Microwave co-pyrolysis characteristics and product component of Chlorella vulgaris and polypropylene under solid acid catalyst/graphite composite additives

Abstract

Appropriate additives can enhance the quality of bio-oil produced through microwave co-pyrolysis. In this paper, solid acid catalyst/graphite (SA/GP) composite additives at different ratios (SA:GP = 10:0, 7:3, 5:5 and 3:7, denoted as SA, S7G3, S5G5 and S3G7, respectively) were prepared. The effects of SA/GP addition (10 %, 20 %, 30 % and 40 %) on co-pyrolysis characteristics, product yield and bio-oil components of Chlorella vulgaris (CV) and polypropylene (PP) were studied by microwave pyrolysis furnace and GC-MS. Results showed only 40 % addition promoted the pre-middle stage of co-pyrolysis when adding SA. The maximum average weight loss rate R_v (0.839 wt%/min) and the minimum total pyrolysis reaction time t_s (88.250 min) were observed at 30 % S3G7. Compared with no additives, the maximum bio-oil yield (29.37 wt%) was obtained at 30 % S5G5 and the maximum hydrocarbon content (42.16 %) was obtained at 30 % S3G7. The porous structure of SA promoted the dehydration and aromatization of small molecules, resulting in a maximum aromatic yield of 11.77 % at 30 % S7G3. Overall, the SA/GP composite additives showed good stability and deoxidizing ability in microwave co-pyrolysis and can be used to improve the yield and quality of bio-oil.