The continuous liquid phase synthesis of nickel phosphide (Ni₂P) nanoparticles was studied in a helically coiled tube (HCT) reactor both in single-phase and two-phase slug flows. The reactants were nickel acetylacetonate and tri-n-octylphosphine (TOP) in a 1-octadecane solvent. For the single-phase mode, various parameters such as reaction temperature, residence time, TOP concentration, and P/Ni ratio were studied. It was found that lower temperatures of 320 and 340 °C resulted in the formation of mixed Ni₁₂P₅ and Ni₂P phases, while a higher temperature of 360 °C gave mostly Ni₂P, with particle sizes increasing from 28 to 42 nm. Upon varying the contact time between 88 and 340 s at 360 °C, a likely sequence of reaction involved an amorphous phase that was transformed in parallel to Ni, Ni₁₂P₅, and Ni₂P. When the flow in the HCT was changed to a two-phase slug flow by using N₂ to split the continuous liquid phase into small liquid columns, the product was nearly 100% Ni₂P and the particle size was as small as 3–4 nm. This was attributed to the enhanced mass transfer in the small liquid columns of the slug flow that led to higher reaction rates. It is highlighted that the HCT operated in a slug flow is an efficient and continuous method for the fabrication of nanoparticles.

中文翻译：

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在螺旋盘管反应器中连续液相合成磷化镍纳米粒子

在螺旋盘管反应器中研究了磷化镍（Ni ₂ P）纳米粒子的连续液相合成过程，该反应器既有单相又有两相。反应物为乙酰丙酮镍和三- ñ在1-十八烷溶剂-octylphosphine（TOP）。对于单相模式，研究了各种参数，例如反应温度，停留时间，TOP浓度和P / Ni比。发现较低的320和340°C温度导致混合的Ni ₁₂ P ₅和Ni ₂ P相的形成，而较高的360°C温度则大部分产生Ni ₂P，粒径从28纳米增加到42纳米。在360°C下在88到340 s之间改变接触时间时，可能的反应顺序涉及非晶相，该相与Ni，Ni ₁₂ P ₅和Ni ₂ P平行转化。当HCT中的流量改变时通过使用N ₂将连续液相分裂成小的液相柱，可得到两相团状流，产物的Ni ₂ P含量接近100％，粒径小至3-4 nm。这归因于团状流的小液体塔中传质的增强，从而导致更高的反应速率。需要强调的是，在团状流中操作的HCT是一种高效且连续的纳米颗粒制造方法。