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.

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.

The atomic economic reaction of acetic acid formation from methane and carbon dioxide via dielectric-barrier discharges at ambient conditions was investigated in this work. A significantly high selectivity of acetic acid (up to 5.3%) has been achieved with high conversions of methane (more than 54.1%) and carbon dioxide (more than 37.4%).

Ni-Fe/Al2O3 catalyst for partial oxidation of methane was prepared first by glow discharge plasma treatment following by calcinations thermally. Such prepared catalyst exhibits better performance over the catalyst prepared without such plasma treatment. The conversion of methane and the selectivity of CO and H2 over the plasma treated catalyst are 97.44, 100 and 100% at 875℃, while, at the same temperature, they are 90.09, 97.28 and 97.09%, respectively, over the catalyst prepared without plasma treatment. At the same methane conversion, the reaction temperature with the plasma treated Ni-Fe/Al2O3 is at least 80℃ lower. TEM characterization shows that the catalytically active species after plasma treatment are still highly dispersed on the support. In addition, the plasma treated Ni-Fe/Al2O3 catalyst also possesses better anti-carbon deposit ability.

In this work, a novel glow discharge plasma treatment of Pd/HZSM-5 catalyst, followed by calcination thermally, has been conducted. Such prepared catalyst presents a higher catalytic activity and an enhanced stability over the catalyst prepared without plasma treatment. The methane conversion over the plasma treated catalyst is close to 100% at 450℃, but it is only ca. 50% at the same temperature over the catalyst without plasma treatment. The XPS, H2 chemisorption and XRD characterizations confirm an enhanced dispersion has been achieved with the plasma reduction (during treatment) followed by oxidation (during calcination). Upon FT-IR analyses, the plasma treatment, followed by calcination thermally, also leads to enhanced Brönsted and Lewis acidities. The amount of Brönsted acid sites of the plasma treated Pd/HZSM-5 catalyst is 1.13 times larger than that of the catalyst without plasma treatment, while the amount of Lewis acid sites of the plasma treated Pd/HZSM-5 catalyst is 1.21 times higher. The enhanced acidities are definitely helpful to increase the dispersion of PdO over the support and improve the interaction between PdO and HZSM-5 support, which leads to a remarkable improvement in the catalyst stability.