Kai-lu Yu

Plasma application for more environmentally friendly catalyst preparation

The present status of catalyst preparation using nonthermal plasma treatment has been summarized in this paper. Improved dispersion, better low-temperature activity, enhanced stability, and better anti-carbon deposition performance can be achieved with nonthermal plasma-treated catalysts. The improvement in catalyst preparation with nonthermal plasma treatment can reduce or avoid the use of hazardous chemicals. Nonthermal plasma catalyst treatment has especially induced a new development of nonthermal plasma for catalyst reduction. The reduction using hydrogen at high temperatures or using hazardous liquid chemicals can be replaced by the developed plasma reduction process. The mechanism for nonthermal plasma treatment has been presented. An analog between the man-made gas discharge plasmas and the environment inside the zeolite pores and around catalyst surface defects is also proposed.

Floating double probe characteristics of non-thermal plasmas in the presence of zeolite

The combination of catalyst and non-thermal plasmas has led to some unusual chemical behaviors, especially with zeolite catalyst. A mechanism has been proposed to explain the observed interaction between catalyst and non-thermal plasmas. This mechanism includes two aspects: plasma promoted or induced catalysis and catalyst enhanced non-equilibrium of non-thermal plasmas. In this paper, we present some direct experimental evidence for the catalyst (zeolite)-enhanced non-equilibrium of non-thermal plasmas suggesting the use of zeolite increases, significantly, the electron temperature of non-thermal plasmas, while the gas temperature remains unchanged. A floating double-probe characteristic has been utilized to measure the electron temperature. Compared to the case without zeolite, the electron temperature of non-thermal plasmas with Mo-Zn/HZSM-5 increases up to 250%, while, at the same time, the discharge power reduces 58%, compared to that without zeolite.

Remarkable improvement in the activity and stability of Pd/HZSM-5 catalyst for methane combustion

Abstract A novel Pd/HZSM-5 catalyst was prepared first by glow discharge plasma treatment followed by calcination thermally. Such prepared catalyst shows a higher activity and an enhanced stability for methane combustion. The XRD characterization and XPS analysis confirm that the plasma preparation leads to a better preparation of PdO active species over the HZSM-5 support. Especially, a plasma-enhanced acidity has been achieved upon the FT-IR analysis. The enhanced acidity plays an important role in stabilizing the dispersed PdO active species on the zeolite support.

Effect of Catalyst Preparation on Carbon Nanotube Growth

A highly dispersed Ni–Fe/Al2O3 catalyst was prepared by glow discharge plasma treatment followed by thermal calcinations. With this plasma prepared catalyst, carbon nanotubes encapsulated with metal particle or filled with nickel nano-wire were produced. This is very different from the conventional catalyst, with which the normal multi-wall carbon nanotubes or nano-capsule chains were synthesized. The plasma preparation leads to a significant change in the interaction between metal and the support.

Preparation of ultrafine Al2O3 using plasma jet and its application for synthesis of dimethyl carbonate

A direct preparation of Al2O3 from aluminum and oxygen under plasma jet conditions has been performed in this work. The XRD characterization of such plasma-prepared alumina shows that a production of i -Al2O3 has been achieved. The size of the alumina particles ranged from several tens to 200 nm, based on SEM analysis. The effectiveness of plasma-prepared alumina as a catalyst support has been demonstrated by the catalytic synthesis of dimethyl carbonate over Pd/Al2O3.