Study On The Mechanism Of Algal Biomass Catalytic Pyrolysis Based On Online Mass Spectrometry

As the main raw material of the third generation of biomass energy,algae can be converted into bio-oil by means of pyrolysis,which is easy to store and to transport.However,the valuable utilization of algae-based bio-oil is difficult to be achieved due to its complex chemical composition.The aim of this work is to obtain the value-added target products by the catalytic pyrolysis.The component of algal biomass is significantly different from that of conventional lignocellulosic biomass,therefore there are reasonable difference in the distribution and the characteristics of pyrolysis products between algal and lignocellulosic biomass.In this work,the catalytic pyrolysis of three kinds of typical algal biomass and a lignocellulosic biomass were conducted in a double micro-fixed reactor.The produced volatiles were monitored in real-time by synchrotron ultraviolet vacuum photoionization mass spectrometry(SVUV-PIMS).The difference in pyrolysis characteristics between algal and lignocellulosic biomass would be discussed.Pyrolysis and catalytic pyrolysis of material poplar,real-time in-situ detection and analysis of product distribution and characteristics during catalytic pyrolysis,and comparative analysis of the similarities and differences of catalytic pyrolysis characteristics between algae and poplar.The main contents of the paper are as follows:The Chapter 1 mainly summarizes the utilization of biomass energy in China,including the characteristics of algae biomass and the technology of thermochemical conversion.Meanwhile,the pyrolysis and catalytic pyrolysis of algal biomass in previous works are introduced in detail and the goals of this work are proposed.The Chapter 2 mainly introduces experimental materials,methods and experimental conditions.Meanwhile,the statistical analysis was conducted to interpret the obtained PI mass spectra.The Chapter 3 mainly introduces the similarities and differences in pyrolysis products distribution between algal and lignocellulosic biomass.The characteristic peaks were determined by the principal component analysis of the PI mass spectra obtained from the pyrolysis of four samples.The pyrolysis products were qualitatively analyzed by GC-MS.The difference in pyrolysis mechanism was also compared.The Chapter 4 introduces the distribution characteristics of the catalytic pyrolysis products of algae and poplar and the deactivation mechanism of the catalyst.Thanks to the online and real-time analysis by SVUV-PIMS,the deactivation of zeolites upon stepwise injections of biomass could be achieved.The statistical analysis of PI mass spectra that was recorded as a function of cumulative biomass-to-catalyst ratios was conducted in order to obtain the trend of catalyst deactivation as well as its influence factors.The Chapter 5 mainly discusses the proposed mechanism of catalyst deactivation in the catalytic process of algae.Through catalyst characterization(e.g.TG,Nadsorption and TEM etc.),the influence factors that lead to catalyst deactivation are discussed.The potential ways to prolong the lifetime of catalyst were proposed based on this work.The Chapter 6 summarizes the conclusions and innovations in this work.The future work is also proposed.