Disclosed is a process and apparatus for removing nitrogen compounds from an alkylation substrate such as benzene. A conventional adsorbent bed can be used to adsorb basic organic nitrogen compounds and a hot adsorbent bed of acidic molecular sieve can adsorb the weakly basic nitrogen compounds such as nitrites. Water facilitates the adsorption of the weakly basic nitrogen compounds. Running an alkylation substrate stream from a fractionation column of elevated temperature and suitable water concentration to the hot adsorbent bed may be advantageous.