an ethylbenzene production system comprises a reactor vessel , a vapor phase ethylene feed stream , a benzene feed stream entering the reactor vessel , and a product stream containing ethylbenzene exiting the reactor vessel . the reactor vessel has an ethylation section and a benzene stripping section , whereby fluid communication via integrated vapor and liquid traffic is maintained between the ethylation section and stripping section . the vapor phase ethylene feed stream contains 3 to 50 mol % ethylene and at least 20 mol % methane entering the reactor vessel .