Abstract:Solid biofuel is considered as a possible substitute for coal in household heat production because of the available and sustainable raw materials, while NOx emissions from its combustion have become a serious problem. Nitrogen-containing compounds in pyrolysis products have important effects on the conversion of fuel-N into NOx-N. Understanding these converting pathways is important for the environmentally friendly use of biomass fuels. The nitrogen migration during pyrolysis of raw and acid leached maize stra… Show more
“…The result suggested that the introduction of H 2 strengthened the thermal cracking of more stable N–A types, which was in accordance with the results of Wang et al and Wei et al The yields of N-6 and N-5 showed a maximum value at 500 and 600 °C, respectively. This might be ascribed to the fact that N–A was converted into more N-6/N-5 through direct cyclization, dimerization, and rearrangement at lower temperatures and the secondary decomposition of N-5/N-6 was enhanced at higher temperatures. ,, At the temperatures from 600 to 800 °C, the N-5 yield decreased faster than N-6, which demonstrated that N-5 showed less thermal stability than N-6 at high temperatures . H radicals were active in the rupture of N-containing ring systems .…”
Section: Resultsmentioning
confidence: 99%
“…Besides, it was found that a H 2 -rich atmosphere produced less heterocyclic–N than an Ar atmosphere at the same temperature. This phenomenon could be explained by two possible reasons: ,,, (1) the H 2 -rich atmosphere suppressed the polymerization of amine–N into heterocyclic–N by deactivating the free radicals and (2) the combination of H 2 and high temperatures promoted the ring-opening reactions of heterocyclic–N, resulting in more NH 3 and HCN.…”
Section: Resultsmentioning
confidence: 99%
“…When the temperature was raised from 500 to 600 °C, the NH 3 –N yield increased from 6.31 to 10.7 wt % under an Ar atmosphere and from 14.31 to 22.78 wt % under a H 2 -rich atmosphere. The generation of NH 3 at low temperatures was primarily due to the direct decomposition of labile N–A in fuels and secondary cracking of amine–N in tar. , Further, the introduction of H 2 considerably aided the thermal cracking of more N–A and amine–N, thereby resulting in more NH 3 –N production . Upon raising the temperature to 800 °C, as much as 19.33 wt % existed as NH 3 –N under an Ar atmosphere.…”
Section: Resultsmentioning
confidence: 99%
“…The N 1s signal was then curve-resolved using peaks with a 70% Gaussian and 30% Lorentzian line shape and a FWHM of 1.7 eV. The peaks at 398.5 ± 0.3, 399.9 ± 0.2, 400.4 ± 0.2, 401.4 ± 0.2, and 402–405 eV corresponding to the energy positions were assigned to the nitrogen functionalities of pyridinic-N (N-6), amide/amine/protein–N (N–A), pyrrolic–N (N-5), quaternary–N (N–Q), and N–oxide (N–X), respectively. ,,, The yield of each nitrogen functionality in chars was calculated as followsYnormalCnormalhnormalanormalr−normalNnormali=mnormalCnormalhnormalanormalr−normalNmnormals−normalN•AnormalCnormalhnormalanormalr−normalNnormali∑AnormalCnormalhnormalanormalr−normalNnormaliwhere A Char–Ni is the peak area of each nitrogen functionality in the XPS spectra of char–N.…”
Section: Methodsmentioning
confidence: 99%
“…The peaks at 398.5 ± 0.3, 399.9 ± 0.2, 400.4 ± 0.2, 401.4 ± 0.2, and 402−405 eV corresponding to the energy positions were assigned to the nitrogen functionalities of pyridinic-N (N-6), amide/amine/protein−N (N−A), pyrrolic−N (N-5), quaternary−N (N−Q), and N−oxide (N−X), respectively. 19,29,41,42 The yield of each nitrogen functionality in chars was calculated as follows…”
Nitrogen-rich biomass pyrolysis has been explored as a green, distributed, and simple alternative for sustainable ammonia production at atmospheric pressure. In this paper, tea waste was selected as a promising feedstock, and H 2 was employed as an enhancer to increase the yield of NH 3 . The nitrogen distribution among three-phase pyrolytic products affected by various temperatures and different atmospheres was compared and discussed. The evolution pathways for fuel−N during tea waste pyrolysis under a H 2 -rich atmosphere were concluded. Results indicated that the introduction of H 2 was favorable for the increase of the gas− N yield but decreased the yields of char−N and tar−N. At lower temperatures, the bond cleavage of amide−N (N−A) in fuels was enhanced by H 2 , which then yielded more NH 3 −N through deamination. Subsequently, H 2 improved the production of nitrile−N in tar, as well as NH 3 −N and HCN−N, by accelerating the secondary cracking of amine−N (tar−N) generated from the decomposition of amide−N. However, the formation of heterocyclic−N in tar through the polymerization of amine−N was restrained under a H 2 -rich atmosphere. Pyrolysis in the presence of H 2 generated a large amount of H radicals. When the temperature continued to increase, sufficient H radicals impressively advanced the ring rupture (into HCN−N) and full hydrogenation (into NH 3 −N) of pyridinic−N/pyrrolic−N (N-6/N-5) in char. Meanwhile, H radicals also intensified the thermal cracking of nitrile−N and ring opening of heterocyclic−N to form more HCN−N and NH 3 −N. Overall, more nitrogen evolved into NH 3 −N and HCN−N during pyrolysis in a H 2 -rich atmosphere, especially at high temperatures. The highest NH 3 yield of 43.33 wt % was achieved at 800 °C under a 25% H 2 + 75% Ar atmosphere.
“…The result suggested that the introduction of H 2 strengthened the thermal cracking of more stable N–A types, which was in accordance with the results of Wang et al and Wei et al The yields of N-6 and N-5 showed a maximum value at 500 and 600 °C, respectively. This might be ascribed to the fact that N–A was converted into more N-6/N-5 through direct cyclization, dimerization, and rearrangement at lower temperatures and the secondary decomposition of N-5/N-6 was enhanced at higher temperatures. ,, At the temperatures from 600 to 800 °C, the N-5 yield decreased faster than N-6, which demonstrated that N-5 showed less thermal stability than N-6 at high temperatures . H radicals were active in the rupture of N-containing ring systems .…”
Section: Resultsmentioning
confidence: 99%
“…Besides, it was found that a H 2 -rich atmosphere produced less heterocyclic–N than an Ar atmosphere at the same temperature. This phenomenon could be explained by two possible reasons: ,,, (1) the H 2 -rich atmosphere suppressed the polymerization of amine–N into heterocyclic–N by deactivating the free radicals and (2) the combination of H 2 and high temperatures promoted the ring-opening reactions of heterocyclic–N, resulting in more NH 3 and HCN.…”
Section: Resultsmentioning
confidence: 99%
“…When the temperature was raised from 500 to 600 °C, the NH 3 –N yield increased from 6.31 to 10.7 wt % under an Ar atmosphere and from 14.31 to 22.78 wt % under a H 2 -rich atmosphere. The generation of NH 3 at low temperatures was primarily due to the direct decomposition of labile N–A in fuels and secondary cracking of amine–N in tar. , Further, the introduction of H 2 considerably aided the thermal cracking of more N–A and amine–N, thereby resulting in more NH 3 –N production . Upon raising the temperature to 800 °C, as much as 19.33 wt % existed as NH 3 –N under an Ar atmosphere.…”
Section: Resultsmentioning
confidence: 99%
“…The N 1s signal was then curve-resolved using peaks with a 70% Gaussian and 30% Lorentzian line shape and a FWHM of 1.7 eV. The peaks at 398.5 ± 0.3, 399.9 ± 0.2, 400.4 ± 0.2, 401.4 ± 0.2, and 402–405 eV corresponding to the energy positions were assigned to the nitrogen functionalities of pyridinic-N (N-6), amide/amine/protein–N (N–A), pyrrolic–N (N-5), quaternary–N (N–Q), and N–oxide (N–X), respectively. ,,, The yield of each nitrogen functionality in chars was calculated as followsYnormalCnormalhnormalanormalr−normalNnormali=mnormalCnormalhnormalanormalr−normalNmnormals−normalN•AnormalCnormalhnormalanormalr−normalNnormali∑AnormalCnormalhnormalanormalr−normalNnormaliwhere A Char–Ni is the peak area of each nitrogen functionality in the XPS spectra of char–N.…”
Section: Methodsmentioning
confidence: 99%
“…The peaks at 398.5 ± 0.3, 399.9 ± 0.2, 400.4 ± 0.2, 401.4 ± 0.2, and 402−405 eV corresponding to the energy positions were assigned to the nitrogen functionalities of pyridinic-N (N-6), amide/amine/protein−N (N−A), pyrrolic−N (N-5), quaternary−N (N−Q), and N−oxide (N−X), respectively. 19,29,41,42 The yield of each nitrogen functionality in chars was calculated as follows…”
Nitrogen-rich biomass pyrolysis has been explored as a green, distributed, and simple alternative for sustainable ammonia production at atmospheric pressure. In this paper, tea waste was selected as a promising feedstock, and H 2 was employed as an enhancer to increase the yield of NH 3 . The nitrogen distribution among three-phase pyrolytic products affected by various temperatures and different atmospheres was compared and discussed. The evolution pathways for fuel−N during tea waste pyrolysis under a H 2 -rich atmosphere were concluded. Results indicated that the introduction of H 2 was favorable for the increase of the gas− N yield but decreased the yields of char−N and tar−N. At lower temperatures, the bond cleavage of amide−N (N−A) in fuels was enhanced by H 2 , which then yielded more NH 3 −N through deamination. Subsequently, H 2 improved the production of nitrile−N in tar, as well as NH 3 −N and HCN−N, by accelerating the secondary cracking of amine−N (tar−N) generated from the decomposition of amide−N. However, the formation of heterocyclic−N in tar through the polymerization of amine−N was restrained under a H 2 -rich atmosphere. Pyrolysis in the presence of H 2 generated a large amount of H radicals. When the temperature continued to increase, sufficient H radicals impressively advanced the ring rupture (into HCN−N) and full hydrogenation (into NH 3 −N) of pyridinic−N/pyrrolic−N (N-6/N-5) in char. Meanwhile, H radicals also intensified the thermal cracking of nitrile−N and ring opening of heterocyclic−N to form more HCN−N and NH 3 −N. Overall, more nitrogen evolved into NH 3 −N and HCN−N during pyrolysis in a H 2 -rich atmosphere, especially at high temperatures. The highest NH 3 yield of 43.33 wt % was achieved at 800 °C under a 25% H 2 + 75% Ar atmosphere.
In this study, six fast growing invasive biomass species; Acacia mearnsii, Broussonetia papyrifera, Lantana camara, Mimosa pigra, Psidium guajava and Senna spectabilis were studied to determine their potential for fuel and biofuel production. Proximate composition, ultimate composition and heating values were determined using standard methods. The thermal analysis, chemical interactions, and morphology were studied using Thermal Gravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FT-IR), and Scanning Electron Microscopy (SEM) analysis respectively. Aspen Plus Version 11 was used to simulate slow, fast and flash pyrolysis of the biomass. Senna spectabilis had the highest heating value of 17.84 MJ/kg and the lowest ash content, making it the most suitable for thermochemical conversion. Based on the compositional analysis, Senna spectabilis also had the highest content of cellulose (48 %), making it most suitable for biofuel production via enzyme saccharification. The Aspen Plus model for the pyrolysis process was used to predict the yields and products of pyrolysis of the biomass species for typical reactor conditions and feedstock composition. The highest yield of biogas, biochar and bio-oil were achieved at 650 °C for all the biomass species. Moreover, Lantana camara was the most suitable for biogas production and Senna spectabilis for biochar and bio-oil production. The influence of the pyrolysis temperature on the pyrolysis products, flue gases and gaseous emissions were also demonstrated in this study.
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