Tianyu Ren,Shengping You,Muyuan Zhang,Yuefei Wang,Wei Qi,Rongxin Su,Zhimin He
Herein, the lignin-to-fuel conversion process was studied using real lignin as feedstock. Unlike model compounds, real lignin poisons the catalyst, causing rapid deactivation. The problem of catalyst deactivation was analyzed in detail for improving the conversion efficiency. We found that heavy carbonaceous deposits on the inner surface of the catalyst were responsible for the fast deactivation encountered in the conventional one-step reaction process. Moreover, the ester structures in lignin, which have previously been neglected in research, were confirmed to considerably worsen catalyst deactivation because they induce easier polymerization and hinder lignin conversion. Based on these points, we developed a three-step method that eliminates serious catalyst deactivation in the lignin-to-fuel conversion process, involving depolymerization of lignin, extraction of lignin monomers and hydrodeoxygenation of lignin monomers. The fuel production was 8.1–17.6-times more efficient using this three-step method than using the one-step batch reaction.
Xin-Ran Ma,Qian-Xue Shen,Fang-Ming Liu,Jun Cao,Li-Hong Ye
A novel three-step anionic micelle–to–cyclodextrin stacking method, facilitated using citric acid–assisted capillary zone electrophoresis, was established for enrichment and detection of cationic pyrrolizidine alkaloids (PAs) in traditional herbs and food samples. In this context, several parameters influencing preconcentration efficiency of the method were investigated, including the type and concentration of anionic surfactants and cyclodextrins (CDs), the sodium dihydrogen phosphate concentration in sodium dodecyl sulfate, CD solution, and sample solutions; and the sample injection time. Furthermore, the limits of detection of crotaline, senecionine, and senecionine N-oxide were found to be 0.006–0.009 μg/mL, with 49–96-fold sensitivity enhancement compared to that of the conventional injection method. The proposed method achieved excellent linearity (R 2 = 0.999) for the target analytes. Under optimal conditions, the method successfully enriched and analyzed two real-world samples, Senecionis scandentis Herba and chrysanthemum honey. The developed method has been adopted to detect and enrich three PAs in successfully.
Oxide dispersion strengthened (ODS) WC Co cemented carbides with excellent mechanical properties were prepared by a facile three-step method. First, the mixture of ammonium paratungstate, cobalt oxalate and aluminum nitrate nonahydrate were roasted to generate precursor powder. Then, the precursor powder was reacted with insufficient carbon black to remove oxygen to aid precise carbon addition in the next step. Finally, depending on the carbon content difference between carbothermic reduction products and target product, the sample was mixed with the required carbon black to prepare WC Co Al 2 O 3 cemented carbides directly by the method of powder sintering . Experiments showed that after the addition of uniformly distributed nano-sized Al 2 O 3 particles, the mechanical properties included hardness and toughness of ODS cemented carbides improved. When the content of Al 2 O 3 was 0.5%, the densification of finally prepared WC-5.5wt%Co-0.5wt%Al 2 O 3 alloy could reach to 99.08%, and the values of fracture toughness and Vickers hardness were 11.35 ± 0.60 MPa·m 1/2 and 1756 ± 20.92 HV, respectively, thus giving excellent results.
危险品化学品经营许可证（带存储）