Production of gasoline range hydrocarbons from catalytic reaction of methane in the presence of ethylene over W/HZSM-5

The catalytic conversion of a methane and ethylene mixture to gasoline range hydrocarbons has been studied over W/HZSM-5 catalyst. The effect of process variables, such as temperature, percentage of volume of ethylene in the methane stream and catalyst loading on the distribution of hydrocarbons was studied. The reaction was conducted in a fixed-bed quartz-micro reactor in the temperature range of 300–500 °C using percentage of volume of ethylene in methane stream between 25 and 75% and catalyst loading of 0.2–0.4 g. The catalyst showed good catalytic performance yielding hydrocarbons consisting of gaseous products along with gasoline range liquid products. The mixed feed stream can be converted to higher hydrocarbons containing a high-liquid gasoline product selectivity (>42%). Non-aromatics C₅–C₁₀ hydrocarbons selectivity in the range of 12–53% was observed at the operating conditions studied. Design of experiment was employed to determine the optimum conditions for maximum liquid hydrocarbon products. The distribution of the gasoline range hydrocarbons (C₅–C₁₀ non-aromatics and aromatics hydrocarbons) was also determined for the optimum conditions.     

Dual effects of supported W catalysts for dehydroaromatization of methane in the absence of oxygen

The screening of a series of W-based catalysts on different supports i.e. HZSM-5, Hβ, USY and Al₂O₃ for the dehydroaromatization of methane (DHAM) revealed that HZSM-5 emerged as the best support. Next, the performance of W/HZSM-5 and W-H₂SO₄/HZSM-5 catalysts for the DHAM reaction was compared to study the effect of acidic treatment in the impregnation method. The results showed that the optimum activity of W-H₂SO₄/HZSM-5 catalyst exceeded that of W/HZSM-5 catalyst. Finally, the influence of Si/Al ratio in the W-H₂SO₄/HZSM-5 catalyst was studied and the catalyst with Si/Al ratio = 30 was found to be the most promising for the DHAM reaction. The remarkable activity of the catalyst is attributed to the presence of dual effects: suitable content of octahedral polymeric and tetrahedral monomeric tungstate species accompanied by proper amount and strength of acid sites in the catalyst.