described are catalyst compositions comprising a hams - 1b crystalline borosilicate molecular sieve incorporated into an inorganic matrix , which have been impregnated with a magnesium compound or with both a phosphorus compound and a magnesium compound , said impregnated compositions having improved para - selectively for toluene alkylation . such impregnated compositions , when used for the alkylation of toluene using methanol , methylether , ethylene , or propylene yield dialkylbenzene products containing a higher proportion of the para - isomer than corresponding unimpregnated borosilicate - based compositions . when toluene is alkylated with propylene using the impregnated catalyst compositions of this invention , a significant increase in para - selectivity among the cymene isomers is obtained at high total - cymene / n - propyltoluene ratios .