Fuel Processing Technology最新文献

Co-combustion of biochar and pet-coke can reduce environmental pollution, provide fuel energy supply and improve fuel reaction characteristics. In this study, the co-combustion characteristics and synergistic behavior of rice straw char (BC) and petcoke (PC) were analyzed based on thermogravimetric analysis and kinetic analysis. The combustion corroborative experiments were conducted based on a fixed bed reactor, and the contents of different forms of potassium (K) during combustion of semi-char were characterized. Raman spectroscopy and X-ray photoelectron spectroscopy were used to characterize the carbon structure order and surface elements distribution characteristics of the semi-char after the combustion. The results showed that the co-combustion reactivity improved with the temperature and the BC blended ratio increase. Moreover, the synergistic effect increased with the temperature decrease and the BC blended ratio increase. The synergistic effect was confirmed to be related to the K migration and transformation, and its behavior was varied with active K content adsorbed by PC. The H₂O-soluble K would be transformed into -COOK during PC combustion. -COOK would reduce the order of PC and increase the content of amorphous carbon during combustion.

Adsorption desulfurization processes employing zeolites as sorbents are considered to be prospective desulfurization methods owing to their cost-effectiveness.

Y zeolites modified with Cu and Ce have excellent adsorption capacity and selectivity for adsorption desulfurization. However, the effect of using different metal precursors on the active sites of these sorbents and their adsorption desulfurization performance still remains ambiguous, which impedes the development of improved desulfurization adsorbents. Herein, Cu(NO₃)₂, Cu(Ac)₂, and CuSO₄ were selected as Cu precursors to prepare a series of CuCeY from CeY zeolite. Desulfurization experimental results indicate that outstanding breakthrough adsorption capacities for thiophene (ca. 6.25 mg·g⁻¹) with benzene as the solvent were achieved by the CuCeY_A. The interaction between the CuCe metals was beneficial for enhancing the electron transfer between Cu²⁺+Ce³⁺/Ce⁴⁺+Cu⁺. Moreover, using different copper precursors significantly changed the redox ability of the adsorbent surface. Changing the copper precursor also had a significant effect on the locations of Cu and Ce ions, and using Cu(Ac)₂ as a metal precursor facilitated the migration of Cu⁺ (53.6%) and cerium species (35.9%) to the supercage. In situ infrared characterization showed that the oligomerization of thiophene on CuCeY_A was significantly restricted due to the lowest B acid content (11.85%) in the CuCeY_A.

Alkali metals and alkaline earth metals (AAEMs) are the most abundant trace elements in biomass, which will provide different effects of catalytic or inhibitory at different time during chemical looping gasification (CLG). However, the role of AAEMs in the catalysis or agglomeration at different time remains unclear in biomass CLG. In this study, the promotion and agglomeration effects of AAEMs on CLG performance is studied under different time and different AAEMs. The results show that K plays a major role in promoting CLG before 20 min and inhibiting CLG at 30 min. Moreover, K promotes the conversion from Fe³⁺ to Fe²⁺ and the earlier existence of more FeAl₂O₄ and Fe₂Al₄Si₅O₁₈, causing obvious agglomeration. Na and Mg provide obvious catalytic and promotional effects after the excitation. Further, more FeO is converted from Fe³⁺ at 3–8 min in Na-AH, leading to the earlier formation of Fe₂Al₄Si₅O₁₈ and agglomeration between particles. Ca obviously promotes the whole CLG process. Furthermore, Ca helps to promote the conversion of Fe₂O₃ to Fe₃O₄, but delay the conversion to FeO and a slower generation of FeAl₂O₄, resulting in less adhesion and obvious inhibition of agglomeration. Mg slightly slows down the conversion of Fe₂O₃ to Fe₃O₄, but earlier generates FeO with a lower strength than other samples, leading to low FeAl₂O₄ and slight agglomeration. In addition, the effect of Mg on reducing agglomeration is weaker than that of Ca, but better than that of K and Na.

Lignin valorization is an important part of increasing the economic viability of sustainable biorefineries. Various methods have been proposed for lignin depolymerization. However, the relationship between lignin structure and its depolymerization behavior hasn't been extensively investigated. This research aims to clarify how the structure and composition of lignins derived from different pretreatment processes affect the downstream catalytic conversion. Herein, optimal organosolv lignin yield above 50% in three different solvent systems were obtained. Meanwhile, three types of hydrolyzed lignin were used as reference lignins. Various lignins were comprehensively characterized by elemental analysis, FT-IR, TGA-DSC and Py-GC/MS techniques. Compared with hydrolyzed lignin, organosolv lignin has higher purity, wider functional group distribution, more uniform structure, as well as a lower G/S ratio. Moreover, lignin depolymerization was carried out with a non-noble metal catalyst Ni/Al₂O₃ and without the addition of H₂. The results showed that transetherification and alkylation reaction were enhanced significantly for organosolv lignin. Total depolymerized aromatics yield from organosolv lignin was 4 to 11 times higher than that of hydrolyzed lignin-rich residues. Notably, Methanol-extracted lignin obtained an optimal yield of 29.7 wt% of monomeric aromatics. Methanol can effectively protect benzylic carbocations formed during organosolv pretreatment, thus minimizing the formation of CC bonds.

Direct syngas conversion for diesel fuel becomes an attractive route for its possibility of utilizing non-petroleum carbon resources. However, there is a limited selectivity of around 36% for diesel hydrocarbons (C₉-C₂₂) via the conventional Fischer-Tropsch process due to the Anderson-Schulz-Flory (ASF) constraint. Herein, bifunctional catalysts composed of zirconium dioxide (ZrO₂) dispersed on multi-walled carbon nanotubes (CNT) (ZrO₂/CNT) were successfully designed and applied for direct conversion of syngas into diesel with selectivity far beyond the ASF limitation. At 350 °C with the pressure of 3 MPa, H₂/CO of 2 and gas hourly space velocity of 2400 mL·h⁻¹·g_cat⁻¹, ZrO₂/CNT gave an unexceptionable C₉-C₂₂ selectivity of 50.74% at a single pass CO conversion of 43.86% compared with those (9.11% and 20.55%, respectively) of ZnO/CNT and those (14.07% and 25.76%, respectively) of ZnO-ZrO₂/CNT. The iso/n-paraffin ratio in the C₉-C₂₂ reached up to 16. Moreover, after 100 h of operation, the catalyst still showed remarkable catalytic activity with CO conversion remaining at 40.61%, diesel hydrocarbon selectivity, and methane selectivity at 42.27% and 7.67%, respectively, while the by-product CO₂ selectivity was also stable at about 3.77%.

Analyzing the effects of texture and chemical structure on hydrogen adsorption performance at room temperature can provide a theoretical basis for accurately constructing carbon-based hydrogen adsorbents. Based on thermal regulation technology, the biochar with different specific surface areas (803.85–2801.88 m²/g) and oxygen content (21.57–41.86%) was successfully prepared by the two-step “carbonization-activation” method. Various characterization methods were used to explore the relationship between the physicochemical structure and hydrogen adsorption characteristics at room temperature. The results show that the hydrogen storage characteristics of biochar at room temperature are controlled by specific surface area, oxygen content, and acidic surface groups. The boundary conditions for promoting/inhibiting hydrogen adsorption are related to oxygen content. In different pressure regions, specific surface area, oxygen content, and the acid surface group have different degrees of effect on hydrogen adsorption, and oxygen content has the most significant impact. The Freundlich model accurately fits the hydrogen adsorption process at room temperature. Among the carbon-based hydrogen storage materials, biochar has excellent hydrogen storage performance, with an adsorption capacity of 0.52 wt% at 50 bar.

Studying pure ethanol spray flame has the potential to achieve the carbon neutrality vision. This paper studies the effects of fuel injection masses (12, 24, 36 mg) and fuel injection pressures (30, 40, 50 MPa) on ethanol spray flame on an optically visualized constant volume combustion chamber. Further compared with the spray flame of methanol and n-butanol. The combustion characteristics and flame development process were revealed by flame self-illumination high-speed imaging method, and the soot distribution was revealed by wavelength integration two-color method. Results show that ethanol spray flame presents an unstable yellow flame with many wrinkles. Small injection masses exist a partial flame-quenching phenomenon. As injection mass increases, the soot lift-off length decreases, and the flame brightness, soot concentration, and ignition delay increase. The high soot concentration areas locate upstream of the flame, and there is almost no soot downstream. Increased injection pressure increases the soot lift-off length and decreases the flame brightness. The ignition delay is shortened from 8.388 ms to 6.955 ms when injection pressure increases from 30 MPa to 40 MPa. But higher injection pressure has a negligible effect on reducing ignition delay. Finally, an ethanol spray combustion conceptual model is proposed. This paper gives particular guiding significance to the future use of carbon-neutral ethanol in diesel engines.

Chemical-looping combustion has attracted considerable attention as a novel combustion technology. In this study, precursors were prepared using the sol–gel method with sucrose complexation followed by combustion to synthesize CuO-based oxygen carriers (OCs) supported on an Al₂O₃–TiO₂ template. The sucrose complexing agent inhibited the release of NO_x during combustion. When the molar ratio of sucrose to Cu(NO₃)₂·3H₂O (R) was <0.36, the NO_x produced included both NO and NO₂. When R exceeded 0.73, the NO_x produced by precursor combustion was primarily NO, and its concentration was greatly reduced. A slower heating rate also reduced the release of NO_x. At a heating rate of 1 °C/min, the release of NO_x was 80% lower than that at a heating rate of 10 °C/min. All OCs were stable for ten redox cycles. Increasing the sucrose complexant content resulted in an initial increase in the reactivity of the OCs followed by a decrease. The best performing OC had an R value of 0.36 and yielded the highest mean CO₂ percentage (61.27%). When R exceeded 1.00, the sintering and agglomeration of CuO-based OCs were severe, and the mean CO₂ yield was reduced to 57.20%. The carbon deposits from the CH₄ decomposition were completely oxidized to CO₂ by the air in the reactor.

A newly developed two-step catalytic pyrolysis process (TSCP) based on poly-generation technology is proposed to convert reed straw (RS) into phenol-rich bio-oil, hydrogen-rich gas, and solid carbon degradation material over iron-loaded activated carbon. The effects of the first step pyrolysis temperature (T1) and catalyst composition on the product distribution and target product selectivity were investigated. When T1 was 350 °C and 10% Fe/AC catalyst was selected, the concentration of phenolic compounds and H₂ peaked at 63.87 area% and 63.29 vol%, respectively. The iron-loaded activated carbon catalysts promoted the decarboxylation and decarbonylation reactions of cellulose and hemicellulose decomposition products, as well as the demethylation and demethoxylation reactions of lignin for the selective production of phenolic compounds and hydrogen gas. In addition, 94.7% quinclorac (10 mg/L) removal was achieved with 0.2 g/L 10% Fe/AC catalyst-doped pyrolysis carbon and 2 mM PMS within 90 min. This study could realize the high-value comprehensive utilization of reed and provide a reference for the full quantitative utilization of other agricultural and forestry wastes.

Volatile-char interaction has been well documented in co-pyrolysis of varied feedstocks, which might also exist in activation process and impact pore evolution of activated carbon (AC). This was investigated herein in activation of mixed sawdust and spirulina with K₂C₂O₄ at 800 °C in two scenarios: one-step direct activation or two-step activation with an intermediate pre‑carbonization. The results showed that volatile-char interaction via cross-polymerisation of the volatiles was more significant in the pre‑carbonization step, forming more biochar/bio-oil while less gases. However, volatile-char interaction was not that important in impacting product yields and evolution of pore structures of AC in activation. This was due to the dominance of gasification/cracking with presence of K₂C₂O₄, minimizing the chances for volatile-char interaction. The in-situ DRIFTS characterization of the activation process showed that removal of oxygen-containing species like CO with K₂C₂O₄ was important for generating pore structures. Comparing with two-step activation, one-step activation of sawdust, spirulina and their mixture without pre‑carbonization all generated the ACs of more developed pore structures and showed higher environmental impact. The pre‑carbonization removed a significant portion of thermally unstable aliphatic structures, enhancing aromatic degree and creating difficulty for generating pores via gasification/cracking in subsequent activation.