Study On The Alkylation Of O-xylene With Tert-butyl Alcohol Over Beta Zeolite

In this dissertation, the alkylation of o-xylene with tert-butyl alcohol over zeolites has been studied in a fixed bed reactor. The effect of ion exchange with metals and hydrothermal treatment on the acidity has been studied. The factors that can affect catalytic activity and conversion have been discussed.The experiment results show that H 3 zeolites has high catalysis efficiency for the alkylation of o-xylene with tert-butyl alcohol. In this reaction, the conversion of tert-butyl alcohol has been as high as 100%. The selectivity of 1,2-dimet HM1-4-tert-butylbezene has reached over 99.6%. There are C13, C14, C15 and so on in products except l,2-dimetHMl-4-tert-butylbezene.The effect of ion exchange with metals and hydrothermal treatment on the acidity had been studied. It is found that Mn and La ion modification could decrease the total amount of acid sites and weaken the acid strength. Co ion modification could increase the total amount. The number of strong acid sites was reduced mainly by hydrothermal treatment. The increase degree of strong acid and weaken acid is more in higher temperature. Strong acid sites will disappear after 600℃.The conversion of o-xylene and tert-butyl alcohol could decrease over metals treatment H# zeolites. The reason is that the decrease of total amount of acid sites and part of channels and pores has been packed. The selectivity of 1,2-dimet HMl-4-tert-butylbezene has increased a little The result of study of alkylation over hydrothermal treatment H# zeolites on different temperature shows that the conversion of o-xylene and tert-butyl alcohol could decrease with the increase of treatment temperature. Especially over 400℃, the conversion of o-xylene and tert-butyl alcohol could dropped wildly.The alkylation of o-xylene with tert-butyl alcohol over zeolites H 3 , HM, and HZSM-5 was investigated. The catalytic activity in a decreasing order was: H β > HM >> HZSM-5, the same as zeolites acid number. The influence of pore size of zeolite on their catalytic nature was studied. HZSM-5 zeolite has low catalytic behavior because 1,2-dimetHMl-4-tert-butylbezene is difficult to diffusion from small pore in HZSM-5 zeolite. H 3 zeolite exhibited good catalytic behavior and stability in the course of alkyation of o-xylene with tert-butyl alcohol.The process for alkylation of o-xylene with tert-butyl alcohol over H 3 zeolite has been optimized. The suitable reaction conditions are as follows: reaction temperature on 140癈, with a space velocity (WHSV h-1) of 1-2 h-1 and a reactant molar ratio(o-xylene / tert-butyl alcohol) of 8. Under the optimized reaction conditions, the conversion of o-xylene has reached over 10.38%, and the selectivity of 1,2-dimetHMl-4-tert-butylbezene has been as high as 96.34%.The study on alkylation of o-xylene with tert-butyl alcohol not only has far-reaching theory meaning, but also has very important reality meaning and broad applied prospect.The innovations of this dissertation lie in:(1) The first synthesis 1,2-dimetHMl-4-tert-butylbezene through alkylation in our country;(2) Correspondence atom economics using zeolites;(3) Be favor of industrialization using fixed bed reactor.