Alkylation systems and processes are described herein. The alkylation system generally includes a preliminary alkylation system containing a preliminary alkylation catalyst therein and adapted to contact an aromatic compound and an alkylating agent with the preliminary alkylation catalyst so as to alkylate the aromatic compound and form a preliminary output stream, wherein the preliminary alkylation system includes a first preliminary alkylation reactor and a second preliminary alkylation reactor connected in parallel to the first preliminary alkylation reactor and a primary alkylation system adapted to receive the preliminary output stream and contact the preliminary output stream and the alkylating agent with a primary alkylation catalyst disposed therein so as to form a primary output stream.