Co-pyrolysis of chlorella vulgaris and kitchen waste with different additives using TG-FTIR and Py-GC/MS

Efficient utilization of biomass and garbage has attracted sharp attention in the context of the energy crisis. Fast catalytic pyrolysis (CFP) of chlorella vulgaris (CV), kitchen waste (KW) and their blends was carried out in this study in order to dispose garbage and develop alternative energy simultaneously. Catalysts of CaCO3, CaO, SiO2 and permutit were considered. Five CV blending degrees of 100, 80, 50, 20 and 0 wt% were studied. Influences of CV to KW ratios and catalyst types on pyrolysis products were primarily studied by thermogravimetric analyzer coupled to Fourier Transform Infrared Spectroscopy (TGA-FTTR) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). TGA-FTIR results showed that the decomposition behavior and the thermal gas release have been advanced after blending, especially at the ratio of 5:5, which indicated that co-pyrolysis promoted the main pyrolysis stage. For the co-pyrolysis of 50% CV with 50% KW, the apparent activation energy decreased by 14.9-19.3% compared to sole CV pyrolysis, 25.8-28.2% compared to sole KW pyrolysis. Regarding thermogravimetric characterization of samples with different additives, permutit possessed the most predominant promoting effect by lowering the initial temperature, increasing main stage mass loss and resulting in less residue mass. Py-GC/MS results demonstrated that CaO had the best positive effect among the four additives. It improved pyrolysis products by reducing acids by 85.9% for CV, 70.2% for KW and 81.7% for 5CV5KW, as well as increasing hydrocarbons to some extent. In summary, CFP of the sample at a blending ratio of 50% CV with 50% KW in the presence of CaO, could be a desirable treatment before further processing step of pyrolysis products.