N-methylated amines are essential bioactive compounds and have been widely used in the fine and bulk chemical industries, as well as in pharmaceuticals, agrochemicals, and dyes. Developing green, efficient, and low-cost catalysts for methylation of amines by using efficient and easily accessible methylating reagents is highly desired yet remains a significant challenge. Herein, we report the selective N-dimethylation of different functional amines with different functional aldehydes under easily handle-able and industrially applicable conditions using carbon-supported Ru nanoparticles (Ru/C) as a heterogeneous catalyst. A broad spectrum of amines could be efficiently converted to their corresponding N, N-dimethyl amines with good compatibility of various functional groups. This method is widely applicable to N-dimethylation of primary amines including aromatic, aliphatic amines with formaldehyde, and synthesis of tertiary amines from primary, secondary amines with different functional aldehydes. The advantage of this newly described method includes operational simplicity, high turnover number, the ready availability of the catalyst, and good functional group compatibility. This Ru/C catalyzed N-dimethylation reaction possibly proceed through a twice N-methylation reaction process.
As an anti-corrosion coating,Dacromet,consisting principally of zinc and aluminum flakes together with chromate matrix,was widely used in many fields,such as automobiles,because of its excellent corrosion protectiveness for steel or other metals and its efficient pollution-free mode of application.But the conventional technology,through heat treating by using common muffle furnace,for Dacromet curing is a technology of low efficiency and high energy consumsion because its lower heating rate and longer curing time.Irradiation curing technology is a method of direct heat transfer by radiation,which has many advantages,of high heating efficiency and heating rate,which can shorten the curing time then enhance the curing efficiency.In this paper,Dacromet coating was cured by using the irradiation curing technology and the common muffle furnace respectively.The results showed that the new process could shorten the curing time for Dacromet about 2/3 without any degradation of its anti-corrosion performance in comparision with the conventional ones.The samples cured by the irradiation technology showed a lower polarization current of the cathode region in potentiodynamic polarization curves.The optimal process is:curing for 7 min～8 min.at 290 ℃～310 ℃.So this study showed a feasibility of application of irradiation technology to the fast curing of Dacromet coating.
Chemo-selective hydrogenation of challenging nitrostyrene to the corresponding product of vinylaniline, ethylbenzenamine, and ethylnitrobenzene separately in high yield is difficult since there exists competitive activation of the C=C double bond and the –NO2 group over most supported metal catalysts. Also, the currently reported catalysts still have some disadvantages of high cost, catalyst reusability and separation problem, catalyst stability and leaching during harsh reaction conditions, waste generation, which disagree with the requirements of low cost, highly active and selective, sustainable, environmentally friendlier, and industrially applicable. Herein we report thin graphene layer encapsulated Ni and Pd nanoparticles core-shell structures as highly active, chemo-selective, and reusable catalysts for hydrogenation of 4-nitrostyrene in both batch reactor and industrially applicable flow reactor. In the standard hydrogenation of 4-nitrostyrene, the optimized catalysts Ni/NiO@-700-200-1-H2O and Pd@NC-2 yield a selectivity to every single product of 4-vinylaniline 99%, 4-ethylbenzenamine 99%, 1-ethyl-4-nitrobenzene 99% through simple changing reaction conditions, the best achieved over Ni and other group metals and higher than the best result reported in the literature. In non-polar solvent toluene, in contrast to traditional catalysts, the Ni@C catalyst is inert for the C=C and is only active about the -NO2, while the N-doped Pd@NC-2 has opposite hydrogenation ability and can hydrogenate the C=C without touching -NO2 in non-polar solvent cyclohexane, which rarely reported in the previous literature. In addition, the catalysts show excellent stability and the 4-nitrostyrene’s hydrogenation can be successfully applied in industrially applicable flow reactors for each of the three product syntheses separately with excellent yield. These discoveries may extend the design of non-noble catalysts with excellent chemoselectivity for use in fine chemicals’ synthesis.
Washing is one of the common technologies in the chlorinated organic pollution site repair, surfactant adding would help washing more chlorinated organics pollution, but it also can be dissolved in eluent with the chlorinated organic together, and increase the difficulty of the eluent treatment. In this text, three surfactants, anionic surfactant (sodium dodecyl benzene sulfonate, SDBS), cationic surfactant (hexadecylpyridinium bromide hydrate, HBH), and nonionic surfactant (Triton X-100, TX-100), would be added in the polluted soil eluent, to study the effect on the dechlorination of HCB by Ag/Fe bimetal and the surface corrosion of Fe in the eluent. The experimental results showed that different surfactant and different surfactant concentration all affected the dechlorination. Nonionic surfactant would promoted the dechlorination significantly; Cationic surfactant promoted the dechlorination in lower concertration and impeded it in higher concentration; Anionic surfactant promoted the dechlorination only in higher concentration. Meanwhile, these three surfactants could not intensify the surface corrosion of Fe, and keep the reaction activity of the Ag/Fe bimetal for a long time. Hence, during the treatment for the eluent by Ag/Fe bimetal, the nonionic surfactant and the anionic surfactant would be recommended, and the cationic surfactant should try to be avoided.
Recently, Integrated Multi-satellite Retrievals for the Global Precipitation Measurement (IMERG) mission and European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5) precipitation datasets have been widely used in remote sensing and atmospheric studies, respectively, because of their high accuracy. A dataset of 268 site-gauge precipitation measurements over the Yellow River Basin in China was used in this study to comprehensively evaluate the performance of three high-resolution precipitation products, each with a spatial resolution of 0.1°, consisting of two satellite-derived datasets, IMERG and multisource weighted-ensemble precipitation (MSWEP), and one ERA5-derived dataset, ERA5-Land. The results revealed that the spatial distribution of IMERG annual precipitation closely resembled that of the observed rainfall and generally exhibited a downward trend from southeast to northwest. Among the three products, IMERG had the best performance at the annual scale, whereas ERA5-Land had the worst performance due to significant overestimation. Specifically, IMERG demonstrated the highest correlation coefficient (CC) above 0.8 and the lowest BIAS and root mean square error (RMSE), with values in most regions of 24.79 mm/a and less than 100 mm/a, respectively, whereas ERA5-Land presented the highest RMSE exceeding 500 mm/a, BIAS of 1265.7 mm/a, and the lowest CC below 0.2 in most regions. At the season scale, IMERG also exhibited the best performance across all four seasons, with a maximum of 17.99 mm/a in summer and a minimum of 0.55 mm/a in winter. Following IMERG, the MSWEP data closely aligned with the observations over the entire area in summer, southern China in spring and winter, and middle China in autumn. In addition, IMERG presented the highest Kling–Gupta efficiency coefficient (KGE) of 0.823 at the annual scale and the highest KGE (>0.77) across all four seasons among the three products compared with ERA5-Land and MSWEP, which had KEG values of −2.718 and −0.403, respectively. Notably, ERA5-Land exhibited a significant positive deviation from the observations at both the annual and seasonal scales, whereas the other products presented relatively smaller biases.
The hydrodynamic characteristics of the airwaterworking solution (a mixture of anthraquinone derivatives, TOP and C9 aromatics, used for industrial production of hydrogen peroxide) three-phase system in a gas-agitated sieve plate extraction column were investigated. The holdups of the dispersed and gaseous phases were measured by the shut-off method, respectively. The effects of the superficial velocities of air, dispersed and continuous phases on the holdups of dispersed and gaseous phases were studied. Correlations for the prediction of holdups of dispersed and gaseous phases in the airwaterworking solution three-phase system have been proposed. The comparison of the predicted data with correlations and experimental data shows quite satisfactory agreement and the average relative deviations are 7.3% for the dispersed phase holdup and 7.1% for the gas phase holdup, respectively.
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