Thermal Science and Engineering Progress
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2023
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IF 4.8
Shuai Guo,Guoliang Qi,Jialiang Gao,Deng Zhao,Kaixin Chen,Chenchen Zhao,Xingcan Li,Guangyu Li
Pyrolysis is an effective method for safely disposing of sewage sludge via conversion into a usable energy source. However, municipal sludge has a high protein content, which is a major source of NO x precursors. This study investigated the effect of CaO on NO x precursor formation during glutamate pyrolysis and demonstrated that CaO occupies the carbo x yl site of glutamic acid at 320 °C, which delays its decomposition and promotes the conversion of glutamic acid from a five- to a si x -membered ring. At 400 °C, heterocyclic nitrogen in the tar peaked from 4.87 to 53.87% after adding CaO. As the temperature increases to 480 °C, CaO might promote the conversion of heterocyclic nitrogen into tricyclic piperazine dione in the tar, which subsequently decomposed to produce HCN in large quantities. At 480 °C, CaO contributed to the decrease in pyrrole, pyridine, and quaternary nitrogen in the semi-coke from 24.81%, 12.93%, and 7.43% to 1.91%, 5.97%, and 1.43%, respectively and promoted HCN hydrolysis to form NH 3 . At 480–680 °C, CaO interacted with NH 3 to form CaCN 2 . The product of CaC x N y decomposition—CaC x —captured NH 3 . At high temperatures, CaO inhibited HCN release, which might be related to the reaction between CaO and HCN to form CaC x N y , subsequently reconverted into CaO at temperatures above 680 °C. These findings provide novel insights into the influence of CaO on amino acid pyrolysis to produce NO x precursors and the regulation of NO x precursor production.
研究领域:
环境科学
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能源与燃料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Jiangtao Meng,Jing Wang,Fengling Yang,Fangqin Cheng
This study proposed a novel strategy to control nitrogen oxides (NOx) precursors by directing nitrogen to adhere to the fuel-N→NH 3 →N 2 pathway. The research aimed to illuminate the regulatory effects of CaO, Fe 2 O 3 , and their mixtures on NO and N 2 O precursors (NH 3 , HCN, and HNCO) during sludge pyrolysis, further sought to establish scientific correlations with varying temperatures and differentiate their impact. The findings indicated that unlike NH 3 , HNCO is generated from the cleavage of amides, sharing its origin with HCN. Notably, the sensitivities of three conditioners to different functional groups result in distinct impacts on precursor emissions. CaO interacted with –OH and N-H functional groups, releasing NH 3 . Fe 2 O 3 , being more responsive to C-H and C-C groups, contributed to HNCO emission. At 750 °C, a CaO-Fe 2 O 3 mixture created Ca x Fe y O z , which selectively reacted with N-H and C≡N, facilitating the conversion of HNCO and HCN to NH 3 . While temperature is a crucial factor in the performance of CaO, its impact on Fe 2 O 3 is primarily confined to transformation of heterocyclic and nitrile . Below 350 °C, Fe 2 O 3 favored the evolution of nitrogen into heterocyclic compounds within tar. Conversely, above 490 °C, it inhibited the formation of nitrile in char, promoting the dehydrogenation of tar into unsaturated aromatic structures. The CaO-Fe 2 O 3 mixtures exhibited a superposition of individual effects from CaO and Fe 2 O 3 , with Ca x Fe y O z stimulating N 2 emission. Importantly, among three conditioners, Fe 2 O 3 showed the most significant abatement effect on NOx precursors, primarily through nitrogen fixation in char, nitrogen enrichment in tar, and precursor oxidation. This research contributes innovative perspectives on nitrogen regulation in nitrogen-rich fuels, the utilization of NH 3 , and effective NO and N 2 O control.
研究领域:
环境科学
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2017
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IF 3.091
Linlin Yi,Huan Liu,Geng Lu,Qiang Zhang,Jiaxing Wang,Hongyun Hu,Hong Yao
Considerable amounts of NOx are generated from the thermal utilization of solid wastes. To control NOx emission, we investigated the influence of mixed Fe/Ca additives on the generation of NOx precursors (HCN and NH3) during pyrolysis at 873, 1073, and 1273 K. Protein, proline, and phenylalanine were selected as model compounds to represent the primary nitrogen forms in typical solid wastes, such as biomass and sludge. According to the results, the iron effect is a remarkable property that enables the obvious reduction of NH3. This was most likely because NH3 was consumed by iron compounds to generate FeNx. Iron compounds facilitated thermal cracking of heterocyclic N with the release of HCN. Ca(OH)2 promoted the conversion of HCN to NH3 and fixed HCN to form CaCxNy simultaneously. These intermediates (FeNx and CaCxNy) play important roles in the reduction of NOx precursors. A lower emission of NOx precursors was observed with mixed Fe/Ca additives than with either Fe or Ca individually. This is because the generation of Ca2Fe2O5 enhanced the tranformation of intermediates to N2. The transformation of intermediates to N2 was enhanced at elevated temperatures, which allows for the lowest emission of precursors (NH3 and HCN) at 1273 K, with a higher ratio of Ca2Fe2O5 in char.
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
ENERGY
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2019
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IF 5.537
Shuai Guo,Tiecheng Liu,Jicheng Hui,Deyong Che,Xingcan Li,Baizhong Sun,Shaohua Li
The addition of CaO has been used to reduce the harmful NO x precursors (NH 3 and HCN) generated by the pyrolysis of municipal sewage sludge . However, the underlying reduction mechanism remains unclear. To address this issue, we systematically investigated the effects of temperature and CaO addition on the generation of NH 3 and HCN during the pyrolysis of sludge protein and a model protein. With increasing temperature from 300 to 900 °C, the inhibitory effect of CaO on NH 3 emission was observed to fluctuate, maximizing at 400 °C. The inhibition was attributed to the reaction of CaO with nitrogen in the produced char to form CaC x N y , resulting in enhanced fixation of the char pyridines and nitriles. The nitriles exhibited high thermal stability and inertness to CaO. The increased nitrile content at high temperatures was attributed to the formation of the species from amines and N-containing heterocycles . The CaC x produced by the thermal decomposition of CaC x N y above 700 °C was found to increase P–N fixation and decrease NH 3 formation. The observed poor inhibitory effect of CaO on NO x precursor formation at 650 °C was attributed to the production of NH 3 via HCN hydrolysis. Because HCN directly reacted with CaO, the inhibition of HCN formation was highest at 650–900 °C, preventing the conversion of char nitriles into HCN.
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
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2022
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IF 7.968
Deyong Che,Liye Wang,Hongpeng Liu,Baizhong Sun,Shuai Guo
Biomass pyrolysis yields fuels and industrial feedstocks but generates large amounts of NO x precursors and is therefore of limited practical use. Herein, we use glutamic acid , histidine , and tyrosine as protein models and palmitic acid as a lipid model to explore the influence of lipids on the emission of NO x precursors during the pyrolysis of protein-rich biomass at various temperatures. The nitrogen-containing components of solid (coke), liquid (tar), and gaseous pyrolysis products were characterized by X-ray photoelectron spectroscopy, gas chromatography-mass spectrometry, and mass spectrometry , respectively, showing that lipids strongly influence the composition of liquid and gaseous products but not that of solid products. The main nitrogenated tar constituents produced in the absence of palmitic acid were identified as heterocycles and amines, whereas amides and nitriles were additionally generated in its presence. The palmitic acid had the most apparent effect on glutamic acid, generating about 34.16% of amides, followed by histidine, which yielded 9.17% amides and only 4.25% of tyrosine. Thus, our results indicate that the pyrolytic generation of NO x precursors from lipid-rich biomass such as sludge can be reduced by optimizing pyrolysis temperature and providing guidance for developing biomass pyrolysis technologies.
研究领域:
生物质能
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环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）