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Two-Step Gasification of Cattle Manure for Hydrogen-Rich Gas Production: Effect of Gasification Temperature, Steam Flow Rate, and Catalysts
Chunbao Chen1, Dianlong Wang1, Ya Xin1,*, Hao Shi1, Qiaoxia Yuan2
Published in Journal of the ASABE 66(1): 107-114 (doi: 10.13031/ja.15241). Copyright 2023 American Society of Agricultural and Biological Engineers.
1Huaiyin Institute of Technology, Huaian, Jiangsu, China.
2Huazhong Agricultural University, Wuhan, Hubei, China.
*Correspondence: xinyf1205@126.com
The authors have paid for open access for this article. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License https://creative commons.org/licenses/by-nc-nd/4.0/
Submitted for review on 18 June 2022 as manuscript number ES 15241; approved for publication as a Research Article by Associate Editor Dr. Deepak Kumar and Community Editor Dr. Kasiviswanathan Muthukumarappan of the Energy Systems Community of ASABE on 7 December 2022.
Highlights
Abstract. This study investigated the hydrogen-rich gas production from cattle manure char by steam gasification. The characteristics of char were studied by proximate analysis, ultimate analysis, thermogravimetric analysis, and XRD analysis. The effects of temperature, heating mode, steam flow rate, and catalyst on syngas yield, hydrogen yield, gas composition, heating value, and carbon conversion efficiency were explored. The results showed that the fixed carbon content in cattle manure char was 34.46%, an increase of 2.24 times compared with that of cattle manure, and the cattle manure char had a high fixed carbon content and thermal stability. The steam gasification indicated that the high temperature and fast heating could obtain high syngas and hydrogen yields. The steam flow rate played an important role in the char and steam reforming reactions. The SiO2 and ash catalysts had an inhibitory effect on the steam gasification of char. However, the K2CO3 catalyst improved the syngas and hydrogen yields. The optimal parameters in this study were 850 °C, fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst. By comparison, the syngas and hydrogen production of char were better than those of biomass. As a result, the steam gasification of char was a promising method for producing hydrogen-rich gas.
Hydrogen is a clean, high-energy-density energy source that works well as a gasoline substitute (Tarhan and Çil, 2021). Additionally, it is mostly produced using fossil fuels like coal, oil, and natural gas. (Zhang et al., 2022). With the increasing environmental pollution caused by fossil fuels in recent years, biomass resources, such as cattle manure (Ashraf et al., 2021), wheat straw, microalgae, etc., have been widely considered. Biomass was a sustainable source of hydrogen production (Opia et al., 2021). They were abundant, widely distributed, and inexpensive (Saleem, 2022; Siddiki et al., 2022).
Using biomass to produce hydrogen can not only solve the environmental pollution problem caused by waste biomass but also alleviate energy demand problems. Biomass gasification was a highly efficient thermochemical process for hydrogen-rich syngas production (mainly H2, CO, CH4, and CO2), which was considered one of the most promising waste treatment practices (Vecten et al., 2021; Wang et al., 2022b). Steam gasification uses steam as a gasifying agent and can increase the heating value and hydrogen concentration of syngas. Generally, before gasification, feedstocks with high moisture content first undergo a drying process. Due to the high energy consumption of the drying process, the in-situ gasification of wet biomass was studied widely. To avoid the dual energy input for drying wet sewage sludge and steam generation, Huang et al. (2018) adopted the co-gasification of wet sewage sludge and torrefied biomass for hydrogen-rich syngas production, indicating that the mixing ratio of wet sewage sludge was between 30% and 55% for a high carbon conversion ratio and hydrogen yield. Adnan and Hossain (2019) integrated the drying and gasification processes of wet microalgal biomass and found that the char from chemical-looping combustion provided a positive effect on the syngas composition, particularly for the gasification of wet biomass. However, the in-situ gasification process was difficult due to the drying, pyrolysis, and gasification processes.
Therefore, two-step gasification was proposed to optimize the gasification process. In this process, the feedstocks were carbonized to obtain char, and the char was used for hydrogen production by steam gasification. The two-step gasification process can increase hydrogen production and reduce tar production. In previous research, the carbonization process in two-step gasification was focused on. Xin et al. (2018) investigated the char properties of cattle manure at various temperatures and moisture contents and discovered that the carbon content increased as temperature increased, and the moisture content can influence the activation energy of char. To well understand the effect of biomass char properties on gasification, Bouraoui et al. (2015) used scanning electron microscopy, nitrogen adsorption manometry, Raman spectroscopy, and X-ray fluorescence to determine the char properties. It was found that the char’s properties strongly affected the gasification behavior and could predict fuel reactivity in the gasification process for the gasifier’s design of char conversion. Xin et al. (2017) used the two-step gasification process and obtained 1.61 m3/kg of syngas production, 0.93 m3/kg of hydrogen yield, and 57.58% hydrogen concentration.
The catalysts can influence the reaction rate and hydrogen yield in the gasification process. Catalytic steam gasification was considered the most advanced method to produce hydrogen-rich gas. Many catalysts have been studied in the gasification process, including alkali metals (Müller, 2022). Kopyscinski et al. (2014) used K2CO3 to catalyze the CO2 gasification of ash-free coal and found that K2CO3 can reduce the reaction temperature of feedstock devolatilization. Yuan et al. (2019) also confirmed K2CO3 had a high catalytic activity for steam gasification.
However, the optimization of the parameters of char steam gasification was insufficiently studied. The effect of gasification temperature, steam flow rate, and catalyst on the steam gasification performance of char is necessary to explore in depth. In addition, the investigation of the effect of ash and SiO2 during the steam gasification of char was novel and limited. Thus, in this study, the hydrogen-rich gas production from cattle manure char by steam gasification was investigated. The characteristics of char were first studied by proximate analysis, ultimate analysis, thermogravimetric analysis, and XRD analysis. The effects of temperature, heating mode, steam flow rate, and catalyst on syngas yield, hydrogen yield, gas composition, heating value, and carbon conversion efficiency were explored to elucidate the cattle manure char’s gasification performance. This study can provide theoretical references for cattle manure disposal and the steam gasification of biochar to produce hydrogen.
Materials and Methods
Materials
The cattle manure was collected from the Dongzheng dairy farm in the Jiangxia District, Wuhan City, Hubei Province, PR China. The cattle manure samples were dried, crushed, and screened to 60 mesh-size particles. The cattle manure contained 24.05% of cellulose, 26.24% of hemicellulose, and 5.16% of lignin.
As previously studied (Xin et al., 2018), the carbonization process was performed in a laboratory-scale fixed bed reaction system (SLG1200-100, Shanghai, China). The fixed-bed system consisted of an electric furnace heater and a quartz tube reactor (1000 mm length and 90 mm inner diameter). The cattle manure char was prepared using cattle manure with a 75% moisture content and a carbonization temperature of 450 °C. The heating rate and carbonization time were 12 °C/min and 40 min, respectively. Then, the cattle manure char was ground to pass through a 100-mesh sieve and stored in airtight containers for further analysis and steam gasification experiments.
Three catalysts, including SiO2, cattle manure ash, and K2CO3, were used in steam gasification experiments. The SiO2 and K2CO3 (CAS Nos. 60676-86-0 and 584-08-7; Shanghai Macklin Biochemical Co., Shanghai, China) were analytical reagents. Cattle manure ash was obtained by ashing dry cattle manure in a muffle furnace at 550 °C for 2 hours.
Steam Gasification
Steam gasification experiments were also carried out in the fixed-bed reactor described above in the Materials Section. Upstream of the reactor was an N2 line and steam generator (Suzhou Richtreatment Environment Technologies Inc., Suzhou, China). Downstream of the reactor was a gas purification system. The generated gas was condensed by a ball condenser, washed with acetone, and dried on silica gel. The purified gas was sampled for further analysis.
In the steam gasification, the effects of heating mode (slow heating and fast heating), temperature (700 to 900 °C), steam flow rate (0 to 2.49 g/min), and catalysts (0.5 g SiO2, 0.5 g ash, 0.5 g K2CO3) on syngas and hydrogen yields were studied. The experimental conditions are summarized in table 1.
| Table 1. Summary of experimental conditions. | ||||
| No. | Mode | Temperature (°C) | Steam Flow Rate (g/min) | Catalyst |
| 1 | Slow heating | 700, 750, 800, 850, 900 | 1.66 | - |
| 2 | Fast heating | 700, 750, 800, 850, 900 | 1.66 | - |
| 3 | Fast heating | 850 | 0, 0.55, 0.83, 1.66, 2.49 | - |
| 4 | Fast heating | 850 | 1.66 | SiO2, ash, K2CO3 |
For each run, nitrogen was flowed to the reactor with a flow rate of 100 ml/min for 30 min to maintain an inert atmosphere, and then 5 g cattle manure char was placed onto the ceramic boat. The feedstock was gasified for 20 minutes under the corresponding conditions in table 1. The produced syngas was condensed using a ball condenser, cleaned with acetone, dried with silica gel, and analyzed by gas chromatography. To minimize the effect of random errors, each run was duplicated, and the average data was reported.
Analytical Methods
The volatile matter (VM) content of samples was determined with a thermal analyzer (SDT Q600, TA Instruments, New Castle, USA). Ash content (AC) was measured using the Laboratory Analytical Procedure (LAP) developed by the National Renewable Energy Laboratory (NREL) (Sluiter et al., 2008). The fixed carbon (FC) content of the test samples was calculated by taking the difference. The elemental compositions (C, H, N, and O) of samples were determined by an elemental analyzer (V Vario Micro Cube CHNS Analyzer, Elementar, Shanghai, China). The O content was calculated using the difference method. Thermogravimetric (TG) and differential thermal gravimetric (DTG) analysis of the samples were both performed by a simultaneous thermal analyzer (TA SDT Q600) under atmospheric pressure. Samples were heated in the TA apparatus from ambient temperature to 1000 °C at a constant heating rate (10 °C/min). To maintain an inert atmosphere and purge the volatiles generated by sample pyrolysis, the carrier gas was ultrahigh purity nitrogen (99.99%) supplied at a constant flow rate of 100 ml/min. The X-ray diffraction (XRD) analysis was conducted using Bruker D8 Advance X-ray diffraction (Bruker, Germany). Scans for cattle manure and manure chars were collected from 10 – 50° (2? scale) using Cu Ka radiation (40 kV, 40 mA) with a scanning speed of 10°/min. The main gas composition (H2, CO, CO2, CH4) was detected by gas chromatography on the GC9790II (FULI, Zhejiang, China) equipped with a thermal conductivity detector, a 1.5 m stainless steel packed column with a 5A molecular sieve, and a Hayesep Q packed column. The temperatures of the injector, detector, and oven were maintained at 55 °C, 100 °C, and 50 °C, respectively. Argon was used as the carrier gas.
The lower heating value (LHVg) of syngas is calculated using equation 1 (Gai et al., 2016), where H2, CO, and CH4 are the molar percent of components of the product gas, respectively, and the coefficient multiplying each component represents the corresponding LHV of each gas, MJ/m3.
(1)
Gas yield (Gp) and hydrogen yield (Hp) mean the volume of gas and hydrogen produced per kilogram of the dry biomass, respectively (Gai et al., 2016), which are calculated as equations 2 and 3:
(2)
(3)
where
Vg = total volume of the produced gas in N2 free basis, (Nm3)
Mc = mass of the dry cattle manure char (kg)
Vh = total volume of the produced hydrogen gas in N2 free basis (Nm3).
The carbon conversion efficiency (Xc) was calculated by equation 4:
(4)
where
Gp = volume of product gas per kilogram (m3/kg)
CO, CO2 and CH4 = the molar percent of components of the product gas, respectively
C = mole content of carbon in cattle manure char.
Energy density (ED) is defined by the ratio of energy evolved in the product gas to energy in the cattle manure char. It was calculated by equation 5 (Chiang et al., 2016):
( 5)
where
Vg is the total volume of the produced gas in N2 free basis (Nm3)
Mc is the mass of the dry cattle manure char (kg).
Weight loss rate (WL) was the percentage of conversion mass to the mass of dry raw material, which is determined by equation 6:
( 6)
where
Mc = mass of the dry cattle manure char (kg)
Mend = mass of solid residue after gasification (kg).
Results and Discussion
Properties of Cattle Manure Char
Proximate and Ultimate Analysis
The cattle manure char yield was 39.6% in the carbonization process. The characteristics of cattle manure char were shown in table 2. The fixed carbon content in cattle manure char was 34.46%, an increase of 2.24 times compared with that of cattle manure. The ash content in cattle manure char was also observed to increase after carbonization. The volatile matters content of cattle manure char was 22.57%, which was 67.53% lower than that of cattle manure. This is consistent with previous research (Xin et al., 2017). The ultimate analysis showed that the C content in cattle manure char was higher than that of cattle manure, while the H and O contents were lower than those of cattle manure. This is a typical phenomenon in carbonization, in which cattle manure loses the -OH functional group of surfaces due to dehydration. And, the C-bound O and H atoms are also lost due to structural core degradation. The deoxygenating process can improve the upgrading of biofuel quality (Xin et al., 2018).
TG and DTG Analysis
To study the pyrolytic behavior and thermal stability of cattle manure and cattle manure char, figure 1 presents the TG and DTG curves of cattle manure and cattle manure char. For cattle manure, the maximum weight loss occurred at 200 to 550 °C due to the degradation of basic organic components such as extractive, hemicellulose, cellulose, and lignin (Chen et al., 2022). As for cattle manure char, it was observed in the DTG curve that the peak at 500 °C referred to the decomposition of lignin remaining in the carbonization process. It was known that the peak of lignin was at 420 °C. Because the lignin content was very low in cattle manure char, the peak of lignin around 500 °C was low and delayed. This indicated that cattle manure char had high thermal stability. This is consistent with previous research (Xin et al., 2018). The peak at 650 °C suggested the decomposition of mineral elements (Wang et al., 2022a). From the TG curves of cattle manure char, it was shown that the cattle manure char started to decompose slowly at around 200 °C. This also indicated that the cattle manure char was relatively stable.
| Table 2. Summary of experimental conditions.[a] | ||||||||
| Samples | VM (%) | FC (%) | AC (%) | C (%) | H (%) | O (%) | N (%) | S (%) |
| Cattle manure | 69.51 | 15.12 | 15.37 | 42.38 | 5.90 | 48.76 | 2.51 | 0.45 |
| Cattle manure char | 22.57 | 34.46 | 42.97 | 46.88 | 2.67 | 47.56 | 2.57 | 0.32 |
[a]Proximate analysis was based on dry basis, and ultimate analysis was based on dry and ash-free basis. | ||||||||
XRD Analysis
The XRD analysis of the cattle manure char demonstrated the presence of mineral crystals (fig. 2). Peaks at 21° and 26° refer to the quartz (SiO2) in cattle manure char. The intensity of the peak at 21° was weak. The sharp peak at 26° indicated that the quartz was well crystallized. Peaks at 28° and 41° were attributed to the presence of sylvite (KCl). The peak at 29° suggested the formation of calcite (CaCO3). The carbonization temperature had an important effect on the formation of CaCO3. The peak at 31° suggested the presence of dolomite, CaMg(CO3)2. The dolomite can be composed when the temperature is increased. The existence of these mineral crystals had a positive effect on the steam gasification performance of cattle manure char.
 |
| Figure 1. TG and DTG curves of cattle manure and cattle manure char. |
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| Figure 2. XRD analysis of cattle manure and cattle manure char. |
Steam Gasification of Cattle manure Char
Effect of Temperature and Heating Mode
The effects of temperature and heating mode on the gas yield and composition were investigated from 700 °C to 900 °C (fig. 3), and the steam flow rate was kept constant at 1.66 g/min. The syngas yield and hydrogen yield increased with increasing temperature for slow heating. This was because high temperatures contributed to the reaction between steam and biochar (Anniwaer et al., 2021). The syngas yields for 850 °C and 900 °C were 1.75 m3/kg and 1.83 m3/kg, respectively, and the corresponding hydrogen yields were 1.02 m3/kg and 1.10 m3/kg, respectively. As for the fast heating (fig. 3c), the trendency was similar when the temperature varied from 700 °C to 900 °C. It was important that the syngas and hydrogen yields of fast heating were higher than those of slow heating. This was due to the adequate reforming reaction of steam and volatiles from char in fast heating. As for slow heating, some volatiles were discharged from the reactor and did not react with steam at the low temperature. The hydrogen yields at 850 °C and 900 °C were 1.10 m3/kg and 1.16 m3/kg, respectively. Therefore, taking energy consumption into consideration, 850 °C and fast heating were suitable conditions for the steam gasification of biochar.
For the gas compositions of slowing heating (fig. 3b), with increasing temperature, the H2 and CO concentrations increased, and the CO2 and CH4 concentrations decreased gradually. This indicated that high temperatures can improve the gasification reaction rate. At fast heating mode (fig. 3d), the H2 concentration reached a maximum (61.5%) at 750 °C, which was consistent with the previous study (Sattar et al., 2014). This was probably because the reverse reaction rate of the water-gas shift (WGS) reaction was faster than the forward reaction rate. The changes in CO, CO2, and CH4 concentrations at fast heating were consistent with those at slow heating. More importantly, the CO concentration for fast heating was high, while the CO2 concentration was low compared with that of slow heating. High CO concentrations can increase the heating value of syngas. Thus, the high temperature and fast heating can improve the syngas yield and gas compositions.
Effect of Steam Flow Rate
The effect of steam flow rates (0, 0.55, 0.83, 1.66, and 2.49 g/min) on gas yields and compositions was studied at 850 °C with fast heating. For the syngas and hydrogen yields (fig. 4a), 1.66 g/min of steam flow rate obtained the highest syngas and hydrogen yields, 1.87 m3/kg and 1.11 m3/kg, respectively. The gas composition analysis revealed that as the steam flow rate increased, CO and CH4 concentrations decreased while H2 and CO2 concentrations increased. This indicated that a high steam flow rate was beneficial to the steam reforming of condensable hydrocarbons (CH4). The main reactions in this process were as follows: CO + H2O = CO2 + H2, CH4 + H2O = 3H2 + CO, and C + H2O = CO + H2. The steam flow rate can mainly affect the water-gas shift reaction. Moreover, the optimal steam flow rate was also affected by reactor scale, biochar characteristics, temperature, and heating mode. In this study, the 1.66 g/min steam flow rate was a suitable steam gasification condition.
  |
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| Figure 3. Effect of temperature on gas yield and compositions ((a) and (b): slow heating; (c) and (d): fast heating). |
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| Figure 4. Effect of steam flow rate on gas yield and compositions. |
Effect of Catalysts
Catalysts can influence product distribution and gas composition. Cattle manure was a biomass resource with high ash content, and the main composition of ash was SiO2. The ash and its main composition may play a role in gasification performance. Therefore, the effect of SiO2 and ash on cattle manure char gasification performance was studied. In figure 5a, the SiO2 and ash had a negative effect on syngas and hydrogen yields. Compared with the control, the syngas yields of the experimental groups with SiO2 and ash were reduced by 14.56% and 8.72%, respectively. This demonstrated that SiO2 cannot catalyze and promote syngas production and instead has a clear inhibitory effect. Studies also showed cattle manure ash inhibited the steam reforming of hydrocarbons and promoted the bio-oil yield (Fürsatz et al., 2021; Yu et al., 2022). However, K2CO3 as a catalyst can obviously increase the syngas yield and hydrogen yield. The hydrogen yield was achieved at 1.15 m3/kg. This was because K2CO3 can catalyze the following reactions (Yuan et al., 2019): K2CO3 + 2C = 2K + 3CO, CH4 + H2O = 3H2 + CO, and C + H2O = CO + H2. Therefore, compared with the SiO2 and ash groups, the CO and H2 concentrations in the K2CO3 group were high, and the CO2 and CH4 concentrations were low (fig. 5b). The hydrogen concentration in the K2CO3 group reached 59.6%.
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| Figure 5. Effect of catalysts on gas yield and compositions. |
Comparison of Steam Gasification Performance of Cattle Manure and Char
The temperature, heating mode, steam flow rate, and catalysts on Gp, LHVg, WL, Xc, and ED were shown in table 3. For the Gp, high temperatures and fast heating can obtain a high gas yield. This resulted from the decomposition and steam reforming of cattle manure char. The appropriate steam flow rate was 1.66 g/min. And the K2CO3 catalyst had a positive effect on gas production. The gas yield for cattle manure char in this study was close to the results of gasification of other biomass reported in the literature under similar operating conditions (Song et al., 2022). The highest gas yield in this study was 1.97 m3/kg, obtained at 900 °C, 1.66 g/min steam flow rate and fast heating. By adding the K2CO3 catalyst, the gas yield at 850 °C was 1.92 m3/kg, which was slightly lower than that at 900 °C. Therefore, the optimal parameters can be selected based on economic benefits. The LHVg of syngas results showed that the LHVg of syngas in fast heating at 700 °C to 900 °C was 8.79 MJ/m3 to 9.41 MJ/m3, higher than that in slow heating mode. This was probably due to the high CH4 and CO concentrations under fast heating mode. The LHVg decreased as the steam flow rate increased. This was because the gas-shift reaction in the water and the steam reforming of hydrocarbons decreased the CH4 and CO concentrations.
The rate of weight loss increased as the temperature rose. The high temperature and suitable steam flow rate (1.66 g/min) can promote the thermal decomposition of cattle manure char. Catalysts can also catalyze the steam gasification of char, resulting in an increase in the weight loss rate. C-conversion efficiency (Xc) increased with the increase of temperature in both heating modes, and the C-conversion efficiency in fast heating mode was higher than that in slow heating mode. This indicated that high temperatures and fast heating can improve char's decomposition and conversion efficiency. In addition, the steam flow rate had an important effect on the C-conversion efficiency. The 1.66 g/min of steam flow rate achieved 86.97% C-conversion efficiency. When using the K2CO3 catalyst, the C-conversion efficiency was the highest, at 88.74%. The energy density (ED) change in trend was also very obvious. Energy density was related to gas yield, showing similar trendency. Therefore, from Gp, LHVg, WL, Xc, and ED, the optimal parameters were 850 °C, fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst.
Furthermore, the performance of gasification has been compared in recent studies. The feedstocks, temperatures, and gasifying agents were shown in table 4. It was found that the steam gasification of char can obtain high syngas production, hydrogen production, and hydrogen concentration. Therefore, two-step gasification was a promising method for producing hydrogen-rich gas.
Conclusions
This study investigated the effects of temperature, heating mode, steam flow rate, and catalyst on the steam gasification performance of cattle manure char. It was demonstrated that high temperatures and fast heating can obtain high syngas and hydrogen yields. And the steam flow rate played an important role in the char and steam reforming reactions. The SiO2 and ash catalysts had an inhibitory effect on the steam gasification of char, while the K2CO3 catalyst enhanced the syngas and hydrogen yields. The optimal parameters in this study were 850 °C, fast heating mode, 1.66 g/min of steam flow rate, and K2CO3 catalyst. Under this parameter, the syngas yield, hydrogen yield, and hydrogen concentration were 1.92 m3/kg, 1.15 m3/kg, and 59.6%, respectively. The corresponding heating value and carbon conversion efficiencies were 8.84 MJ/m3 and 88.74%, respectively. Therefore, cattle manure char is a suitable feedstock for hydrogen production by steam gasification.
| Table 3. Steam gasification performance of cattle manure char under different conditions. | ||||||||||||||
| Mode | Temperature (°C) | Steam Flow Rate (g/min) | Catalyst | Gp (m3/kg) | LHVg (MJ/m3) | WL (%) | Xc (%) | ED | ||||||
| Slow heating | 700 | 1.66 | - | 0.48 | 8.73 | 27.20 | 24.10 | 0.29 | ||||||
| 750 | 0.77 | 8.42 | 30.80 | 38.02 | 0.45 | |||||||||
| 800 | 1.40 | 8.58 | 49.80 | 68.52 | 0.83 | |||||||||
| 850 | 1.75 | 8.49 | 57.80 | 83.30 | 1.03 | |||||||||
| 900 | 1.83 | 8.92 | 59.60 | 82.89 | 1.13 | |||||||||
| Fast heating | 700 | 1.66 | - | 0.59 | 8.92 | 29.20 | 29.18 | 0.36 | ||||||
| 750 | 0.89 | 9.10 | 31.20 | 39.12 | 0.56 | |||||||||
| 800 | 1.37 | 8.79 | 44.20 | 61.84 | 0.83 | |||||||||
| 850 | 1.87 | 8.98 | 52.00 | 86.97 | 1.15 | |||||||||
| 900 | 1.97 | 9.41 | 64.00 | 92.03 | 1.28 | |||||||||
| Fast heating | 850 | 0 | - | 0.33 | 11.35 | 24.40 | 20.06 | 0.26 | ||||||
| 0.55 | 1.52 | 9.21 | 48.40 | 73.29 | 0.96 | |||||||||
| 0.83 | 1.50 | 9.50 | 48.40 | 73.02 | 0.98 | |||||||||
| 1.66 | 1.87 | 8.98 | 52.00 | 86.97 | 1.15 | |||||||||
| 2.49 | 1.80 | 9.00 | 53.20 | 81.18 | 1.12 | |||||||||
| Fast heating | 850 | 1.66 | - | 1.87 | 8.98 | 52.00 | 86.97 | 1.15 | ||||||
| SiO2 | 1.60 | 8.98 | 56.00 | 75.78 | 0.99 | |||||||||
| Ash | 1.70 | 8.96 | 56.00 | 80.40 | 1.05 | |||||||||
| K2CO3 | 1.92 | 8.84 | 58.20 | 88.74 | 1.17 | |||||||||
Table 4. Comparison of syngas and hydrogen productions in different studies. | ||||||||||||||
| Feedstocks | Temperature (°C) | Gasifying Agents | Syngas Production (m3/kg) | Hydrogen Production (m3/kg) | Hydrogen Concentration (%) | Reference | ||||||||
| Yak manure | 800 | Steam | 0.72 | 0.40 | 55.0 | (Fu et al., 2022) | ||||||||
| Raw cedarwood Biochar | 850 | Steam | 1.92 6.22 | 1.25 3.90 | 65.0 62.7 | (Anniwaer et al., 2021) | ||||||||
| Hydrothermally carbonized cow manure | 850 | Air CO2 | 2.50 1.90 | 0.95 0.57 | 38.0 30.0 | (Saha et al., 2019) | ||||||||
| RDF-landfill Biomass Biochar | 800 | Steam | 0.42 1.18 1.71 | 0.16 0.57 0.97 | 38.0 48.2 56.6 | (Zaini et al., 2020) | ||||||||
| Cattle manure char | 850 | Steam | 1.92 | 1.15 | 59.6 | This study | ||||||||
Acknowledgments
This research was financially supported by the Natural Science Foundation of Jiangsu Province (Grant No. BK20191053), the Special Fund for Agro-scientific Research in the Public Interest (201303091), and the Natural Science Foundation of Jiangsu Province (Grant No. BK20191054). The authors gratefully acknowledge their support.
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