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Direct conversion of methane to higher hydrocarbons over tungsten modified HZSM-5 catalysts in presence of oxygen

Saidina Amin, Nor Aishah and Soon, Ee Pheng (2004) Direct conversion of methane to higher hydrocarbons over tungsten modified HZSM-5 catalysts in presence of oxygen. In: Annual Fundamental Science Seminar 2004 (AFSS 2004), 14-15 June 2004, Ibnu Sina Institute for Fundamental Science Studies,UTM.

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Abstract

The direct conversion of methane to higher hydrocarbons in the presence of oxygen was studied over tungsten modified HZSM-5 zeolite catalysts. W-H2SO4/HZSM-5 catalyst was prepared from impregnating HZSM-5 with a H2SO4-acidified solution of ammonium meta-tungstate (pH = 2-3) whilst W/HZSM-5 and WO3/HZSM-5 catalysts were prepared from impregnating HZSM-5 with a neutral solution of ammonium meta-tungstate and physical- mixture of solid WO3 with HZSM-5, respectively. It was found that the W-H2SO4/HZSM-5 showed the highest activity compared to W/HZSM-5 and WO3/HZSM-5. UV diffuse reflectance spectra (UV DRS) provided evidence for the existence of octahedral polymeric tungsten species on the W-H2SO4/HZSM-5 catalyst. The results clearly imply that the observed high catalytic activity of W-H2SO4/HZSM-5 catalyst was closely correlated to the octahedral coordinated tungsten species as catalytically active species. Over a 2%W-H2SO4/HZSM-5 catalyst and under reaction conditions of 823C, 0.1MPa and F/W =1500 ml/g-cat∙hr, the average methane conversion reached ≈20% with the average aromatic yield at being 9% after 200 minutes of time on stream. In addition, methane conversion in nonoxidative condition was also carried out and the results showed that the catalytic activity was drastically decreased with time on stream. Consequently, we concluded that that the durability of the catalysts was greatly enhanced in the presence of suitable amount of O2.

Item Type:Conference or Workshop Item (Paper)
Uncontrolled Keywords:Aromatization, methane, oxygen, UV DRS, W-H2SO4/HZSM-5
Subjects:T Technology > T Technology (General)
Divisions:Chemical and Natural Resources Engineering (Formerly known)
ID Code:6331
Deposited By: Norhani Jusoh
Deposited On:17 Sep 2008 09:55
Last Modified:01 Jun 2010 15:41

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