397 / 2018-06-26 23:07:42

Co-pyrolysis of Microalgae and Low-rank coal:Co-pyrolysis of Microalgae and Low-rank coal: syngerstic Effect from Products Distribution and Radical Analysisfrom Products Distribution and Radical Analy

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Co-pyrolysis of coal and microalgae biomass can not only effectively cope with the challenges such as environmental pollution and greenhouse gas emissions, which caused by the traditional utilizatin of coal, but also open up tremendous potential of biomass energy. The thermochemical reaction activity of microalgae biomass is high and the synergy effect in the co-pyrolysis process can promote coal decomposition. It is significant that revealing the the mechanism of product formation of co-pyrolysis between coal and microalgae. This paper focuses on the co-pyrolysis behaviour, products distributions, kinetic characteristics as well as the change of free radicals in pyrolysis products of the Shenmu low-rank coal and microalgae biomass and its main components.
Table 1 g-factor of the samples
g-ALC g-ALC-300 g-ALC-400 g-ALC-500 g-ALC-600
Gaussian 2.00282 2.00276 2.00264 2.00260 2.00265
Lorentz-I 2.00433 2.00387 2.00407 2.00394 2.00411
Lorentz -II 2.02305 2.04275 2.00239 2.00289 2.00299
The free-radical evolution characteristics from semi-coke of the organic components of the low rank coal and the typical organic components of the microalgae were analyzed. The EPR (Electron Paramagnetic Resonance) was performed for the acid coal, glycine and their mixtures at different pyrolysis temperatures. The results showed that low-rank coal and glycine generated plenty of free radicals and the radicals recombined in the co-pyrolysis process. The synergy effect in the co-pyrolysis was free radicals interact with each other lead to the yield of the product not equal the simple linear superposition of the two samples. When acid low-rank coal was pyrolyzed, it generated large amounts of aromatic radicals and fragments of heteroatom-containing alkyl radicals first. With the temperature increasing, free radical fragments reacted to form gases, tar, and char. In the initial stage of pyrolysis, glycine mainly produced -CH2-, carbon-based radical fragments. These radicals reacted with each other to produce CO2 and CO. With the temperature increasing, -NH2 and -OH radicals formed NH3, HCN, and H2 and other products. The EPR spectra of acid low-rank coal were subjected to peak separation. The results showed that in the pyrolysis process of low-rank coal, aromatic hydrocarbon radicals, heteroatom radicals, oxygen-containing radicals and aliphatic hydrocarbon radicals were mainly included.