PROMOTION OF METHANE CONVERSION CATALYSTS INTO HIGHER HYDROCARBONS

The effects of the type of initial salt of a sodium promoter on the activity and selectivity of silica-supported manganese and lead catalysts, used in the oxidative coupling of methane, were investigated. The type of sodium salt is much less significant for catalysts containing an active phase which does not react with the support, e.g. MnO(x)/SiO2 than for lead catalysts, where the presence of sodium facilitates phase transformations connected with the reactions of the support with the lead phase. The type and amount of the new phases are dependent on the sodium salt applied. For the former catalysts an increase in the activity and selectivity to hydrocarbons C2+ was not accompanied by changes in the ratios of the compounds formed, e.g. C2=/C2- and C3+/C2+. The ratios of the lead catalysts are dependent on the kind of anion with which the sodium was introduced into the catalyst. With rising reaction temperatures the type of sodium salt used has a smaller significance.