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Investigation of the synergistic mechanism during biomass and coal gangue co-gasification
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Yonghong NIU1, 2, 3, *, Qing SHAO1, Hao LI2, 4, Zaiwei ZHANG3
Journal of Fuel Chemistry and Technology | 2026, 54(5) : 20250216-941 - 20250216-950
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Journal of Fuel Chemistry and Technology | 2026, 54(5): 20250216-941-20250216-950
• RESEARCH PAPER •
Investigation of the synergistic mechanism during biomass and coal gangue co-gasification
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Yonghong NIU1, 2, 3, *, Qing SHAO1, Hao LI2, 4, Zaiwei ZHANG3
Affiliations
  • 1School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China
  • 2School of Mining and Coal, Inner Mongolia University of Science and Technology, Baotou 014010, China
  • 3Qiao Dongfang Biofuel Group Co., Ltd., Baotou 014060, China
  • 4Engineering Training Center of Inner Mongolia University of Science and Technology, Baotou 014010, China
Published: 2026-05-10 doi: 10.1016/S1872-5813(26)60637-8
Outline
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Biomass is considered as a sustainable green coal alternative, and its thermochemical conversion—particularly hydrogen-rich gasification technology—represents an effective pathway for achieving high-value utilization. Co-gasification of biomass with coal gangue enables synergistic utilization of carbon resources, offering significant potential for emission reduction and efficiency enhancement. To elucidate how typical biomass components govern the gasification process, three feedstocks with distinct, dominant characteristics were selected: pine stick (high cellulose content, representing highly reactive volatiles), soybean straw (high nitrogen, exemplifying feedstock prone to nitrogenous tar formation), and corn stover (high ash with abundant K+, reflecting catalytically active inorganics). Under fixed conditions (850 °C, steam flow rate of 2 mL/min, N2 flow rate of 75 mL/min), their co-gasification with coal gangue was investigated. Results indicated that the compositional differences led to distinct synergistic patterns and product distributions. All systems achieved the highest hydrogen yield in the syngas at a 5∶5 raw material mass ratio. The high-cellulose pine stick system yielded the most H2 (9.06 mmol/g) and H2+CO yield (15.25 mmol/g), exhibiting a “three high, three low” advantage due to efficient volatile reforming. In contrast, the high-ash/K+ corn stover system showed the strongest synergy for CO (SI = 1.22, where the Synergy Index (SI) > 0 indicates a synergistic promoting effect), promoted by the catalytic Boudouard reaction. The high-nitrogen soybean straw system, while achieving an optimal H2/CO ratio (2.00), suffered from suppressed syngas yield due to the inhibitory effect of nitrogenous tars. This study confirms that biomass composition-specifically cellulose, ash/K+, and nitrogen content-differentially regulates syngas production and synergy by steering dominant reaction pathways, providing a theoretical basis for the targeted conversion of waste resources.

biomass  /  coal gangue  /  co-gasification  /  synergistic effect  /  synthesis gas
牛永红, 邵晴, 李浩, 张在维. 生物质与煤矸石共气化及协同机制研究. 燃料化学学报（中英文）, 2026 , 54 (5) : 20250216-941 -20250216-950 . DOI: 10.1016/S1872-5813(26)60637-8
Yonghong NIU, Qing SHAO, Hao LI, Zaiwei ZHANG. Investigation of the synergistic mechanism during biomass and coal gangue co-gasification[J]. Journal of Fuel Chemistry and Technology, 2026 , 54 (5) : 20250216-941 -20250216-950 . DOI: 10.1016/S1872-5813(26)60637-8
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In the context of China’s “dual carbon” strategic goals, the development of clean and renewable energy technologies has become imperative. Biomass, as the sole renewable carbon resource capable of being converted into gaseous, liquid and solid fuels[1], holds significant potential. The Blue Book released by the Bioenergy Industry Branch of the China Industrial Promotion Association shows that China’s main biomass resources have an annual output of about 34.94 billion tons, and the amount of biomass resources used for energy is about 46.1 million tons[2], however, the utilization rate remains below 20%, indicating substantial room for improvement. At the same time, the coal industry generates massive amounts of solid waste, with coal gangue (CG) being a prominent example. Its annual emission exceeds 700 million tons, leading to a cumulative stockpile of over 4.5 billion tons, posing severe environmental challenges[3−4]. The co-gasification of biomass and coal gangue presents a promising pathway for the synergistic and high-value utilization of these two solid carbon-containing resources, enabling the simultaneous reduction of waste and production of clean energy.
The physicochemical properties of the feedstocks have a profound influence on the distribution and quality of gasification products. Existing research has demonstrated that key biomass characteristics, such as cellulose/lignin content, ash composition, and nitrogen contentare critical factors affecting gas yield and composition[5−6]. For instance, Zhang et al.[7] reported a significant synergy during the co-gasification of low-ash coal and potassium-rich biomass, attributing to the catalytic effects of alkali metals. Gong et al.[8] found that the high volatile of soybean straw provided reactive intermediates during co-gasification, enhancing carbon conversion and syngas yield. Furthermore, Li et al.[9] observed that both corn stover and soybean straw significantly promoted the gasification reactivity of biochar. Our previous work[10] also revealed that alkali and alkaline earth metals (AAEMs) in pine wood can catalyze the gasification of CG, while the high-temperature environment sustained by the gasification of fixed carbon in CG facilitates the cracking of biomass-derived tars, creating a mutual synergistic enhancement. Despite these valuable insights, systematic comparative studies on the co-gasification of coal gangue with biomass feedstocks possessing distinctly different representative components remain scarce. The specific regulatory roles and synergistic mechanisms of biomass components—such as the catalytic effects of cellulose-derived volatile, the inhibiting influence of nitrogen-containing compounds, and the dual role of ash (as both a catalyst and an inhibitor)—are not yet fully understood. In particular, a comparative analysis of how these distinct biomass types regulate syngas composition and hydrogen production efficiency within the same co-gasification system is lacking.
To address this research gap, this study strategically selected three representative biomass: pine wood (characterized by high cellulose content), soybean straw (characterized by high nitrogen content), and corn stover (characterized by high ash content). The objective is to systematically investigate their co-gasification with coal gangue, focusing on the differences in syngas yield, hydrogen selectivity, and synergistic effects. This work aims to elucidate the underlying regulatory mechanisms governed by biomass characteristics, thereby providing a theoretical foundation for the targeted and efficient conversion of waste resources.
1　Materials and methods
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1.1　Raw materials
Experimental raw materials pine stick (labeled as PS) was sourced from Baotou City, Inner Mongolia; Soybean straw (SS) and corn stover (CS) were sourced from Songyuan City, Jilin Province; CG was obtained from Taiyuan City, Shanxi Province. All samples were crushed using a jaw crusher, and screened through a 200 mesh sieve. Tables 1 and 2 present the ultimate analysis, proximate analysis, and compositional analysis of each experimental feedstock, respectively.
1.2　Gasification process
As shown in Figure 1, the gasification experiment employed a custom-built two-stage fixed-bed reactor. The reactor was heated from room temperature to the target temperature of 850 °C at a heating rate of 25 °C/min and maintained at this temperature for the duration of the experiment. The experiment employed high-purity N2 as the carrier gas at a flow rate of 75 mL/min. Deionized water was injected using a syringe pump at a flow rate of 2 mL/min, vaporized in a pre-heating zone, and served as the gasifying agent.
Before each experiment, the airtightness of the experimental apparatus was verified by pressurizing the system with N2 and monitoring for pressure drop. The biomass and coal gangue were thoroughly mixed at predetermined mass ratios of 10∶0, 7∶3, 5∶5, 3∶7 and 0∶10. For each run, a total mass of 5.0 g of the mixture was accurately weighed and loaded into a quartz boat. The quartz boat was then rapidly inserted into the constant-temperature zone of the reactor once the target temperature was stable. Rapid devolatilization of the feedstock occurred, producing volatile matter and syngas. The gaseous products passed through a series of condensers and a gas scrubber filled with color-changing silica gel to remove condensable tars and moisture. The resulting non-condensable dry gases were collected in a gas sampling bag over a period of 10 min for subsequent composition analysis.
1.3　Data analysis
Gaseous products were analyzed using an Agilent 8890B gas chromatograph (GC) equipped with TCD and FID detectors for H2, CO, CO2, N2 and hydrocarbons. Experimental analysis of biomass-coal gangue co-gasification primarily includes syngas yield (Ysyngas), syngas ratio (H2/CO), higher heating value (HHV), carbon conversion efficiency (CCE) and synergy index (SI). Calculation formulas are as follows[11]:
$ {Y}_{{\mathrm{syngas}}}=\left(1-{C}_{{{{\mathrm{N}}}_{2}}}\right)\times {V}_{{{{\mathrm{N}}}_{2}}}\times t/\left({C}_{{{{\mathrm{N}}}_{2}}}\times m\right)\times {10}^{-3} $
In equation (1), Ysyngas denotes the synthesis gas yield in m3/kg; $C_{{\mathrm{N}}_2} $ represents the volume fraction of N2 in the gas bag in %; $V_{{\mathrm{N}}_2} $ denotes the N2 flow rate at 75 mL/min; t indicates the gas collection time at 10 min; m represents the mass of raw material used per experiment at 5.0 g.
$ {{\mathrm{H}}}_{2}/{\mathrm{CO}}={C}_{{{{\mathrm{H}}}_{2}}}/{C}_{{\mathrm{CO}}} $
In equation (2), H2/CO denotes the synthesis gas ratio, and Ci represents the volume fraction of gas i, expressed in %.
$ \begin{split} {\mathrm{HHV}}=&12.63\times {C}_{{\mathrm{CO}}}+12.75\times {C}_{{{{\mathrm{H}}}_{2}}}+39.82\times {C}_{{{{\mathrm{CH}}}_{4}}}+\\& 80\times {C}_{{{{\mathrm{C}}}_{n}}{{{\mathrm{H}}}_{m}}}\end{split} $
In equation (3), HHV denotes the higher heating value of the gas, expressed in MJ/m3. Since the concentration of CnHm is relatively low, the calorific value of a typical hydrocarbon (ethane or propane) is used as an approximate value (80 MJ/m3).
$ \mathrm{CCE}=\frac{\left(Y_{\mathrm{CO}}+Y_{\mathrm{CO}_2}+Y_{\mathrm{CH}_4}+Y_{\mathrm{C}_n\mathrm{H}_m}\right)\times10^{-3}\times12}{C} $
In equation (4), CCE denotes carbon conversion rate, expressed in percent; Yi denotes the yield of gas i, expressed in mmol/g.
$ {X}_{{\mathrm{Calculated}}}=\left(1-\alpha \right){X}_{{\mathrm{CG}}}+\alpha {X}_{i} $
$ {\mathrm{SI}}=\frac{{X}_{{\mathrm{Experimental}}}-{X}_{{\mathrm{Calculated}}}}{{X}_{{\mathrm{Calculated}}}} $
In equations (5) and (6), XCalculated denotes the theoretical gas yield during co-gasification, XExperimental represents the actual gas yield from co-gasification, α is the biomass mass fraction in the CG-biomass mixture expressed as a percentage, while XCG and Xi denote the gas yields from gangue and biomass gasification, respectively. SI denotes the synergistic effect index for the co-gasification of CG and biomass. SI > 0 indicates that co-gasification promotes the production of the gas, while SI < 0 indicates that it inhibits the gas production. A larger absolute value of SI signifies a stronger influence.
2　Results and discussion
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Under the established reaction conditions, this study systematically conducted co-gasification experiments of three typical biomass types (PS, SS and CS) with CG at different blending ratios, and conducted an in-depth analysis of their synergistic reaction mechanisms.
2.1　Co-gasification of PS and CG
PS is rich in cellulose and rapidly releases hydrogen-rich volatiles within the low-temperature pyrolysis range (300–500 °C)[12], supplying reactive oxygen species to CG. The fixed carbon in CG undergoes steam reforming with pine volatile under high-temperature steam conditions[13]. Concurrently, mineral components such as Fe, K and Ca in CG catalyze tar reforming[12], significantly reducing coke formation and enhancing overall syngas yield[14]. Figures 2 and 3 illustrate the composition and yield variations of gaseous components in the co-gasification products of PS and CG as a function of their mass ratio. The high oxygen content in PS consumes potential hydrogen sources, forming H2O. Its high volatile matter requires substantial steam for reforming to effectively convert into H2, hence the H2 volume fraction decreases with increasing PS proportion. However, the H2 yield exhibits a non-monotonic trend, first increasing then decreasing, and reaching a maximum at the mass ratio of 5∶5. Both the CO volume fraction and yield significantly increase with rising PS proportion, rising from 12% to 34% and from 0.41 to 7.22 mmol/g, respectively. This phenomenon stems from the suppression of the water-gas shift reaction within the co-gasification system[15]. CO2 yield reached its lowest point at a mass ratio of 5∶5, where synergistic effects effectively reduced carbon loss. This outcome stems from the catalytic effect of minerals in CG on tar cracking[16] and the promoting effect of PS volatiles on coal gasification[17].
Experimental results indicate that the total syngas yield from CG gasification was 2.16 mmol/g, with a hydrogen yield of 1.75 mmol/g. When PS was gasified alone, the H2+CO yield reached 13.18 mmol/g, with a hydrogen yield of 5.96 mmol/g. Notably, when PS and CG were co-gasified at a 5∶5 mass ratio, the total syngas yield reached a maximum of 15.25 mmol/g, with the H2 yield significantly increased to 9.06 mmol/g. Compared to single CG gasification, the co-gasification system achieved a 593% increase in total syngas yield and a 417% increase in H2 yield. Compared to PS gasification alone, the co-gasification system increased the total syngas yield by 15% and the H2 yield by 52%. This series of data clearly demonstrates that the co-gasification process of PS and CG produces a significant synergistic effect on both H2 and total syngas yields.
Figure 4 shows various gasification performance parameters for co-gasification of PS and CG at different mass ratios, including gas yield, syngas ratio, gross calorific value, and carbon conversion rate. Experimental results indicate: As the PS proportion increases, the Ysyngas initially increases and then decreases, peaking at 0.54 m3/kg at a PS:CG mass ratio of 7:3, CO volume fraction significantly improves, and syngas ratio demonstrates a monotonically decreasing characteristic, the value decreased from 4.31 to 0.83. The gross calorific value peaks of 9.24 MJ/m3 at a mass ratio of 3∶7, attributable to the synergistic effect between the carbon-rich matrix provided by the high proportion of CG and the active volatile matter introduced by PS. This synergistic effect promotes increased CO production and elevates the overall volume fraction of combustible gases. At this ratio, the H2/CO yield was only 9.65 mmol/g, significantly lower than the peak yield of 15.25 mmol/g at the 5∶5 mixture ratio (Figure 3), indicating a non-synchronous optimization phenomenon between HHV and yield. Carbon conversion rate data further revealed the synergistic mechanism: pure pine gasification (PS:CG=0:10), lacking mineral catalysis, underwent tar polymerization reactions forming carbon deposits, resulting in a low CCE of 6.66%; In contrast, within the 5∶5 co-gasification system, minerals in CG effectively catalyze tar cracking, while PS volatile promote the pore development in coal coke. This synergistic interaction drives efficient conversion of carbon elements into gaseous products[18], the CCE was maximally increased to 43.92%, significantly enhancing the carbon conversion in syngas.
As shown in Figure 5, the co-gasification of PS and CG produces positive synergistic effects on all gases, with the most pronounced effect observed for hydrogen. The synergistic effect indices for H2 and CO both peaked at 1.75 and 0.91, respectively, when the mass ratio of PS to CG was 5∶5. This aligns with the earlier conclusion that the total syngas yield reached its maximum at this ratio. At a mass ratio of 3∶7 for PS and CG, the CnHm synergistic index was only 0.2. The co-gasification of PS and CG promoted the cracking of tar[19], effectively suppressing CnHm production and converting it into syngas. In summary, the optimal feedstock ratio for producing syngas via the co-gasification of PS and CG is 5∶5.
2.2　Co-gasification of SS and CG
Figures 6 and 7, respectively, reveal the influence patterns of different mass ratios of SS and CG on the volume fractions and yields of co-gasification products. Experimental results indicate that as the SS proportion increases, the H2 volume fraction exhibits a non-monotonic change pattern of first rising, then decreasing. The volume fractions of CO and CH4 show an overall downward trend. Key product yield peaks exhibit distinct distributions: the H2 yield peak (8.66 mmol/g) occurs at a mass ratio of 5∶5, while the yield peaks for CO, CO2 and CH4 simultaneously appear at a mass ratio of 7∶3. The simultaneous peak in multi-component yields at the 7∶3 ratio is attributed to the dual effect triggered by excess oxygen introduced at high SS ratios. This promotes gasification oxidation reactions, enhancing CO and CO2 production, while increasing hydrogen consumption in the methanation reaction (CO + 3H2 → CH4 + H2O), thereby indirectly inhibiting H2 accumulation[18].
Experimental results indicate: The syngas yield from CG gasification alone is 2.16 mmol/g, with H2 yield at 1.75 mmol/g. The syngas yield from SS gasification alone is 8.69 mmol/g, with H2 yield at 4.99 mmol/g. When SS and CG were co-gasified at a 5∶5 mass ratio, the total syngas yield significantly increased to 12.99 mmol/g, with an H2 yield of 8.66 mmol/g. Compared to single CG gasification, the co-gasification system achieved a 490% increase in total syngas yield and a 394% increase in H2 yield. Compared to pure SS gasification, the total syngas yield increased by 49% and the H2 yield increased by 73%. These results confirm that co-gasification of SS and CG exhibits a significant synergistic enhancement effect on both syngas and H2 yields.
Figure 8 presents the comprehensive performance parameters of co-gasification with varying mass ratios of SS and CG, including syngas yield, syngas ratio, gross calorific value, and carbon conversion rate. Experimental results indicate that as the SS proportion increases, the CO volume fraction continuously rises, while the Ysyngas first increases and then decreases, rising from 0.35 m3/kg for SS alone and 0.08 m3/kg for CG alone to 0.49 m3/kg at a 5∶5 mass ratio and peaking at 0.54 m3/kg at a 7∶3 ratio. The oxygen-enriched characteristics of biomass promote oxidation reactions, leading to a monotonically decreasing H2/CO ratio (with CO increasing at a higher rate than H2)，the H2/CO ratio decreased from 4.31 to 1.55, which is primarily due to the high fixed carbon content in CG promoting the occurrence of the Boudouard and water-gas reactions, while the high ash content in SS leads to deterioration of the mass transfer process.
HHV peaked at 8.51 MJ/m3 at a 3∶7 mass ratio，this indicates that at this SS∶CG ratio, the mixed utilization efficiency of the two feedstocks is the highest, and the synergistic promoting effect is the strongest at this point. The carbon-rich matrix of CG synergistically enhanced combustible gas concentration with SS volatiles, though H2+CO yield reached only 8.93 mmol/g at this ratio. The CCE peaked at the 7∶3 ratio. However, the high-oxygen environment promoted the Boudouard reaction[19], diverting carbon toward CO2 formation. Consequently, both H2+CO and H2 yield were lower than the optimized values achieved at the 5∶5 ratio (Ysyngas = 12.99 mmol/g, H2=8.66 mmol/g, Figure 7).
Figure 9 displays the distribution of synergistic effect indices for the co-gasification of SS and CG. The study confirms that all gas components exhibit positive synergistic effects, with hydrogen (H2) demonstrating the most pronounced synergistic intensity. The synergy indices for H2 and CO peaked at a 5∶5 mass ratio of SS to CG, reaching 1.56 and 1.11, respectively. This phenomenon directly corroborates the earlier conclusion regarding the peak syngas yield. The synergistic effect of light hydrocarbons CnHm continuously increased with rising CG proportion, peaking at 1.22 at a 7∶3 ratio.
This primarily resulted from minerals in CG effectively catalyzing the cracking of light hydrocarbons derived from SS hemicellulose tar. However, the high ash content of SS tends to cover catalytically active sites, hindering mass transfer processes[20]. Its inherently high nitrogen content promotes the formation of pyridine-containing nitrogenous tars, thereby inhibiting the depth of gasification reactions[21–22]. Considering gas yield, H2 selectivity and synergistic effect intensity comprehensively, a 5∶5 mass ratio of SS to CG was established as the optimal co-gasification mixture.
2.3　Co-gasification of CS and CG
Figures 10 and 11 systematically reveal the influence patterns of different mass ratios of CS and CG co-gasification on the volume fractions and yields of gas components. The study indicates that the H2 volume fraction exhibits a continuous decreasing trend with increasing corn stover proportion, dropping from 50% to 33%. However, the H2 yield demonstrates a nonlinear characteristic of first increasing and then decreasing, reaching a peak of 8.75 mmol/g at a mass ratio of 5∶5.
The significant increase in total syngas volume dilutes the H2 concentration but substantially enhances the H2 yield. Concurrently, the CO volume fraction increased from 12% to 28% with rising corn stover proportion. Its yield peaked at 5.63 mmol/g at a mass ratio of 7∶3 and exhibited a secondary peak of 5.29 mmol/g at 5∶5, reflecting the sustained promotion of oxidation reactions by biomass’s oxygen-rich characteristics.
Experimental data indicate that the syngas yield from CG gasification alone is 2.16 mmol/g, with an H2 yield of 1.75 mmol/g; while CS gasification yielded 9.56 mmol/g of synthesis gas and 5.22 mmol/g of H2.
When CS and CG were co-gasified at a 5∶5 mass ratio, synthesis gas yield peaked at 14.24 mmol/g, with H2 yield reaching 8.75 mmol/g. Compared to CG gasification alone, this co-gasification system significantly increased syngas yield by 559% and H2 yield by 400%. Compared to CS gasification alone, it increased syngas yield by 48% and H2 yield by 67%. These results confirm that co-gasification of CS and CG exhibits significant synergistic effects on hydrogen and syngas production.
Figure 12 shows the gasification performance parameters for co-gasification of CS and CG at different mass ratios, including gas yield, syngas ratio, gross calorific value, and carbon conversion rate. As shown in Figure 12, Ysyngas from individual gasification of CS is 0.35 m3/kg. As the CS proportion increases, Ysyngas increases up to a 7:3 mass ratio and then declines, peaking at 0.53 m3/kg at a 7:3 ratio. The nitrogen gas yield during co-gasification of CS and CG is higher than when each is gasified separately. However, as the corn stover proportion increases, CO production rises, the H2/CO ratio decreased from 4.31 to 1.29, leading to a monotonically decreasing H2+CO yield. The gross calorific value peaks at a 5∶5 mass ratio of CS to CG. The maximum value is 8.41 MJ/m3, indicating the highest fuel efficiency at this point. In Figure 12, the carbon conversion rate, reached its maximum at a mass ratio of 7∶3, with a peak value of 58.29%. However, the H2+CO yield at this ratio was lower than that at a 5∶5 ratio. This occurs because the 7∶3 ratio produces more CO and CO2; yet the hydrogen yield is lower than at the 5∶5 ratio. Considering all performance parameters, the gasification performance was optimal when the CS:CG ratio was 5∶5.
Figure 13 shows the synergistic effect index diagram for the co-gasification of CS and CG. The figure indicates that the co-gasification of CS and CG produces positive synergistic effects on all gases, with the most significant positive synergistic effect observed for H2. The synergy indices for H2 and CO both peaked at 1.43 and 1.22, respectively, when the mass ratio of CS to CG was 5∶5. This aligns with the earlier conclusion that the total syngas yield reached its maximum at this ratio. Simultaneously, the synergistic effect on CO2 production is strong during co-gasification, peaking at 1.15 when the CS to CG mass ratio is 5∶5. This occurs because K+ in CS ash catalyzes the Boudouard reaction[23–24], but ash sintering inhibits secondary reactions[20] while simultaneously increasing carbon loss[25–26]. The synergistic effect of CnHm increases with higher CG ratios, peaking at 1.04 when the CS to CG mass ratio is 7∶3. In summary, the optimal feedstock ratio for co-gasification of CS and CG to produce synthesis gas is 5∶5.
3　Comparative analysis
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As shown in Table 3, CS exhibits high ash content and demonstrates the strongest promotion effect on CO production during co-gasification with CG, making it suitable for blending in industrial applications requiring low synthesis gas ratios. SS exhibits high nitrogen and protein content. During pyrolysis, proteins generate nitrogen-containing radicals[27], which are synergistically amplified by minerals in CG during co-gasification. Consequently, soybean straw possesses high CnHm characteristics, which are unfavorable for syngas production. However, it is suitable for replacing chemical feedstocks[28] and exhibits the highest H2/CO ratio, making it suitable for blending in industrial applications requiring high syngas ratios. co-gasification of PS and CG exhibits “three highs” and “three lows.”
The “three highs” refer to the highest syngas yield, strongest synergistic effect on H2 and highest carbon conversion rate. The “three lows” denote the lowest synergistic effect on CnHm, the lowest synergistic effect on methane, and the lowest CO2 yield. This is attributed to PS’s high cellulose content. During gasification, cellulose hydrolysis produces light oxygenated intermediates that efficiently generate H2 via steam reforming[29]. Simultaneously, lignin in PS releases phenolic radicals that quench tar condensation chain reactions, suppressing tar formation. This makes it suitable for syngas production and clean hydrogen energy generation.
Figure 14 illustrates the synergistic mechanism of co-gasification between biomass and CG, which originates from the complementary physicochemical properties of both materials and the synergistic effects of multi-step reactions. Specifically, highly reactive free radicals (·H, ·OH) generated from cellulose pyrolysis in biomass[30] diffuse through the gas phase to the CG surface. These radicals attack and break their inert Si–O and Al–O bonds[31], creating active sites. The newly formed radical sites significantly enhance surface reactivity, promoting oxidation, hydrolysis, and ion exchange reactions to activate the CG. Concurrently, minerals like K and Ca in CG catalyze tar reforming reactions[32], synergizing with biomass volatiles to enhance coal-coke gasification and effectively reduce coking. In reaction pathways, K+ preferentially catalyzes the Boudouard reaction to promote CO production, while Ca2+ tends to catalyze the water-gas shift reaction to enhance H2 generation, enabling targeted regulation of syngas composition. However, synergistic effects are constrained by biomass properties: nitrogen-rich tar from high-nitrogen biomass pyrolysis readily coats active sites[33], while ash melting in high-ash biomass impedes mass transfer, collectively inhibiting gasification reactions. The co-gasification synergistic mechanism arises from the coordinated action of multiple pathways, including radical activation, targeted metal ion catalysis, and tar cracking. Different biomass characteristics exert differential control over the gasification process by influencing active site availability and mass transfer efficiency.
4　Conclusion
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This study systematically investigated the co-gasification of three representative biomass types—PS (high cellulose), SS (high nitrogen), and CS (high ash)—with CG, revealing the regulatory mechanisms of biomass characteristics on syngas production and synergistic effects. The main conclusions are as follows:
co-gasification demonstrates significant synergy, with optimal product distribution being precisely directed by feedstock composition. All three systems achieved peak syngas yields at a 5∶5 mass ratio. However, their optimal products differed substantially due to distinct key components: The PS (high cellulose) system achieved the highest hydrogen yield (9.06 mmol/g)，H2+CO yield (15.25 mmol/g) and H2 synergy index (SI=1.75), exhibiting a “three highs and three lows” advantage. The CS (high ash/K+) system showed the strongest synergy for CO production (SI=1.22), making it an ideal source for CO-rich syngas. The SS (high nitrogen) system achieved an ideal H2/CO ratio (2.00), although its high nitrogen content led to nitrogen-containing tar that suppressed the overall yield.
The synergistic mechanism originates from the complementarity of physicochemical properties and competition among reaction pathways. The synergy is governed by multiple pathways: radical activation (biomass pyrolysis radicals cleaving inert bonds in CG); directed catalysis by AAEMs (K+ preferentially catalyzing the Boudouard reaction, while Ca2+ promotes the water-gas shift reaction); and catalytic tar cracking and its inhibition (CG minerals cracking tars, while by-products from high-nitrogen or high-ash biomass weaken this effect). The key components of the biomass determine which of these pathways becomes dominant.
This research clarifies the mechanism by which key biomass components (cellulose, nitrogen, ash and AAEMs) govern the distribution of products and the intensity of synergy by regulating the dominant reaction pathways during co-gasification, providing a theoretical basis for the targeted conversion of waste resources.
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doi: 10.1016/S1872-5813(26)60637-8
  • Receive Date：2025-09-03
  • Online Date：2026-09-23
  • Published：2026-05-10
Article Data
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History
  • Received：2025-09-03
  • Revised：2025-09-25
  • Accepted：2025-10-06
Affiliations
    1School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China
    2School of Mining and Coal, Inner Mongolia University of Science and Technology, Baotou 014010, China
    3Qiao Dongfang Biofuel Group Co., Ltd., Baotou 014060, China
    4Engineering Training Center of Inner Mongolia University of Science and Technology, Baotou 014010, China

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表12种不同金属材料的力学参数
科
Family		 属数
Number of
genus		 种数
Number of
species		 占总种数比例
Percentage of
total species (%)		 属
Genus		 种数
Number of
species		 占总种数比例
Percentage of total
species (%)
鹅膏菌科Amanitaceae 2 11 5.26 鹅膏菌属 Amanita 10 4.78
小菇科 Mycenaceae 2 12 5.74 丝盖伞属 Inocybe 5 2.39
多孔菌科 Polyporaceae 8 14 6.70 蜡蘑属 Laccaria 5 2.39
红菇科 Russulaceae 3 23 11.00 小皮伞属 Marasmius 6 2.87
小菇属 Mycena 11 5.26
光柄菇属 Pluteus 5 2.39
红菇属 Russula 17 8.13
栓菌属 Trametes 5 2.39
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