The Research Of Catalytic Pyrolysis Of Cyanobacteria In Taihu Lake

Cyanobacterial bloom caused by eutrophication is one of the frequent environmental disasters all over the world. Algal bloom not only affects water landscape, but also releases algal toxins which may deteriorate human health and biosafety. With rapid pyrolysis and liquefaction technology, the collected blue-green algae from cyanobacterial blooms can be converted to bio-oil. The method helps reduce the nutrient load of water and prevent the deterioration of water quality. It blazes a new way for the utilization of blue-green algae.In order to efficiently utilize the biomass waste of algae bloom harvested in Taihu Lake, China, a set of fixed-bed pyrolysis equipment was established. Rice straw was chosen as the raw material and Mg-Al composite metal oxide was chosen as the catalyst. Both vacuum pyrolysis, vacuum catalytic pyrolysis and atmospheric catalytic pyrolysis were investigated. Besides, the influence of pyrolysis temperature, reaction time and the amount of catalysts on bio-oil yield and quality were taken into consideration. The components of bio-oil were analyzed by elemental analysis and GC-MS analysis. As for vacuum pyrolysis, the bio-oil yield reached its apogee of 47%at final pyrolysis temperature of 400 ℃ and reaction time of 40min. As for vacuum catalytic pyrolysis, when catalyst amount was 1:2, pyrolysis temperature was 400℃ and reaction time was 50min, bio-oil yield reached its apogee of 47%. As for atmospheric catalytic pyrolysis with nitrogen as the carrier gas, when catalyst amount was 3:4, pyrolysis temperature was 450℃ and reaction time was 40min, bio-oil yield reached its apogee of 54.5%. In comparison, bio-oil yield made with atmospheric catalytic pyrolysis was highest. The research of atmospheric catalytic pyrolysis is the most promising for the future.On condition that pyrolysis temperature was 450℃and reaction time was 40min, the bio-oil yield of atmospheric pyrolysis was 35.5%, the solid yield was 27.75% and the gas yield was 36.75%. However, the bio-oil yield of atmospheric catalytic pyrolysis(pyrolysis temperature was 450℃, reaction time was 40min and catalyst amount was 3:4) was 54.5%, the solid yield was 15% and the gas yield was 30.5%. It turned out that Mg-Al composite metal oxide catalyst benefits the bio-oil formation while prohibits the formation of char and gas.As for atmospheric catalytic pyrolysis reaction, change reaction temperature in the case of the reaction time and catalyst amount were kept constant. When the temperature was 350℃, bio-oil yield was 42%. When the temperature was 450℃, bio-oil yield was 54.5%. The experiment result indicates that high pyrolysis temperature promotes bio-oil formation.In addition, X ray diffraction result indicates that the crystal phase of the catalyst didn’t change much after the reaction. The catalyst can be reused.