Conversion mechanism of fuel-N during pyrolysis of biomass wastes
| Autor: | Guilin Xie, Zhongyang Luo, Chunjiang Yu, Xiaorui Liu |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Chemistry
020209 energy General Chemical Engineering Organic Chemistry Analytical chemistry Energy Engineering and Power Technology Biomass chemistry.chemical_element 02 engineering and technology Straw Nitrogen Gas analyzer Fuel Technology 020401 chemical engineering Palm kernel 0202 electrical engineering electronic engineering information engineering Char 0204 chemical engineering Fourier transform infrared spectroscopy Pyrolysis |
| Zdroj: | Fuel. 246:42-50 |
| ISSN: | 0016-2361 |
| Popis: | To investigate the conversion of nitrogen bound in biomass fuel (abbreviated to fuel-N) during biomass pyrolysis, wheat straw (WS), rice straw (RS), spent coffee grounds (SCG) and palm kernel cake (PKC) were isothermally pyrolyzed in a horizontal tube reactor at the temperature range of 500–900 °C. The concentrations of light gaseous nitrogen containing species (gas-N) were measured online by a Fourier transform infrared (FTIR) spectroscopy gas analyzer, and the corresponding conversion rates were calculated. Results indicated that the conversion of fuel-N to gas-N as well as the evolution of N-functionalities in the portion of fuel-N that maintained in the char (char-N) were consistent regardless of the original N-functionalities in biomass samples. The conversion of fuel-N was found to be highly reliant on the temperature and fuel-N content. 17–47% of the fuel-N was finally retained in the char during pyrolysis. Therefore, the evolution of the N-functionalities from fuel-N to char-N was analyzed by X-ray photoelectron spectroscopy (XPS). Amide-N (N-A) was confirmed to be the dominant N-functionality in the raw biomass samples, and a small amount of pyrrolic-N (N-5), pyridinic-N (N-6) and quaternary-N (N-Q) were also identified. After pyrolysis, N-A was completely vanished in the char. However, only a very small fraction of N-A was decomposed into NH3 while most of it was preferentially converted to other gas-N (HCN, HNCO and NO) and N-5/N-6. For N-5/N-6, most of them preferred to retain in the char. As the temperature increased, a small amount of N-5/N-6 was converted to more stable N-Q and N-oxides (N-X) structures. Contrary to expected, N-A was also the main contributor to the formation of HCN, while the contribution from N-5/N-6 was less important. Finally, the conversion mechanism of fuel-N was concluded. |
| Databáze: | OpenAIRE |
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