What Is Dealkylation?
The process of removing alkyl groups from hydrocarbon molecules. There are catalytic dealkylation, hydrogen dealkylation and steam dealkylation methods. Cycloalkanes, alkylbenzenes, alkylnaphthalenes, etc. can all be subjected to dealkylation reactions, but so far only the hydrogen and hydrogenation alkylation processes of toluene and alkylnaphthalenes have been industrialized.
Dealkylation
Right!
- Chinese name
- Dealkylation
- Find the time
- 1937
- Find people
- ..Ipatiev
- Preparation
- Thermal Hydrogen Dealkylation and Catalytic Hydrogen Dealkylation
- The process of removing alkyl groups from hydrocarbon molecules. There are catalytic dealkylation, hydrogen dealkylation and steam dealkylation methods. Cycloalkanes, alkylbenzenes, alkylnaphthalenes, etc. can all be subjected to dealkylation reactions, but so far only the hydrogen and hydrogenation alkylation processes of toluene and alkylnaphthalenes have been industrialized.
- In 1937, .. Ipatiev and others found that in the presence of a hydrogen donor, the use of aluminum trichloride as a catalyst can break the side chain on the aromatic ring to form
- Hydrogen dealkylation has two methods: thermal hydrogenation and catalytic hydrogenation:
- No catalyst is needed for thermal dehydroalkylation, but it must be reacted at high temperature (about 700 ° C) to have a sufficient reaction rate. This method has poor selectivity. The reaction pressure is 2.5 to 4 MPa, and the molar ratio of hydrogen to hydrocarbon is 2 to 6: 1.
- Catalytic dehydroalkylation can increase selectivity. The catalyst used is chromium, molybdenum or cobalt oxides supported on alumina-silica (see metal oxide catalysts). The reaction temperature is 550 to 650 ° C, the pressure is 2.5 to 7.0 MPa, and the molar ratio of hydrogen to hydrocarbon is 4 to 10: 1. The use of excess hydrogen can prevent the catalyst from coking and can bring out the reaction heat. The main side reaction of dehydroalkylation is hydrogenation cracking to generate C 1 C 6 alkanes; in addition, biphenyl and polycyclic compounds are also formed.
- Hydrogen dealkylation is an exothermic reaction. Catalytic hydrogen dealkylation generally uses an adiabatic reactor. In order to remove heat, a multi-stage series reactor can also be used. The reactors are quenched with hydrogen or toluene. Thermal dehydrogenation is often carried out in a homogeneous tubular reactor. Due to the high reaction temperature, the reactor is made of alloy steel containing nickel and chromium.