Preliminary Study on Copyrolysis of Spent Mushroom Substrate as

Energy Conversion and Management 2018 165, 45-52 ... of bio-oil produced by the pyrolysis of mixed oil shale semi-coke and spent mushroom substrate...
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Preliminary study on co-pyrolysis of spent mushroom substrate as biomass and Huadian oil shale Haifeng Jiang, Sunhua Deng, Jie Chen, Li Zhang, Mingyue Zhang, Jianing Li, Shu Li, and Junfeng Li Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.6b01085 • Publication Date (Web): 11 Jul 2016 Downloaded from http://pubs.acs.org on July 11, 2016

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Preliminary study on co-pyrolysis of spent mushroom substrate as biomass and Huadian oil shale †











Haifeng Jiang , Sunhua Deng , Jie Chen , Li Zhang , Mingyue Zhang , Jianing Li , Shu Li†, Junfeng Li†,* †

College of Chemistry, Jilin University, Changchun 130012, P.R. China



College of Construction Engineering, Jilin University, Changchun 130012, P.R.

China *E-mail: [email protected] Haifeng Jiang: [email protected] Sunhua Deng: [email protected] Jie Chen: [email protected] Li Zhang: [email protected] Mingyue Zhang: [email protected] Jianing Li: [email protected] Shu Li: [email protected]

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Abstract In this work, thermal behaviors of Huadian oil shale, spent mushroom substrate and their mixture were investigated in a thermogravimetric analyzer. The Coats–Redfern method was adopted to calculate kinetic parameters. The results indicated that there existed remarkable synergetic effects during the co-pyrolysis. In addition, an comparison of the experimental and the calculated yields was carried out over a temperature range of 490-590℃ by a lab-scale retorting reactor. It showed that synergetic effects between raw materials promoted the producing of oil and gas and reduced the formation of solid residues. Besides, characteristics of the obtained oil indicated that the presence of spent mushroom substrate produced significant influences on the chemical component distribution. Keywords: oil shale; spent mushroom substrate; co-pyrolysis; kinetics; synergetic effect.

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1. Introduction The significant rise in global population, coupled with the rapid development of the industrial technology, has caused huge energy consumption, but we still rely on fossil fuels as the main energy sources at present. As one of the most important unconventional fuel resources, oil shale has attracted increasing attention across the world. In China, oil shale reserves are estimated at about 2.43 × 1010 tons1, which is favorable to decrease the dependence on petroleum. Additionally, it is worth mentioning that China is also the largest mushroom growing and consuming country in the world2, and it thus produces a large number of spent mushroom substrates (SMS) every year. In 2010, the total yield of SMS had reached 13 million tons, and it would further rise in the future2. However, there is no effective treatment for SMS at present, it is still processed by the traditional methods such as burning as household biofuel or discarding in the field3. It not only leads to the low utilization rate, but also causes serious environmental problems such as pollutants, acid rain and CO2 emission4, 5. Therefore, it is essential to investigate the conversion technology, instead of burning them for destroying after harvest. Pyrolysis, as an efficient conversion technology, can convert fossil fuels (eg. coal, oil shale) and biomass resources into various valuable products namely oil, gas and solid residues. On one hand, some studies on pyrolysis condition and the retorting equipment have carried out in order to increase the conversion efficiency of fossil fuels and biomass materials. For example, Nazzal et al.6 studied influence of grain size on shale oil yield by a semi-continuous fluidised bed, the retained amount of oil 3 ACS Paragon Plus Environment

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on the small particles was considered as a main factor to increase shale oil yield. The pyrolysis of corncob was carried out in the work of Demiral et al.7, they summarized that the continuous increase of final pyrolysis temperature tended to increase the gas yield, but not the liquid yield. Moreover, Lin et al.8 investigated pyrolysis of Yilan oil shale in indirectly heated fixed bed with internals, the results indicated that the addition of internals was beneficial to increase shale oil yield and enhance heating efficiency to shale particles in conventional fixed bed. The similar conclusions were also reported in the work of Lai et al.9 in which pyrolysis of oil shale was performed by using an innovative moving bed with internals. On the other hand, more and more researchers pay their attentions to the co-pyrolysis of fossil fuels and biomass resources. Researchers expect the addition of biomass can improve the pyrolysis characteristics of fossil fuels. However, synergies in the thermal behavior and production characterization were still controversial. Weiland et al.10 studied co-pyrolysis of switchgrass and bituminous coal, the substantial interaction was not found. The work of Moghtaderi et al.11 also showed the lack of synergy via co-pyrolysis of coal and pine sawdust. Hu et al.12 summarized that the inhibition of oil shale was stronger than the promotion of C. vulgaris during the co-pyrolysis. However, the work of Guo and Bi13 showed that the existence of corncob caused significant synergetic effects when co-fired with Thai lignite, resulting in an increase of liquid yield. The work of Zhang et al.14 also reported an increase in the liquid yield via co-pyrolysis of Dayan lignite and legume straw in a free fall reactor. Moreover, Johannes et al.15 studied interactions between oil shale and willow under supercritical 4 ACS Paragon Plus Environment

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condition, a positive synergy was reflected in the increase of high polar heterocompounds in the oil. Therefore, it could be concluded that the type of the biomass used was an important factor to determine the occurrence of synergy during the co-pyrolysis. Spent mushroom substrate, as an organic solid waste residue after cultivation of edible fungi2, has been applied in some aspects2, 16-18. However, much less attention is given to its pyrolysis characteristics, especially influences of SMS on products distribution and liquid characterization when co-pyrolysis with oil shale. In this work, co-pyrolysis of spent mushroom substrate as biomass and Huadian oil shale was investigated by a combination of the thermogravimetric analyzer and the lab-scale reactor. The aims are to explore whether the existence of SMS causes synergetic effects during the co-pyrolysis, and further investigate influences of synergetic effects between raw materials on products distribution and liquid characteristics. 2. Experimental Section 2.1. Raw materials The spent lark mushroom substrate (SLMS) was collected from Jilin province of China. The oil shale investigated in this paper was Huadian oil shale. Each raw material was crashed and sieved for obtaining the desirable particles (below 0.9mm). The processed raw materials were dried at 70℃ for 8h, and then blended at the mass ratio of 1:1 by physical mixing. The final processed sample was stored in a wide mouthed bottle at room condition. The fundamental characteristics of Huadian oil shale and SLMS were listed in Table 119, 20. 5 ACS Paragon Plus Environment

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2.2. Experimental apparatus and procedure 2.2.1. Pyrolysis in the thermogravimetric analyzer The thermogravimetric (TG) analyzer (Henven, Beijing) was used to investigate thermal events of oil shale, SLMS and the blended sample. About 8mg sample was distributed uniformly in the crucible, and it was heated from ambient temperature to 750℃ with the heating rate of 10℃/min. The flow rate of nitrogen was kept at 50ml/min during the whole experimental process. In order to investigate the possible synergetic effect between spent mushroom substrate and oil shale, the theoretical TG data of the blended sample was calculated by Eq.(1). The corresponding differential thermogravimetric (DTG) data was obtained by taking the derivative of the theoretical TG data. STheoretial = S oilshale ∗ c + S SLMS ∗ (1 − c )

(1)

where Soilshale and SSLMS were the mass percentage of solid residues (sum of char and initial sample) at the different temperature spots, which were obtained from the TG data. The c was the mass fraction of oil shale in the mixture. In this work, the c value was 0.5. 2.2.2. Pyrolysis experiment in the retorting reactor The co-pyrolysis experiments were carried out in a lab-scale retorting reactor, which was exhibited in Figure 1. The retorting reactor was consisted of three zones: the feed inlet, the retorting zone and the liquid condenser zone. About 50g sample was added into the reactor from feed inlet, and then transported to the retorting zone by the rotation of motor and screw feeder. The retorting zone (170mm length and 20mm 6 ACS Paragon Plus Environment

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inner diameter) was consisted of two stainless steel tubes with the heating jackets. The final pyrolysis temperature was controlled by the temperature controller, accurately. The formed cracking gases were cooled by a vertical orientation counter-current condenser tube. The oil vapors were condensed at a liquid collector surrounded by ice. Solid residues were collected in the solid collector, and then weighted. In the whole process, the feed rate of feedstock was 0.52g/min, and the flow rate of nitrogen was 200ml/min. The water-toluene distillation method8 was adopted for separating oil and water in the liquids. The total mass of the liquid phase was recorded as M E ,1 . The mass of water was determined by ASTMD95-2010, and it was defined as M E ,2 . So, the oil mass =M E ,1 − M E ,2 . The yields of oil, water and solid residues were obtained by Eq.(2), and the gas yield was calculated by difference. The average yield of each product from at least three experiments was considered as the final experiment result.

YE ,i =

M E ,i ME

×100%

(2)

where ME was the initial mass of sample, and YE,i was the experimental yields of i (oil, water and solid residues ). The average relative deviation between the experimental and the calculated yield was used to evaluate the strength of synergetic effects at different final pyrolysis temperatures21. It was calculated by Eqs.(3) and (4).

YCal .i = YOS ,i ∗ c + YSLMS ,i ∗ (1 − c) DArd ,i =

YBle,i − YCal ,i YCal ,i

×100%

(3) (4)

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where DArd,i was the average relative deviation of i. YOS,i and YSLMS,i were the experimental average yield of individual raw materials. YBle,i and YCal,i were the experimental and the calculated yield, respectively. 2.3. Kinetic calculation The various kinetic models about pyrolysis of fossil fuels and biomass resources had been proposed by many investigators. In this part, the Coats–Redfern model was used to calculate the related kinetic parameters. The co-pyrolysis was regarded as the first order reaction 22, 23. The final reaction equation was described by Eq. (5):  AR  2RT  E  ln(1 − x)  ln − =− + ln  1 −  2  T RT E    βE 

(5)

where E was the apparent activation energy, A was the pre-exponential factor, β was heating rate for non-isothermal condition. T was the absolute temperature. R was the gas constant. x was the weight loss fraction, which was calculated by Eq. (6): x =

W W

i i

− W − W

(6)

T f

where Wi and WT was the initial mass and the mass at temperature T. Wf was the final mass at the end of the mass loss process. As seen from Eq. (5), the value of

 AR  2 RT ln  1 − E βE 

  

for E was essentially constant,

and thus the Eq. (5) could be considered to be a linear equation at a specific temperature range. The slope and intercept of straight line were determined through plotting the left side of Eq. (5) versus 1 . Hence, the values of the apparent activation T

energy and pre-exponential factor were obtained.

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2.4. Characterization methods The contents of carbon(C), hydrogen (H) and nitrogen (N) of the oils were analyzed by the Vario EL Cube Elementar. The oxygen (O) content was calculated by difference. The FT-IR spectra were recorded by using a SHIMDZU 1.50SU1 model Fourier transform infrared spectrometer (FT-IR). The spectra range and the spectral resolution were 500-4000 cm-1 and 4 cm-1, respectively. The chemical class compositions of the oils were detected by using Agilent 7890 gas chromatograph equipped with the Agilent 5975N mass spectrometer (GC-MS) which was fitted with a HP-5MS capillary column (30 m × 0.32 mm inner diameter × 0.25µm thickness). The oven temperature was initially held at 50 °C for 3 min and then increased to 280 °C at 5 °C/min and held 10 min. The flow rate of Helium as the carrier gas was controlled at 1 ml/min. The injector temperature was kept at 250℃. The split ratio was 1:50. The analysis work of chemical components in the obtained oils was performed by the National Institute of Standards and Technology mass spectrum search program (Version 2.0). The X-ray diffraction (XRD) patterns of oil shale and SLMS ash were recorded by using an Ultima IV X-ray diffractometer equipped with Cu Ka radiation. The metal element contents in the SLMS were tested by Energy-dispersive spectroscopy (EDS) with an H JEOL JXA-840 EDX system attached to the SEM microscope.

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3. Results and discussion 3.1. XRD and EDS characterization of raw materials The XRD pattern of the Huadian oil shale was shown in the Figure 2. The quartz and calcite were dominant minerals in Huadian oil shale. The clay compositions were also observed, including kaolinite, montmorillonite. It had been reported that mineral matters had high catalytic activity24, and thus the presence of these mineral matters could produce some positive influences. In addition, the EDS analysis results showed that the SLMS had 30.72±0.04% of calcium, 2.64±0.03% of magnesium, 2.22± 0.04% of potassium and 0.50±0.11% of sodium. Some transition metal elements were also detected from the SLMS. The contents of iron, cobalt, nickel were 0.83± 0.03%, 0.45±0.01% and 1.26±0.07%, respectively. These metallic species were also considered to play an important role in the catalytic pyrolysis process. 3.2. The synergetic effect in TG analysis 3.2.1. Thermal behavior of SLMS and oil shale Figure 3(a) and (b) displayed the TG and DTG curves of oil shale and SLMS. Because of differences in the chemical component and structure, oil shale and SLMS showed different mass loss behaviors. The pyrolysis process of raw materials could be categorized into three decomposition stages. In the first stage, the mass loss behaviors of both raw materials were mainly owing to the vaporization of moisture and the decomposition of small polymers. The significant disorganization processes of organic matters happened at 230-510℃for SLMS and 350-520℃ for oil shale. At the second stage, kerogen in the oil shale was cracked to produce pyrolytic bitumen, and 10 ACS Paragon Plus Environment

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then decomposed to form the gaseous products released from the shale particle25, 26. For SLMS, organic matters (eg. hemicellulose, cellulose and lignin) were also devolatilized, which were reflected in two decomposition steps. From DTG curve of SLMS, it was observed that the mass loss peak at 220-365℃was higher than that at 366-510℃. It indicated that the decomposition of hemicellulose and cellulose was primary in the pyrolysis process of biomass. Moreover, some oxygenated compounds (eg. CO, CO2) and hydrogen donor species were also produced by the rupture of chemical bonds between atoms, dehydration reactions and polymerization reactions27. Thus, the second stage was considered as the main stage that raw materials were cracked to produce oil vapors and other gaseous products. At the final stage, two mass loss peaks centered at about 680℃ for SLMS and 705℃ for oil shale were observed from the DTG curves. According to literatures, it could be caused by the decomposition of carbonates in the feedstock28, 29. 3.2.2. Influence of synergetic effect on co-pyrolysis behavior A comparison between pyrolysis of raw materials and co-pyrolysis was displayed in the Figure 3(a) and (b). The TG and DTG curves obtained by co-pyrolysis lied between raw materials. As seen from the TG and DTG curves of the mixture, the mass loss processes at the temperature ranges of 230-356 ℃ and 357-510 ℃ were attributed to the disintegration of SLMS and oil shale in the blended sample, respectively. In comparison with pure oil shale, the addition of SLMS caused the mass loss behaviors in all stages shifted toward the lower temperature region. Notly, the peak temperature corresponding to the maximum decomposition rate (Tmax) of oil 11 ACS Paragon Plus Environment

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shale was decreased about 14 ℃ compared to pure oil shale pyrolysis. These observations indicated that the presence of SLMS improved pyrolysis characteristics of oil shale. Some interactions might be existed during the co-pyrolysis. In order to get deeper understanding about the possible synergetic effects between oil shale and SLMS, the experimental and the calculated curves of the blended sample were displayed in Figure 3(c) and (d). There was an obvious lag observed from the comparison between the experimental and the calculated curve. As seen from the experimental TG curve, there were about 33.81% of volatiles released from the blended sample in the range of 230-510℃, which was increased about 2.96% compared to the calculated data. The mass losses at the decomposition stage of SLMS and oil shale in the blended sample were 13.29% and 20.52%, respectively. Comparing with the calculated data, the mass loss at the decomposition stage of SLMS was increased about 1.21%, and an increase of 1.75% was obtained at the decomposition stage of oil shale in the mixture. In addition, the remarkable deviations between the experimental and the calculated values were also reflected in the DTG curves. It could be found that the maximum weight loss rate at the main decomposition stage of the mixture was occurred at lower temperature. Meanwhile, the maximum mass loss rates of both biomass and oil shale were higher than the calculated values, which were increased about 0.02 %/℃ and 0.01%/℃, respectively. The improvement of pyrolysis characteristics of SLMS could be explained by catalytic activities of the clay in the oil shale, which had been mentioned in section 3.1. Based on the above results, it was concluded that there existed remarkable 12 ACS Paragon Plus Environment

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synergetic effects during the co-pyrolysis. The improvement of pyrolysis characteristics of oil shale during co-pyrolysis was associated with the basic characteristics of SLMS. It was well known that because of high content of alkali and alkaline earth metals (AAEMs), biomass could produce significant catalytic effects for the decomposition of fossil fuels. Rich hydrogen radicals produced by biomass were also beneficial to accelerate the disorganization process. Additionally, the work of Ma et al.30 showed that the presence of iron-containing compound was favorable to decrease temperature of bitumen peak generation and promote the producing of free radicals. Thus, the positive influences on thermal behavior of oil shale in the mixture were observed in this work. 3.2.3. Kinetic analysis The estimation of kinetic parameters during the pyrolysis process was vital, because it could pave the way for optimizing the operating conditions as well as supply guidance on the investigation of the underlying mechanism31. Based on above discuss, the presence of SLMS significantly influenced pyrolysis characteristics of oil shale in the blended sample, and thus this part was mainly focused on variation of kinetic parameters of oil shale with/without SLMS during the co-pyrolysis. The apparent activation energy of oil shale at the main decomposition stage (350-520℃) was about 61.14 kJ/mol, which had been calculated by our earlier work20. In this part, the obtained apparent activation energy and correlation coefficient of oil shale in the mixture at the temperature range of 378-510℃were 27.49 kJ/mol and 0.9164, respectively. The high correlation coefficient indicated the reliability of calculation 13 ACS Paragon Plus Environment

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model. It could be found that due to the addition of biomass, the apparent activation energy of oil shale in the blended sample was significantly decreased. The similar result was also obtained by the work of Wang et al32. The E value of oil shale was decreased about 33 kJ/mol compared to pure oil shale. Combining with the analysis of co-pyrolysis behavior, the result further demonstrated that some interactions were existed during the co-pyrolysis, and the existence of SLMS effectively reduced the required energy to occur the cracking reactions, resulting in the enhancement of the disintegration of oil shale. 3.3. The synergy effect in the retorting reactor 3.3.1. Pyrolysis of SLMS and oil shale The pyrolysis experiments at the temperature range of 490-590℃ were carried out in the retorting reactor, because pyrolysis temperature was an important parameter to influence products distribution. Table 2 listed the average yields of the obtained oil, water, gas and solid residue. It could be seen that pyrolysis of oil shale produced amounts of solid residues, while pyrolysis of SLMS in which liquids (oil +water) and solids equally dominated the obtained production. It was attributed to the high ash content of oil shale. As an increase of pyrolysis temperature, the solid yield for oil shale decreased from 76.00 wt.% to 65.13 wt.%. Moreover, for both oil shale and SLMS, the oil yield was monotonically raised as temperature was increased from 490 to 540℃. While, the increase of gas yield was primary when the temperature was above 540℃. This was mainly because that high temperature enhanced secondary cracking reactions of the formed oil vapors and solid residues, contributing to the 14 ACS Paragon Plus Environment

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formation of gaseous products. 3.3.2. Influence of synergetic effect on products distribution The experimental and the calculated yields of liquids and solid residue obtained from co-pyrolysis was listed in the Table 3. The total yields of oil and gas at the temperature of 490, 540 and 590℃ were 36.51wt.%, 40.75wt.% and 46.91wt.%, respectively. The average relative deviations between the experiment and the calculated value were 6.20% for 490℃, 15.93% for 540℃ and 11.66% for 590℃, indicating the highest carbon conversion efficiency occurred at 540℃. At the temperature of 540℃,it could be seen that the experimental yields of oil and gas were higher than the calculated values, while the yields of solid residue and water obtained from the pyrolysis experiment were lower. The relative deviations for oil, gas and solid residue were 19.40%, 13.58% and 5.43%, respectively. In addition, compared to the pyrolysis of oil shale without SLMS, the total yield of oil and gas obtained by co-pyrolysis at 540℃ were increased about 27.90%, and the solid residue yield was decreased about 16.89%. The results showed that synergetic effects between raw materials greatly promoted the producing of oil and gas and reduced the formation of solid residue during the pyrolysis. The alkali-rich biomass displayed as catalyst for oil shale pyrolysis had been stated in the section 3.2.2. In addition, it should be noted that most of inherent metallic components were still retained in the formed ash. Some researchers’ studies33,34 had reported that the metal potassium in the ash played an important role in the catalytic process of fossil fuels. Figure 4 showed that the potassium exist in SLMS ash was in the form of KCl, not others such as KAlSiO4, 15 ACS Paragon Plus Environment

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KAlSi2O6, KAlSi3O8. Part of potassium in SLMS could be considered to be in the form of water soluble (eg. carboxylates)34. This meant that the potassium in the SLMS ash was a good catalyst for oil shale pyrolysis, which promoted the secondary reactions such as cracking and dehydrogenation, leading to the increase of the liquid and gas yields and the decrease of the solid yield. Besides, the work of zhang et al.35 reported that some volatiles–char interactions were existed during the co-pyrolysis of fossil fuels and biomass, resulting in an increase of liquid yield and a decrease of solid yield, and it thus was also considered as a factor to effect products distribution. 3.4. Characterization of the obtained oils from co-pyrolysis 3.4.1. Ultimate analysis The C, H and O contents of the oils were 73.65±2.82%, 10.52±0.92% and 13.91±0.24% for shale oil, and 69.05±0.06%, 9.65±0.10%, 18.53%±0.06% for SLMS oil. After the co-pyrolysis, the C, H and O contents were 75.20±0.31%, 8.99 ±0.23% and12.87±0.35%, respectively. The co-pyrolysis of oil shale and SLMS caused an increase of the carbon content and a decrease of the hydrogen content in the liquid product. And, the oxygen content of the oil was also reduced after co-pyrolysis, indicating the oxygen in the oil could be removed due to the existence of SLMS. 3.4.2. FT-IR analysis The FT-IR spectra of the oils produced from oil shale, SLMS and the blended sample were shown in the Figure 5, and the main absorbance peaks had been marked. For all spectra, a shoulder absorbance peak at around 3310 cm-1 was attributed to the C-H stretching vibration of phenols. The absorbance peaks at a range of 3032-3073 16 ACS Paragon Plus Environment

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cm-1 was caused by the C-H stretching vibration of aromatic ring. The peaks between 2852 and 2926 cm-1 and by 1462-1509 cm-1 was associated with aliphatic hydrocarbons (AHs). Moreover, the absorbance peaks at 1729 cm-1 represented the C=O stretching vibration, indicating the presence of ketones or esters. The C-O stretching vibration and O-H bending peaks at 1034-1261 cm-1 indicated the presence of primary, secondary and tertiary alcohols22. Other peaks between 693 and 807 cm-1 were corresponded to the vibrations of aromatic groups. It was worth noting that after co-pyrolysis, the functional groups distribution of the obtained oil by co-pyrolysis showed obvious differences. It was found that the absorbance peak represented esters or ketones performed low peak intensity, while the peaks represented alcohols showed high intensity when co-pyrolysis with SLMS. This could be due that abundance hydrogen radicals produced by biomass promoted the occurrence of hydrogenation reactions during the co-pyrolysis, and it thus caused more compounds contained C=O functional group were converted into the alcohols in the oil produced. Additionally, it could also be seen that due to the addition of SLMS, the absorbance peaks intensity of aliphatic hydrocarbons was lower, but the peaks intensity of aromatics were higher than those of pure oil shale pyrolysis. The phenomenon seemed to suggest the addition of SLMS increase the production of aromatics in the oil. It was further supported by the results of GC-MS analysis. 3.4.3. GC-MS analysis Figure 6 showed the GC-MS chromatograms of liquid products, and some representative chemical compound groups had been marked. From Figure 6(a), the 17 ACS Paragon Plus Environment

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shale oil contained a fairly large proportion of aliphatic hydrocarbons, which occupied about 56.24% of total peak area in the detected components. Figure 6(b) showed that about 26.73% of phenol and its derivatives dominated the detected components in the oil derived from SLMS. A comparison of organic phase in the oil produced from pyrolysis of oil shale with/without SLMS was shown in the Figure 7. On one hand, after the co-pyrolysis, the peak areas of alcohols and phenols were increased about 0.69% and 1.57%, respectively, and the total peak area of esters and ketones was decreased about 0.73%. These had a good agreement with the results of FTIR spectra. It was noteworthy that esters and ketones were considered to be undesirable products for the stability and heating value of the oil36, and thus the reduction suggested that the addition of SLMS was benefit to improve the quality of oil. On the other hand, compared to the pure oil shale, the AHs content was decreased from 54.74% to 53.01%, while, the peak area of aromatics was increased from 1.52% to 8.96%. These variations further showed that the addition of SLMS enhanced the aromatization reaction of aliphatic hydrocarbons during the co-pyrolysis. Iliopoulou et al.36 noted that the heterogeneous catalysts loaded with metal cobalt could significantly increase the selectivity of chemical components toward aromatics in the oil. Considering our work, because of differences in the characteristics of raw materials, most of volatile matters in the biomass were released at lower temperature than that of oil shale, and thus the formed coke by the SLMS could be considered as a heterogeneous catalyst loaded with metal species during the pyrolysis of oil shale. Further, it caused an enhancement that the AHs turned into aromatics via the oilgomerization and 18 ACS Paragon Plus Environment

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cylization aromatization reactions37 as well as through the Diels-Alder reaction36. Besides, it should be noted that the enhancement of aromatization reactions indicated the rise of dehydrogenation effects. This could explain that why the hydrogen content in the oil was reduced after co-pyrolysis. Figure 8 presented the main components of organic phase (peak area above 0.2%) in the oil produced by co-pyrolysis. Aromatic hydrocarbons were prevalent with o-xylene being the most selectively produced compound, which indirectly reflected the strong selectively toward aromatics. Moreover, some potentially high value chemical components were detected in the oil. For example, phenols and aromatic hydrocarbons (ARs) were considered as the high valuable products. Alcohols had been used in the production of beverage, essence, dyestuff, fuel38. Naphthalenes and indenes could also be converted to the useful hydrocarbons via (hydro)cracking refinery process36, 39. 4. Conclusions In this work, the investigations on co-pyrolysis of oil shale and spent mushroom substrate were carried out by a combination of the TG analyze and the retorting reactor, in order to study influences of SLMS on pyrolysis of Huadian oil shale. The main conclusions were summarized as follows: (1)The TG analysis showed that the presence of SLMS significantly improved pyrolysis characteristics of oil shale. Because of the addition of biomass, Tmax was decreased about 14℃observed from thermal behavior of oil shale in the mixture. Further, the comparison between experiment and calculated curve and the analysis 19 ACS Paragon Plus Environment

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results of kinetics revealed that remarkable synergetic effects were existed during the co-pyrolysis. (2) Pyrolysis Experiments in the retorting reactor showed that temperature significantly influenced the products distribution. The maximum yield of oil was obtained at 540℃with the yield of 16.99 wt.%. Compared to the calculated values, the yields of oil and gas were increased about 19.40% and 13.58%, respectively. And, the yield of solid residues was decreased about 5.43%. These results indicated that synergetic effects between raw materials greatly promoted the producing of oil and gas and reduced the formation of solid residue. (3) The addition of SLMS influenced the chemical components distribution of the oil. After co-pyrolysis, the increase of alcohols and aromatics contents in the oil were attributed to the enhancement of hydrogenation reaction and the increase of selectivity toward aromatics during the co-pyrolysis. The analysis results of organic phase further showed that the obtained oil had high potential utilization value. 5. Acknowledgement The work was supported by Graduate Innovation Fund of Jilin University (Project 2015082) and Resource Evaluation Sector of China Geological Survey (Grant 1212011220797). References (1) Zhang, H.; Song, Y.; Sheng, Y.; Zheng, K.; Ding, S.; Yuan, B.; Xu, X.; Zou, H., The photoluminescence properties of tri-colour silicoaluminate phosphors prepared from oil shale ash. Opt. Mater.2015, 47, 143-148. 20 ACS Paragon Plus Environment

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(2) Gao, W.; Liang, J.; Pizzul, L.; Feng, X. M.; Zhang, K.; Castillo, M. d. P., Evaluation of spent mushroom substrate as substitute of peat in Chinese biobeds. Int. Biodeter. Biodegr.2015, 98, 107-112. (3) Abnisa, F.; Arami-Niya, A.; Wan Daud, W. M. A.; Sahu, J. N.; Noor, I. M., Utilization of oil palm tree residues to produce bio-oil and bio-char via pyrolysis. Energy Convers. Manage. 2013, 76, 1073-1082. (4) Aboyade, A. O.; Carrier, M.; Meyer, E. L.; Knoetze, H.; Görgens, J. F., Slow and pressurized co-pyrolysis of coal and agricultural residues. Energy Convers. Manage. 2013, 65, 198-207. (5) Duan, P.; Jin, B.; Xu, Y.; Wang, F., Co-pyrolysis of microalgae and waste rubber tire in supercritical ethanol. Chem. Eng. J.2015, 269, 262-271. (6) Nazzal; J. M., The influence of grain size on the products yield and shale oil composition from the Pyrolysis of Sultani oil shale. Energy Convers. Manage. 2008, 49, 3278-3286. (7) Demiral, Đ.; Eryazıcı, A.; Şensöz, S., Bio-oil production from pyrolysis of corncob (Zea mays L.). Biomass Bioenergy 2012, 36, 43-49. (8) Lin, L.; Zhang, C.; Li, H.; Lai, D.; Xu, G., Pyrolysis in indirectly heated fixed bed with internals: The first application to oil shale. Fuel Process. Technol. 2015, 138, 147-155. (9) Lai, D.; Chen, Z.; Shi, Y.; Lin, L.; Zhan, J.; Gao, S.; Xu, G., Pyrolysis of oil shale by solid heat carrier in an innovative moving bed with internals. Fuel. 2015,159, 943-951. 21 ACS Paragon Plus Environment

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(10) Weiland, N. T.; Means, N. C.; Morreale, B. D., Product distributions from isothermal co-pyrolysis of coal and biomass. Fuel. 2012, 94, 563-570. (11) Meesri, C.; Moghtaderi, B., Lack of synergetic effects in the pyrolytic characteristics of woody biomass/coal blends under low and high heating rate regimes. Biomass Bioenergy. 2002, 23, 55-66. (12) Hu, Z.; Ma, X.; Li, L., The synergistic effect of co-pyrolysis of oil shale and microalgae to produce syngas. J .Energy.Inst. 2015. (13) Guo, M.; Bi, J.C., Characteristics and application of co-pyrolysis of coal/biomass blends with solid heat carrier. Fuel Process. Technol. 2015, 138, 743-749. (14) Zhang, L.; Xu, S.; Zhao, W.; Liu, S., Co-pyrolysis of biomass and coal in a free fall reactor. Fuel. 2007, 86, 353-359. (15) Johannes, I.; Luik, H.; Palu, V.; Kruusement, K.; Gregor, A., Synergy in co-liquefaction of oil shale and willow in supercritical water. Fuel. 2015, 144, 180-187. (16) Nakatsuka, H.; Oda, M.; Hayashi, Y.; Tamura, K., Effects of fresh spent mushroom substrate of Pleurotus ostreatus on soil micromorphology in Brazil. Geoderma. 2016, 269, 54-60. (17) Tuhy, Ł.; Samoraj, M.; Witkowska, Z.; Rusek, P.; Chojnacka, K., Conversion of spent mushroom substrate into micronutrient fertilizer via biosorption in a pilot plant. Ecol. Eng. 2015, 84, 370-374. (18) García-Delgado, C.; Yunta, F.; Eymar, E., Bioremediation of multi-polluted soil by spent mushroom (Agaricus bisporus) substrate: Polycyclic aromatic hydrocarbons 22 ACS Paragon Plus Environment

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degradation and Pb availability. J. Hazard. Mater. 2015, 300, 281-288. (19) Jiang, H.; Cheng, Z.; Zhao, T.; Liu, M.; Zhang, M.; Li, J.; Hu, M.; Zhang, L.; Li, J., Pyrolysis kinetics of spent lark mushroom substrate and characterization of bio-oil obtained from the substrate. Energy Convers. Manage.2014, 88, 259-266. (20) Jiang, H.; Song, L.; Cheng, Z.; Chen, J.; Zhang, L.; Zhang, M.; Hu, M.; Li, J.; Li, J., Influence of pyrolysis condition and transition metal salt on the product yield and characterization via Huadian oil shale pyrolysis. J. Anal. Appl. Pyrol. 2015, 112, 230-236. (21) Yang, X.; Yuan, C.; Xu, J.; Zhang, W., Co-pyrolysis of Chinese lignite and biomass in a vacuum reactor. Bioresour Technol.2014, 173, 1-5. (22) Kılıç, M.; Pütün, A. E.; Uzun, B. B.; Pütün, E., Converting of oil shale and biomass into liquid hydrocarbons via pyrolysis. Energy Convers. Manage. 2014, 78, 461-467. (23) Ma, Y.; Li, S., Study of the Characteristics and Kinetics of Oil Sand Pyrolysis. Energy Fuels. 2010, 24 , 1844-1847. (24) Hu, M.; Cheng, Z.; Zhang, M.; Liu, M.; Song, L.; Zhang, Y.; Li, J., Effect of Calcite, Kaolinite, Gypsum, and Montmorillonite on Huadian Oil Shale Kerogen Pyrolysis. Energy Fuels. 2014, 28, 1860-1867. (25) Williams, P. F. V., Thermogravimetry and decomposition kinetics of British Kimmeridge Clay oil shale. Fuel. 1985, 64,540-545. (26) Al-Ayed, O. S.; Matouq, M.; Anbar, Z.; Khaleel, A. M.; Abu-Nameh, E., Oil shale pyrolysis kinetics and variable activation energy principle. Appli. Energy 2010, 23 ACS Paragon Plus Environment

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biomass. Appl.Energy. 2014, 132, 426-434. (35) Zhang, J.; Quan, C.; Qiu, Y.; Xu, S., Effect of char on co-pyrolysis of biomass and coal in a free fall reactor. Fuel Process. Technol. 2015, 135, 73-79. (36) Iliopoulou, E. F.; Stefanidis, S.; Kalogiannis, K.; Psarras, A. C.; Delimitis, A.; Triantafyllidis, K. S.; Lappas, A. A., Pilot-scale validation of Co-ZSM-5 catalyst performance in the catalytic upgrading of biomass pyrolysis vapours.Green Chem. 2014, 16, 662. (37) Kelkar, S.; Saffron, C. M.; Li, Z.; Kim, S.-S.; Pinnavaia, T. J.; Miller, D. J.; Kriegel, R., Aromatics from biomass pyrolysis vapour using a bifunctional mesoporous catalyst. Green Chem. 2014, 16, 803-812. (38) Zhang, Z.H.; Balasubramanian, R., Investigation of particulate emission characteristics of a diesel engine fueled with higher alcohols/biodiesel blends. Appl. Energy. 2016, 163, 71-80. (39) Dorado, C.; Mullen, C. A.; Boateng, A. A., H-ZSM5 Catalyzed Co-Pyrolysis of Biomass and Plastics. ACS Sustainable Chem. Eng. 2014, 2, 301-311.

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Figures: Figure1. The apparatus diagram of the retorting reactor.

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Figure 2. The XRD pattern of Huadian oil shale.

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Figure 3. The TG and DTG curves of oil shale, SLMS and the blended sample.

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Figure 4. The XRD pattern of SLMS ash.

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Figure 5.The FT-IR spectra of the oils produced from pyrolysis of raw materials and the blended sample.

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Figure 6. The GC–MS chromatograms of the oils produced from pyrolysis of (a) oil shale, (b) SLMS, (c) the blended sample.

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Figure 7. The peak area of organic phase in the oils produced from oil shale, SLMS and the blended sample.

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Figure 8. The tentative components of organic phase in the oil obtained by co-pyrolysis

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Tables: Table 1. The fundamental characteristics of Huadian oil shale and SLMSa. Oil shale

SLMS

Moisture

2.8±0.67

10.7±0.09

Volatiles

29.5±0.04

72.1±0.03

Fix carbon

2.4±0.36

8.1±0.41

Ash

65.3±0.02

9.1±0.19

C

30.23±0.07

40.96±0.38

H

4.37±0.23

4.93±0.08

N

0.52±0.04

1.15±0.13

O

64.88±1.28

52.96±0.01

Proximate analysisb

Ultimate analysisc

a

: obtained from the early work19, 20.

b

: air dry basis, wt.%

c

: dry basis,%

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Table 2. The average yields of pyrolysis products derived from oil shale and SLMS at different temperatures. 490℃

540℃

590℃

Oil

6.91 ±0.04

16.89±0.15

14.35±0.07

Gas

16.59±0.48

14.97±0.18

20.03±0.57

Water

0.50±0.01

1.66±0.02

0.49±0.01

Solid residue

76.00±0.53

66.48±0.03

65.13±0.64

Oil

10.68±0.07

11.56±0.49

9.26±0.03

Gas

34.57±1.61

26.87±0.74

40.36±0.07

Water

9.41±0.29

11.22±0.03

13.89±0.01

Solid residue

45.34±0.42

50.35±0.21

36.49±0.04

Yields from Oil shale (wt.%)

Yields from SLMS (wt.%)

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Table 3. The experimental and the calculated yields obtained by co-pyrolysis.

Temperature

Yield

(℃)

(wt.%)

490

Exp.

8.97±0.18

27.54±0.68

2.66±0.03

60.83±0.03

Cal.

8.80

25.58

4.95

60.67

Exp.

16.99±0.02

23.76±0.07

4.00±0.14

55.25±0.05

Cal.

14.23

20.92

6.43

58.42

Exp.

6.93±0.02

39.98±0.11

2.97±0.08

50.12±0.04

Cal.

11.81

30.20

7.18

50.81

540

590

Oil

Gas

Water

Solid residue

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Graphical abstract

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