Thermal cracking behavior, products distribution and char/steam gasification kinetics of seawater Spirulina by TG-FTIR and Py-GC/MS

Abstract

In this study, fast pyrolysis of seawater Spirulina, is carried out to evaluate the potential of deriving valuable chemicals and fuel molecules from this seawater algae variety. The devolatilization behavior and gaseous product evolution of seawater Spirulina were carried out by TG-FTIR. Py-GC-MS was employed to investigate the composition and distribution of volatile products formed from the seawater Spirulina through high-temperature fast pyrolysis process. Finally, the seawater Spirulina char gasification reactivity and kinetic parameters were evaluated using advanced methods of volume, shrinking core and random pore. Results indicate that the thermal cracking process of seawater Spirulina mainly consisted of three reaction stages, including dehydration and drying stage, fast pyrolysis stage and residues slow decomposition stage. High heating rate has significant effect on the performance of devolatilization profiles. H 2 O, CH 4 , CO 2 , HNCO, NH 3 , HCN, CO, CeO bond and C]O bond were the typical gaseous products released from the fast pyrolysis stage of seawater Spirulina. The maximum release rate of seawater Spirulina for CH 4 was located at about 450 C, corresponding to the main pyrolysis of long-chain fatty acids from lipid fraction. The high temperature fast pyrolysis of seawater Spirulina resulted in aliphatic (alkanes, alkenes) and aromatic hydrocarbons, esters, oxygenates (carboxylic acids, aldehydes, ketones, and alcohols), phenolics, and nitrogen-and sulfur-containing organic compounds. Above 750 C was considered as the optimum temperature, which can reduce the generation of oxygenated compounds, and the content of nitrogen and phenolic compounds were decreased, maximum yield of quantified hydrocarbons was observed. The increase of gasification temperature can obviously improve the gasification reactivity of seawater Spirulina chars. The activation energies of the VM, SCM and RPM models of seawater Spirulina chars were 187.95, 173.14 and 154.34 kJ/mol, respectively. RPM displays a significant fitness with the experimental data than those of the other two models.

Improving Nitrogen Retention in Algal Biochar Pyrolysis by Co‐Pyrolysis with Glucose

“…Comparing the FT‐IR spectrum of this initial degradation peak of GL and G50‐S50 ( Figure A, spectra a and b) reveals large O─H stretching (3500–4000 cm −1[ 40 ] ) and H 2 O bending (1550–1680 cm −1[ 41 ] ) absorption bands, which can be assigned to the evolution of water and possibly some other ─OH─containing functionalities, e.g., alcohols, phenolics. This water would originate from the dehydration reactions that occur at this temperature during the pyrolysis of GL.…”

Physiochemical structure of semicoke derived from co‐carbonization of coal and sawdust blends

“…The above results indicate that some part of oxygen species in sawdust transfer into semicoke because of the transformation of phenol hydroxyl into polycyclic compounds linked with oxygenated functional group. 7,24 Liu et al 26 also reported that the main oxygen species in the semicoke was phenol hydroxyl that could form stable structures with aromatic ring through a strong π bond due to the conjugation of lone pair of electrons existing on the oxygen of phenol hydroxyl.…”

“…It was reported that carbon originated from biomass may adhere to the surface of coal, and inhibited the evolution of volatile matter, and then promoteed the mesophase formation 22 ; Hydrogen in biomass may act as the fluidity enhancers to promote the formation of coal plasticity, and favored for developing an optical anisotropic mosaic 14,18,23 ; Higher content of oxygen in biomass not only inhibits the formation of mesophase, but also prevents the development of the anisotropic structure. 19,[24][25][26] The microporosity of the semicoke derived from biomass/coals co-coking was also increased by the catalytic activity of the alkali and alkaline earth metal (AAEMs). 27,28 The incorporation of biomass into the blending coal may also significantly affect the physiochemical structure of the semicoke derived from co-carbonization of biomass/coal blends such as the functional groups, carbon structure, surface morphologies, and optical texture.…”

“…27,28 The incorporation of biomass into the blending coal may also significantly affect the physiochemical structure of the semicoke derived from co-carbonization of biomass/coal blends such as the functional groups, carbon structure, surface morphologies, and optical texture. 24,29,30 Meanwhile, the physiochemical structural properties of the semicoke is usually continued in the resultant coke during the coking process. 16,31 Therefore, in-depth investigation of the physiochemical structural properties of the semicoke obtained from the biomass/coals can help to understand the influences of biomass incorporation on coke formation mechanism.…”

Pyrolysis behaviors, kinetics, and byproducts of enzymatic hydrolysis residues for lignocellulosic biorefining

“…Thermogravimetric analysis combined with infrared spectroscopy (TG-IR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) is the most common way to estimate pyrolysis behavior and byproducts of biomass, polymers, and even waste (Li et al 2017a;Chen et al 2019;Li et al 2020). The TG-IR method allows facile evaluation of pyrolysis by determining the decomposition characteristics and products as well as the measurement of multiple gas products in a complex matrix simultaneously and in real-time (Ferreira et al 2019).…”