Alkylation of aromatic substrates and transalkylation process

A process for the alkylation of an aromatic substrate with an alkylating agent comprising:

• providing an alkylation reaction zone containing an alkylation catalyst;
• introducing a feedstock comprising an aromatic substrate, an alkylating agent, and an amount of nitrogen containing compounds selected from the group consisting of methylamine, dimethylamine, ethylamine, trimethylamine, and combinations thereof into an inlet of the alkylation reaction zone and into contact with the alkylation catalyst;
• wherein the aromatic substrate is benzene and the alkylating agent is ethylene;
• operating the alkylation reaction zone at temperature and pressure conditions sufficient to cause alkylation of the aromatic substrate with the alkylating agent in the presence of the alkylation catalyst to produce an alkylation product comprising a mixture of the aromatic substrate, monoalkylated aromatic components, and polyalkylated aromatic components;
• withdrawing the alkylation product from the alkylation reaction zone;
• wherein the amount of said nitrogen containing compounds in the feedstock are monitored in a range of from 15 to 35 wppm by dry colorimetry;
• wherein monitoring the amount of said nitrogen containing compounds comprises:
• vaporizing a sample of the feedstock, or obtaining a sample of the feedstock that is in the gaseous phase;
• and
• sending the sample through a porous substrate carrying a reagent that changes color in proportion with the amount of said nitrogen containing compounds.