Catalytic pyrolysis of microalgae and their three major components: Carbohydrates, proteins, and lipids

To better understand the pyrolysis of microalgae, the different roles of three major components (carbohydrates, proteins, and lipids) were investigated on a pyroprobe. Cellulose, egg whites, and canola oil were employed as the model compounds of the three components, respectively. Non-catalytic pyrolysis was used to identify and quantify some major products and several reaction pathways were proposed for the pyrolysis of each model compound. Catalytic pyrolysis was then carried out with HZSM-5 for the production of aromatic hydrocarbons at different temperatures and catalyst to feed ratios. The aromatic yields of all feedstocks were significantly improved when the catalyst to biomass ratio increased from 1:1 to 5:1. Egg whites had the lowest aromatic yield among the model compounds under all reaction conditions, which suggests that proteins can hardly be converted to aromatics with HZSM-5. Lipids, although only accounted for 12.33% of Chlorella, contributed about 40% of aromatic production from algal biomass.