This paper discusses catalyst preparation using thermal and cold plasmas. In general, there are three main trends in preparing catalysts using plasma technologies: (1) plasma chemical synthesis of ultrafine particle catalysts; (2) plasma assisted deposition of catalytically active compounds on various carriers, especially plasma spraying for the preparation of supported catalysts; (3) plasma enhanced preparation or plasma modification of catalysts. Compared to conventional catalyst preparation, there are several advantages of using plasmas, including: (1) a highly distributed active species; (2) reduced energy requirements; (3) enhanced catalyst activation, selectivity, and lifetime; (4) shortened preparation time. These advantages are leading to many potential applications of plasma prepared catalysts.

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.

A novel method for starch modification is investigated. Starch is highly cross linked by glow discharge plasma, without the assistance of conventional chemical agents, thus avoiding any environmental concerns. An energy-charge-transfer mechanism is suggested for the function of plasma. This process could be useful for the production of large quantities of modified starch.

A diesel fuel additive has been synthesized from conversion of dimethyl ether(DME) using dielectric barrier dischargeŽDBD.plasma at atmospheric pressure and low temperatures. A high conversion of DME has been achieved. The product of such conversion is a mixture of hydrocarbons and oxygenates that can be used as high-performance diesel fuel additives. The maximum conversion of DME reached 47.2% with a selectivity of liquid product (a mixture of dimethoxy-containing hydrocarbons) more than 39.0% at 1208C and a 30 mlrmin flow rate of DME.

CO2 is the final product of combustion of all fossil fuels. CO2 itself has little value by far, but it contributes more than 50% to the man-made greenhouse effect among all the greenhouse gases. There is still no proven technology for the chemical utilization of such a plentiful carbon resource. Recently, non-thermal plasmas have been found to be effective in the activation of CO2 for the formation of more valuable hydrocarbons. The non-thermal plasma approaches can even be performed at ambient condition. In this review, the present state of carbon dioxide utilization via non-thermal plasmas is addressed.