Patent ID: 6355851
Filing Date: 2002-03-12
Classification: C07C

Abstract:
A method of improving the activity and lifetime of a zeolite catalyst in a process for synthesizing cumene, said method comprising:a) pre-treating a benzene feedstock containing catalyst poisons comprising olefinic compounds, said benzene feedstock pre-treating comprising: contacting said benzene feedstock with a clay to convert said olefinic compounds contained in said benzene feedstock to polymers, alkylaromatics and other hydrocarbons having a higher boiling point than benzene, said clay being at a temperature within the range of about 200 to 500Â° F., said benzene feedstock being under a pressure during said contacting with said clay to maintain said benzene feedstock in a liquid phase; distilling said benzene feedstock after said contacting with said clay, to separate said benzene feedstock from said polymers, alkylaromatics and other hydrocarbons having a higher boiling point than benzene; b) pre-treating a propylene feedstock, said propylene feedstock containing trace sodium compounds, trace moisture and catalyst poisons comprising nitrogen-containing compounds, sulfur-containing compounds and oxygen-containing compounds, said propylene feedstock pre-treating comprising: contacting said propylene feedstock with an alumina to remove said trace sodium compounds and a first portion of said trace moisture; contacting said propylene feedstock with a molecular sieve to remove a second portion of said trace moisture; contacting said propylene feedstock with a first modified alumina to remove said nitrogen-containing compounds, said oxygen-containing compounds and a first portion of said sulfur-containing compounds, said contacting with said first modified alumina occurring after said contacting with said alumina and said contacting with said molecular sieve; contacting said propylene feedstock with a second modified alumina to remove a second portion of said sulfur-containing compounds, said second portion of said sulfur-containing compounds comprising hydrogen sulfide and carbonyl sulfide; c) reacting said pre-treated benzene with said pre-treated propylene in the presence of a zeolite catalyst to form cumene.