Influence of Reaction Atmosphere (N2, CO, CO2, and H2) on ZSM-5

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Influence of reaction atmosphere (N2, CO, CO2 and H2) on ZSM-5 catalyzed microwave-induced fast pyrolysis of medicinal herb residue for biofuel production Bo Zhang, and Jing Zhang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02106 • Publication Date (Web): 09 Aug 2017 Downloaded from http://pubs.acs.org on August 18, 2017

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Influence of reaction atmosphere (N2, CO, CO2 and H2) on ZSM-5 catalyzed microwave-induced fast pyrolysis of medicinal herb residue for biofuel production Bo Zhang*,† and Jing Zhang‡ †

Key Laboratory of Energy Thermal Conversion and Control of Ministry of

Education, Southeast University, Nanjing, Jiangsu 210096, China ‡

School of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University,

Nanjing, Jiangsu, 211816, China

_____________________

Corresponding Author *Tel.: +86 025 83794700. Fax: +86 025 83794700. E-mail: [email protected] or [email protected] (B. Zhang).

ABSTRACT: Microwave-induced catalytic fast pyrolysis (MICFP) of medicinal herb residue (MHR) is implemented to produce biofuel with the use of ZSM-5 catalyst and microwave receptive material (SiC). This research aims to explore the effect of reaction atmosphere on the pyrolytic product yields and oil chemical compositions. The Results demonstrate that CO atmosphere leads to the lowest total liquid and oil fraction yields and the highest water yield. The hydrocarbon relative contents in bio-oil of the four reaction atmospheres follow the order of CO > CO2 > H2 ≈ N2, while the oxygenate relative contents in bio-oil show the opposite tendency. Besides,

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CO atmosphere gives rise to the lowest selectivity of methoxy-containing phenols in oil fraction and thus can favor the production of a more stable pyrolytic bio-oil. Additionally, CO2 atmosphere causes the highest yield of syngas (CO+ H2), which can be used as high quality fuel.

1. INTRODUCTION Medicinal herb residue (MHR) is the solid waste derived from medicinal herbs after extraction of effective ingredients. As the cradle of Chinese medicine, the estimated MHR potential is over 13 million tons per year in Chinese medicine industry.1 Characterized by its prohibitively high moisture content, MHR is easy to decay, thus potentially risking the environment and human race.2,3 Therefore, the treatment of MHR has seen increasing interest in recent years. Recently, anaerobic digestion, incineration and landfill are usually used for the exploitation of MHR.4,5 Nonetheless, all of these disposal methods may lead to secondary environmental pollution of the underground water, soil, and air and have become less acceptable.6,7

On the other hand, as a kind of nonconventional biomass, MHR can also be hailed as an important renewable resource.8,9 Therefore, an alternative management technique for MHR is catalytic fast pyrolysis (CFP) for biofuel extraction although seldom such use has been reported previously. The addition of acidic catalysts can accomplish the removal of oxygenated chemicals in bio-oil, thus reducing the oxygen content, lowering the viscosity, increasing the calorific value, improving the stability 2


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and promoting the quality of bio-oil.10-13 Many research efforts have been paid to the upgrading of bio-oil with catalysts, and among various tested acidic catalysts, ZSM-5 zeolite has been demonstrated to be the best catalyst for de-oxygenating pyrolytic oils and facilitating hydrocarbon formation.14-18

Recently, microwave radiation has shown tremendous promise as an alternative new platform in biomass CFP process,19,20 which possess many additional advantages in contrast with electric heating method, such as uniform fast internal heating, rapid start-up and shut-down, easy to operate and maintain, dispense with biomass smash and low cost. Additionally, the employment of different carbonaceous substances that identified as microwave receptive materials, such as charcoal, activated carbon, biochar or SiC, has the potential to remarkably promote microwave heating rate, and therefore, is beneficial for promoted bio-oil production and ameliorative bio-oil quality.21,22 Nowadays, a novel combination of microwave heating and microwave receptive materials in biomass CFP process has been of growing interest.23-25 In our work, a new conversion route of microwave-induced catalytic fast pyrolysis (MICFP) of MHR to extract energy is proposed and investigated using ZSM-5 catalyst and microwave receptive material (SiC). As a result of the direct microwave heating and thermal conduction from hot carbonaceous material (microwave receptive material), MHR is thermally pyrolyzed into primary volatile pyrolytic products, and these primary volatile pyrolytic products are subsequently in situ catalytically upgraded to produce hydrocarbon-rich bio-oil with the use of ZSM-5.

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Additionally, as we know, biomass CFP process can lead to the production of various light gases (CO, CO2, H2 and so forth), and we hypothesis that the recycling of these light gases can avoid the need for additional carrier gas (N2) into reactor and may cause beneficial influence on bio-oil production. Thus, in this study we implement experiments to explore the influence of pure CO, CO2 or H2 atmosphere on biomass CFP process. In the future, we will consider of testing the effect of a multi-component atmosphere on catalytic pyrolysis, thus ideally expanding further biomass valorization via a closed loop system. Zhang et al.26 explored the influence of N2, CO, CO2, H2 and CH4 atmospheres on pyrolysis of corncob for bio-oil formation, and their results demonstrated that CH4 environment gave rise to the highest liquid yield while the lowest value was obtained under CO atmosphere. Besides, it was found that more oxygenates in bio-oil could be transformed into light non-condensable gases when CO or H2 was emplyed as carrier gas. Switchgrass fast pyrolysis under various reactive gas atmospheres was performed by Pilon and Lavoie27 and Tarves et al.28, and it was revealed that pyrolytic products with more hydrocabons and less oxygenates could be achieved under CH4 and H2 environments. Meesuk et al.29 performed CFP of rice husk under N2 and H2 atmospheres with different catalysts, and their results showed that CFP with catalysts at H2 atmosphere could remove more oxygen in bio-oil in contrast with N2 environment. Mante et al.30 recycled non-condensable gaseous product as carrier gas and studied its influence on CFP of biomass with FCC catalyst, and it was elucidated that liquid production was

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promoted and char/coke formation was retarded during biomass CFP after recycling of non-condensable gaseous product. Moreover, recycling of non-condensable gaseous product resulted in an augmentation of aromatic compounds in bio-oil and a decrease in methoxy, carboxylic and sugar fractions. Addtionally, Mellin et al.31 even simulated the influence of various reaction atmospheres on biomass pyrolysis in a fluidized bed using computational fluid dynamics models. In this paper, MICFP of MHR is carried out in a microwave oven with N2, CO, CO2 and H2 as carrier gas, respectively. Influence of reaction atmosphere on the pyrolysis yields and characteristics is studied and discussed. In our research, we investigate the influence of reaction atmospheres with microwave processing as heating method, ZSM-5 as catalyst and MHR as biomass candidate, which shows good originality and novelty. Besides, some findings in the study are different from the results obtained in previous literatures (especially the influence of H2 atmosphere).26-31

2. MATERIALS AND METHODS 2.1. MHR and Catalyst. MHR, obtained from a pharmaceutical company in Yancheng, China, is employed as the biomass feedstock in our experiments. Before experiment, MHR feedstocks are treated under 105 oC for 24 h for drying, and then fully ground and sieved using a sifter (40-mesh). The air-dried MHR has 8.79 wt.% moisture, 71.44 wt.% volatile, 9.65 wt.% ash, and 10.12 wt.% fixed carbon (proximate analysis). Additionally, the dried MHR has 42.17 wt.% carbon, 5.21 wt.% hydrogen, 51.48 wt.% oxygen, 1.01 wt.% nitrogen and 0.13 wt.% sulfur (elemental

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composition). Besides, the dried MHR contains 27.97 wt.% cellulose, 25.12 wt.% hemicellulose, and 29.55 wt.% lignin, respectively.

ZSM-5 catalyst in the protonated form with a silicon-to-aluminum ratio of 30, particle diameter of 10 µm and surface area of 365 m2/g is obtained from Nankai University Catalyst Plant (Tianjin, China). Before experiments, ZSM-5 is calcined in air at 500 oC for 5 h for its activation.

2.2. MICFP Apparatus. MICFP experiments are implemented in a well swept commercial microwave oven (W25800K-01AG, 800W, Fotile Company, Zhejiang, China). The experimental setup (see Figure 1) is composed of: (1) Gas supply unit; (2) semi-continuous MHR feeder; (3) MHR; (4) inlet quartz connector; (5) microwave-induced reactor; (6) reaction parameter setting panel; (7) flat-bottom quartz reaction chamber; (8) microwave receptive material (first static bed); (9) zeolite and microwave receptive material mixture (second static bed); (10) filter unit; (11) outlet quartz linker; (12) thermoelectric couple for temperature measurement in (8) and (9); (13) connecting tube; (14) liquid fraction collector; (15) condenser; (16) connection to a gas bag.

In this experiment, the used N2, CO, CO2 and H2 gases are purchased from Maikesi Nanfen Special Gas Co., Ltd. in Nanjing. During each run, microwave receptive materials (SiC) with particle size of < 1 mm are employed. Correspondingly,

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a total of 600 g microwave receptive materials are put into the flat-bottom quartz reaction chamber so that a microwave receptive material static bed can be formed. Subsequently, the flat-bottom reaction chamber is placed in the chamber of the microwave-induced reactor. When all the tubes and pipes in MICFP apparatus are connected, ZSM-5 zeolite (5 g) and microwave receptive material mixture is prepared and placed in the bottom position of the outlet quartz linker so that the second upgrading static bed can be formed. Prior to pyrolysis, a carrier gas stream is bubbled into MICFP system (volumetric flow rate: 200 mL/min). After the microwave-induced reactor is initiated, the microwave-induced heating progresses. When the pre-set reaction temperature in static beds (8) and (9) is obtained (550 oC), MHR feeder is switched on so that 20 g MHR samples can be dropped onto the pre-heated microwave receptive material static bed for pyrolysis. Experimentally, thermal decomposition of MHR proceeds in the flat-bottom quartz reaction chamber and then the further catalyzed transformation of primary volatile pyrolytic products progresses once these primary volatile pyrolytic products go into the outlet quartz linker and contact catalyst. Besides, a microwave control unit is designed and utilized to keep a pre-set pyrolysis and upgrading temperature in static beds (8) and (9) through instantaneous start-up and shut-down of MICFP apparatus. Additionally, each experiment runs 30 min.

2.3. Product Analysis. After each experiment, the microwave-induced reactor is turned off while carrier gas is still maintained until a room temperature in the entire

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system is reached. The used ZSM-5 zeolite and SiC mixture from upgrading fixed bed is gathered with great care and treated under 120 oC for 1 h for drying. Subsequently, the dried used catalyst is calcined in air at 650 oC for 2 h for the determination of coke yield. Additionally, char yield in this experiment is determined via mass difference in the flat-bottom quartz reaction chamber. The total liquid (water fraction & oil fraction) yield is calculated via mass difference in the liquid fraction collector, whereas that of non-condensable gaseous product is determined with this equation: Mass of non-condensable gaseous product = Mass of total collected gas - Mass of total carrier gas. Besides, Karl Fischer Titration method is used to determine the content of water fraction in bio-oil. The oil fraction content in bio-oil is obtained using follwing equation: Yield of oil fraction = Yield of total liquid - Water fraction content in total liquid ×Yield of total liquid. It is worth noting that after each experiment we find that the mass of corresponding gaseous compound collected in the gas bag is higher than the mass of corresponding carrier gas introduced into the reaction system. In this view, therefore, the carrier gas can be seen as a kind of catalyst which can promote the conversion of corresponding gaseous product into other products, while the carrier gas itself does not participate in the pyrolysis reactions. Hence, it is correct to calculate the product yield using weight difference. On the other hand, the chemical compounds in oil fraction and non-condensable gaseous products are analyzed using the methods described elsewhere.14,15,26

2.4. Data Processing. Peak selectivities of aromatic hydrocarbons and phenols in

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oil fraction are calculated and compared in this perspective. The selectivity of a sort of aromatics or phenols is defined and calculated based on eq 1.

Si =

ci ∑ ci

(1)

where Si is the selectivity of a sort of aromatics or phenols (e.g. benzene or phenol); c i is the relative concentration of a sort of aromatics or phenols;

∑c

i

is the

relative concentration of overall aromatics or phenols.

3. RESULTS AND DISCUSSION 3.1. Product Distribution. The overall pyrolytic product distribution from MICFP of MHR under different reaction atmospheres are plotted in Figure 2(a) and (b). The results demonstrate that MICFP of MHR under CO atmosphere gives rise to the minimum yields of total liquid (33.2%) and oil fraction (20.6%) and the maximum water fraction yield in bio-oil (12.6%). The yields of oil fraction from all four reaction atmospheres follow the order of N2 > CO2 > H2 > CO. The influence of CO atmosphere on product distribution can be explained by the following reason: The polarity of CO potentially promotes the further decomposition of aromatic rings, side chains, ether linkages and aliphatic rings in condensable volatile organic vapors,32 and it thus cracks large-molecule oxygenated chemicals into smaller molecular fragments. As a result, more condensable volatile organic vapors is capable of diffusion into those narrow inner structure of microporous zeolite accompanied with subsequent sufficient conversion once passing through the catalyst layer, thus forming more water and non-condensable gas. Therefore, the minimum yields of oils and total liquid and 9


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the maximum H2O yield are achieved under CO environment. For the case of H2 atmosphere, no significant change of the water yield (10.7%) is observed compared to 10.4% and 10.8% obtained under N2 and CO2 atmospheres, respectively. The direct hydrodeoxygenation of bio-oil to form H2O in the presence of H2 is typically run with high temperature (200-400 oC), high pressure (7-14 MPa) and harsh equipment requirement in general,9 and the mild H2 atmosphere condition (ambient pressure) in this research is unable to favor the conversion of oxygenates in oil fraction into water. As a consequence, H2 atmosphere has no significant effect on water formation. Besides, as elucidated in Figure 2(b), MICFP of MHR under CO2 atmosphere results in a gas yield of 48.8%, the maximum value compared with 42.8%, 47.4% and 44.8% obtained under N2, CO and H2 atmospheres, respectively. Likewise, due to reactions between carbonaceous solid residue and CO2 to produce CO during MICFP of MHR as it progresses, MICFP of MHR under CO2 atmosphere produces less char and coke than others.

3.2. Chemical Compositions in Oil Fraction. Figure 3 presents the relative concentrations of different oil fraction chemical families from MICFP of MHR under different reaction atmospheres. As illustrated, the hydrocarbon relative contents in bio-oil of all four reaction atmospheres follow the order of CO > CO2 > H2 ≈ N2, while the relative concentrations of oxygenates in oil fraction show the opposite tendency (N2 ≈ H2 > CO2 > CO). Once the primary volatile pyrolytic products go into the outlet quartz linker and contact ZSM-5 zeolite layer, oxygenates in

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condensable

volatile

organic

vapors

will

be

depleted

through

cracking,

deoxygenation, decarboxylation, cyclization, aromatization and alkylation inside the internal structure of ZSM-5 via a hydrocarbon pool intermediate, thus converting oxygenated compounds into light gases and forming hydrocarbons through the catalyzed transformation of hydrogen and carbon.20,33-36 For CO atmosphere, as abovementioned, CO can facilitate the production of smaller molecular fragments. As such, more oxygenated chemicals are fragmented and subsequently go into inner structure of microporous zeolite, thereby being transformed into hydrocarbons. Hence, CO atmosphere leads to a highest hydrocarbon relative content and lowest oxygenate relative content in obtained bio-oil. As to CO2 atmosphere, it has recently been corroborated that CO2 environment is capable of promotion of expedited thermal decomposition of some volatile organic compounds in biomass pyrolytic vapors, resulting in a enhanced production of hydrocarbons and CO by unknown reactions.37 Consequently, oxygenated chemical depletion and hydrocarbon formation can also be facilitated under CO2 atmosphere in comparison with N2 atmosphere. Additionally, H2 atmosphere is observed to have a insignificantly slight effect on oil chemical compositions in contrast with N2 atmosphere. This result is in keeping with the aforementioned results and discussion on product distribution.

On the other hand, it should be pointed out that an elevated relative content of phenols is observed under CO environment compared with N2, CO2 and H2 atmospheres. Phenols are mainly from depolymerization of lignin. CO atmosphere

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augments the relative content of phenols because CO favors the cracking of lignin and its derivatives (e.g. phenolic lignin fragments). In addition, as elucidated in Figure 3(a), CO2 environment forms more acids (relative content of 16.6%) than any other reaction atmosphere (N2: 14.2%, CO: 10.1%, H2: 14.6%). There are two main reasons to explain this result: (1) reaction between pyrolytic solid residue and carbon dioxide may lead to the formation of acetic acid.38 (2) CO2 is capable of reaction with VOCs which are chemically reactive and evolved from biomass pyrolysis, thus forming observable acids in bio-oil.

3.3.

Production

of

Aromatic

Hydrocarbons

and

Phenols.

ZSM-5

aluminosilicate zeolite, crystalline material composed of SiO4 and [AlO4]- tetrahedra, has a 3-dimensional intersecting pore structure accompanied with channel size of 0.55-0.56 nm, exactly conducive to the production of aromatics and phenols. Hence, ZSM-5 zeolite poses a significant shape-selectivity for the generation of aromatics and phenolic compounds.39,40 The detailed relative peak areas and peak selectivities of aromatics and phenols in oil fraction under varied reaction atmospheres are summarized in Table 1. As can be seen, aromatics include benzene, toluene, ethylbenzene, xylene, indene as well as polycyclic aromatic hydrocarbons (PAHs). As illustrated in Table 1, benzene, toluene and xylene are always the most part under all reaction atmospheres, accounting for the relative content of 19.2-25.5% and selectivity of 82.4-83.7%. The relative content of each kind of aromatics in bio-oil also tends to increase with following sequence: CO > CO2 > H2 ≈ N2. These results

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are consistent with the discussion in preceding text. Moreover, the maximum selectivities of benzene and xylene are gained under H2 atmosphere, while that of toluene is obtained in the presence of CO2. In addition, further study on the formation of PAHs is needed due to their carcinogenic toxicity.

The phenol relative contents and selectivities are also outlined in Table 1. As high value-added chemicals, bio-derived phenols are ready for end use as fuels, solvents or basic raw materials for polymers and resins. As can be seen, among all bio-derived

phenolic

2-methoxy-4-vinylphenol,

compounds, 2-methoxy-phenol,

phenol, and

2,6-dimethoxy-phenol,

3-tert-butyl-4-hydroxyanisole

account for the largest share. Besides, the highest relative content (5.4%) and selectivity

(24.0%)

of

overall

non-methoxy-containing

phenols

(phenol

+

4-ethyl-phenol) are achieved under CO atmosphere. As reported, methoxy-containing compounds can act as the polymerization precursors in bio-oil,14 and therefore, the results demonstrate that MICFP of MHR under CO reaction atmosphere is a good method to produce a more stable pyrolytic bio-oil.

3.4. Composition of Non-condensable Gas. Figure 4 shows the yields of several major non-condensable gas compositions from MICFP of MHR, including CO, CO2, H2 and CH4. The results demonstrate that performing MICFP of MHR at CO atmosphere causes the highest yield of CO2 in comparison with other reaction atmospheres. This can be explained by the fact that: (1) CO can promote the

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conversion of condensable volatile organic vapors into hydrocarbons and non-condensable gases especially CO2 with ZSM-5. (2) CO environment can facilitate Boudouard reaction (2CO→CO2+C), causing a augmentation of the yield of CO2 in non-condensable gas. Additionally, the yield of CO obtained at CO2 atmosphere is higher than those of obtained in other atmospheres. This may be explained with heterogeneous reactions between solid residual and CO2 to produce CO during MICFP of MHR as it progresses. Besides, compared to N2 and H2 atmospheres, CO and CO2 atmospheres are observed to tend to facilitate the production of syngas (CO+H2), which can be used as high quality fuel. Furthermore, the highest yield of syngas found is 20.1% at CO2 atmosphere.

4. CONCLUSIONS This research investigates the influence of reaction atmosphere on the pyrolysis yields and oil chemical compositions during MICFP of MHR. It is illustrated that CO atmosphere gives rise to the lowest yields of oils and total liquid as well as the highest water yield. The hydrocarbon relative concentrations in bio-oil of the four reaction atmospheres follow the order of CO > CO2 > H2 ≈ N2. Besides, CO atmosphere results in the lowest selectivity of methoxy-containing phenols and can produce a more stable pyrolytic bio-oil. Additionally, the highest yield of syngas (CO+ H2) is 20.1% in the presence of CO2.

ACKNOWLEDGEMENTS 14


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We acknowledge the Jiangsu Natural Science Foundation (No. BK20170679), the National Basic Research Program of China (973 Program) (No. 2013CB228106), and the Fundamental Research Funds for the Central Universities (No. 3203007207) for their financial support.

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Table 1. Production of Aromatic Hydrocarbons and Phenols in Oil Fraction Relative content (%)

Selectivity (%)

Compound N2

CO

CO2

H2

N2

CO

CO2

H2

Benzene

3.6

4.9

4.0

3.7

15.7

15.8

15.4

16.6

Toluene

6.2

9.1

7.8

6.1

27.1

29.5

29.9

26.9

Ethylbenzene

0.6

0.8

0.7

0.6

2.5

2.5

2.6

2.7

Xylene

9.4

11.5

10.0

9.4

41.0

37.1

38.5

41.9

Indene

0.2

0.5

0.3

0.3

1.0

1.5

1.2

1.4

PAHs

2.9

4.2

3.2

2.4

12.8

13.6

12.4

10.5

Total

22.9

30.9

26.0

22.5

100.0

100.0

100.0

100.0

Phenol

1.2

3.6

1.8

1.5

5.9

16.0

10.9

7.6

4-ethyl-Phenol

0.8

1.8

0.4

0.4

3.9

8.0

2.4

2.0

2-methoxy-Phenol

2.7

1.9

2.0

2.0

13.2

8.4

12.1

10.2

2-methoxy-4-methyl-Phenol

1.7

1.5

0.8

2.1

8.3

6.7

4.8

10.7

4-ethyl-2-methoxy-Phenol

1.8

2.0

0.9

0.9

8.8

8.9

5.5

4.6

2-methoxy-4-vinylphenol

4.7

4.2

2.4

5.5

22.9

18.7

14.5

27.9

2,6-dimethoxy-Phenol

3.2

2.7

3.9

2.5

15.6

12.0

23.6

12.7

3-tert-Butyl-4-hydroxyanisole

1.9

2.3

1.5

2.0

9.3

10.2

9.1

10.2

Aromatic hydrocarbons

Phenols

20


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Energy & Fuels

4-methoxy-3-(methoxymethyl)-Phenol

0.8

0.8

1.4

0.9

3.9

3.6

8.5

4.6

2,6-dimethoxy-4-(2-propenyl)-Phenol

0.9

0.7

1.1

0.6

4.4

3.1

6.7

3.0

4-methoxybenzene-1,2-diol

0.8

1.0

0.3

1.3

3.9

4.4

1.8

6.6

Total

20.5

22.5

16.5

19.7

100.0

100.0

100.0

100.0

21


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure captions

Figure 1. Schematic diagram of MICFP experimental setup. Figure 2. Product distribution. (a) yields of total liquid, oil fraction and water; (b) yields of char, coke and gas.

Figure 3. Chemical compositions in oil fraction. (a) relative contents of different chemical families; (b) relative contents of hydrocarbons and oxygenates.

Figure 4. Composition of non-condensable gas.

22


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Page 23 of 26

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Energy & Fuels

Figure 1. Schematic diagram of MICFP experimental setup.

23


Energy & Fuels

40 Total liquid

Oil fraction

Water

Yield (%)

30

20

10

0 CO

N2

CO2

H2

Reaction atmosphere

(a)

Char

50

Coke

Gas

40

Yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 26

30

20

10

0 N2

CO

CO2

H2

Reaction atmosphere

(b)

Figure 2. Product distribution. (a) yields of total liquid, oil fraction and water; (b) yields of char, coke and gas.

24


Page 25 of 26

35 N2

Relative content (%)

30

CO

CO2

H2

25 20 15 10 5 0

ons Acidslcohols Estersrbonyls henolsSugarsFurans Others carb P A o Ca r d Hy

Chemical compositions (a)

70 60

Relative content (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

N2

CO

CO2

H2

50 40 30 20 10 0

Hydrocarbons

Oxygenates

Chemical compositions (b)

Figure 3. Chemical compositions in oil fraction. (a) relative contents of different chemical families; (b) relative contents of hydrocarbons and oxygenates.

25


Energy & Fuels

25

CO

CO2

H2

CH4

20

Yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 26

15

10

5

0 N2

CO

CO2

H2

Reaction atmosphere Figure 4. Composition of non-condensable gas.

26


Influence of Reaction Atmosphere (N2, CO, CO2, and H2) on ZSM-5

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