Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

STUDY ON CATALYTIC ESTERIFICATION OF METHANE INOLEUM CATALYZED BY IODINEBeata Michalkiewicz, Monika JarosińskaPP-I-9Szczecin University of Technical, Institute of Chemical and Environment Engineering,ul. Pulaskiego 10, 70-322 Szczecin, Poland,E-mail: beata.michalkiewicz@ps.pl, Telephone: (+4891) 4494730, Fax: (+4891) 4494686Conventional conversions of methane into other useful chemical, such as methanol andhigher hydrocarbons, require the energy-intensive step of synthesis gas formation. Recently,substantial research activity has been conducted in the area of methane conversion without theuse of synthesis gases. One of the most promising processes in this field is the oxidation ofmethane to methanol via methyl bisulfate using either sulfuric acid or oleum. The reaction iscatalyzed by mercury [1, 2], platinum [3], palladium [4], iodine [5, 6] ions. This process hassome obvious advantages: (i) bypassing synthesis gas formation; (ii) low reactiontemperature; (iii) high methane conversion.In present paper, we focus on the study of the methane esterification rate under differentexperimental conditions for iodine catalysts. Systematic experiments were applied to definethe equation describing the reaction rate. The reaction rate depends on the concentration of thecatalyst, temperature, the sulfur trioxide concentration, and the methane pressure. The processwas run in an autoclave under 2 – 7 MPa pressure, at 90 – 180 °C. We examine oleumconcentrations 0 – 25 wt% SO 3 . Bjerrum at al. [5] investigated iodine as catalysts forconversion of methane to methyl bisufate in 65 wt% oleum to optimize the reaction. It is veryuseful to use weaker oleum than Bjerrum. The focus of the publication by Periana et al. withiodine as catalyst [6] in weak oleum (2 – 3 wt% SO 3 ) was the reaction mechanism and notreaction rate.We have found that the following reactions took place:CH 4 + SO 3 + H 2 SO 4 → CH 3 OSO 3 H + SO 2 + H 2 O [1]CH 4 + 4SO 3 → CO 2 + 4SO 2 + 2H 2 O [2]H 2 O + SO 3 → H 2 SO 4 [3]The selectivity of methane oxidation to methyl bisulphate was close to 100%. The carbondioxide yield was below 1%. Practically, the only product of methane oxidation isCH 3 OSO 3 H.In the reactor a phenomenon of mass transfer with chemical reaction takes place. Thesystem of differential equations which represents the process can not be solved analytically sowe decided to find empirical equation of the ester formation.227