NONOXIDATIVE METHANE CONVERSION TO ACETYLENE OVER ZEOLITE IN A LOW-TEMPERATURE PLASMA

Previous investigations have found that the plasma catalytic conversio n of methane is a low-temperature process for the activation of methan e, the major component of natural gas. In this paper, the production o f acetylene via plasma catalytic conversion of methane over NaY zeolit e is discussed. Hydrogen is produced as a by-product during this plasm a catalytic methane conversion. A methane/hydrogen feed with oxygen as an additive and helium as a diluent has been studied in this investig ation. The CH4/H-2/O-2 system is found to be more selective for the pr oduction of C-2 hydrocarbons, compared to the CH4/O-2, CH4/H2O, and CH 4/CO2 systems reported previously. A higher hydrogen concentration fee d is more favorable for acetylene formation. The selectivity and yield of C-2 hydrocarbons are related to the hydrogen feed rate, gas temper ature, concentration of oxygen additive, and flowrate. The highest yie ld of C-2 hydrocarbons (32%) is obtained at the lowest flowrate used ( 10 cm(3)/s; residence time similar to 2.3 s). A reaction mechanism is also presented to explain the experimental results, (C) 1998 Academic Press.