Transformation of Nitrogen and Evolution of N-Containing Species

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Transformation of nitrogen and evolution of Ncontaining species during algae pyrolysis Wei Chen, Haiping Yang, Yingquan Chen, Mingwei Xia, Xu Chen, and Hanping Chen Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 10 May 2017 Downloaded from http://pubs.acs.org on May 10, 2017

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Environmental Science & Technology

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[Title Page]

2 3

Transformation of nitrogen and evolution of N-containing species during algae

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pyrolysis

5 6

Wei Chen, Haiping Yang*, Yingquan Chen*, Mingwei Xia, Xu Chen, Hanping

7

Chen

8 9

State Key Laboratory of Coal Combustion, School of Power and Energy

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Engineering, Huazhong University of Science and Technology, 430074 Wuhan,

11

China

12 13

E-mail: [email protected], [email protected],

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[email protected], [email protected], [email protected],

15

[email protected].

16 17

Correspondence information: Haiping Yang, [email protected]; Yingquan

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Chen, [email protected]; 1037 Luoyu Road, 430074 Wuhan, P. R.

19

China; Tel: +086+027-87542417-8109; fax: +086+027-87545526.

1

ACS Paragon Plus Environment


20

Transformation of nitrogen and evolution of N-containing species during algae

21

pyrolysis

22

Wei Chen, Haiping Yang*, Yingquan Chen*, Mingwei Xia, Xu Chen, Hanping Chen

23

State Key Laboratory of Coal Combustion, School of Energy and Power Engineering,

24

Huazhong University of Science and Technology, 430074 Wuhan, China

25

Abstract

26

Transformation and evolution mechanisms of nitrogen during algae pyrolysis were

27

investigated in depth with exploration of N-containing products under variant

28

temperature. Results indicated nitrogen in algae is mainly in the form of protein-N

29

(~90%) with some inorganic-N. At 400~600°C, protein-N in algae cracked firstly with

30

algae pyrolysis and formed pyridinic-N, pyrrolic-N and quaternary-N in char. The

31

content of protein-N decreased significantly, while that of pyrrolic-N and quaternary-N

32

increased gradually with temperature increasing. Pyridinic-N and pyrrolic-N formation

33

was due to deamination or dehydrogenation of amino acids; subsequently, some

34

pyridinic-N converted to quaternary-N. Increasing temperature decreased amides

35

content greatly while increased that of nitriles and N-heterocyclic compounds

36

(pyridines, pyrroles, and indoles) in bio-oil. Amides were formed through NH3 reacting

37

with fatty acids, that underwent dehydration to form nitriles. Besides, NH3 and HCN

38

yields increased gradually. NH3 resulted from ammonia-N, labile amino acids and

39

amides decomposition, while HCN came from nitrile decomposition. At 700~800°C, 2


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evolution trend of N-containing products was similar with that at 400~600°C. While N-

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heterocyclic compounds in bio-oil mainly came from pyrifinic-N, pyrrolic-N and

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quaternary-N decomposition. Moreover, cracking of pyridinic-N and pyrrolic-N

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produced HCN and NH3. A mechanism of nitrogen transformation during algae

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pyrolysis is proposed based on amino acids decomposition.

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Key words: Algae; Pyrolysis; Nitrogen transformation; Amino acids; N-containing

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species

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Introduction

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Global interest in renewable and alternative energy resources has greatly increased

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in recent years, due to serious environment problems, fossil fuel depletion, and concerns

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about energy security.1, 2 Among potential renewable energy sources, algae is extremely

51

promising because of fast growth rates, high potential biofuel yield, high CO2 use

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capability, and the possibility of cultivation on waste water to remove N, P and heavy

53

metals.3, 4 Algae pyrolysis is attracting increasing concern,5-8 as the higher mass yield

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(up to 80 wt.%) of liquid fuel and the more energy (up to 70%) in liquid products.9, 10

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However, different from agricultural straw and woody wastes, algae shows higher

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nitrogen content, which can be as high as 10 wt.%, far more than the content in coal,

57

sewage sludge and terrestrial biomass.7,

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emission and transformation might be one main concern for algae pyrolysis, as it might

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be converted to various N-containing compounds, such as NH3, HCN, the NOx

60

precursors, which may lead to potential nitrogen-related pollution (such as severe

11-13

Hence, the issue related to nitrogen

3



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photochemical smog, ozone depletion, acid rains and greenhouse effect).7,

14-20

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Furthermore, nitrogen content of pyrolytic oil can reach 12 wt.%, subsequent utilization

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of which would also lead to the secondary pollution.7 However, the N-containing

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compounds in bio-oil, such as pyrrole, pyridine, and indole, can be used to synthesize

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pharmaceuticals, perfumes and other chemicals.14, 15 N-containing char can be used in

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catalysis, pollutants adsorption and electrode materials.21-23 Thus, understanding

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nitrogen transformation is critical for the utilization of algae pyrolysis. However,

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limited information is available on the nitrogen fate during algae pyrolysis.

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Nitrogen conversion during coal pyrolysis has been investigated widely over the

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past decades.24-28 Kelemen et al.28 pointed out that N-containing species in coal would

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convert to pyridinic-N and quaternary-N in char at higher pyrolysis temperature. Tan et

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al.29, 30 reported that unstable N-containing compounds in the volatiles could generate

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HCN, while stable N-containing species in char could release NH3 during coal pyrolysis.

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However, in algae, nitrogen exists mainly as protein-N,4 whereas in coal, the dominant

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N-containing species are pyridine-N, pyrrole-N and quaternary-N.27, 31 It suggested that

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there might be different conversion processes of nitrogen for algae. Given the

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dominance of protein-N, the N-containing species in pyrolysis products should come

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from amino acids decomposition. Although Gallois et al.32 investigated the pyrolysis

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mechanism of 20 amino acids, and Choi et al.33 found that pyrolysis of amino acid

80

monomer could generate lots of N-heterocyclic compounds in bio-oil. However,

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nitrogen evolution in algae is greatly different from amino acid monomer. As Chen et

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al.11 pointed out that lignin could promote nitrogen transformation into gas during co4


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pyrolysis of lignin with amino acid, while cellulose promoted nitrogen conversion into

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bio-oil. Furthermore, Ren et al.13, 34 found that hemicellulose inhibited NH3 formation

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during co-pyrolysis of hemicellulose with amino acid. These studies suggested that

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biomass components had great effect on nitrogen conversion during pyrolysis. However,

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different from lignocellulosic biomass, lipids (consist of triglycerides), carbohydrates

88

(consist of alginic acid, mannitol, laminarin, and fucoidan), and proteins (consist of

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amino acids) are the main components of algae, and different pyrolysis behavior of

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these components should be showed.3, 35-38 Thus, lipids and carbohydrates in algae

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could also exert important effect on the formation of N-containing species. However,

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no related information on the formation and evolution of N-containing species could be

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obtained during algae pyrolysis, despite such information being crucial for

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understanding nitrogen decomposition mechanism in algae. Besides, nitrogen sources

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in algae must be elucidated to determine nitrogen reaction pathways. Thus, a better

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understanding of amino acids compositions and structures in algae samples is needed

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to clarify mechanism of nitrogen evolution.

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In this study, nitrogen distribution and transformation mechanisms during algae

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pyrolysis were explored with Spirulina platensis (SP, with higher proteins),

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Nannochloropsis sp. (NS, rich in lipids), and Enteromorpha prolifera (EP, enriched with

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carbohydrates) as typical algae. The possible pathways of nitrogen transformation was

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explored based on the distribution and evolution of pyrolysis products of algae at

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variant temperature. It is significant for the understanding of nitrogen evolution during

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algae pyrolysis and for the controlling nitrogen emission during algae utilization. 5



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Experimental section

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Fast pyrolysis experiment

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Nannochloropsis sp. (NS) was purchased from Yantai Hairong Biology

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Technology Co., Ltd, while Spirulina platensis (SP) and Enteromorpha prolifera (EP)

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were provided by China Agricultural University. The algae were dried at 105°C for 24

110

h, then crushed and sieved (600°C).

398

Associated content

399

Supporting information

400

Raw algal characteristics, N-containing species evolution in bio-oil and char from

401

NS and EP, and releasing properties of NH3 and HCN (Tables S1-S4 and Figures S120


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S5).

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Author information

404

Corresponding Author

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*Phone: +086-027-87542417-8109; email: [email protected].

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*Phone: +086-027-87542417-8109; email: [email protected].

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Notes

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The authors declare no competing financial interest.

409

Acknowledgements

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The authors wish to express their great appreciation of the financial support from

411

the National Nature Science Foundation of China (51406061 and 51622604), the

412

National Basic Research Program of China (973 Program: 2013CB228102), the Special

413

Fund for Agro-scientific Research in the Public Interest (201303095), the Fundamental

414

Research Funds for the Central Universities, the technical support from Analytical and

415

Testing

416

(http://atc.hust.edu.cn).

417

References

418

1.

Center

in

Huazhong

University

of

Science

&

Technology

Chiodo, V.; Zafarana, G.; Maisano, S.; Freni, S.; Urbani, F. Pyrolysis of different

419

biomass: Direct comparison among Posidonia Oceanica, Lacustrine Alga and

420

White-Pine. Fuel 2016, 164, 220-227.

421

2.

Yuan, T.; Tahmasebi, A.; Yu, J. Comparative study on pyrolysis of 21



422

lignocellulosic and algal biomass using a thermogravimetric and a fixed-bed

423

reactor. Bioresour. Technol. 2015, 175, 333-341.

424

3.

Chen, Y.; Wu, Y.; Hua, D.; Li, C.; Harold, M. P.; Wang, J.; Yang, M.

425

Thermochemical conversion of low-lipid microalgae for the production of

426

liquid fuels: challenges and opportunities. Rsc Adv. 2015, 5 (24), 18673-18701.

427

4.

Yu, G.; Zhang, Y.; Schideman, L.; Funk, T.; Wang, Z. Distributions of carbon

428

and nitrogen in the products from hydrothermal liquefaction of low-lipid

429

microalgae. Energ. Environ. Sci. 2011, 4 (11), 4587-4595.

430

5.

Biller, P.; Ross, A. B. Pyrolysis GC-MS as a novel analysis technique to

431

determine the biochemical composition of microalgae. Algal Res. 2014, 6, 91-

432

97.

433

6.

Appl. Pyrolysis 2013, 103, 134-141.

434 435

7.

8.

Miao, X. L.; Wu, Q. Y.; Yang, C. Y. Fast pyrolysis of microalgae to produce renewable fuels. J. Anal. Appl. Pyrolysis 2004, 71 (2), 855-863.

438 439

Wang, K.; Brown, R. C. Catalytic pyrolysis of microalgae for production of aromatics and ammonia. Green Chem. 2013, 15 (3), 675-681.

436 437

Yanik, J.; Stahl, R.; Troeger, N.; Sinag, A. Pyrolysis of algal biomass. J. Anal.

9.

Serrano-Ruiz, J. C.; Dumesic, J. A. Catalytic routes for the conversion of

440

biomass into liquid hydrocarbon transportation fuels. Energ. Environ. Sci. 2011,

441

4 (1), 83-99.

442 443

10.

Huber, G. W.; Iborra, S.; Corma, A. Synthesis of transportation fuels from biomass: Chemistry, catalysts, and engineering. Chem. Rev. 2006, 106 (9), 22


Page 22 of 36

Page 23 of 36


4044-4098.

444 445

11.

Chen, H.; Si, Y.; Chen, Y.; Yang, H.; Chen, D.; Chen, W. NOx precursors from

446

biomass pyrolysis: Distribution of amino acids in biomass and Tar-N during

447

devolatilization using model compounds. Fuel 2017, 187, 367-375.

448

12.

sludge pyrolysis. Energ Fuel 2015, 29 (8), 5088-5094.

449 450

Wei, L.; Wen, L.; Yang, T.; Zhang, N. Nitrogen transformation during sewage

13.

Ren, Q.; Zhao, C. NOx and N2O precursors from biomass pyrolysis: Role of

451

cellulose, hemicellulose and lignin. Environ. Sci. Technol. 2013, 47 (15), 8955-

452

8961.

453

14.

Tian, K.; Liu, W. J.; Qian, T. T.; Jiang, H.; Yu, H. Q. Investigation on the

454

evolution of N-containing organic compounds during pyrolysis of sewage

455

sludge. Environ. Sci. Technol. 2014, 48 (18), 10888-10896.

456

15.

Zhu, X.; Yang, S.; Wang, L.; Liu, Y.; Qian, F.; Yao, W.; Zhang, S.; Chen, J.

457

Tracking the conversion of nitrogen during pyrolysis of antibiotic mycelial

458

fermentation residues using XPS and TG-FTIR-MS technology. Environ. Pollut.

459

2016, 211, 20-27.

460

16.

Wang, K.; Brown, R. C.; Homsy, S.; Martinez, L.; Sidhu, S. S. Fast pyrolysis of

461

microalgae remnants in a fluidized bed reactor for bio-oil and biochar

462

production. Bioresour. Technol. 2013, 127, 494-499.

463

17.

Tian, Y.; Zhang, J.; Zuo, W.; Chen, L.; Cui, Y.; Tan, T. Nitrogen conversion in

464

relation to NH3 and HCN during microwave pyrolysis of sewage sludge.

465

Environ. Sci. Technol. 2013, 47 (7), 3498-3505. 23



466

18.

Pan, P.; Hu, C.; Yang, W.; Li, Y.; Dong, L.; Zhu, L.; Tong, D.; Qing, R.; Fan, Y.

467

The direct pyrolysis and catalytic pyrolysis of Nannochloropsis sp. residue for

468

renewable bio-oils. Bioresour. Technol. 2010, 101 (12), 4593-4599.

469

19.

transformation from amino acid. Environ. Sci. Technol. 2012, 46 (7), 4236-4240.

470 471

Ren, Q.; Zhao, C. NOx and N2O precursors from biomass pyrolysis: Nitrogen

20.

Hansson, K. M.; Samuelsson, J.; Tullin, C.; Åmand, L. E. Formation of HNCO,

472

HCN, and NH3 from the pyrolysis of bark and nitrogen-containing model

473

compounds. Combust. Flame 2004, 137 (3), 265-277.

474

21.

during its pyrolysis. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00647.

475 476

Liu, W. J.; Li, W. W.; Jiang, H.; Yu, H. Q. Fates of chemical elements in biomass

22.

Luo, W.; Wang, B.; Heron, C. G.; Allen, M. J.; Morre, J.; Maier, C. S.; Stickle,

477

W. F.; Ji, X. Pyrolysis of cellulose under ammonia leads to nitrogen-doped

478

nanoporous carbon generated through methane formation. Nano Lett. 2014, 14

479

(4), 2225-2229.

480

23.

Chen, W.; Yang, H.; Chen, Y.; Chen, X.; Fang, Y.; Chen, H. Biomass pyrolysis

481

for nitrogen-containing liquid chemicals and nitrogen-doped carbon materials.

482

J. Anal. Appl. Pyrolysis 2016, 120, 186-193.

483

24.

Chang, L. P.; Xie, Z. L.; Xie, K. C.; Pratt, K. C.; Hayashi, J.; Chiba, T.; Li, C.

484

Z. Formation of NOx precursors during the pyrolysis of coal and biomass. Part

485

VI. Effects of gas atmosphere on the formation of NH3 and HCN. Fuel 2003,

486

82 (10), 1159-1166.

487

25.

J. R. Pels; F. Kapteun; Moulijn, J. A.; Q. Zhu; Thomas, K. M. Evolution of 24


Page 24 of 36

Page 25 of 36


488

nitrogen functionalities in carbonaceous materials during pyrolysis. Carbon

489

1995, 33 (11), 1641-1653.

490

26.

Tian, F. J.; Yu, J. L.; McKenzie, L. J.; Hayashi, J.; Li, C. Z. Formation of NOx

491

precursors during the pyrolysis of coal and biomass. Part IX. Effects of coal ash

492

and externally loaded-Na on fuel-N conversion during the reforming of coal and

493

biomass in steam. Fuel 2006, 85 (10-11), 1411-1417.

494

27.

Yuan, S.; Zhou, Z. j.; Li, J.; Wang, F. c. Nitrogen conversion during rapid

495

pyrolysis of coal and petroleum coke in a high-frequency furnace. Appl. Energy

496

2012, 92, 854-859.

497

28.

Kelemen, S. R.; Gorbaty, M. L.; Kwiatek, P. J.; Fletcher, T. H.; Watt, M.; Solum,

498

M. S.; Pugmire, R. J. Nitrogen transformations in coal during pyrolysis. Energ

499

Fuel 1998, 12 (1), 159-173.

500

29.

Tan, L. L.; Li, C. Z. Formation of NOx and SOx precursors during the pyrolysis

501

of coal and biomass. Part II. Effects of experimental conditions on the yields of

502

NOx and SOx precursors from the pyrolysis of a Victorian brown coal. Fuel 2000,

503

79 (15), 1891-1897.

504

30.

Tan, L. L.; Li, C. Z. Formation of NOx and SOx precursors during the pyrolysis

505

of coal and biomass. Part I. Effects of reactor configuration on the determined

506

yields of HCN and NH3 during pyrolysis. Fuel 2000, 79 (15), 1883-1889.

507

31.

McKenzie, L. J.; Tian, F. J.; Li, C. Z. NH3 formation and destruction during the

508

gasification of coal in oxygen and steam. Environ. Sci. Technol. 2007, 41 (15),

509

5505-5509. 25



510

32.

Page 26 of 36

Gallois, N.; Templier, J.; Derenne, S. Pyrolysis-gas chromatography–mass

511

spectrometry of the 20 protein amino acids in the presence of TMAH. J. Anal.

512

Appl. Pyrolysis 2007, 80 (1), 216-230.

513

33.

acid monomer. J. Chromatogr. A 2011, 1218 (46), 8443-8455.

514 515

Choi, S.-S.; Ko, J.-E. Analysis of cyclic pyrolysis products formed from amino

34.

Ren, Q.; Zhao, C.; Chen, X.; Duan, L.; Li, Y.; Ma, C. NOx and N2O precursors

516

(NH3 and HCN) from biomass pyrolysis: Co-pyrolysis of amino acids and

517

cellulose, hemicellulose and lignin. P. Combust. Inst. 2011, 33 (2), 1715-1722.

518

35.

Du, Z.; Hu, B.; Ma, X.; Cheng, Y.; Liu, Y.; Lin, X.; Wan, Y.; Lei, H.; Chen, P.;

519

Ruan, R. Catalytic pyrolysis of microalgae and their three major components:

520

Carbohydrates, proteins, and lipids. Bioresour. Technol. 2013, 130, 777-782.

521

36.

Kumar, G.; Shobana, S.; Chen, W. H.; Bach, Q. V.; Kim, S. H.; Atabani, A. E.;

522

Chang, J. S. A review of thermochemical conversion of microalgal biomass for

523

biofuels: chemistry and processes. Green Chem. 2017, 19 (1), 44-67.

524

37.

carbohydrates of brown macro-algae. Fuel 2011, 90 (2), 598-607.

525 526

Anastasakis, K.; Ross, A. B.; Jones, J. M. Pyrolysis behaviour of the main

38.

Chen, W.; Yang, H.; Chen, Y.; Xia, M.; Yang, Z.; Wang, X.; Chen, H. Algae

527

pyrolytic poly-generation: Influence of component difference and temperature

528

on

529

https://doi.org/10.1016/j.energy.2017.05.019.

530 531

39.

products

characteristics.

Energy

2017,

DOI:

Chen, Y.; Yang, H.; Wang, X.; Zhang, S.; Chen, H. Biomass-based pyrolytic polygeneration system on cotton stalk pyrolysis: Influence of temperature. 26


Page 27 of 36


Bioresour. Technol. 2012, 107 (0), 411-418.

532 533

40.

Liu, H.; Zhang, Q.; Hu, H.; Liu, P.; Hu, X.; Li, A.; Yao, H. Catalytic role of

534

conditioner CaO in nitrogen transformation during sewage sludge pyrolysis. P.

535

Combust. Inst. 2015, 35 (3), 2759-2766.

536

41.

Debono, O.; Villot, A. Nitrogen products and reaction pathway of nitrogen

537

compounds during the pyrolysis of various organic wastes. J. Anal. Appl.

538

Pyrolysis 2015, 114, 222-234.

539

42.

Britt, P. F.; Buchanan, A. C.; Owens Jr, C. V.; Todd Skeen, J. Does glucose

540

enhance the formation of nitrogen containing polycyclic aromatic compounds

541

and polycyclic aromatic hydrocarbons in the pyrolysis of proline? Fuel 2004,

542

83 (11–12), 1417-1432.

543

43.

Liu, G.; Wright, M. M.; Zhao, Q.; Brown, R. C.; Wang, K.; Xue, Y. Catalytic

544

pyrolysis of amino acids: Comparison of aliphatic amino acid and cyclic amino

545

acid. Energy Convers. Manage. 2016, 112, 220-225.

546

44.

Sharma, R. K.; Chan, W. G.; Seeman, J. I.; Hajaligol, M. R. Formation of low

547

molecular weight heterocycles and polycyclic aromatic compounds (PACs) in

548

the pyrolysis of α-amino acids. J. Anal. Appl. Pyrolysis 2003, 66 (1–2), 97-121.

549

45.

Appl. Pyrolysis 2010, 89 (1), 74-86.

550 551

Choi, S. S.; Ko, J. E. Dimerization reactions of amino acids by pyrolysis. J. Anal.

46.

Sharma, R. K.; Chan, W. G.; Hajaligol, M. R. Product compositions from

552

pyrolysis of some aliphatic α-amino acids. J. Anal. Appl. Pyrolysis 2006, 75 (2),

553

69-81. 27



554

47.

Schmiers, H.; Friebel, J.; Streubel, P.; Hesse, R.; Kopsel, R. Change of chemical

555

bonding of nitrogen of polymeric N-heterocyclic compounds during pyrolysis.

556

Carbon 1999, 37 (12), 1965-1978.

557

48.

Kim, S. W.; Koo, B. S.; Lee, D. H. A comparative study of bio-oils from

558

pyrolysis of microalgae and oil seed waste in a fluidized bed. Bioresour. Technol.

559

2014, 162, 96-102.

560

49.

Lorenzetti, C.; Conti, R.; Fabbri, D.; Yanik, J. A comparative study on the

561

catalytic effect of H-ZSM5 on upgrading of pyrolysis vapors derived from

562

lignocellulosic and proteinaceous biomass. Fuel 2016, 166, 446-452.

563 564

28


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Figure captions

566

Abstract Graphic.

567

Figure 1. Schematic diagram of algal pyrolysis system for investigating nitrogen

568

transformation.

569

Figure 2. The nitrogen distribution of algae pyrolysis products.

570

Figure 3. Figure 3 N1s spectra of SP pyrolysis chars at different temperature (a)-(e)

571

and relative content of XPS N 1s peaks of three algae (f)-(h).

572

Figure 4. The releasing properties of NH3 and HCN from SP pyrolysis (a and b), and

573

yields of NH3-N and HCN-N from algae pyrolysis (c).

574

Figure 5. Mechanisms of nitrogen transformation and possible reaction pathways

575

during algae pyrolysis.

576

29



Amides

Page 30 of 36

3 NH

Quaternary-N

Nitriles

Indoles

Algae

Char

Inorganic-N Protein-N (amino acids)

Pyrrolic-N

Pyridinic-N HCN

Pyridines

Pyrroles

NH 3 577 578 Abstract Graphic. 579 580

30


Bio-oil

Gas

Page 31 of 36


Mass flow controller

Quartz basket

Ar

Gas bag

Valve Quartz reactor &

7 0

Ice-water mixture

NaOH H2SO4

ĉ

Temperature controller Electric furnace

PC

Mass spectrometry Air Ċ Color changing silica gel

Ice-water mixture or liquid nitrogen 581 582

Figure 1 Schematic diagram of algal pyrolysis system for investigating nitrogen

583

transformation.

584

31



70

Nbio-oil

N yields (wt.%)

60 50 40 30 20 10

400

585

Nchar

Ngas

0 500

600

700

800

Temperature (°C)

586

Figure 2. The nitrogen distribution of algae pyrolysis products (Ngas = 100wt.% - Nchar

587

–Nbio-oil). ■: SP; ●: NS; ▲: EP.

588

32


Page 32 of 36

Page 33 of 36


a

400°C

b

Protein-N Pyridinic-N

Pyrrolic-N Quaternary-N

404

500°C

Intensity (a.u.)

Intensity (a.u.)

Protein-N

402

400

Pyrrolic-N Quaternary-N

398

404

Binding Energy (eV)

589

c

Quaternary-N

402

400

e

800°C

404

396


402

400

Binding Energy (eV)

398

f 90 Relative content (%)

Intensity (a.u.)

Quaternary-N

398

Quaternary-N

398


Pyrrolic-N

400

Pyrrolic-N

Binding Energy (eV)

590

402

Binding Energy (eV)

700°C

Intensity (a.u.)

Intensity (a.u.)

Pyrrolic-N

404

d

Pyridinic-N

Protein-N

600°C

Pyridinic-N

SP

50 40 30 20 10

404

402

400

0

398

NS

40 30 20 10 0

400

500

600

Temperature (°C)

700

h 80 Relative content (%)

Relative content (%)

g 90

592

20

Binding Energy (eV)

591

800

EP

40 30 20 10

20

400

500

600

Temperature (°C)

700

800

0

20

400

500

600

Temperature (°C)

700

800

593

Figure 3 N1s spectra of SP pyrolysis chars at different temperature (a)-(e) and relative

594

content of XPS N 1s peaks of three algae (f)-(h). ■: protein-N; ●: pyridinic-N; ▲:

595

pyrrolic-N; ▼: quaternary-N. 33



NH3

Ion current (A) 0

b

400°C 500°C 600°C 700°C 800°C

500

1000

1500

Time (s)

596

0

c 25

1000

Time (s)

1500

SP NS EP

15

20 15

10

10

5

5

400

500

600

700

Temperature (°C)

HCN-N yield (wt.%)

NH3-N yield (wt.%)

597

500

25

20

0

400°C 500°C 600°C 700°C 800°C

HCN

Ion current (A)

a

Page 34 of 36

0

800

598

Figure 4. The releasing properties of NH3 and HCN from SP pyrolysis (a and b), and

599

yields of NH3-N and HCN-N from algae pyrolysis (c).

600

34


Page 35 of 36


HCN

NH3/NO Inorganic-N (1)(2) + (NH4 , NO3 /NO2 ) (3)

Lysine

Glutamic acid

Aspartic acid

(11)

Pyridinic-N (5)(10)

(12)

Pyrrolic-N

(9)

Quaternary-N

(7)

Arginine

(8)

Proline Phenylalanine

Decomposing

(15) (16)

Tyrosine Tryptophan Others

Cracking

(6)

Leucine Protein-N (Amino acids)

Cracking

(4)

Valine Algae (N)

(18)

HCN

NH3

Indoles Pyrroles

Pyridines

(17)

N-heterocyclic compounds NH3/NH2* Fatty acids (13)

(14) Amides Nitriles (Hexadecanamide) (Hexadecannitrile)

601 602

Figure 5. Mechanisms of nitrogen transformation and possible reaction pathways

603

during algae pyrolysis. Black: possible reaction pathways at lower temperatures; red:

604

possible reaction pathways at higher temperatures.

605 606

35



607

Page 36 of 36

Table 1. N-containing compounds in bio-oil derived from SP N-containing compounds Amines and amides 2-Methoxy-p-phenylenediamine 9-Octadecenamide Hexadecanamide N-Methyldodecanamide Nitriles Butanenitrile, 3-methylIsoamyl cyanide Benzonitrile Benzonitrile, 2-methylBenzenepropanenitrile Hexadecanenitrile N-heterocyclic compounds Oxazole Pyridine Pyrrole Pyridine, 2-methyl1H-Pyrrole, 2-methyl1H-Pyrrole, 3-methylPyridine, 3,5-dimethylIndole 1H-Indole, 3-methyl1H-Indole, 2-methylPyrimido[1,2-a]azepine, 2,3,4,6,7,8,9,10-octahydro2-Ethyl-3-methoxypyrazine 6,6-Dimethyl-2-azaspiro[4.4]non-1-ene Propyloctahydroindolizin-8-yl)methanol

Relative content (area %) 400°C 500°C 600°C 700°C 15.76 14.28 12.64 4.62 1.16 1.55 1.14 13.50 12.74 11.50 4.62 1.10 7.99 8.13 9.56 7.62 1.83 2.08 1.20 1.62 1.85 2.11 1.17 1.38 1.79 1.80 5.63 5.13 4.09 1.63 7.75 10.25 11.69 16.59 1.24 2.45 3.26 1.11 2.35 1.73 4.76 4.16 4.45 5.63 1.52 2.44 3.61

800°C 0

3.70 2.27 1.43 20.09 3.91 3.81 1.67 1.06 6.29 1.57 1.77

1.29

1.75

1.32 1.96

1.24

608

36


Transformation of Nitrogen and Evolution of N-Containing Species

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