Catalytic pyrolysis-gc/ms of spirulina: evaluation of a highly proteinaceous biomass source for production of fuels and chemicals

Authors: CHAGAS, BRUNA - Universidade Federal Do Rio Grande Do Norte; Dorado, Christina; Serapiglia, Michelle; Mullen, Charles; Boateng, Akwasi; MELO, MARCUS - Universidade Federal Do Rio Grande Do Norte; ATAIDE, CARLOS - Universidade Federal De Uberlândia

Submitted to: Fuel
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2016
Publication Date: 3/28/2016
Publication URL: https://handle.nal.usda.gov/10113/62246
Citation: Chagas, B.M., Dorado, C., Serapiglia, M., Mullen, C.A., Boateng, A.A., Melo, M.A., Ataide, C.H. 2016. Catalytic pyrolysis-gc/ms of spirulina: evaluation of a highly proteinaceous biomass source for production of fuels and chemicals. Fuel. 179:124-134.

Interpretive Summary: The production of chemicals and fuels from a non-petroleum renewable source can be achieved by the pyrolysis of biomass. Biomass is the largest source of renewable carbon on Earth and it can be converted to a liquid known as bio-oil via pyrolysis. But bio-oil cannot be used directly as a fuel or chemical source due to the high oxygen, water and acid content. The proportions of these undesirable properties are directly related to the feedstock from which the bio-oil was derived. Lignocellulosic biomass, or biomass that is made up of lignin and cellulose, tends to produce bio-oil that is high in oxygen, water and acid content due to the high oxygen content of the lignin and cellulose. Choosing a feedstock with a lower oxygen content can improve the properties of the resulting bio-oil. For example microalgae contain little to no lignin or cellulose and are made up of mostly lipids and or proteins. Bio-oil from microalgae tends to be more deoxygenated than bio-oil from lignocellulosic sources. The bio-oil from algae does have high nitrogen content due to the proteins present in the feedstock and is an issue that must be addressed. Studies on the deoxygenation of lignocellulosic bio-oil via catalytic pyrolysis are extensive and zeolites have been found to be the best catalysts for removing oxygen from the resulting bio-oil. In this study the catalytic pyrolysis of Spirulina algae was tested using 9 different zeolite catalysts with varying biomass to catalyst ratios in an effort to find the conditions that produced the most fuel compatiable compounds and reduced the amount of nitrogen containing compounds in the resulting pyrolysis products. The results of this work showed that it was possible to manipulate the production of specific compounds based on the catalyst type and loading, although nitrogen containing compounds were not reduced significantly by zeolites. These experiments can advise future work on improving the de-nitrogenation abilities of catalysts for the pyrolysis of feedstocks with high nitrogen content such as microalgae.

Technical Abstract: Pyrolysis of microalgae offers a pathway towards the production of compounds derived from the thermal decomposition of triglycerides, proteins as well as lignocelluloses and their combinations thereof. When catalytically induced, this could lead to the production of fuels and chemicals including aromatic hydrocarbons and protein-derived biochemicals. We studied catalytic pyrolysis of Spirulina (Anthrospira spp.) over several zeolite catalysts using pyrolysis/GC-MS to explore the optimum and scalable conditions for the production of stable liquid intermediates via condensable vapor analysis. Nine catalysts of different pore sizes, shapes and SiO2/Al2O3 ratios were tested in this study including H-ZSM-5 (SiO2/Al2O3 = 23), H-ZSM-5 (50), H-ZSM-5 (280), H-B (25), H-B (38), H-B (300), H-Y, mordenite and ferrierite at three catalyst/biomass ratios (1:1, 5:1 and 10:1). It was found that the high acidity HZSM-5 catalysts with low Si/Al = 23 could maxmize the conversion of Spirulina to aromatic hydrocarbons, but lower acidty catalysts increased the production of aliphatic hydrocarbons, phenols and certain nitrogenates. The component analysis shows that it is possible to favor one set of chemical species over another for the conversion of spirulina by varying the catalyst types and loadings allowing for the flexibility to engineer scaled systems for higher yields of particular chemical classes such as aromatic hydrocarbons, phenols, aromatic nitrogenates via the manipulation of the catalyst properties or loadings.