Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Dynamic Effect of Drilling Fluid Filtrate Reducers on Hydrate Formation
No full textHydrate formation and decomposition are major challenges in marine hydrate development drilling. Filtrate reducers are important additives in water-based drilling fluids that reduce methane hydrate formation. However, research on the influence of commonly used filtrate reducers in drilling fluids on hydrate formation is limited. Here, we investigated the effects of three filtrate reducers, humic acid potassium (KHm), hydroxypropyl starch (HPS), and hydrolyzed polyacrylonitrile sodium salt (Na-HPAN), on methane hydrate formation kinetics and those of different concentrations under an initial pressure of 6 MPa and different initial pressures (6, 8, 10, and 12 MPa) in the same concentration system. The KHm solution (1-3%) promoted hydrate formation at 4 degrees C and 6 MPa, the Na-HPAN solution (0.3-1.5%) inhibited hydrate formation, and the HPS solution (0.1-1.5%) inhibited hydrate formation in the first 10 h of reaction but promoted a large amount of hydrate formation after the inhibition failure. At 4 degrees C, higher initial pressures led to earlier and faster formation of CH4 hydrate in large quantities in the filtrate reducer solution. An extreme gas hydrate conversion value was observed, indicating that the initial pressure is crucial when using a filtrate reducer. These observations provide a crucial basis for flow assurance and water-based drilling fluid design
Co-production of hydrogen and carbon nanotubes via catalytic pyrolysis of polyethylene over Fe/ZSM-5 catalysts: Effect of Fe loading on the catalytic activity
No full textThermochemical conversion is a promising waste plastic recycling technology from both an economic and environmental point of view, as it can convert plastics into high-value chemicals. In this work, the co-production of hydrogen and carbon nanotubes (CNTs) by catalytic pyrolysis of polyethylene over Fe/ZSM-5 catalysts with different Fe loading (5, 10, 20 and 30 wt%) was investigated using a two-stage fixed bed reactor. The results show that the yield of CNTs and hydrogen increases first and then decreases with the increase of Fe loading. The 20Fe/ZSM-5 catalyst generated the highest CNTs yield of 262.24 mg/gPE and the maximum hydrogen production of 31.72 mmol/gPE. The fresh and spent catalysts were characterized by XRD, H2-TPR, SEM, TEM, etc., in order to explore the correlation between the catalytic activity and the Fe active metal load of the catalysts. The results showed that, within a certain range, the number of active sites increased with the increase of Fe loading, which promoted the conversion of hydrogen and CNTs. However, when the Fe loading reached 30%, the active particles agglomerated and inhibited the growth of CNTs. 30Fe/ZSM-5 catalyst produced many carbon nanoonions (CNOs) and carbon nanofibers (CNFs). Overall, in terms of the yield of the produced hydrogen and CNTs, the 20Fe/ZSM-5 catalyst shows the best catalytic performance
Selective production of aromatics from catalytic fast pyrolysis of cassava residues over vanadium modified ZSM-5: Experimental and kinetic study
No full textIn the present study, vanadium modified ZSM-5 catalysts (denoted as xV/ZSM-5) were applied for the fast pyrolysis of cassava residues. Systematical structural characterizations were carried out to reveal the basic characteristics of as-prepared xV/ZSM-5. Remarkably, the incorporation of vanadium species endowed the catalysts with large amounts of Bronsted and Lewis acid sites, thus facilitating the formation of aromatics via catalytic cleavage, dehydration, decarbonylation, decarboxylation, cyclization, and aromatization. Among the asprepared xV/ZSM-5, 3V/ZSM-5 was found to be much more efficient in the fast pyrolysis of cassava residues into aromatics. The total yield of aromatics was up to 22.63 wt% at 750 degrees C with a heating rate of 10 degrees C/ms, and the corresponding apparent activation energy of 211.9 kJ/mol was attained. The recycling experiments demonstrated that the vanadium modified ZSM-5 catalysts presented good thermal stability and could be reused for several cycles. Furthermore, plausible reaction mechanism for the fast pyrolysis of cassava residues over vanadium modified ZSM-5 was discussed in depth
Upcycling of aureomycin hydrochloride residue into highly meso-microporous carbon with remarkable adsorption capacity for benzene capture
No full textThe exploration of high-value utilization of antibiotic bacteria residues is of great importance at the environmental and resource levels. In this study, we report an aureomycin hydrochloride residue-derived activated carbon and its application in the adsorption of hazardous benzene. Self-N-doped activated carbon with excellent benzene adsorption properties was prepared by K2CO3-assisted activation pyrolysis using aureomycin hydrochloride residue as carbon and nitrogen sources. It is found that the pore structure and the benzene adsorption behavior could be optimized through regulating the mass ratio of K2CO3 to carbon (mK2CO3/mC) and the activation temperature. Under the pyrolysis conditions of mK2CO3/mC = 3:1 and 800 degrees C, the specific surface area and total pore volume of the as-prepared carbon reached 1564 m2 g-1 and 0.70 cm3 g-1, respectively, whereas those of the micropores were 1440 m2 g-1 and 0.48 cm3 g-1, respectively, implying that the proportion of micropores reached 68.6%. The adsorption capacity of benzene based on the optimal adsorbent (AHRC-3PC-800) was as high as 1303 mg g-1 at 25 degrees C and relative pressure (P/P0) of 0.9-1. Therefore, the aureomycin hydrochloride residuebased activated carbon adsorbent has a broad application prospect in the removal of volatile organic compounds
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