Ni-Mg Bimetallic Catalysts for Preparation of Multi-Walled Carbon Nanotubes from Polypropylene: Influence of the Ratio of Ni/Mg

Abstract

This study designs Ni-Mg bimetallic catalysts for preparation of multi-walled carbon nanotubes (MWCNTs) from polypropylene (PP). The study further investigates the in°uence of Mg content on the catalytic activity of Ni catalyst. It is found that bimetallic Ni-Mg catalysts have higher reduction temperature, smaller Ni particle size and improved stability. Consequently, the addition of Mg not only enhances the yield of MWCNTs, but simultaneously improves the morphology and graphitization of MWCNTs. The activities of the bimetallic Ni-Mg catalysts are dependent on their composition. Among the di®erent Ni-Mg bimetallic catalysts ration, Ni-Mg catalyst shows the highest activity when the ratio of Ni/Mg is 9/1. Moreover, the obtained MWCNTs presents smooth surface with highest graphitization degree. With our bimetallic Ni-Al catalyst, it is promising to achieve mass production of MWCNTs by using waste polymers as feedstock.

Universal Ni‐Mo‐Mg catalysts combined with carbon blacks for the preparation of carbon nanotubes from polyolefins

“…For promoting the size stability and catalytic activity of monometallic catalysts, Shen et al . prepared Al‐Ni and Mg‐Ni bimetallic catalyst to combine with organically modified clay for the synthesis of CNTs from PP . In our previous works, a kind of trimetallic catalysts, i.e.…”

Synergetic Effects of Molybdenum and Magnesium in Ni–Mo–Mg Catalysts on the One-Step Carbonization of Polystyrene into Carbon Nanotubes

“…It demonstrates that the presence of small amounts of amorphous MgO can impose proper carbon solubility in Ni–Mg catalysts for the growth of CNTs from PS. In Shen’s work, it was demonstrated that the MgO could effectively enhance the thermal stability and catalytic lifetime of Ni active phase. In this work, we further revealed that the presence of interaction between NiO and MgO, namely the formation of MgNiO 2 , played an important role for the control of carbon solubility.…”

“…Wen et al reported a universal degradation additive (nanosized carbon black), which showed high synergetic efficiency for the one-step carbonization of PP, PE, and PS into CNTs with the presence of NiO . Recently, Shen et al reported two new carbonization catalysts (i.e., Ni/MgO and Ni/Al 2 O 3 ) and achieved a very high carbonization rate of ∼80% of PP with the help of OMMT. , In addition, Tang and Gong have done many works on the application of final obtained CNTs and the conversion of PP, PE, and PS into other carbon nanomaterials with one-step carbonization. − …”

“…In a previous work, Gong has demonstrated that the NiO catalysts with relatively small particle sizes favor the formation of long and uniformed CNT structures in one-step PP carbonization . In Shen’s works, , the utilization of Ni/Al 2 O 3 or Ni/MgO has been demonstrated to improve the CNT quality from PP with respect to NiO catalysts. Over the past few years, our group has discovered that further combination of Mo to Ni/MgO shows high efficiency for the conversion of PP, PE, and PS into CNTs with the presence of carbon black additives. , However, the carbonizing ability of the Ni/Mo/MgO catalysts for the PS carbonization is still very weak; and the addition of additives, such as carbon black, seems to be indispensable.…”

“…Over the past few years, our group has discovered that further combination of Mo to Ni/MgO shows high efficiency for the conversion of PP, PE, and PS into CNTs with the presence of carbon black additives. , However, the carbonizing ability of the Ni/Mo/MgO catalysts for the PS carbonization is still very weak; and the addition of additives, such as carbon black, seems to be indispensable. Moreover, similar to the combined catalysts used in one-step plastic carbonization, , the function of Mo and MgO in Ni/Mo/MgO remains elusive. As such, addressing clearly the role of Mo and MgO in Ni/Mo/MgO should be very crucial for the development of PS carbonization.…”