Direct Conversion of Methane into Methanol and Formaldehyde in an RF Plasma Environment I: A Preliminary Study

Abstract

The direct conversion of methane (CH 4 ) into methanol (CH 3 OH) and HCHO in an Argon (Ar) 50W radio-frequency plasma system was applied and the effects of various feed compositions, CH 4 /O 2 ratio, and plasma discharge areas were compared. Additionally, the effects of various methane to oxygen ratios and plasma discharge areas were studied. It was found that in an Ar stream, the CH 3 OH conversion ratio in the CH 4 /O 2 plasma system was higher than that in CH 4 /CO, CO/H 2 and CH 4 /H 2 /O 2 plasma systems.The conversion of CH 4 reached 19.1% at CH 4 /O 2 = 40/60; the yield of CH 3 OH was 1.12% and 16.0% CO, the major product, was produced. A larger plasma discharge area, resulting in a longer residence time, corresponded to higher CH 4 conversion, but a lower CH 3 OH conversion ratio, because of further decomposition into CO and CO 2 . Interestingly, no carbon deposition was observed in the RF plasma system, and the carbon balance was between 0.94 and 1.19.

Autocatalytic Photo-Oxidation Process of C₃-C₄Fraction to Methanol

“…The mixture of propanebutane is fed in through the reactor cap (2) which is at the upper part of the reactor and then heated to a temperature of 100 o C. It is then made to pass through a 1.4mm thick quartz glass tube (3) followed by the irradiation of the reaction mixture at the light/radiation source (4) at a wavelength λ = 420 nm and at a transmission which is not less than 92%. The reaction mixture is then delivered into the trap (5) where the acidic solution is condensed at 90 o C. Trap usage was to prevent the partial ablation of hydrogen nitrate in the reaction zone. Future Optical Materials and Circuit Design The reaction mixture is then cooled by circulating water in the refrigerator condenser ( 6) made up of a copper tube that overlaps in a grid or coiling pattern.…”

“…The promotion of homogeneous catalytic reaction [2,3] by the activated methane requires a standard method such as plasma techniques [4,5], photolysis [6][7][8], etc, since it has become highly desirable to develop a catalyst for such reaction to enable operations under "mild" conditions with greater control over thermodynamics and kinetic processes as well as provide product selectivity and high reaction rates. Presently, the development of effective methods and approaches for the direct oxidation of methane to methanol under mild conditions suffers low methane conversion and poor methanol selectivity, hence, has not been scientifically proven.…”

Conversion of Carbonyl Sulfide Using a Low-Temperature Discharge Approach

“…1) applied here is similar to that used in previous investigations on the destruction of hazardous air pollutants (Tsai et al, 2004;Wang et al, 2005). A laboratory scale reactor that was wrapped by two external copper electrodes coupled to a 13.56 MHz RF generator (Fritz Huttinger Elektronik Gmbh, PFG 600) with a matching network (Matchbox PFM) was used.…”

Optical Emission Spectroscopy in Cooking Exhaust from a Wet Scrubber/Atmospheric Plasma Reactor

“…Wang et al (2003) studied decomposition of boron trifluoride in the RF plasma environment and showed the reaction in the BF 3 /O 2 /Ar plasma system generated B 2 O 3 fine particles and led to the deposition of a white substance on the surface of the reactor. Wang et al (2005) studied direct conversion of methane into methanol and formaldehyde in an RF plasma environment and found that in an Ar stream, the CH 3 OH conversion ratio in the CH 4 /O 2 plasma system was higher than that in CH 4 /CO, CO/H 2 and CH 4 /H 2 /O 2 plasma systems. The conversion of CH 4 reached 19.1% at CH 4 /O 2 = 40/60; the yield of CH 3 OH was 1.12% and 16.0% CO, the major product, was produced.…”