Thermogravimetric and mass spectrometry analyses of cellulose pyrolysis under the synergistic effect of CaO and K₂HPO₄∙3H₂O

ABSTRACT

The cellulose pyrolysis processes under the individual and synergistic effects of CaO and K₂HPO₄∙3H₂O were studied by the thermogravimetric-mass spectrometric analysis (TG-MS) technique, mainly focusing on the changes of some important products such as CH₄ during the pyrolysis process under different conditions. The experimental results showed that after the addition of CaO, the amounts of CO, CH₄, and other species decreased. CaO could fix the “CO₂-like reactive intermediate” produced during the cellulose pyrolysis process, thus reducing the evolution of CO₂ in the temperature range of 300–440°C and continuing the CO₂ evolution in the temperature range of 520–710°C. When K₂HPO₄∙3H₂O was added, the amounts of CO, CH₄, CO₂, and other gaseous species increased, indicating that K₂HPO₄∙3H₂O could significantly change the pyrolysis reaction process, such as promoting the benzene ring formation reactions involving small molecules such as toluene. When the mixture of CaO and K₂HPO₄∙3H₂O was added, the weight loss at the initial stage of pyrolysis was relatively moderate compared to that adding K₂HPO₄∙3H₂O alone. At the same time, an obvious weight loss appears in the pyrolysis process in the temperature range of 600–770°C, and the amounts of various species generated increased compared to those generated in the single catalytic pyrolysis. Therefore, CaO and K₂HPO₄∙3H₂O exhibited a strong synergistic effect in the pyrolysis process.

KEYWORDS:

• CaO
• K₂HPO₄∙3H₂O
• cellulose
• pyrolysis
• TG-MS

Additional information

Funding

The authors would like to thank the National Natural Science Foundation of China (51506128), the National Natural Science Foundation of China (51776001) and the China Postdoctoral Science Foundation (158043).