Gasification of lipid-extracted microalgae biomass promoted by waste eggshell as CaO catalyst

Abstract Significant amounts of lipid-extracted microalgae biomass (LMB) could be generated as a by-product from biodiesel production, therefore its ability to be processed into and converted into a more valuable product needs to be explored to determine its true potential market value. In this study, the catalytic gasification of two LMB's, Spirulina platensis and Chlorella vulgaris , were performed in a thermogravimetric analyzer with mass spectrometry. The CaO based catalyst, naturally derived from waste eggshell, was varied to determine influence of catalyst loading (10, 30 and 50 wt%). The reactions were conducted over a 30–800 °C temperature range, in 5% O 2 /Ar at a 500 mL min −1 flow rate. Scanning electron microscopy and X-ray diffraction methods were utilized to characterize and observe physicochemical changes among the standard, fresh and calcined catalysts. For Spirulina platensis , H 2 yield was improved with an increased catalyst loading from 53.6 to 110.0%, whereas CO and CO 2 yields decreased by 58 and 52%, respectively, compared with the absence of the catalyst. For Chlorella vulgaris , H 2 yields were increased as a result of increasing catalyst loading from 21.2 to 114.4%, whereas CO and CO 2 decreased by 50.0 and 55.0%, respectively, compared with the absence of the catalyst. The CaO catalyst promoted the catalytic activity and captured CO 2 via CaO absorption property which encouraged the water gas shift reaction to occur to a greater extent, which in turn increased the H 2 production.