Improved light olefin yield from methyl bromide coupling over modified SAPO-34 molecular sieves.

As an alternative to the partial oxidation of methane to synthesis gas followed by methanol synthesis and the subsequent generation of olefins, we have studied the production of light olefins (ethylene and propylene) from the reaction of methyl bromide over various modified microporous silico-aluminophosphate molecular-sieve catalysts with an emphasis on SAPO-34. Some comparisons of methyl halides and methanol as reaction intermediates in their conversion to olefins are presented. Increasing the ratio of Si/Al and incorporation of Co into the catalyst framework improved the methyl bromide yield of light olefins over that obtained using standard SAPO-34.

Direct coupling of bromine-mediated methane activation and carbon-deposit gasification.

The direct bromination of methane offers a quite selective (>98 %) route towards methane activation but shifts the problem of fuel production to converting and handling corrosive methyl bromide. The direct conversion of methyl bromide, at about 200 degrees C, into light hydrocarbons can be catalyzed under pressure by AlBr(3) resulting in the formation of propane-rich mixtures of light hydrocarbons, carbonaceous deposits, and HBr. After releasing the gaseous products, the addition of hydrogen at 260 degrees C allows a quantitative conversion of the carbonaceous deposits into the same range of light hydrocarbons.