PAPERmaking! Vol8 Nr3 2022

Z. Liu, M. Hughes, Y. Tong et al.

Energy 239 (2022) 121925

Table 2 Bio-oil compounds quanti fi ed by GC-FID (based on selected standard components).

800 C non-catalytic (0B)

800 C p-sludge catalyzed (Cycle 1)

800 C p-sludge catalyzed (Cycle 3)

800 C p-sludge catalyzed (Cycle 5)

Compounds (wt%, raw basis)

Aldehyde

ND a

Acetaldehyde

0.03 0.01 0.01

ND ND

m-Tolualdehyde

3,5-Dimethoxy-4- hydroxybenzeldehyde

0.27

0.28

Coniferaldehyde

0.01 0.01

ND ND

Vanillin

Ketone 4 0 -Hydroxy-3 0 -methoxyacetophenone 0.02

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

3,4-Dimethoxyacetophenone

0.77 0.05 0.44 0.72

Guaiacyl acetone

2 0 ,4 0 -Dimethoxyacetophenone

3 0 ,5 0 -Dimethoxy-4 0 - hydroxyacetophenone

Phenol

0.06 0.41 0.08 0.16 0.04 0.41 0.07 0.01 0.11 0.11 0.02 0.02 0.35 0.04 0.02 0.01 0.44 0.04 1.05 0.02 0.09

2-Ethylphenol 3-Ethylphenol

2,5-Dimethylphenol 2,6-Dimethylphenol 3,4-Dimethylphenol 2,6-Dimethoxyphenol

4-Methyl-2,6-dimethoxyphenol

o-Cresol

m,p-Cresol

3-Methoxy-5-methylphenol Guaiacol 4-Ethyl-2-methoxyphenol 2-Methoxy-4-propylphenol 2-Methoxy-4-methylphenol 2-Methoxy-4-vinylphenol

Ether

Anisole

2-Methylanisole 3-Methylanisole 4-Vinylanisole

1,2,3-Trimethoxybenzene 1,2,4-Trimethoxybenzene Alcohol 1,2-Benzenedimethanol 2,5-Dimethoxybenzylalcohol

2.51 0.03

ND ND

Other Aromatics Ethylbenzene

0.04 0.02 0.04 0.37 0.99 0.33 0.02

0.26

0.23

0.27

p-/m-Xylene composite

ND ND

o-Xylene Styrene

0.06

0.05

0.06

4-Ethoxystyrene

ND ND ND

2,3-Dimethoxytoluene 3,4-Dimethoxytoluene

a ND: Not Detected.

combustion due to the least coke deposition. With the increase of p-sludge biochar use cycles, the weight loss between 425 C and 550 C (i.e. the coke combustion) increased. Accordingly, smaller weight loss occurred during the carbonaceous matrix combustion. These results demonstrated that coke built up during cyclic uses, which was in accordance with the SEM-EDS analysis. Moreover, because the catalytic activity decreased, the weight loss during coke combustion (between 425 C and 550 C) increased much less after fi ve cycles when compared to cycle 1 and cycle 3.

thermogravimetry) plots of used p-sludge biochars (TG and DTG fi gures are shown in Fig. 8) have three characteristic combustion peaks starting at 375 C. These peaks are located between 375 C and 425 C, between 425 C and 550 C, and between 550 C and 675 C, which were attributed to the combustions of condensed light hydrocarbons (e.g. aliphatic compounds), coke (e.g. monoa- tomic carbon, aromatic compounds), and the remaining carbona- ceous matrix, respectively [41 e 43]. As for the new p-sludge biochar, its DTG curve shows a small fl at peak between 425 Cand 550 C, which could be due to a very small amount of coke formed on the p-sludge biochar surface during biochar making. The new p- sludge biochar had the largest peak of carbonaceous matrix

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