyphenol(10.99%) and 4-ethyl-2-methoxyphenol(5.57%).