Hydrofining of low-grade lignite liquefied oils into high-density liquid fuels is a critical pathway for their value-added utilization. However, abundant condensed aromatic rings (ARs) and O atoms in such crude oils pose significant challenges for secondary upgrading, particularly in achieving concurrent AR hydrogenation and hydrodeoxygenation in one-pot to produce alkyl cyclanes. In view of this, Co-CoN x @C 650 was constructed by a cascade preparation strategy consisting of in-situ co-pyrolysis and NH 3 nitridation. It has highly dispersed Co-CoN x dual-sites and carbon substrate with abundant defects/vacancies, and exhibits good performance in AR hydrogenation and hydrodeoxygenation. In addition, this catalyst can effectively activate H 2 and promote the synergistic transfer of H ··· H, δ+ H ··· H δ− , and H · . Good accessibility, cyclic stability, and renewability make it suitable for the hydrogenation of medium/large-sized molecules such as naphth-2-ol and aryl ethers into cyclanes. The liquefied oil (SP TD ) from Dongming lignite thermal dissolution in n -hexane is rich in aromatics (76.1 %), while refined oil (CHSP TD ) from catalytic hydrofining over Co-CoN x @C 650 is rich in saturated hydrocarbons (91.7 %), especially alkyl cyclanes (69.8 %). The efficient conversion of aromatic-oxygenated moieties demonstrated by Co-CoN x @C 650 provides a new solution for converting low-grade lignite liquefied oils into value-added cyclanes-rich liquid fuels.
Yidong Zhou,Zhijian Ke,Hangting Ye,Mengting Hong,Yifei Xu,Mingliang Zhang,Wankui Jiang,Qing Hong
Carbaryl is a widely used carbamate pesticide in agriculture. The strain Rhizobium sp. X9 possesses the typical carbaryl degradation pathway in which carbaryl is mineralized via 1-naphthol, salicylate, and gentisate. In this study, we cloned a carbaryl hydrolase gene cehA and a novel two-component 1-naphthol hydroxylase gene cehC1C2. CehA mediates carbaryl hydrolysis to 1-naphthol and CehC1, an FMNH2 or FADH2-dependent monooxygenase belonging to the HpaB superfamily, and hydroxylates 1-naphthol in the presence of reduced nicotinamide-adenine dinucleotide (FMN)/flavin adenine dinucleotide (FAD), and the reductase CehC2. CehC1 has the highest amino acid similarity (58%) with the oxygenase component of a two-component 4-nitrophenol 2-monooxygenase, while CehC2 has the highest amino acid similarity (46%) with its reductase component. CehC1C2 could utilize both FAD and FMN as the cofactor during the hydroxylation, although higher catalytic activity was observed with FAD as the cofactor. The optimal molar ratio of CehC1 to CehC2 was 2:1. The Km and Kcat/Km values of CehC1 for 1-naphthol were 74.71 ± 16.07 μM and (8.29 ± 2.44) × 10–4 s–1·μM–1, respectively. Moreover, the enzyme activities and substrate spectrum between CehC1C2 and previously reported 1-naphthol hydroxylase McbC were compared. The results suggested that McbC had a higher 1-naphthol hydroxylation activity, while CehC1C2 had a broader substrate spectrum.
Coal water slurry (CWS) modified with traditional linear naphthalene sulfonate formaldehyde (NSF) polymers exhibited limited stability in long-haul pipeline transportation, because of low steric hindrance energy (V S ) between coal particles. To study the effect of structural modification of dispersant on the V S value, a branched multi-arm poly(sodium acryloyloxy-2-naphthalenesulfonate) (Ma-PANS) dispersant was synthesized by controlled/living radical polymerization (CRP), using vinyl monomer sodium acryloyloxy-2-naphthalenesulfonate (ANS) with triple functional groups as precursor. The making-slurry experiment results showed that the viscosity of Yulin CWS modified with Ma-PANS dropped 319 mPa·s, and its stability was remained at 100% after 30 days. The effects of the structural modification on adsorption amount, adsorption parameters and adsorption conformation were also analyzed by adsorption experiments and molecular dynamics (MD) simulations. The results showed that the specific conformation of Ma-PANS contributed to improving adsorption parameters. This reduced the diffusion rate of dispersant on coal surface, resulting in enhanced stability of slurry. Moreover, the numerical calculation results based on the extended Derjaguin-Landau-Verwey-Overbeek theory (eDLVO) showed that the enhancements on dispersion and stability were attributed to the structure of dispersant being changed from linear to multi-arm. The unique multi-arm structure brought significant increase in the V S value when impeding the approach among particles and disrupting flocculation, thus effectively enhanced dispersion and stability of CWS.
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